Merge remote-tracking branch 'upstream/main' into tendons

.github/workflows/build.yml

@@ -148,6 +148,7 @@ jobs:
         cd build &&
         cmake ..
         -DCMAKE_BUILD_TYPE:STRING=Release
+        -DCMAKE_INTERPROCEDURAL_OPTIMIZATION:BOOL=OFF
         -DCMAKE_INSTALL_PREFIX:STRING=${{ matrix.tmpdir }}/mujoco_install
         -DMUJOCO_BUILD_EXAMPLES:BOOL=OFF
         ${{ matrix.cmake_args }}
@@ -192,6 +193,7 @@ jobs:
         cd build &&
         cmake ..
         -DCMAKE_BUILD_TYPE:STRING=Release
+        -DCMAKE_INTERPROCEDURAL_OPTIMIZATION:BOOL=OFF
         -Dmujoco_ROOT:STRING=${{ matrix.tmpdir }}/mujoco_install
         ${{ matrix.cmake_args }}
     - name: Build samples
@@ -204,6 +206,7 @@ jobs:
         cd build &&
         cmake ..
         -DCMAKE_BUILD_TYPE:STRING=Release
+        -DCMAKE_INTERPROCEDURAL_OPTIMIZATION:BOOL=OFF
         -Dmujoco_ROOT:STRING=${{ matrix.tmpdir }}/mujoco_install
         ${{ matrix.cmake_args }}
     - name: Build simulate

README.md

@@ -41,7 +41,7 @@ release can be found in the [changelog] in the latest branch.
 There are two easy ways to get started with MuJoCo:
 
 1. **Run `simulate` on your machine.**
-[This video](https://www.youtube.com/watch?v=0ORsj_E17B0) shows a screen capture
+[This video](https://www.youtube.com/watch?v=P83tKA1iz2Y) shows a screen capture
 of `simulate`, MuJoCo's native interactive viewer. Follow the steps described in
 the [Getting Started] section of the documentation to get `simulate` running on
 your machine.

cmake/MujocoOptions.cmake

@@ -104,6 +104,10 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang
   endif()
 endif()
 
+if(NOT CMAKE_INTERPROCEDURAL_OPTIMIZATION AND (CMAKE_BUILD_TYPE AND NOT CMAKE_BUILD_TYPE STREQUAL "Debug"))
+  set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
+endif()
+
 include(MujocoHarden)
 set(EXTRA_COMPILE_OPTIONS ${EXTRA_COMPILE_OPTIONS} ${MUJOCO_HARDEN_COMPILE_OPTIONS})
 set(EXTRA_LINK_OPTIONS ${EXTRA_LINK_OPTIONS} ${MUJOCO_HARDEN_LINK_OPTIONS})

doc/APIreference/APIglobals.rst

@@ -414,12 +414,6 @@ shown in the table below. Their names are in the format ``mjKEY_XXX``. They corr
      - 50
      - The maximum depth of each body and mesh bounding volume hierarchy. If this large limit is exceeded, a warning
        is raised and ray casting may not be possible. For a balanced hierarchy, this implies 1E15 bounding volumes.
-   * - ``mjMAXVFS``
-     - 200
-     - The maximal number of characters in the name of each file in the virtual file system.
-   * - ``mjMAXVFSNAME``
-     - 100
-     - The maximal number of characters in the name of each file in the virtual file system.
    * - ``mjNEQDATA``
      - 11
      - The maximal number of real-valued parameters used to define each equality constraint. Determines the size of
@@ -534,6 +528,14 @@ shown in the table below. Their names are in the format ``mjKEY_XXX``. They corr
 Macros
 ^^^^^^
 
+
+.. _mjUSESINGLE:
+
+mjUSESINGLE
+~~~~~~~~~~~
+
+Compile-time flag, see :ref:`mjtNum`.
+
 .. _mjDISABLED:
 
 mjDISABLED

doc/APIreference/APItypes.rst

@@ -54,24 +54,28 @@ The two types below are defined in `mjtnum.h <https://github.com/google-deepmind
 mjtNum
 ^^^^^^
 
-This is the floating-point type used throughout the simulator. If the symbol ``mjUSEDOUBLE`` is defined in
+This is the floating-point type used throughout the simulator. When using the default build configuration, ``mjtNum`` is
-``mjmodel.h``, this type is defined as ``double``, otherwise it is defined as ``float``. Currently only the
+defined as ``double``. If the symbol ``mjUSESINGLE`` is defined, ``mjtNum`` is defined as ``float``.
-double-precision version of MuJoCo is distributed, although the entire code base works with single-precision as well.
-We may release the single-precision version in the future for efficiency reasons, but the double-precision version
-will always be available. Thus it is safe to write user code assuming double precision. However, our preference is to
-write code that works with either single or double precision. To this end we provide math utility functions that are
-always defined with the correct floating-point type.
 
-Note that changing ``mjUSEDOUBLE`` in ``mjtnum.h`` will not change how the library was compiled, and instead will
+Currently only the double-precision version of MuJoCo is distributed, although the entire code base works with
+single-precision as well. We may release the single-precision version in the future, but the
+double-precision version will always be available. Thus it is safe to write user code assuming double precision.
+However, our preference is to write code that works with either single or double precision. To this end we provide math
+utility functions that are always defined with the correct floating-point type.
+
+Note that changing ``mjUSESINGLE`` in ``mjtnum.h`` will not change how the library was compiled, and instead will
 result in numerous link errors. In general, the header files distributed with precompiled MuJoCo should never be
 changed by the user.
 
 .. code-block:: C
 
-   #ifdef mjUSEDOUBLE
+   // floating point data type and minval
-       typedef double mjtNum;
+   #ifndef mjUSESINGLE
+     typedef double mjtNum;
+     #define mjMINVAL    1E-15       // minimum value in any denominator
    #else
-       typedef float mjtNum;
+     typedef float mjtNum;
+     #define mjMINVAL    1E-15f
    #endif
 
 
@@ -578,6 +582,18 @@ Item types used in the UI framework.
 
 .. mujoco-include:: mjtItem
 
+
+.. _mjtSection:
+
+mjtSection
+~~~~~~~~~~
+
+State of a UI section.
+
+.. mujoco-include:: mjtSection
+
+
+
 .. _tySpecEnums:
 
 Spec

doc/APIreference/functions.rst

@@ -1203,7 +1203,7 @@ mj_defaultVFS
 
 .. mujoco-include:: mj_defaultVFS
 
-Initialize VFS to empty (no deallocation).
+Initialize an empty VFS, mj_deleteVFS must be called to deallocate the VFS.
 
 .. _mj_addFileVFS:
 
@@ -1224,15 +1224,6 @@ mj_addBufferVFS
 
 Add file to VFS from buffer, return 0: success, 1: full, 2: repeated name, -1: failed to load.
 
-.. _mj_findFileVFS:
-
-mj_findFileVFS
-~~~~~~~~~~~~~~
-
-.. mujoco-include:: mj_findFileVFS
-
-Return file index in VFS, or -1 if not found in VFS.
-
 .. _mj_deleteFileVFS:
 
 mj_deleteFileVFS
@@ -1249,16 +1240,7 @@ mj_deleteVFS
 
 .. mujoco-include:: mj_deleteVFS
 
-Delete all files from VFS.
+Delete all files from VFS and deallocates VFS internal memory.
-
-.. _mj_makeEmptyFileVFS:
-
-mj_makeEmptyFileVFS
-~~~~~~~~~~~~~~~~~~~
-
-.. mujoco-include:: mj_makeEmptyFileVFS
-
-deprecated: use mj_copyBufferVFS.
 
 .. _Initialization:
 
@@ -4131,6 +4113,15 @@ mjs_findFrame
 
 Find frame by name.
 
+.. _mjs_findKeyframe:
+
+mjs_findKeyframe
+~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_findKeyframe
+
+Find keyframe by name.
+
 .. _mjs_getDefault:
 
 mjs_getDefault
@@ -4185,6 +4176,231 @@ mjs_nextChild
 
 Return body's next child of the same type; return NULL if child is last.
 
+.. _mjs_firstElement:
+
+mjs_firstElement
+~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_firstElement
+
+Return spec's first element of selected type.
+
+.. _mjs_nextElement:
+
+mjs_nextElement
+~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_nextElement
+
+Return spec's next element; return NULL if element is last.
+
+.. _mjs_asBody:
+
+mjs_asBody
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asBody
+
+Safely cast an element as mjsBody, or return NULL if the element is not an mjsBody.
+
+.. _mjs_asGeom:
+
+mjs_asGeom
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asGeom
+
+Safely cast an element as mjsGeom, or return NULL if the element is not an mjsGeom.
+
+.. _mjs_asJoint:
+
+mjs_asJoint
+~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asJoint
+
+Safely cast an element as mjsJoint, or return NULL if the element is not an mjsJoint.
+
+.. _mjs_asSite:
+
+mjs_asSite
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asSite
+
+Safely cast an element as mjsSite, or return NULL if the element is not an mjsSite.
+
+.. _mjs_asCamera:
+
+mjs_asCamera
+~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asCamera
+
+Safely cast an element as mjsCamera, or return NULL if the element is not an mjsCamera.
+
+.. _mjs_asLight:
+
+mjs_asLight
+~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asLight
+
+Safely cast an element as mjsLight, or return NULL if the element is not an mjsLight.
+
+.. _mjs_asFrame:
+
+mjs_asFrame
+~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asFrame
+
+Safely cast an element as mjsFrame, or return NULL if the element is not an mjsFrame.
+
+.. _mjs_asActuator:
+
+mjs_asActuator
+~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asActuator
+
+Safely cast an element as mjsActuator, or return NULL if the element is not an mjsActuator.
+
+.. _mjs_asSensor:
+
+mjs_asSensor
+~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asSensor
+
+Safely cast an element as mjsSensor, or return NULL if the element is not an mjsSensor.
+
+.. _mjs_asFlex:
+
+mjs_asFlex
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asFlex
+
+Safely cast an element as mjsFlex, or return NULL if the element is not an mjsFlex.
+
+.. _mjs_asPair:
+
+mjs_asPair
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asPair
+
+Safely cast an element as mjsPair, or return NULL if the element is not an mjsPair.
+
+.. _mjs_asEquality:
+
+mjs_asEquality
+~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asEquality
+
+Safely cast an element as mjsEquality, or return NULL if the element is not an mjsEquality.
+
+.. _mjs_asExclude:
+
+mjs_asExclude
+~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asExclude
+
+Safely cast an element as mjsExclude, or return NULL if the element is not an mjsExclude.
+
+.. _mjs_asTendon:
+
+mjs_asTendon
+~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asTendon
+
+Safely cast an element as mjsTendon, or return NULL if the element is not an mjsTendon.
+
+.. _mjs_asNumeric:
+
+mjs_asNumeric
+~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asNumeric
+
+Safely cast an element as mjsNumeric, or return NULL if the element is not an mjsNumeric.
+
+.. _mjs_asText:
+
+mjs_asText
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asText
+
+Safely cast an element as mjsText, or return NULL if the element is not an mjsText.
+
+.. _mjs_asTuple:
+
+mjs_asTuple
+~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asTuple
+
+Safely cast an element as mjsTuple, or return NULL if the element is not an mjsTuple.
+
+.. _mjs_asKey:
+
+mjs_asKey
+~~~~~~~~~
+
+.. mujoco-include:: mjs_asKey
+
+Safely cast an element as mjsKey, or return NULL if the element is not an mjsKey.
+
+.. _mjs_asMesh:
+
+mjs_asMesh
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asMesh
+
+Safely cast an element as mjsMesh, or return NULL if the element is not an mjsMesh.
+
+.. _mjs_asHField:
+
+mjs_asHField
+~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asHField
+
+Safely cast an element as mjsHField, or return NULL if the element is not an mjsHField.
+
+.. _mjs_asSkin:
+
+mjs_asSkin
+~~~~~~~~~~
+
+.. mujoco-include:: mjs_asSkin
+
+Safely cast an element as mjsSkin, or return NULL if the element is not an mjsSkin.
+
+.. _mjs_asTexture:
+
+mjs_asTexture
+~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asTexture
+
+Safely cast an element as mjsTexture, or return NULL if the element is not an mjsTexture.
+
+.. _mjs_asMaterial:
+
+mjs_asMaterial
+~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_asMaterial
+
+Safely cast an element as mjsMaterial, or return NULL if the element is not an mjsMaterial.
+
 .. _AttributeSetters:
 
 Attribute setters
@@ -4341,15 +4557,6 @@ mjs_resolveOrientation
 
 Resolve alternative orientations to quat, return error if any.
 
-.. _mjs_fullInertia:
-
-mjs_fullInertia
-~~~~~~~~~~~~~~~
-
-.. mujoco-include:: mjs_fullInertia
-
-Compute quat and diag inertia from full inertia matrix, return error if any.
-
 .. _ElementInitialization:
 
 Element initialization

doc/XMLreference.rst

@@ -1564,17 +1564,21 @@ still be specified here but this functionality is now deprecated and will be rem
    This and the remaining attributes control the generation of procedural textures. If the value of this attribute is
    different from "none", the texture is treated as procedural and any file names are ignored. The keywords have the
    following meaning:
-   The **gradient** type generates a color gradient from rgb1 to rgb2. The interpolation in color space is done through
-   a sigmoid function. For cube and skybox textures the gradient is along the +Y axis, i.e., from top to bottom for
-   skybox rendering.
 
-   The **checker** type generates a 2-by-2 checker pattern with alternating colors given by rgb1 to rgb2. This is
+   **gradient**
-   suitable for rendering ground planes and also for marking objects with rotational symmetries. Note that 2d textures
+      Generates a color gradient from rgb1 to rgb2. The interpolation in color space is done through
-   can be scaled so as to repeat the pattern as many times as necessary. For cube and skybox textures, the checker
+      a sigmoid function. For cube and skybox textures the gradient is along the +Y axis, i.e., from top to bottom for
-   pattern is painted on each side of the cube.
+      skybox rendering.
 
-   The **flat** type fills the entire texture with rgb1, except for the bottom face of cube and skybox textures which is
+   **checker**
-   filled with rgb2.
+      Generates a 2-by-2 checker pattern with alternating colors given by rgb1 and rgb2. This is suitable for rendering
+      ground planes and also for marking objects with rotational symmetries. Note that 2d textures can be scaled so as
+      to repeat the pattern as many times as necessary. For cube and skybox textures, the checker pattern is painted on
+      each side of the cube.
+
+   **flat**
+      Fills the entire texture with rgb1, except for the bottom face of cube and skybox textures which is
+      filled with rgb2.
 
 .. _asset-texture-rgb1:
 
@@ -1604,21 +1608,23 @@ still be specified here but this functionality is now deprecated and will be rem
 
 :at:`random`: :at-val:`real, "0.01"`
    When the mark attribute is set to "random", this attribute determines the probability of turning on each pixel. Note
-   that larger textures have more pixels, and the probability here is applied independently to each pixel - thus the
+   that larger textures have more pixels, and the probability here is applied independently to each pixel -- thus the
    texture size and probability need to be adjusted jointly. Together with a gradient skybox texture, this can create
-   the appearance of a night sky with stars.
+   the appearance of a night sky with stars. The random number generator is initialized with a fixed seed.
 
 .. _asset-texture-width:
 
 :at:`width`: :at-val:`int, "0"`
-   The width of the procedural texture, i.e., the number of columns in the image. For cube and skybox procedural
+   The width of a procedural texture, i.e., the number of columns in the image. Larger values usually result in higher
-   textures the width and height must be equal. Larger values usually result in higher quality images, although in some
+   quality images, although in some cases (e.g. checker patterns) small values are sufficient. For textures loaded from
-   cases (e.g. checker patterns) small values are sufficient.
+   files, this attribute is ignored.
 
 .. _asset-texture-height:
 
 :at:`height`: :at-val:`int, "0"`
-   The height of the procedural texture, i.e., the number of rows in the image.
+   The height of the procedural texture, i.e., the number of rows in the image. For cube and skybox textures, this
+   attribute is ignored and the height is set to 6 times the width. For textures loaded from files, this attribute is
+   ignored.
 
 .. _asset-texture-hflip:
 

doc/changelog.rst

@@ -7,30 +7,70 @@ Upcoming version (not yet released)
 
 General
 ^^^^^^^
-1. Added a new API for :doc:`procedural model manipulation<programming/modeledit>`. Fixes :github:issue:`364`.
+.. admonition:: Breaking API changes
+   :class: attention
+
+   1. Removed deprecated ``mj_makeEmptyFileVFS`` and ``mj_findFileVFS`` functions. The constants ``mjMAXVFS`` and
+      ``mjMAXVFSNAME`` are also removed as they are no longer needed.
+
+      **Migration:** Use :ref:`mj_addBufferVFS` to copy a buffer into a VFS file directly.
+
+   2. Calls to :ref:`mj_defaultVFS` may allocate memory inside VFS, and the corresponding
+      :ref:`mj_deleteVFS` must be called to deallocate any internal allocated memory.
+
+   3. Deprecated :ref:`mju_rotVecMat` and :ref:`mju_rotVecMatT` in favor of :ref:`mju_mulMatVec3` and
+      :ref:`mju_mulMatTVec3`. These function names and argument order are more consistent with the rest of the API.
+      The older functions have been removed from the Python bindings and will be removed from the C API in the next
+      release.
+
+4. The :ref:`VFS<Virtualfilesystem>` implementation has been rewritten in C++ and is now considerably more efficient in
+   speed and memory footprint.
+5. Added a new API for :doc:`procedural model manipulation<programming/modeledit>`. Fixes :github:issue:`364`.
    Still missing:
 
    - Detailed documentation.
-   - Python bindings.
 
 .. youtube:: ZXBTEIDWHhs
    :align: right
    :width: 240px
 
-2. Added support for orthographic cameras. This is available for both fixed cameras and the free camera, using the
+6. Added support for orthographic cameras. This is available for both fixed cameras and the free camera, using the
    :ref:`camera/orthographic<body-camera-orthographic>` and :ref:`global/orthographic<visual-global-orthographic>`
    attributes, respectively.
-3. Added :ref:`maxhullvert<asset-mesh-maxhullvert>`, the maximum number of vertices in a mesh's convex hull.
+7. Added :ref:`maxhullvert<asset-mesh-maxhullvert>`, the maximum number of vertices in a mesh's convex hull.
-4. Added :ref:`mj_setKeyframe` for saving the current state into a model keyframe.
+8. Added :ref:`mj_setKeyframe` for saving the current state into a model keyframe.
-5. Added support for ``ball`` joints in the URDF parser ("spherical" in URDF).
+9. Added support for ``ball`` joints in the URDF parser ("spherical" in URDF).
-6. Deprecated :ref:`mju_rotVecMat` and :ref:`mju_rotVecMatT` in favor of :ref:`mju_mulMatVec3` and
+10. Replaced ``mjUSEDOUBLE`` which was previously hard-coded in
-   :ref:`mju_mulMatTVec3`. These functions names and argument ordering are more consistent with the rest of the API.
+    `mjtnum.h <https://github.com/google-deepmind/mujoco/blob/main/include/mujoco/mjtnum.h>`__
+    with the build-time flag ``mjUSESINGLE``. If this symbol is not defined, MuJoCo will use double-precision floating
+    point, as usual. If ``mjUSESINGLE`` is defined, MuJoCo will use single-precision floating point. See :ref:`mjtNum`.
+
+    Relatedly, fixed various type errors that prevented building with single-precision.
+11. Quaternions in ``mjData->qpos`` and ``mjData->mocap_quat`` are no longer normalized in-place by
+    :ref:`mj_kinematics`. Instead they are normalized when they are used. After the first step, quaternions in
+    ``mjData->qpos`` will be normalized.
 
 MJX
 ~~~
-7. Added support for :ref:`elliptic friction cones<option-cone>`.
+12. Added support for :ref:`elliptic friction cones<option-cone>`.
-8. Fixed a bug that resulted in less-optimal linesearch solutions for some difficult constraint settings.
+13. Fixed a bug that resulted in less-optimal linesearch solutions for some difficult constraint settings.
-9. Fixed a bug in the Newton solver that sometimes resulted in less-optimal gradients.
+14. Fixed a bug in the Newton solver that sometimes resulted in less-optimal gradients.
+
+
+.. youtube:: P83tKA1iz2Y
+   :align: right
+   :width: 360px
+
+Simulate
+^^^^^^^^
+15. Added improved tutorial video.
+16. Improved the Brownian noise generator.
+
+|br| |br| |br| |br|
+
+Python bindings
+^^^^^^^^^^^^^^^
+17. Fixed a memory leak when using ``copy.deepcopy()`` on a ``mujoco.MjData`` instance (:github:issue:`1572`).
 
 Version 3.1.6 (Jun 3, 2024)
 ---------------------------
@@ -199,10 +239,10 @@ General
    :at:`ctrlrange` or :at:`actrange` (respectively), according to the range of the transmission
    target (joint or tendon). See :ref:`position/inheritrange<actuator-position-inheritrange>` for
    details.
-2. Deprecated :ref:`mj_makeEmptyFileVFS` in favor of :ref:`mj_addBufferVFS`. :ref:`mjVFS` now computes checksums of
+2. Deprecated ``mj_makeEmptyFileVFS`` in favor of :ref:`mj_addBufferVFS`. :ref:`mjVFS` now computes checksums of
    its internal file buffers. :ref:`mj_addBufferVFS` allocates an empty buffer with a given name in an mjVFS and
    copies the data buffer into it, combining and replacing the deprecated two-step process of calling
-   :ref:`mj_makeEmptyFileVFS` followed by a direct copy into the given mjVFS internal file buffer.
+   ``mj_makeEmptyFileVFS`` followed by a direct copy into the given mjVFS internal file buffer.
 3. Added :ref:`mj_angmomMat` which computes the ``3 x nv`` angular momentum matrix :math:`H(q)`, providing the linear
    mapping from generalized velocities to subtree angular momentum :math:`h = H \dot q`. Contribution by
    :github:user:`v-r-a`.

doc/includes/references.h

@@ -139,29 +139,29 @@ struct mjData_ {
   int     nplugin;           // number of plugin instances
 
   // stack pointer
-  size_t  pstack;            // first available mjtNum address in stack
+  size_t  pstack;            // first available byte in stack
   size_t  pbase;             // value of pstack when mj_markStack was last called
 
   // arena pointer
   size_t  parena;            // first available byte in arena
 
-  // memory utilization stats
+  // memory utilization statistics
-  size_t  maxuse_stack;                      // maximum stack allocation in bytes
+  size_t  maxuse_stack;                       // maximum stack allocation in bytes
-  size_t  maxuse_threadstack[mjMAXTHREAD];   // maximum stack allocation per thread in bytes
+  size_t  maxuse_threadstack[mjMAXTHREAD];    // maximum stack allocation per thread in bytes
-  size_t  maxuse_arena;                      // maximum arena allocation in bytes
+  size_t  maxuse_arena;                       // maximum arena allocation in bytes
-  int     maxuse_con;                        // maximum number of contacts
+  int     maxuse_con;                         // maximum number of contacts
-  int     maxuse_efc;                        // maximum number of scalar constraints
+  int     maxuse_efc;                         // maximum number of scalar constraints
-
-  // diagnostics
-  mjWarningStat warning[mjNWARNING];  // warning statistics
-  mjTimerStat   timer[mjNTIMER];      // timer statistics
 
   // solver statistics
   mjSolverStat  solver[mjNISLAND*mjNSOLVER];  // solver statistics per island, per iteration
-  int     solver_nisland;           // number of islands processed by solver
+  int           solver_nisland;               // number of islands processed by solver
-  int     solver_niter[mjNISLAND];  // number of solver iterations, per island
+  int           solver_niter[mjNISLAND];      // number of solver iterations, per island
-  int     solver_nnz[mjNISLAND];    // number of non-zeros in Hessian or efc_AR, per island
+  int           solver_nnz[mjNISLAND];        // number of nonzeros in Hessian or efc_AR, per island
-  mjtNum  solver_fwdinv[2];         // forward-inverse comparison: qfrc, efc
+  mjtNum        solver_fwdinv[2];             // forward-inverse comparison: qfrc, efc
+
+  // diagnostics
+  mjWarningStat warning[mjNWARNING];          // warning statistics
+  mjTimerStat   timer[mjNTIMER];              // timer statistics
 
   // variable sizes
   int     ne;                // number of equality constraints
@@ -179,8 +179,8 @@ struct mjData_ {
   //-------------------- end of info header
 
   // buffers
-  void*   buffer;            // main buffer; all pointers point in it                (nbuffer bytes)
+  void*   buffer;            // main buffer; all pointers point in it            (nbuffer bytes)
-  void*   arena;             // arena+stack buffer                     (nstack*sizeof(mjtNum) bytes)
+  void*   arena;             // arena+stack buffer                               (narena bytes)
 
   //-------------------- main inputs and outputs of the computation
 
@@ -274,7 +274,7 @@ struct mjData_ {
 
   // computed by mj_collisionTree
   mjtNum*  bvh_aabb_dyn;     // global bounding box (center, size)               (nbvhdynamic x 6)
-  mjtByte* bvh_active;       // volume has been added to collisions              (nbvh x 1)
+  mjtByte* bvh_active;       // was bounding volume checked for collision        (nbvh x 1)
 
   //-------------------- POSITION, VELOCITY dependent
 
@@ -344,7 +344,7 @@ struct mjData_ {
   //-------------------- arena-allocated: POSITION dependent
 
   // computed by mj_collision
-  mjContact* contact;        // list of all detected contacts                    (ncon x 1)
+  mjContact* contact;        // array of all detected contacts                   (ncon x 1)
 
   // computed by mj_makeConstraint
   int*    efc_type;          // constraint type (mjtConstraint)                  (nefc x 1)
@@ -394,11 +394,11 @@ struct mjData_ {
   //-------------------- arena-allocated: POSITION, VELOCITY, CONTROL/ACCELERATION dependent
 
   // computed by mj_fwdConstraint/mj_inverse
-  mjtNum* efc_b;            // linear cost term: J*qacc_smooth - aref            (nefc x 1)
+  mjtNum* efc_b;             // linear cost term: J*qacc_smooth - aref           (nefc x 1)
-  mjtNum* efc_force;        // constraint force in constraint space              (nefc x 1)
+  mjtNum* efc_force;         // constraint force in constraint space             (nefc x 1)
-  int*    efc_state;        // constraint state (mjtConstraintState)             (nefc x 1)
+  int*    efc_state;         // constraint state (mjtConstraintState)            (nefc x 1)
 
-  // ThreadPool for multithreaded operations
+  // thread pool pointer
   uintptr_t threadpool;
 };
 typedef struct mjData_ mjData;
@@ -699,11 +699,7 @@ struct mjLROpt_ {                 // options for mj_setLengthRange()
 };
 typedef struct mjLROpt_ mjLROpt;
 struct mjVFS_ {                               // virtual file system for loading from memory
-  int      nfile;                             // number of files present
+  void* impl_;                                // internal pointer to VFS memory
-  char     filename[mjMAXVFS][mjMAXVFSNAME];  // file name without path
-  size_t   filesize[mjMAXVFS];                // file size in bytes
-  void*    filedata[mjMAXVFS];                // buffer with file data
-  uint64_t filestamp[mjMAXVFS];               // checksum of the file data
 };
 typedef struct mjVFS_ mjVFS;
 struct mjOption_ {                // physics options
@@ -1220,7 +1216,7 @@ struct mjModel_ {
   int*      tex_pathadr;          // address of texture asset path; -1: none  (ntex x 1)
 
   // materials
-  int*      mat_texid;            // texture id; -1: none                     (nmat x 1)
+  int*      mat_texid;            // indices of textures; -1: none            (nmat x mjNTEXMAT)
   mjtByte*  mat_texuniform;       // make texture cube uniform                (nmat x 1)
   float*    mat_texrepeat;        // texture repetition for 2d mapping        (nmat x 2)
   float*    mat_emission;         // emission (x rgb)                         (nmat x 1)
@@ -1512,92 +1508,97 @@ struct mjrRect_ {                 // OpenGL rectangle
   int height;                     // height (usually buffer height)
 };
 typedef struct mjrRect_ mjrRect;
-struct mjrContext_ {              // custom OpenGL context
+struct mjrContext_ {                // custom OpenGL context
   // parameters copied from mjVisual
-  float lineWidth;                // line width for wireframe rendering
+  float lineWidth;                  // line width for wireframe rendering
-  float shadowClip;               // clipping radius for directional lights
+  float shadowClip;                 // clipping radius for directional lights
-  float shadowScale;              // fraction of light cutoff for spot lights
+  float shadowScale;                // fraction of light cutoff for spot lights
-  float fogStart;                 // fog start = stat.extent * vis.map.fogstart
+  float fogStart;                   // fog start = stat.extent * vis.map.fogstart
-  float fogEnd;                   // fog end = stat.extent * vis.map.fogend
+  float fogEnd;                     // fog end = stat.extent * vis.map.fogend
-  float fogRGBA[4];               // fog rgba
+  float fogRGBA[4];                 // fog rgba
-  int shadowSize;                 // size of shadow map texture
+  int shadowSize;                   // size of shadow map texture
-  int offWidth;                   // width of offscreen buffer
+  int offWidth;                     // width of offscreen buffer
-  int offHeight;                  // height of offscreen buffer
+  int offHeight;                    // height of offscreen buffer
-  int offSamples;                 // number of offscreen buffer multisamples
+  int offSamples;                   // number of offscreen buffer multisamples
 
   // parameters specified at creation
-  int fontScale;                  // font scale
+  int fontScale;                    // font scale
-  int auxWidth[mjNAUX];           // auxiliary buffer width
+  int auxWidth[mjNAUX];             // auxiliary buffer width
-  int auxHeight[mjNAUX];          // auxiliary buffer height
+  int auxHeight[mjNAUX];            // auxiliary buffer height
-  int auxSamples[mjNAUX];         // auxiliary buffer multisamples
+  int auxSamples[mjNAUX];           // auxiliary buffer multisamples
 
   // offscreen rendering objects
-  unsigned int offFBO;            // offscreen framebuffer object
+  unsigned int offFBO;              // offscreen framebuffer object
-  unsigned int offFBO_r;          // offscreen framebuffer for resolving multisamples
+  unsigned int offFBO_r;            // offscreen framebuffer for resolving multisamples
-  unsigned int offColor;          // offscreen color buffer
+  unsigned int offColor;            // offscreen color buffer
-  unsigned int offColor_r;        // offscreen color buffer for resolving multisamples
+  unsigned int offColor_r;          // offscreen color buffer for resolving multisamples
-  unsigned int offDepthStencil;   // offscreen depth and stencil buffer
+  unsigned int offDepthStencil;     // offscreen depth and stencil buffer
-  unsigned int offDepthStencil_r; // offscreen depth and stencil buffer for resolving multisamples
+  unsigned int offDepthStencil_r;   // offscreen depth and stencil buffer for multisamples
 
   // shadow rendering objects
-  unsigned int shadowFBO;         // shadow map framebuffer object
+  unsigned int shadowFBO;           // shadow map framebuffer object
-  unsigned int shadowTex;         // shadow map texture
+  unsigned int shadowTex;           // shadow map texture
 
   // auxiliary buffers
-  unsigned int auxFBO[mjNAUX];    // auxiliary framebuffer object
+  unsigned int auxFBO[mjNAUX];      // auxiliary framebuffer object
-  unsigned int auxFBO_r[mjNAUX];  // auxiliary framebuffer object for resolving
+  unsigned int auxFBO_r[mjNAUX];    // auxiliary framebuffer object for resolving
-  unsigned int auxColor[mjNAUX];  // auxiliary color buffer
+  unsigned int auxColor[mjNAUX];    // auxiliary color buffer
-  unsigned int auxColor_r[mjNAUX];// auxiliary color buffer for resolving
+  unsigned int auxColor_r[mjNAUX];  // auxiliary color buffer for resolving
+
+  // materials with textures
+  int mat_texid[mjMAXMATERIAL*mjNTEXMAT];  // material texture ids (-1: no texture)
+  int mat_texuniform[mjMAXMATERIAL];       // texture repetition for 2d mapping
+  int mat_texrepeat[mjMAXMATERIAL*2];      // texture repetition for 2d mapping
 
   // texture objects and info
-  int ntexture;                   // number of allocated textures
+  int ntexture;                        // number of allocated textures
-  int textureType[100];           // type of texture (mjtTexture) (ntexture)
+  int textureType[mjMAXTEXTURE];       // type of texture (mjtTexture) (ntexture)
-  unsigned int texture[100];      // texture names
+  unsigned int texture[mjMAXTEXTURE];  // texture names
 
   // displaylist starting positions
-  unsigned int basePlane;         // all planes from model
+  unsigned int basePlane;           // all planes from model
-  unsigned int baseMesh;          // all meshes from model
+  unsigned int baseMesh;            // all meshes from model
-  unsigned int baseHField;        // all hfields from model
+  unsigned int baseHField;          // all height fields from model
-  unsigned int baseBuiltin;       // all buildin geoms, with quality from model
+  unsigned int baseBuiltin;         // all builtin geoms, with quality from model
-  unsigned int baseFontNormal;    // normal font
+  unsigned int baseFontNormal;      // normal font
-  unsigned int baseFontShadow;    // shadow font
+  unsigned int baseFontShadow;      // shadow font
-  unsigned int baseFontBig;       // big font
+  unsigned int baseFontBig;         // big font
 
   // displaylist ranges
-  int rangePlane;                 // all planes from model
+  int rangePlane;                   // all planes from model
-  int rangeMesh;                  // all meshes from model
+  int rangeMesh;                    // all meshes from model
-  int rangeHField;                // all hfields from model
+  int rangeHField;                  // all hfields from model
-  int rangeBuiltin;               // all builtin geoms, with quality from model
+  int rangeBuiltin;                 // all builtin geoms, with quality from model
-  int rangeFont;                  // all characters in font
+  int rangeFont;                    // all characters in font
 
   // skin VBOs
-  int nskin;                      // number of skins
+  int nskin;                        // number of skins
-  unsigned int* skinvertVBO;      // skin vertex position VBOs (nskin)
+  unsigned int* skinvertVBO;        // skin vertex position VBOs (nskin)
-  unsigned int* skinnormalVBO;    // skin vertex normal VBOs (nskin)
+  unsigned int* skinnormalVBO;      // skin vertex normal VBOs (nskin)
-  unsigned int* skintexcoordVBO;  // skin vertex texture coordinate VBOs (nskin)
+  unsigned int* skintexcoordVBO;    // skin vertex texture coordinate VBOs (nskin)
-  unsigned int* skinfaceVBO;      // skin face index VBOs (nskin)
+  unsigned int* skinfaceVBO;        // skin face index VBOs (nskin)
 
   // character info
-  int charWidth[127];             // character widths: normal and shadow
+  int charWidth[127];               // character widths: normal and shadow
-  int charWidthBig[127];          // chacarter widths: big
+  int charWidthBig[127];            // chacarter widths: big
-  int charHeight;                 // character heights: normal and shadow
+  int charHeight;                   // character heights: normal and shadow
-  int charHeightBig;              // character heights: big
+  int charHeightBig;                // character heights: big
 
   // capabilities
-  int glInitialized;              // is OpenGL initialized
+  int glInitialized;                // is OpenGL initialized
-  int windowAvailable;            // is default/window framebuffer available
+  int windowAvailable;              // is default/window framebuffer available
-  int windowSamples;              // number of samples for default/window framebuffer
+  int windowSamples;                // number of samples for default/window framebuffer
-  int windowStereo;               // is stereo available for default/window framebuffer
+  int windowStereo;                 // is stereo available for default/window framebuffer
-  int windowDoublebuffer;         // is default/window framebuffer double buffered
+  int windowDoublebuffer;           // is default/window framebuffer double buffered
 
   // framebuffer
-  int     currentBuffer;          // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
+  int     currentBuffer;            // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
 
   // pixel output format
-  int     readPixelFormat;        // default color pixel format for mjr_readPixels
+  int     readPixelFormat;          // default color pixel format for mjr_readPixels
 
   // depth output format
-  int     readDepthMap;           // depth mapping: mjDEPTH_ZERONEAR or mjDEPTH_ZEROFAR
+  int     readDepthMap;             // depth mapping: mjDEPTH_ZERONEAR or mjDEPTH_ZEROFAR
 };
 typedef struct mjrContext_ mjrContext;
 typedef enum mjtGeomInertia_ {     // type of inertia inference
@@ -1649,7 +1650,7 @@ typedef struct mjSpec_ {           // model specification
   mjtByte strippath;               // automatically strip paths from mesh files
   mjtByte fitaabb;                 // meshfit to aabb instead of inertia box
   mjtByte degree;                  // angles in radians or degrees
-  char euler[3];                   // sequence for euler rotations
+  char eulerseq[3];                // sequence for euler rotations
   mjString* meshdir;               // mesh and hfield directory
   mjString* texturedir;            // texture directory
   mjtByte discardvisual;           // discard visual geoms in parser
@@ -1743,7 +1744,6 @@ typedef struct mjsFrame_ {         // frame specification
 typedef struct mjsJoint_ {         // joint specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjtJoint type;                   // joint type
 
   // kinematics
@@ -1781,7 +1781,6 @@ typedef struct mjsJoint_ {         // joint specification
 typedef struct mjsGeom_ {          // geom specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // classname
   mjtGeom type;                    // geom type
 
   // frame, size
@@ -1828,7 +1827,6 @@ typedef struct mjsGeom_ {          // geom specification
 typedef struct mjsSite_ {          // site specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // frame, size
   double pos[3];                   // position
@@ -1850,7 +1848,6 @@ typedef struct mjsSite_ {          // site specification
 typedef struct mjsCamera_ {        // camera specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // extrinsics
   double pos[3];                   // position
@@ -1878,7 +1875,6 @@ typedef struct mjsCamera_ {        // camera specification
 typedef struct mjsLight_ {         // light specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // frame
   double pos[3];                   // position
@@ -1904,7 +1900,6 @@ typedef struct mjsLight_ {         // light specification
 typedef struct mjsFlex_ {          // flex specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // contact properties
   int contype;                     // contact type
@@ -1943,7 +1938,6 @@ typedef struct mjsFlex_ {          // flex specification
 typedef struct mjsMesh_ {          // mesh specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* content_type;          // content type of file
   mjString* file;                  // mesh file
   double refpos[3];                // reference position
@@ -1974,7 +1968,6 @@ typedef struct mjsHField_ {        // height field specification
 typedef struct mjsSkin_ {          // skin specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* file;                  // skin file
   mjString* material;              // name of material used for rendering
   float rgba[4];                   // rgba when material is omitted
@@ -1999,7 +1992,6 @@ typedef struct mjsSkin_ {          // skin specification
 typedef struct mjsTexture_ {       // texture specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjtTexture type;                 // texture type
 
   // method 1: builtin
@@ -2031,7 +2023,6 @@ typedef struct mjsTexture_ {       // texture specification
 typedef struct mjsMaterial_ {      // material specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* texture;               // name of texture (empty: none)
   mjtByte texuniform;              // make texture cube uniform
   float texrepeat[2];              // texture repetition for 2D mapping
@@ -2047,7 +2038,6 @@ typedef struct mjsMaterial_ {      // material specification
 typedef struct mjsPair_ {          // pair specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* geomname1;             // name of geom 1
   mjString* geomname2;             // name of geom 2
 
@@ -2071,7 +2061,6 @@ typedef struct mjsExclude_ {       // exclude specification
 typedef struct mjsEquality_ {      // equality specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjtEq type;                      // constraint type
   double data[mjNEQDATA];          // type-dependent data
   mjtByte active;                  // is equality initially active
@@ -2084,7 +2073,6 @@ typedef struct mjsEquality_ {      // equality specification
 typedef struct mjsTendon_ {        // tendon specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // stiffness, damping, friction
   double stiffness;                // stiffness coefficient
@@ -2118,7 +2106,6 @@ typedef struct mjsWrap_ {          // wrapping object specification
 typedef struct mjsActuator_ {      // actuator specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // gain, bias
   mjtGain gaintype;                // gain type
@@ -2160,7 +2147,6 @@ typedef struct mjsActuator_ {      // actuator specification
 typedef struct mjsSensor_ {        // sensor specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // sensor definition
   mjtSensor type;                  // type of sensor
@@ -2286,6 +2272,11 @@ typedef enum mjtItem_ {           // UI item type
 
   mjNITEM                         // number of item types
 } mjtItem;
+typedef enum mjtSection_ {        // UI section state
+  mjSECT_CLOSED = 0,              // closed state (regular section)
+  mjSECT_OPEN,                    // open state (regular section)
+  mjSECT_FIXED                    // fixed section: always open, no title
+} mjtSection;
 struct mjuiState_ {               // mouse and keyboard state
   // constants set by user
   int nrect;                      // number of rectangles used
@@ -2333,6 +2324,8 @@ struct mjuiThemeSpacing_ {        // UI visualization theme spacing
   int scroll;                     // scrollbar width
   int label;                      // label width
   int section;                    // section gap
+  int cornersect;                 // corner radius for section
+  int cornersep;                  // corner radius for separator
   int itemside;                   // item side gap
   int itemmid;                    // item middle gap
   int itemver;                    // item vertical gap
@@ -2346,9 +2339,14 @@ struct mjuiThemeColor_ {          // UI visualization theme color
   float master[3];                // master background
   float thumb[3];                 // scrollbar thumb
   float secttitle[3];             // section title
+  float secttitle2[3];            // section title: bottom color
+  float secttitlecheck[3];        // section title with checkbox
+  float secttitlecheck2[3];       // section title with checkbox: bottom color
   float sectfont[3];              // section font
   float sectsymbol[3];            // section symbol
   float sectpane[3];              // section pane
+  float separator[3];             // separator title
+  float separator2[3];            // separator title: bottom color
   float shortcut[3];              // shortcut background
   float fontactive[3];            // font active
   float fontinactive[3];          // font inactive
@@ -2398,6 +2396,7 @@ struct mjuiItem_ {                // UI item
   void *pdata;                    // data pointer (type-specific)
   int sectionid;                  // id of section containing item
   int itemid;                     // id of item within section
+  int userid;                     // user-supplied id (for event handling)
 
   // type-specific properties
   union {
@@ -2409,20 +2408,23 @@ struct mjuiItem_ {                // UI item
 
   // internal
   mjrRect rect;                   // rectangle occupied by item
+  int skip;                       // item skipped due to closed separator
 };
 typedef struct mjuiItem_ mjuiItem;
 struct mjuiSection_ {             // UI section
   // properties
   char name[mjMAXUINAME];         // name
-  int state;                      // 0: closed, 1: open
+  int state;                      // section state (mjtSection)
   int modifier;                   // 0: none, 1: control, 2: shift; 4: alt
   int shortcut;                   // shortcut key; 0: undefined
+  int checkbox;                   // 0: none, 1: hidden, 2: unchecked, 2: checked
   int nitem;                      // number of items in use
   mjuiItem item[mjMAXUIITEM];     // preallocated array of items
 
   // internal
   mjrRect rtitle;                 // rectangle occupied by title
   mjrRect rcontent;               // rectangle occupied by content
+  int lastclick;                  // last mouse click over this section
 };
 typedef struct mjuiSection_ mjuiSection;
 struct mjUI_ {                    // entire UI
@@ -2441,10 +2443,12 @@ struct mjUI_ {                    // entire UI
   int maxheight;                  // height when all sections open
   int scroll;                     // scroll from top of UI
 
-  // mouse focus
+  // mouse focus and count
   int mousesect;                  // 0: none, -1: scroll, otherwise 1+section
   int mouseitem;                  // item within section
   int mousehelp;                  // help button down: print shortcuts
+  int mouseclicks;                // number of mouse clicks over UI
+  int mousesectcheck;             // 0: none, otherwise 1+section
 
   // keyboard focus and edit
   int editsect;                   // 0: none, otherwise 1+section
@@ -2465,6 +2469,7 @@ struct mjuiDef_ {                 // table passed to mjui_add()
   int state;                      // state
   void* pdata;                    // pointer to data
   char other[mjMAXUITEXT];        // string with type-specific properties
+  int otherint;                   // int with type-specific properties
 };
 typedef struct mjuiDef_ mjuiDef;
 typedef enum mjtCatBit_ {         // bitflags for mjvGeom category
@@ -2635,21 +2640,22 @@ struct mjvGeom_ {                 // abstract geom
   int      objtype;               // mujoco object type; mjOBJ_UNKNOWN for decor
   int      objid;                 // mujoco object id; -1 for decor
   int      category;              // visual category
-  int      texid;                 // texture id; -1: no texture
+  int      matid;                 // material id; -1: no textured material
-  int      texuniform;            // uniform cube mapping
   int      texcoord;              // mesh or flex geom has texture coordinates
   int      segid;                 // segmentation id; -1: not shown
 
-  // OpenGL info
+  // spatial transform
-  float    texrepeat[2];          // texture repetition for 2D mapping
   float    size[3];               // size parameters
   float    pos[3];                // Cartesian position
   float    mat[9];                // Cartesian orientation
+
+  // material properties
   float    rgba[4];               // color and transparency
   float    emission;              // emission coef
   float    specular;              // specular coef
   float    shininess;             // shininess coef
   float    reflectance;           // reflectance coef
+
   char     label[100];            // text label
 
   // transparency rendering (set internally)
@@ -2782,7 +2788,7 @@ struct mjvFigure_ {               // abstract 2D figure passed to OpenGL rendere
 
   // line data
   int     linepnt[mjMAXLINE];     // number of points in line; (0) disable
-  float   linedata[mjMAXLINE][2*mjMAXLINEPNT]; // line data (x,y)
+  float   linedata[mjMAXLINE][2*mjMAXLINEPNT];  // line data (x,y)
 
   // output from renderer
   int     xaxispixel[2];          // range of x-axis in pixels
@@ -3068,10 +3074,8 @@ typedef struct mjvSceneState_ mjvSceneState;
 void mj_defaultVFS(mjVFS* vfs);
 int mj_addFileVFS(mjVFS* vfs, const char* directory, const char* filename);
 int mj_addBufferVFS(mjVFS* vfs, const char* name, const void* buffer, int nbuffer);
-int mj_findFileVFS(const mjVFS* vfs, const char* filename);
 int mj_deleteFileVFS(mjVFS* vfs, const char* filename);
 void mj_deleteVFS(mjVFS* vfs);
-int mj_makeEmptyFileVFS(mjVFS* vfs, const char* filename, int filesize);
 mjModel* mj_loadXML(const char* filename, const mjVFS* vfs, char* error, int error_sz);
 mjSpec* mj_parseXML(const char* filename, const mjVFS* vfs, char* error, int error_sz);
 mjSpec* mj_parseXMLString(const char* xml, const mjVFS* vfs, char* error, int error_sz);
@@ -3525,7 +3529,7 @@ mjsText* mjs_addText(mjSpec* s);
 mjsTuple* mjs_addTuple(mjSpec* s);
 mjsKey* mjs_addKey(mjSpec* s);
 mjsPlugin* mjs_addPlugin(mjSpec* s);
-mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, int parentid, int* id);
+mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, const mjsDefault* parent);
 mjsMesh* mjs_addMesh(mjSpec* s, mjsDefault* def);
 mjsHField* mjs_addHField(mjSpec* s);
 mjsSkin* mjs_addSkin(mjSpec* s);
@@ -3536,12 +3540,38 @@ mjsBody* mjs_findBody(mjSpec* s, const char* name);
 mjsBody* mjs_findChild(mjsBody* body, const char* name);
 mjsMesh* mjs_findMesh(mjSpec* s, const char* name);
 mjsFrame* mjs_findFrame(mjSpec* s, const char* name);
+mjsKey* mjs_findKeyframe(mjSpec* s, const char* name);
 mjsDefault* mjs_getDefault(mjsElement* element);
 mjsDefault* mjs_findDefault(mjSpec* s, const char* classname);
 mjsDefault* mjs_getSpecDefault(mjSpec* s);
 int mjs_getId(mjsElement* element);
 mjsElement* mjs_firstChild(mjsBody* body, mjtObj type);
 mjsElement* mjs_nextChild(mjsBody* body, mjsElement* child);
+mjsElement* mjs_firstElement(mjSpec* s, mjtObj type);
+mjsElement* mjs_nextElement(mjSpec* s, mjsElement* element);
+mjsBody* mjs_asBody(mjsElement* element);
+mjsGeom* mjs_asGeom(mjsElement* element);
+mjsJoint* mjs_asJoint(mjsElement* element);
+mjsSite* mjs_asSite(mjsElement* element);
+mjsCamera* mjs_asCamera(mjsElement* element);
+mjsLight* mjs_asLight(mjsElement* element);
+mjsFrame* mjs_asFrame(mjsElement* element);
+mjsActuator* mjs_asActuator(mjsElement* element);
+mjsSensor* mjs_asSensor(mjsElement* element);
+mjsFlex* mjs_asFlex(mjsElement* element);
+mjsPair* mjs_asPair(mjsElement* element);
+mjsEquality* mjs_asEquality(mjsElement* element);
+mjsExclude* mjs_asExclude(mjsElement* element);
+mjsTendon* mjs_asTendon(mjsElement* element);
+mjsNumeric* mjs_asNumeric(mjsElement* element);
+mjsText* mjs_asText(mjsElement* element);
+mjsTuple* mjs_asTuple(mjsElement* element);
+mjsKey* mjs_asKey(mjsElement* element);
+mjsMesh* mjs_asMesh(mjsElement* element);
+mjsHField* mjs_asHField(mjsElement* element);
+mjsSkin* mjs_asSkin(mjsElement* element);
+mjsTexture* mjs_asTexture(mjsElement* element);
+mjsMaterial* mjs_asMaterial(mjsElement* element);
 void mjs_setString(mjString* dest, const char* text);
 void mjs_setStringVec(mjStringVec* dest, const char* text);
 mjtByte mjs_setInStringVec(mjStringVec* dest, int i, const char* text);
@@ -3559,7 +3589,6 @@ void mjs_setDefault(mjsElement* element, mjsDefault* def);
 void mjs_setFrame(mjsElement* dest, mjsFrame* frame);
 const char* mjs_resolveOrientation(double quat[4], mjtByte degree, const char* sequence,
                                    const mjsOrientation* orientation);
-const char* mjs_fullInertia(double quat[4], double inertia[3], const double fullinertia[6]);
 void mjs_defaultSpec(mjSpec* spec);
 void mjs_defaultOrientation(mjsOrientation* orient);
 void mjs_defaultBody(mjsBody* body);

doc/programming/samples.rst

@@ -84,7 +84,7 @@ data plots. The model file can be specified as a command-line argument, or loade
 functionality. This code sample uses the native UI to render various controls, and provides an
 illustration of how the new UI framework is intended to be used. Below is a screen-capture of ``simulate`` in action:
 
-..  youtube:: 0ORsj_E17B0
+..  youtube:: P83tKA1iz2Y
     :width: 95%
     :align: center
 
@@ -94,7 +94,7 @@ selected object by holding Ctrl and dragging the mouse. Dragging the mouse alone
 are keyboard shortcuts for pausing the simulation, resetting, and re-loading the model file. The latter functionality is
 very useful while editing the model in an XML editor.
 
-The code is quite long yet reasonably commented, so it is best to just read it. Here we provide a high-level overview.
+The code is long yet reasonably commented, so it is best to just read it. Here we provide a high-level overview.
 The ``main()`` function initializes both MuJoCo and GLFW, opens a window, and install GLFW callbacks for mouse and
 keyboard handling. Note that there is no render callback; GLFW puts the user in charge, instead of running a rendering
 loop behind the scenes. The main loop handles UI events and rendering. The simulation is handled in a background

include/mujoco/mjdata.h

@@ -167,29 +167,29 @@ struct mjData_ {
   int     nplugin;           // number of plugin instances
 
   // stack pointer
-  size_t  pstack;            // first available mjtNum address in stack
+  size_t  pstack;            // first available byte in stack
   size_t  pbase;             // value of pstack when mj_markStack was last called
 
   // arena pointer
   size_t  parena;            // first available byte in arena
 
-  // memory utilization stats
+  // memory utilization statistics
-  size_t  maxuse_stack;                      // maximum stack allocation in bytes
+  size_t  maxuse_stack;                       // maximum stack allocation in bytes
-  size_t  maxuse_threadstack[mjMAXTHREAD];   // maximum stack allocation per thread in bytes
+  size_t  maxuse_threadstack[mjMAXTHREAD];    // maximum stack allocation per thread in bytes
-  size_t  maxuse_arena;                      // maximum arena allocation in bytes
+  size_t  maxuse_arena;                       // maximum arena allocation in bytes
-  int     maxuse_con;                        // maximum number of contacts
+  int     maxuse_con;                         // maximum number of contacts
-  int     maxuse_efc;                        // maximum number of scalar constraints
+  int     maxuse_efc;                         // maximum number of scalar constraints
-
-  // diagnostics
-  mjWarningStat warning[mjNWARNING];  // warning statistics
-  mjTimerStat   timer[mjNTIMER];      // timer statistics
 
   // solver statistics
   mjSolverStat  solver[mjNISLAND*mjNSOLVER];  // solver statistics per island, per iteration
-  int     solver_nisland;           // number of islands processed by solver
+  int           solver_nisland;               // number of islands processed by solver
-  int     solver_niter[mjNISLAND];  // number of solver iterations, per island
+  int           solver_niter[mjNISLAND];      // number of solver iterations, per island
-  int     solver_nnz[mjNISLAND];    // number of non-zeros in Hessian or efc_AR, per island
+  int           solver_nnz[mjNISLAND];        // number of nonzeros in Hessian or efc_AR, per island
-  mjtNum  solver_fwdinv[2];         // forward-inverse comparison: qfrc, efc
+  mjtNum        solver_fwdinv[2];             // forward-inverse comparison: qfrc, efc
+
+  // diagnostics
+  mjWarningStat warning[mjNWARNING];          // warning statistics
+  mjTimerStat   timer[mjNTIMER];              // timer statistics
 
   // variable sizes
   int     ne;                // number of equality constraints
@@ -207,8 +207,8 @@ struct mjData_ {
   //-------------------- end of info header
 
   // buffers
-  void*   buffer;            // main buffer; all pointers point in it                (nbuffer bytes)
+  void*   buffer;            // main buffer; all pointers point in it            (nbuffer bytes)
-  void*   arena;             // arena+stack buffer                     (nstack*sizeof(mjtNum) bytes)
+  void*   arena;             // arena+stack buffer                               (narena bytes)
 
   //-------------------- main inputs and outputs of the computation
 
@@ -302,7 +302,7 @@ struct mjData_ {
 
   // computed by mj_collisionTree
   mjtNum*  bvh_aabb_dyn;     // global bounding box (center, size)               (nbvhdynamic x 6)
-  mjtByte* bvh_active;       // volume has been added to collisions              (nbvh x 1)
+  mjtByte* bvh_active;       // was bounding volume checked for collision        (nbvh x 1)
 
   //-------------------- POSITION, VELOCITY dependent
 
@@ -372,7 +372,7 @@ struct mjData_ {
   //-------------------- arena-allocated: POSITION dependent
 
   // computed by mj_collision
-  mjContact* contact;        // list of all detected contacts                    (ncon x 1)
+  mjContact* contact;        // array of all detected contacts                   (ncon x 1)
 
   // computed by mj_makeConstraint
   int*    efc_type;          // constraint type (mjtConstraint)                  (nefc x 1)
@@ -422,11 +422,11 @@ struct mjData_ {
   //-------------------- arena-allocated: POSITION, VELOCITY, CONTROL/ACCELERATION dependent
 
   // computed by mj_fwdConstraint/mj_inverse
-  mjtNum* efc_b;            // linear cost term: J*qacc_smooth - aref            (nefc x 1)
+  mjtNum* efc_b;             // linear cost term: J*qacc_smooth - aref           (nefc x 1)
-  mjtNum* efc_force;        // constraint force in constraint space              (nefc x 1)
+  mjtNum* efc_force;         // constraint force in constraint space             (nefc x 1)
-  int*    efc_state;        // constraint state (mjtConstraintState)             (nefc x 1)
+  int*    efc_state;         // constraint state (mjtConstraintState)            (nefc x 1)
 
-  // ThreadPool for multithreaded operations
+  // thread pool pointer
   uintptr_t threadpool;
 };
 typedef struct mjData_ mjData;

include/mujoco/mjmodel.h

@@ -29,8 +29,6 @@
 #define mjMAXIMP        0.9999    // maximum constraint impedance
 #define mjMAXCONPAIR    50        // maximum number of contacts per geom pair
 #define mjMAXTREEDEPTH  50        // maximum bounding volume hierarchy depth
-#define mjMAXVFS        2000      // maximum number of files in virtual file system
-#define mjMAXVFSNAME    1000      // maximum filename size in virtual file system
 
 
 //---------------------------------- sizes ---------------------------------------------------------
@@ -44,7 +42,7 @@
 #define mjNIMP          5         // number of solver impedance parameters
 #define mjNSOLVER       200       // size of one mjData.solver array
 #define mjNISLAND       20        // number of mjData.solver arrays
-
+#define mjNTEXMAT       6         // number of textures per material
 
 //---------------------------------- enum types (mjt) ----------------------------------------------
 
@@ -399,11 +397,7 @@ typedef struct mjLROpt_ mjLROpt;
 //---------------------------------- mjVFS ---------------------------------------------------------
 
 struct mjVFS_ {                               // virtual file system for loading from memory
-  int      nfile;                             // number of files present
+  void* impl_;                                // internal pointer to VFS memory
-  char     filename[mjMAXVFS][mjMAXVFSNAME];  // file name without path
-  size_t   filesize[mjMAXVFS];                // file size in bytes
-  void*    filedata[mjMAXVFS];                // buffer with file data
-  uint64_t filestamp[mjMAXVFS];               // checksum of the file data
 };
 typedef struct mjVFS_ mjVFS;
 
@@ -935,7 +929,7 @@ struct mjModel_ {
   int*      tex_pathadr;          // address of texture asset path; -1: none  (ntex x 1)
 
   // materials
-  int*      mat_texid;            // texture id; -1: none                     (nmat x 1)
+  int*      mat_texid;            // indices of textures; -1: none            (nmat x mjNTEXMAT)
   mjtByte*  mat_texuniform;       // make texture cube uniform                (nmat x 1)
   float*    mat_texrepeat;        // texture repetition for 2d mapping        (nmat x 2)
   float*    mat_emission;         // emission (x rgb)                         (nmat x 1)

include/mujoco/mjrender.h

@@ -15,14 +15,15 @@
 #ifndef MUJOCO_MJRENDER_H_
 #define MUJOCO_MJRENDER_H_
 
+#include <mujoco/mjmodel.h>
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
 
 #define mjNAUX          10        // number of auxiliary buffers
-#define mjMAXTEXTURE    1000      // maximum number of textures
+#define mjMAXTEXTURE    100       // maximum number of textures
-
+#define mjMAXMATERIAL   100       // maximum number of materials with textures
 
 //---------------------------------- primitive types (mjt) -----------------------------------------
 
@@ -76,92 +77,97 @@ typedef struct mjrRect_ mjrRect;
 
 //---------------------------------- mjrContext ----------------------------------------------------
 
-struct mjrContext_ {              // custom OpenGL context
+struct mjrContext_ {                // custom OpenGL context
   // parameters copied from mjVisual
-  float lineWidth;                // line width for wireframe rendering
+  float lineWidth;                  // line width for wireframe rendering
-  float shadowClip;               // clipping radius for directional lights
+  float shadowClip;                 // clipping radius for directional lights
-  float shadowScale;              // fraction of light cutoff for spot lights
+  float shadowScale;                // fraction of light cutoff for spot lights
-  float fogStart;                 // fog start = stat.extent * vis.map.fogstart
+  float fogStart;                   // fog start = stat.extent * vis.map.fogstart
-  float fogEnd;                   // fog end = stat.extent * vis.map.fogend
+  float fogEnd;                     // fog end = stat.extent * vis.map.fogend
-  float fogRGBA[4];               // fog rgba
+  float fogRGBA[4];                 // fog rgba
-  int shadowSize;                 // size of shadow map texture
+  int shadowSize;                   // size of shadow map texture
-  int offWidth;                   // width of offscreen buffer
+  int offWidth;                     // width of offscreen buffer
-  int offHeight;                  // height of offscreen buffer
+  int offHeight;                    // height of offscreen buffer
-  int offSamples;                 // number of offscreen buffer multisamples
+  int offSamples;                   // number of offscreen buffer multisamples
 
   // parameters specified at creation
-  int fontScale;                  // font scale
+  int fontScale;                    // font scale
-  int auxWidth[mjNAUX];           // auxiliary buffer width
+  int auxWidth[mjNAUX];             // auxiliary buffer width
-  int auxHeight[mjNAUX];          // auxiliary buffer height
+  int auxHeight[mjNAUX];            // auxiliary buffer height
-  int auxSamples[mjNAUX];         // auxiliary buffer multisamples
+  int auxSamples[mjNAUX];           // auxiliary buffer multisamples
 
   // offscreen rendering objects
-  unsigned int offFBO;            // offscreen framebuffer object
+  unsigned int offFBO;              // offscreen framebuffer object
-  unsigned int offFBO_r;          // offscreen framebuffer for resolving multisamples
+  unsigned int offFBO_r;            // offscreen framebuffer for resolving multisamples
-  unsigned int offColor;          // offscreen color buffer
+  unsigned int offColor;            // offscreen color buffer
-  unsigned int offColor_r;        // offscreen color buffer for resolving multisamples
+  unsigned int offColor_r;          // offscreen color buffer for resolving multisamples
-  unsigned int offDepthStencil;   // offscreen depth and stencil buffer
+  unsigned int offDepthStencil;     // offscreen depth and stencil buffer
-  unsigned int offDepthStencil_r; // offscreen depth and stencil buffer for resolving multisamples
+  unsigned int offDepthStencil_r;   // offscreen depth and stencil buffer for multisamples
 
   // shadow rendering objects
-  unsigned int shadowFBO;         // shadow map framebuffer object
+  unsigned int shadowFBO;           // shadow map framebuffer object
-  unsigned int shadowTex;         // shadow map texture
+  unsigned int shadowTex;           // shadow map texture
 
   // auxiliary buffers
-  unsigned int auxFBO[mjNAUX];    // auxiliary framebuffer object
+  unsigned int auxFBO[mjNAUX];      // auxiliary framebuffer object
-  unsigned int auxFBO_r[mjNAUX];  // auxiliary framebuffer object for resolving
+  unsigned int auxFBO_r[mjNAUX];    // auxiliary framebuffer object for resolving
-  unsigned int auxColor[mjNAUX];  // auxiliary color buffer
+  unsigned int auxColor[mjNAUX];    // auxiliary color buffer
-  unsigned int auxColor_r[mjNAUX];// auxiliary color buffer for resolving
+  unsigned int auxColor_r[mjNAUX];  // auxiliary color buffer for resolving
+
+  // materials with textures
+  int mat_texid[mjMAXMATERIAL*mjNTEXMAT];  // material texture ids (-1: no texture)
+  int mat_texuniform[mjMAXMATERIAL];       // texture repetition for 2d mapping
+  int mat_texrepeat[mjMAXMATERIAL*2];      // texture repetition for 2d mapping
 
   // texture objects and info
-  int ntexture;                   // number of allocated textures
+  int ntexture;                        // number of allocated textures
-  int textureType[100];           // type of texture (mjtTexture) (ntexture)
+  int textureType[mjMAXTEXTURE];       // type of texture (mjtTexture) (ntexture)
-  unsigned int texture[100];      // texture names
+  unsigned int texture[mjMAXTEXTURE];  // texture names
 
   // displaylist starting positions
-  unsigned int basePlane;         // all planes from model
+  unsigned int basePlane;           // all planes from model
-  unsigned int baseMesh;          // all meshes from model
+  unsigned int baseMesh;            // all meshes from model
-  unsigned int baseHField;        // all hfields from model
+  unsigned int baseHField;          // all height fields from model
-  unsigned int baseBuiltin;       // all buildin geoms, with quality from model
+  unsigned int baseBuiltin;         // all builtin geoms, with quality from model
-  unsigned int baseFontNormal;    // normal font
+  unsigned int baseFontNormal;      // normal font
-  unsigned int baseFontShadow;    // shadow font
+  unsigned int baseFontShadow;      // shadow font
-  unsigned int baseFontBig;       // big font
+  unsigned int baseFontBig;         // big font
 
   // displaylist ranges
-  int rangePlane;                 // all planes from model
+  int rangePlane;                   // all planes from model
-  int rangeMesh;                  // all meshes from model
+  int rangeMesh;                    // all meshes from model
-  int rangeHField;                // all hfields from model
+  int rangeHField;                  // all hfields from model
-  int rangeBuiltin;               // all builtin geoms, with quality from model
+  int rangeBuiltin;                 // all builtin geoms, with quality from model
-  int rangeFont;                  // all characters in font
+  int rangeFont;                    // all characters in font
 
   // skin VBOs
-  int nskin;                      // number of skins
+  int nskin;                        // number of skins
-  unsigned int* skinvertVBO;      // skin vertex position VBOs (nskin)
+  unsigned int* skinvertVBO;        // skin vertex position VBOs (nskin)
-  unsigned int* skinnormalVBO;    // skin vertex normal VBOs (nskin)
+  unsigned int* skinnormalVBO;      // skin vertex normal VBOs (nskin)
-  unsigned int* skintexcoordVBO;  // skin vertex texture coordinate VBOs (nskin)
+  unsigned int* skintexcoordVBO;    // skin vertex texture coordinate VBOs (nskin)
-  unsigned int* skinfaceVBO;      // skin face index VBOs (nskin)
+  unsigned int* skinfaceVBO;        // skin face index VBOs (nskin)
 
   // character info
-  int charWidth[127];             // character widths: normal and shadow
+  int charWidth[127];               // character widths: normal and shadow
-  int charWidthBig[127];          // chacarter widths: big
+  int charWidthBig[127];            // chacarter widths: big
-  int charHeight;                 // character heights: normal and shadow
+  int charHeight;                   // character heights: normal and shadow
-  int charHeightBig;              // character heights: big
+  int charHeightBig;                // character heights: big
 
   // capabilities
-  int glInitialized;              // is OpenGL initialized
+  int glInitialized;                // is OpenGL initialized
-  int windowAvailable;            // is default/window framebuffer available
+  int windowAvailable;              // is default/window framebuffer available
-  int windowSamples;              // number of samples for default/window framebuffer
+  int windowSamples;                // number of samples for default/window framebuffer
-  int windowStereo;               // is stereo available for default/window framebuffer
+  int windowStereo;                 // is stereo available for default/window framebuffer
-  int windowDoublebuffer;         // is default/window framebuffer double buffered
+  int windowDoublebuffer;           // is default/window framebuffer double buffered
 
   // framebuffer
-  int     currentBuffer;          // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
+  int     currentBuffer;            // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
 
   // pixel output format
-  int     readPixelFormat;        // default color pixel format for mjr_readPixels
+  int     readPixelFormat;          // default color pixel format for mjr_readPixels
 
   // depth output format
-  int     readDepthMap;           // depth mapping: mjDEPTH_ZERONEAR or mjDEPTH_ZEROFAR
+  int     readDepthMap;             // depth mapping: mjDEPTH_ZERONEAR or mjDEPTH_ZEROFAR
 };
 typedef struct mjrContext_ mjrContext;
 

include/mujoco/mjspec.h

@@ -118,7 +118,7 @@ typedef struct mjSpec_ {           // model specification
   mjtByte strippath;               // automatically strip paths from mesh files
   mjtByte fitaabb;                 // meshfit to aabb instead of inertia box
   mjtByte degree;                  // angles in radians or degrees
-  char euler[3];                   // sequence for euler rotations
+  char eulerseq[3];                // sequence for euler rotations
   mjString* meshdir;               // mesh and hfield directory
   mjString* texturedir;            // texture directory
   mjtByte discardvisual;           // discard visual geoms in parser
@@ -222,7 +222,6 @@ typedef struct mjsFrame_ {         // frame specification
 typedef struct mjsJoint_ {         // joint specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjtJoint type;                   // joint type
 
   // kinematics
@@ -262,7 +261,6 @@ typedef struct mjsJoint_ {         // joint specification
 typedef struct mjsGeom_ {          // geom specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // classname
   mjtGeom type;                    // geom type
 
   // frame, size
@@ -311,7 +309,6 @@ typedef struct mjsGeom_ {          // geom specification
 typedef struct mjsSite_ {          // site specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // frame, size
   double pos[3];                   // position
@@ -335,7 +332,6 @@ typedef struct mjsSite_ {          // site specification
 typedef struct mjsCamera_ {        // camera specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // extrinsics
   double pos[3];                   // position
@@ -365,7 +361,6 @@ typedef struct mjsCamera_ {        // camera specification
 typedef struct mjsLight_ {         // light specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // frame
   double pos[3];                   // position
@@ -393,7 +388,6 @@ typedef struct mjsLight_ {         // light specification
 typedef struct mjsFlex_ {          // flex specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // contact properties
   int contype;                     // contact type
@@ -434,7 +428,6 @@ typedef struct mjsFlex_ {          // flex specification
 typedef struct mjsMesh_ {          // mesh specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* content_type;          // content type of file
   mjString* file;                  // mesh file
   double refpos[3];                // reference position
@@ -470,7 +463,6 @@ typedef struct mjsHField_ {        // height field specification
 typedef struct mjsSkin_ {          // skin specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* file;                  // skin file
   mjString* material;              // name of material used for rendering
   float rgba[4];                   // rgba when material is omitted
@@ -497,7 +489,6 @@ typedef struct mjsSkin_ {          // skin specification
 typedef struct mjsTexture_ {       // texture specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjtTexture type;                 // texture type
 
   // method 1: builtin
@@ -531,7 +522,6 @@ typedef struct mjsTexture_ {       // texture specification
 typedef struct mjsMaterial_ {      // material specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* texture;               // name of texture (empty: none)
   mjtByte texuniform;              // make texture cube uniform
   float texrepeat[2];              // texture repetition for 2D mapping
@@ -549,7 +539,6 @@ typedef struct mjsMaterial_ {      // material specification
 typedef struct mjsPair_ {          // pair specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjString* geomname1;             // name of geom 1
   mjString* geomname2;             // name of geom 2
 
@@ -577,7 +566,6 @@ typedef struct mjsExclude_ {       // exclude specification
 typedef struct mjsEquality_ {      // equality specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
   mjtEq type;                      // constraint type
   double data[mjNEQDATA];          // type-dependent data
   mjtByte active;                  // is equality initially active
@@ -592,7 +580,6 @@ typedef struct mjsEquality_ {      // equality specification
 typedef struct mjsTendon_ {        // tendon specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // stiffness, damping, friction
   double stiffness;                // stiffness coefficient
@@ -630,7 +617,6 @@ typedef struct mjsWrap_ {          // wrapping object specification
 typedef struct mjsActuator_ {      // actuator specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // gain, bias
   mjtGain gaintype;                // gain type
@@ -674,7 +660,6 @@ typedef struct mjsActuator_ {      // actuator specification
 typedef struct mjsSensor_ {        // sensor specification
   mjsElement* element;             // element type
   mjString* name;                  // name
-  mjString* classname;             // class name
 
   // sensor definition
   mjtSensor type;                  // type of sensor

include/mujoco/mjtnum.h

@@ -17,12 +17,8 @@
 
 //---------------------------------- floating-point definition -------------------------------------
 
-// compile-time configuration options
-#define mjUSEDOUBLE               // single or double precision for mjtNum
-
-
 // floating point data type and minval
-#ifdef mjUSEDOUBLE
+#ifndef mjUSESINGLE
   typedef double mjtNum;
   #define mjMINVAL    1E-15       // minimum value in any denominator
 #else

include/mujoco/mjui.h

@@ -26,6 +26,7 @@
 #define mjMAXUIRECT     25      // maximum number of rectangles
 
 #define mjSEPCLOSED     1000    // closed state of adjustable separator
+#define mjPRESERVE      2000    // preserve section or separator state
 
 
 // key codes matching GLFW (user must remap for other frameworks)
@@ -106,6 +107,13 @@ typedef enum mjtItem_ {           // UI item type
 } mjtItem;
 
 
+typedef enum mjtSection_ {        // UI section state
+  mjSECT_CLOSED = 0,              // closed state (regular section)
+  mjSECT_OPEN,                    // open state (regular section)
+  mjSECT_FIXED                    // fixed section: always open, no title
+} mjtSection;
+
+
 // predicate function: set enable/disable based on item category
 typedef int (*mjfItemEnable)(int category, void* data);
 
@@ -163,6 +171,8 @@ struct mjuiThemeSpacing_ {        // UI visualization theme spacing
   int scroll;                     // scrollbar width
   int label;                      // label width
   int section;                    // section gap
+  int cornersect;                 // corner radius for section
+  int cornersep;                  // corner radius for separator
   int itemside;                   // item side gap
   int itemmid;                    // item middle gap
   int itemver;                    // item vertical gap
@@ -180,9 +190,14 @@ struct mjuiThemeColor_ {          // UI visualization theme color
   float master[3];                // master background
   float thumb[3];                 // scrollbar thumb
   float secttitle[3];             // section title
+  float secttitle2[3];            // section title: bottom color
+  float secttitlecheck[3];        // section title with checkbox
+  float secttitlecheck2[3];       // section title with checkbox: bottom color
   float sectfont[3];              // section font
   float sectsymbol[3];            // section symbol
   float sectpane[3];              // section pane
+  float separator[3];             // separator title
+  float separator2[3];            // separator title: bottom color
   float shortcut[3];              // shortcut background
   float fontactive[3];            // font active
   float fontinactive[3];          // font inactive
@@ -236,6 +251,7 @@ struct mjuiItem_ {                // UI item
   void *pdata;                    // data pointer (type-specific)
   int sectionid;                  // id of section containing item
   int itemid;                     // id of item within section
+  int userid;                     // user-supplied id (for event handling)
 
   // type-specific properties
   union {
@@ -247,6 +263,7 @@ struct mjuiItem_ {                // UI item
 
   // internal
   mjrRect rect;                   // rectangle occupied by item
+  int skip;                       // item skipped due to closed separator
 };
 typedef struct mjuiItem_ mjuiItem;
 
@@ -256,15 +273,17 @@ typedef struct mjuiItem_ mjuiItem;
 struct mjuiSection_ {             // UI section
   // properties
   char name[mjMAXUINAME];         // name
-  int state;                      // 0: closed, 1: open
+  int state;                      // section state (mjtSection)
   int modifier;                   // 0: none, 1: control, 2: shift; 4: alt
   int shortcut;                   // shortcut key; 0: undefined
+  int checkbox;                   // 0: none, 1: hidden, 2: unchecked, 2: checked
   int nitem;                      // number of items in use
   mjuiItem item[mjMAXUIITEM];     // preallocated array of items
 
   // internal
   mjrRect rtitle;                 // rectangle occupied by title
   mjrRect rcontent;               // rectangle occupied by content
+  int lastclick;                  // last mouse click over this section
 };
 typedef struct mjuiSection_ mjuiSection;
 
@@ -287,10 +306,12 @@ struct mjUI_ {                    // entire UI
   int maxheight;                  // height when all sections open
   int scroll;                     // scroll from top of UI
 
-  // mouse focus
+  // mouse focus and count
   int mousesect;                  // 0: none, -1: scroll, otherwise 1+section
   int mouseitem;                  // item within section
   int mousehelp;                  // help button down: print shortcuts
+  int mouseclicks;                // number of mouse clicks over UI
+  int mousesectcheck;             // 0: none, otherwise 1+section
 
   // keyboard focus and edit
   int editsect;                   // 0: none, otherwise 1+section
@@ -315,6 +336,7 @@ struct mjuiDef_ {                 // table passed to mjui_add()
   int state;                      // state
   void* pdata;                    // pointer to data
   char other[mjMAXUITEXT];        // string with type-specific properties
+  int otherint;                   // int with type-specific properties
 };
 typedef struct mjuiDef_ mjuiDef;
 

include/mujoco/mjvisualize.h

@@ -230,21 +230,22 @@ struct mjvGeom_ {                 // abstract geom
   int      objtype;               // mujoco object type; mjOBJ_UNKNOWN for decor
   int      objid;                 // mujoco object id; -1 for decor
   int      category;              // visual category
-  int      texid;                 // texture id; -1: no texture
+  int      matid;                 // material id; -1: no textured material
-  int      texuniform;            // uniform cube mapping
   int      texcoord;              // mesh or flex geom has texture coordinates
   int      segid;                 // segmentation id; -1: not shown
 
-  // OpenGL info
+  // spatial transform
-  float    texrepeat[2];          // texture repetition for 2D mapping
   float    size[3];               // size parameters
   float    pos[3];                // Cartesian position
   float    mat[9];                // Cartesian orientation
+
+  // material properties
   float    rgba[4];               // color and transparency
   float    emission;              // emission coef
   float    specular;              // specular coef
   float    shininess;             // shininess coef
   float    reflectance;           // reflectance coef
+
   char     label[100];            // text label
 
   // transparency rendering (set internally)
@@ -393,7 +394,7 @@ struct mjvFigure_ {               // abstract 2D figure passed to OpenGL rendere
 
   // line data
   int     linepnt[mjMAXLINE];     // number of points in line; (0) disable
-  float   linedata[mjMAXLINE][2*mjMAXLINEPNT]; // line data (x,y)
+  float   linedata[mjMAXLINE][2*mjMAXLINEPNT];  // line data (x,y)
 
   // output from renderer
   int     xaxispixel[2];          // range of x-axis in pixels

include/mujoco/mjxmacro.h

@@ -413,7 +413,7 @@
     X   ( int,     tex_adr,               ntex,          1                    ) \
     X   ( mjtByte, tex_rgb,               ntexdata,      1                    ) \
     XMJV( int,     tex_pathadr,           ntex,          1                    ) \
-    XMJV( int,     mat_texid,             nmat,          1                    ) \
+    XMJV( int,     mat_texid,             nmat,          mjNTEXMAT            ) \
     XMJV( mjtByte, mat_texuniform,        nmat,          1                    ) \
     XMJV( float,   mat_texrepeat,         nmat,          2                    ) \
     XMJV( float,   mat_emission,          nmat,          1                    ) \

include/mujoco/mujoco.h

@@ -74,7 +74,7 @@ MJAPI extern const char* mjRNDSTRING[mjNRNDFLAG][3];
 
 //---------------------------------- Virtual file system -------------------------------------------
 
-// Initialize VFS to empty (no deallocation).
+// Initialize an empty VFS, mj_deleteVFS must be called to deallocate the VFS.
 MJAPI void mj_defaultVFS(mjVFS* vfs);
 
 // Add file to VFS, return 0: success, 1: full, 2: repeated name, -1: failed to load.
@@ -83,18 +83,12 @@ MJAPI int mj_addFileVFS(mjVFS* vfs, const char* directory, const char* filename)
 // Add file to VFS from buffer, return 0: success, 1: full, 2: repeated name, -1: failed to load.
 MJAPI int mj_addBufferVFS(mjVFS* vfs, const char* name, const void* buffer, int nbuffer);
 
-// Return file index in VFS, or -1 if not found in VFS.
-MJAPI int mj_findFileVFS(const mjVFS* vfs, const char* filename);
-
 // Delete file from VFS, return 0: success, -1: not found in VFS.
 MJAPI int mj_deleteFileVFS(mjVFS* vfs, const char* filename);
 
-// Delete all files from VFS.
+// Delete all files from VFS and deallocates VFS internal memory.
 MJAPI void mj_deleteVFS(mjVFS* vfs);
 
-// deprecated: use mj_copyBufferVFS.
-MJAPI int mj_makeEmptyFileVFS(mjVFS* vfs, const char* filename, int filesize);
-
 
 //---------------------------------- Parse and compile ---------------------------------------------
 
@@ -893,7 +887,7 @@ MJAPI int mjs_isWarning(mjSpec* s);
 
 //---------------------------------- Standard math -------------------------------------------------
 
-#ifdef mjUSEDOUBLE
+#if !defined(mjUSESINGLE)
   #define mju_sqrt    sqrt
   #define mju_exp     exp
   #define mju_sin     sin
@@ -1498,7 +1492,7 @@ MJAPI mjsKey* mjs_addKey(mjSpec* s);
 MJAPI mjsPlugin* mjs_addPlugin(mjSpec* s);
 
 // Add default.
-MJAPI mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, int parentid, int* id);
+MJAPI mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, const mjsDefault* parent);
 
 
 //---------------------------------- Assets --------------------------------------------------------
@@ -1536,6 +1530,9 @@ MJAPI mjsMesh* mjs_findMesh(mjSpec* s, const char* name);
 // Find frame by name.
 MJAPI mjsFrame* mjs_findFrame(mjSpec* s, const char* name);
 
+// Find keyframe by name.
+MJAPI mjsKey* mjs_findKeyframe(mjSpec* s, const char* name);
+
 // Get default corresponding to an element.
 MJAPI mjsDefault* mjs_getDefault(mjsElement* element);
 
@@ -1554,6 +1551,81 @@ MJAPI mjsElement* mjs_firstChild(mjsBody* body, mjtObj type);
 // Return body's next child of the same type; return NULL if child is last.
 MJAPI mjsElement* mjs_nextChild(mjsBody* body, mjsElement* child);
 
+// Return spec's first element of selected type.
+MJAPI mjsElement* mjs_firstElement(mjSpec* s, mjtObj type);
+
+// Return spec's next element; return NULL if element is last.
+MJAPI mjsElement* mjs_nextElement(mjSpec* s, mjsElement* element);
+
+// Safely cast an element as mjsBody, or return NULL if the element is not an mjsBody.
+MJAPI mjsBody* mjs_asBody(mjsElement* element);
+
+// Safely cast an element as mjsGeom, or return NULL if the element is not an mjsGeom.
+MJAPI mjsGeom* mjs_asGeom(mjsElement* element);
+
+// Safely cast an element as mjsJoint, or return NULL if the element is not an mjsJoint.
+MJAPI mjsJoint* mjs_asJoint(mjsElement* element);
+
+// Safely cast an element as mjsSite, or return NULL if the element is not an mjsSite.
+MJAPI mjsSite* mjs_asSite(mjsElement* element);
+
+// Safely cast an element as mjsCamera, or return NULL if the element is not an mjsCamera.
+MJAPI mjsCamera* mjs_asCamera(mjsElement* element);
+
+// Safely cast an element as mjsLight, or return NULL if the element is not an mjsLight.
+MJAPI mjsLight* mjs_asLight(mjsElement* element);
+
+// Safely cast an element as mjsFrame, or return NULL if the element is not an mjsFrame.
+MJAPI mjsFrame* mjs_asFrame(mjsElement* element);
+
+// Safely cast an element as mjsActuator, or return NULL if the element is not an mjsActuator.
+MJAPI mjsActuator* mjs_asActuator(mjsElement* element);
+
+// Safely cast an element as mjsSensor, or return NULL if the element is not an mjsSensor.
+MJAPI mjsSensor* mjs_asSensor(mjsElement* element);
+
+// Safely cast an element as mjsFlex, or return NULL if the element is not an mjsFlex.
+MJAPI mjsFlex* mjs_asFlex(mjsElement* element);
+
+// Safely cast an element as mjsPair, or return NULL if the element is not an mjsPair.
+MJAPI mjsPair* mjs_asPair(mjsElement* element);
+
+// Safely cast an element as mjsEquality, or return NULL if the element is not an mjsEquality.
+MJAPI mjsEquality* mjs_asEquality(mjsElement* element);
+
+// Safely cast an element as mjsExclude, or return NULL if the element is not an mjsExclude.
+MJAPI mjsExclude* mjs_asExclude(mjsElement* element);
+
+// Safely cast an element as mjsTendon, or return NULL if the element is not an mjsTendon.
+MJAPI mjsTendon* mjs_asTendon(mjsElement* element);
+
+// Safely cast an element as mjsNumeric, or return NULL if the element is not an mjsNumeric.
+MJAPI mjsNumeric* mjs_asNumeric(mjsElement* element);
+
+// Safely cast an element as mjsText, or return NULL if the element is not an mjsText.
+MJAPI mjsText* mjs_asText(mjsElement* element);
+
+// Safely cast an element as mjsTuple, or return NULL if the element is not an mjsTuple.
+MJAPI mjsTuple* mjs_asTuple(mjsElement* element);
+
+// Safely cast an element as mjsKey, or return NULL if the element is not an mjsKey.
+MJAPI mjsKey* mjs_asKey(mjsElement* element);
+
+// Safely cast an element as mjsMesh, or return NULL if the element is not an mjsMesh.
+MJAPI mjsMesh* mjs_asMesh(mjsElement* element);
+
+// Safely cast an element as mjsHField, or return NULL if the element is not an mjsHField.
+MJAPI mjsHField* mjs_asHField(mjsElement* element);
+
+// Safely cast an element as mjsSkin, or return NULL if the element is not an mjsSkin.
+MJAPI mjsSkin* mjs_asSkin(mjsElement* element);
+
+// Safely cast an element as mjsTexture, or return NULL if the element is not an mjsTexture.
+MJAPI mjsTexture* mjs_asTexture(mjsElement* element);
+
+// Safely cast an element as mjsMaterial, or return NULL if the element is not an mjsMaterial.
+MJAPI mjsMaterial* mjs_asMaterial(mjsElement* element);
+
 
 //---------------------------------- Attribute setters ---------------------------------------------
 
@@ -1612,9 +1684,6 @@ MJAPI void mjs_setFrame(mjsElement* dest, mjsFrame* frame);
 MJAPI const char* mjs_resolveOrientation(double quat[4], mjtByte degree, const char* sequence,
                                          const mjsOrientation* orientation);
 
-// Compute quat and diag inertia from full inertia matrix, return error if any.
-MJAPI const char* mjs_fullInertia(double quat[4], double inertia[3], const double fullinertia[6]);
-
 
 //---------------------------------- Element initialization  ---------------------------------------
 

introspect/codegen/generate_structs.py

@@ -166,9 +166,15 @@ class MjStructVisitor:
     elif (node.get('kind') == 'TypedefDecl' and
           node['type']['qualType'].startswith('struct mj') and
           node['name'] not in _EXCLUDED):
-      struct = self._structs[node['type']['qualType']]
+      declname = node['type']['qualType']
-      self._typedefs[node['name']] = ast_nodes.StructDecl(
+      try:
-          name=node['name'], declname=struct.declname, fields=struct.fields)
+        struct = self._structs[declname]
+      except KeyError:
+        self._typedefs[node['name']] = ast_nodes.StructDecl(
+            name=node['name'], declname=declname, fields=())
+      else:
+        self._typedefs[node['name']] = ast_nodes.StructDecl(
+            name=node['name'], declname=struct.declname, fields=struct.fields)
 
   def resolve_all_anonymous(self) -> None:
     """Replaces anonymous struct placeholders with corresponding decl."""

introspect/enums.py

@@ -800,4 +800,14 @@ ENUMS: Mapping[str, EnumDecl] = dict([
              ('mjNITEM', 14),
          ]),
      )),
+    ('mjtSection',
+     EnumDecl(
+         name='mjtSection',
+         declname='enum mjtSection_',
+         values=dict([
+             ('mjSECT_CLOSED', 0),
+             ('mjSECT_OPEN', 1),
+             ('mjSECT_FIXED', 2),
+         ]),
+     )),
 ])

introspect/functions.py

@@ -38,7 +38,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  ),
              ),
          ),
-         doc='Initialize VFS to empty (no deallocation).',
+         doc='Initialize an empty VFS, mj_deleteVFS must be called to deallocate the VFS.',  # pylint: disable=line-too-long
      )),
     ('mj_addFileVFS',
      FunctionDecl(
@@ -96,26 +96,6 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Add file to VFS from buffer, return 0: success, 1: full, 2: repeated name, -1: failed to load.',  # pylint: disable=line-too-long
      )),
-    ('mj_findFileVFS',
-     FunctionDecl(
-         name='mj_findFileVFS',
-         return_type=ValueType(name='int'),
-         parameters=(
-             FunctionParameterDecl(
-                 name='vfs',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjVFS', is_const=True),
-                 ),
-             ),
-             FunctionParameterDecl(
-                 name='filename',
-                 type=PointerType(
-                     inner_type=ValueType(name='char', is_const=True),
-                 ),
-             ),
-         ),
-         doc='Return file index in VFS, or -1 if not found in VFS.',
-     )),
     ('mj_deleteFileVFS',
      FunctionDecl(
          name='mj_deleteFileVFS',
@@ -148,31 +128,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  ),
              ),
          ),
-         doc='Delete all files from VFS.',
+         doc='Delete all files from VFS and deallocates VFS internal memory.',
-     )),
-    ('mj_makeEmptyFileVFS',
-     FunctionDecl(
-         name='mj_makeEmptyFileVFS',
-         return_type=ValueType(name='int'),
-         parameters=(
-             FunctionParameterDecl(
-                 name='vfs',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjVFS'),
-                 ),
-             ),
-             FunctionParameterDecl(
-                 name='filename',
-                 type=PointerType(
-                     inner_type=ValueType(name='char', is_const=True),
-                 ),
-             ),
-             FunctionParameterDecl(
-                 name='filesize',
-                 type=ValueType(name='int'),
-             ),
-         ),
-         doc='deprecated: use mj_copyBufferVFS.',
      )),
     ('mj_loadXML',
      FunctionDecl(
@@ -9543,13 +9499,9 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  ),
              ),
              FunctionParameterDecl(
-                 name='parentid',
+                 name='parent',
-                 type=ValueType(name='int'),
-             ),
-             FunctionParameterDecl(
-                 name='id',
                  type=PointerType(
-                     inner_type=ValueType(name='int'),
+                     inner_type=ValueType(name='mjsDefault', is_const=True),
                  ),
              ),
          ),
@@ -9751,6 +9703,28 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Find frame by name.',
      )),
+    ('mjs_findKeyframe',
+     FunctionDecl(
+         name='mjs_findKeyframe',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsKey'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='s',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjSpec'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='name',
+                 type=PointerType(
+                     inner_type=ValueType(name='char', is_const=True),
+                 ),
+             ),
+         ),
+         doc='Find keyframe by name.',
+     )),
     ('mjs_getDefault',
      FunctionDecl(
          name='mjs_getDefault',
@@ -9861,6 +9835,416 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc="Return body's next child of the same type; return NULL if child is last.",  # pylint: disable=line-too-long
      )),
+    ('mjs_firstElement',
+     FunctionDecl(
+         name='mjs_firstElement',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsElement'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='s',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjSpec'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='type',
+                 type=ValueType(name='mjtObj'),
+             ),
+         ),
+         doc="Return spec's first element of selected type.",
+     )),
+    ('mjs_nextElement',
+     FunctionDecl(
+         name='mjs_nextElement',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsElement'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='s',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjSpec'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc="Return spec's next element; return NULL if element is last.",
+     )),
+    ('mjs_asBody',
+     FunctionDecl(
+         name='mjs_asBody',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsBody'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsBody, or return NULL if the element is not an mjsBody.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asGeom',
+     FunctionDecl(
+         name='mjs_asGeom',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsGeom'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsGeom, or return NULL if the element is not an mjsGeom.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asJoint',
+     FunctionDecl(
+         name='mjs_asJoint',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsJoint'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsJoint, or return NULL if the element is not an mjsJoint.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asSite',
+     FunctionDecl(
+         name='mjs_asSite',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsSite'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsSite, or return NULL if the element is not an mjsSite.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asCamera',
+     FunctionDecl(
+         name='mjs_asCamera',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsCamera'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsCamera, or return NULL if the element is not an mjsCamera.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asLight',
+     FunctionDecl(
+         name='mjs_asLight',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsLight'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsLight, or return NULL if the element is not an mjsLight.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asFrame',
+     FunctionDecl(
+         name='mjs_asFrame',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsFrame'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsFrame, or return NULL if the element is not an mjsFrame.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asActuator',
+     FunctionDecl(
+         name='mjs_asActuator',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsActuator'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsActuator, or return NULL if the element is not an mjsActuator.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asSensor',
+     FunctionDecl(
+         name='mjs_asSensor',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsSensor'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsSensor, or return NULL if the element is not an mjsSensor.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asFlex',
+     FunctionDecl(
+         name='mjs_asFlex',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsFlex'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsFlex, or return NULL if the element is not an mjsFlex.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asPair',
+     FunctionDecl(
+         name='mjs_asPair',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsPair'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsPair, or return NULL if the element is not an mjsPair.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asEquality',
+     FunctionDecl(
+         name='mjs_asEquality',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsEquality'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsEquality, or return NULL if the element is not an mjsEquality.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asExclude',
+     FunctionDecl(
+         name='mjs_asExclude',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsExclude'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsExclude, or return NULL if the element is not an mjsExclude.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asTendon',
+     FunctionDecl(
+         name='mjs_asTendon',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsTendon'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsTendon, or return NULL if the element is not an mjsTendon.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asNumeric',
+     FunctionDecl(
+         name='mjs_asNumeric',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsNumeric'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsNumeric, or return NULL if the element is not an mjsNumeric.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asText',
+     FunctionDecl(
+         name='mjs_asText',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsText'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsText, or return NULL if the element is not an mjsText.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asTuple',
+     FunctionDecl(
+         name='mjs_asTuple',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsTuple'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsTuple, or return NULL if the element is not an mjsTuple.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asKey',
+     FunctionDecl(
+         name='mjs_asKey',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsKey'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsKey, or return NULL if the element is not an mjsKey.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asMesh',
+     FunctionDecl(
+         name='mjs_asMesh',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsMesh'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsMesh, or return NULL if the element is not an mjsMesh.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asHField',
+     FunctionDecl(
+         name='mjs_asHField',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsHField'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsHField, or return NULL if the element is not an mjsHField.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asSkin',
+     FunctionDecl(
+         name='mjs_asSkin',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsSkin'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsSkin, or return NULL if the element is not an mjsSkin.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asTexture',
+     FunctionDecl(
+         name='mjs_asTexture',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsTexture'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsTexture, or return NULL if the element is not an mjsTexture.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_asMaterial',
+     FunctionDecl(
+         name='mjs_asMaterial',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsMaterial'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc='Safely cast an element as mjsMaterial, or return NULL if the element is not an mjsMaterial.',  # pylint: disable=line-too-long
+     )),
     ('mjs_setString',
      FunctionDecl(
          name='mjs_setString',
@@ -10216,37 +10600,6 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Resolve alternative orientations to quat, return error if any.',
      )),
-    ('mjs_fullInertia',
-     FunctionDecl(
-         name='mjs_fullInertia',
-         return_type=PointerType(
-             inner_type=ValueType(name='char', is_const=True),
-         ),
-         parameters=(
-             FunctionParameterDecl(
-                 name='quat',
-                 type=ArrayType(
-                     inner_type=ValueType(name='double'),
-                     extents=(4,),
-                 ),
-             ),
-             FunctionParameterDecl(
-                 name='inertia',
-                 type=ArrayType(
-                     inner_type=ValueType(name='double'),
-                     extents=(3,),
-                 ),
-             ),
-             FunctionParameterDecl(
-                 name='fullinertia',
-                 type=ArrayType(
-                     inner_type=ValueType(name='double', is_const=True),
-                     extents=(6,),
-                 ),
-             ),
-         ),
-         doc='Compute quat and diag inertia from full inertia matrix, return error if any.',  # pylint: disable=line-too-long
-     )),
     ('mjs_defaultSpec',
      FunctionDecl(
          name='mjs_defaultSpec',

introspect/structs.py

@@ -91,43 +91,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
          declname='struct mjVFS_',
          fields=(
              StructFieldDecl(
-                 name='nfile',
+                 name='impl_',
-                 type=ValueType(name='int'),
+                 type=PointerType(
-                 doc='number of files present',
+                     inner_type=ValueType(name='void'),
-             ),
-             StructFieldDecl(
-                 name='filename',
-                 type=ArrayType(
-                     inner_type=ValueType(name='char'),
-                     extents=(2000, 1000),
                  ),
-                 doc='file name without path',
+                 doc='internal pointer to VFS memory',
-             ),
-             StructFieldDecl(
-                 name='filesize',
-                 type=ArrayType(
-                     inner_type=ValueType(name='size_t'),
-                     extents=(2000,),
-                 ),
-                 doc='file size in bytes',
-             ),
-             StructFieldDecl(
-                 name='filedata',
-                 type=ArrayType(
-                     inner_type=PointerType(
-                         inner_type=ValueType(name='void'),
-                     ),
-                     extents=(2000,),
-                 ),
-                 doc='buffer with file data',
-             ),
-             StructFieldDecl(
-                 name='filestamp',
-                 type=ArrayType(
-                     inner_type=ValueType(name='uint64_t'),
-                     extents=(2000,),
-                 ),
-                 doc='checksum of the file data',
              ),
          ),
      )),
@@ -2950,7 +2918,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=PointerType(
                      inner_type=ValueType(name='int'),
                  ),
-                 doc='texture id; -1: none                     (nmat x 1)',
+                 doc='indices of textures; -1: none            (nmat x mjNTEXMAT)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='mat_texuniform',
@@ -4183,7 +4151,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
              StructFieldDecl(
                  name='pstack',
                  type=ValueType(name='size_t'),
-                 doc='first available mjtNum address in stack',
+                 doc='first available byte in stack',
              ),
              StructFieldDecl(
                  name='pbase',
@@ -4223,22 +4191,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='int'),
                  doc='maximum number of scalar constraints',
              ),
-             StructFieldDecl(
-                 name='warning',
-                 type=ArrayType(
-                     inner_type=ValueType(name='mjWarningStat'),
-                     extents=(8,),
-                 ),
-                 doc='warning statistics',
-             ),
-             StructFieldDecl(
-                 name='timer',
-                 type=ArrayType(
-                     inner_type=ValueType(name='mjTimerStat'),
-                     extents=(15,),
-                 ),
-                 doc='timer statistics',
-             ),
              StructFieldDecl(
                  name='solver',
                  type=ArrayType(
@@ -4266,7 +4218,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                      inner_type=ValueType(name='int'),
                      extents=(20,),
                  ),
-                 doc='number of non-zeros in Hessian or efc_AR, per island',
+                 doc='number of nonzeros in Hessian or efc_AR, per island',
              ),
              StructFieldDecl(
                  name='solver_fwdinv',
@@ -4276,6 +4228,22 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='forward-inverse comparison: qfrc, efc',
              ),
+             StructFieldDecl(
+                 name='warning',
+                 type=ArrayType(
+                     inner_type=ValueType(name='mjWarningStat'),
+                     extents=(8,),
+                 ),
+                 doc='warning statistics',
+             ),
+             StructFieldDecl(
+                 name='timer',
+                 type=ArrayType(
+                     inner_type=ValueType(name='mjTimerStat'),
+                     extents=(15,),
+                 ),
+                 doc='timer statistics',
+             ),
              StructFieldDecl(
                  name='ne',
                  type=ValueType(name='int'),
@@ -4329,14 +4297,14 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=PointerType(
                      inner_type=ValueType(name='void'),
                  ),
-                 doc='main buffer; all pointers point in it                (nbuffer bytes)',  # pylint: disable=line-too-long
+                 doc='main buffer; all pointers point in it            (nbuffer bytes)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='arena',
                  type=PointerType(
                      inner_type=ValueType(name='void'),
                  ),
-                 doc='arena+stack buffer                     (nstack*sizeof(mjtNum) bytes)',  # pylint: disable=line-too-long
+                 doc='arena+stack buffer                               (narena bytes)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='qpos',
@@ -4756,7 +4724,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=PointerType(
                      inner_type=ValueType(name='mjtByte'),
                  ),
-                 doc='volume has been added to collisions              (nbvh x 1)',  # pylint: disable=line-too-long
+                 doc='was bounding volume checked for collision        (nbvh x 1)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='flexedge_velocity',
@@ -4987,7 +4955,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=PointerType(
                      inner_type=ValueType(name='mjContact'),
                  ),
-                 doc='list of all detected contacts                    (ncon x 1)',  # pylint: disable=line-too-long
+                 doc='array of all detected contacts                   (ncon x 1)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='efc_type',
@@ -5239,26 +5207,26 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=PointerType(
                      inner_type=ValueType(name='mjtNum'),
                  ),
-                 doc='linear cost term: J*qacc_smooth - aref            (nefc x 1)',  # pylint: disable=line-too-long
+                 doc='linear cost term: J*qacc_smooth - aref           (nefc x 1)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='efc_force',
                  type=PointerType(
                      inner_type=ValueType(name='mjtNum'),
                  ),
-                 doc='constraint force in constraint space              (nefc x 1)',  # pylint: disable=line-too-long
+                 doc='constraint force in constraint space             (nefc x 1)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='efc_state',
                  type=PointerType(
                      inner_type=ValueType(name='int'),
                  ),
-                 doc='constraint state (mjtConstraintState)             (nefc x 1)',  # pylint: disable=line-too-long
+                 doc='constraint state (mjtConstraintState)            (nefc x 1)',  # pylint: disable=line-too-long
              ),
              StructFieldDecl(
                  name='threadpool',
                  type=ValueType(name='uintptr_t'),
-                 doc='ThreadPool for multithreaded operations',
+                 doc='thread pool pointer',
              ),
          ),
      )),
@@ -5483,14 +5451,9 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  doc='visual category',
              ),
              StructFieldDecl(
-                 name='texid',
+                 name='matid',
                  type=ValueType(name='int'),
-                 doc='texture id; -1: no texture',
+                 doc='material id; -1: no textured material',
-             ),
-             StructFieldDecl(
-                 name='texuniform',
-                 type=ValueType(name='int'),
-                 doc='uniform cube mapping',
              ),
              StructFieldDecl(
                  name='texcoord',
@@ -5502,14 +5465,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='int'),
                  doc='segmentation id; -1: not shown',
              ),
-             StructFieldDecl(
-                 name='texrepeat',
-                 type=ArrayType(
-                     inner_type=ValueType(name='float'),
-                     extents=(2,),
-                 ),
-                 doc='texture repetition for 2D mapping',
-             ),
              StructFieldDecl(
                  name='size',
                  type=ArrayType(
@@ -7957,7 +7912,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
              StructFieldDecl(
                  name='offDepthStencil_r',
                  type=ValueType(name='unsigned int'),
-                 doc='offscreen depth and stencil buffer for resolving multisamples',  # pylint: disable=line-too-long
+                 doc='offscreen depth and stencil buffer for multisamples',
              ),
              StructFieldDecl(
                  name='shadowFBO',
@@ -8001,6 +7956,30 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='auxiliary color buffer for resolving',
              ),
+             StructFieldDecl(
+                 name='mat_texid',
+                 type=ArrayType(
+                     inner_type=ValueType(name='int'),
+                     extents=(600,),
+                 ),
+                 doc='material texture ids (-1: no texture)',
+             ),
+             StructFieldDecl(
+                 name='mat_texuniform',
+                 type=ArrayType(
+                     inner_type=ValueType(name='int'),
+                     extents=(100,),
+                 ),
+                 doc='texture repetition for 2d mapping',
+             ),
+             StructFieldDecl(
+                 name='mat_texrepeat',
+                 type=ArrayType(
+                     inner_type=ValueType(name='int'),
+                     extents=(200,),
+                 ),
+                 doc='texture repetition for 2d mapping',
+             ),
              StructFieldDecl(
                  name='ntexture',
                  type=ValueType(name='int'),
@@ -8035,12 +8014,12 @@ STRUCTS: Mapping[str, StructDecl] = dict([
              StructFieldDecl(
                  name='baseHField',
                  type=ValueType(name='unsigned int'),
-                 doc='all hfields from model',
+                 doc='all height fields from model',
              ),
              StructFieldDecl(
                  name='baseBuiltin',
                  type=ValueType(name='unsigned int'),
-                 doc='all buildin geoms, with quality from model',
+                 doc='all builtin geoms, with quality from model',
              ),
              StructFieldDecl(
                  name='baseFontNormal',
@@ -8255,7 +8234,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  doc='angles in radians or degrees',
              ),
              StructFieldDecl(
-                 name='euler',
+                 name='eulerseq',
                  type=ArrayType(
                      inner_type=ValueType(name='char'),
                      extents=(3,),
@@ -8719,13 +8698,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtJoint'),
@@ -8893,13 +8865,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='classname',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtGeom'),
@@ -9108,13 +9073,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(
@@ -9212,13 +9170,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(
@@ -9358,13 +9309,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(
@@ -9483,13 +9427,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='contype',
                  type=ValueType(name='int'),
@@ -9665,13 +9602,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='content_type',
                  type=PointerType(
@@ -9862,13 +9792,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='file',
                  type=PointerType(
@@ -9985,13 +9908,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtTexture'),
@@ -10121,13 +10037,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='texture',
                  type=PointerType(
@@ -10214,13 +10123,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='geomname1',
                  type=PointerType(
@@ -10352,13 +10254,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtEq'),
@@ -10435,13 +10330,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='stiffness',
                  type=ValueType(name='double'),
@@ -10596,13 +10484,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='gaintype',
                  type=ValueType(name='mjtGain'),
@@ -10793,13 +10674,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='name',
              ),
-             StructFieldDecl(
-                 name='classname',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtSensor'),
@@ -11350,6 +11224,16 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='int'),
                  doc='section gap',
              ),
+             StructFieldDecl(
+                 name='cornersect',
+                 type=ValueType(name='int'),
+                 doc='corner radius for section',
+             ),
+             StructFieldDecl(
+                 name='cornersep',
+                 type=ValueType(name='int'),
+                 doc='corner radius for separator',
+             ),
              StructFieldDecl(
                  name='itemside',
                  type=ValueType(name='int'),
@@ -11416,6 +11300,30 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='section title',
              ),
+             StructFieldDecl(
+                 name='secttitle2',
+                 type=ArrayType(
+                     inner_type=ValueType(name='float'),
+                     extents=(3,),
+                 ),
+                 doc='section title: bottom color',
+             ),
+             StructFieldDecl(
+                 name='secttitlecheck',
+                 type=ArrayType(
+                     inner_type=ValueType(name='float'),
+                     extents=(3,),
+                 ),
+                 doc='section title with checkbox',
+             ),
+             StructFieldDecl(
+                 name='secttitlecheck2',
+                 type=ArrayType(
+                     inner_type=ValueType(name='float'),
+                     extents=(3,),
+                 ),
+                 doc='section title with checkbox: bottom color',
+             ),
              StructFieldDecl(
                  name='sectfont',
                  type=ArrayType(
@@ -11440,6 +11348,22 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='section pane',
              ),
+             StructFieldDecl(
+                 name='separator',
+                 type=ArrayType(
+                     inner_type=ValueType(name='float'),
+                     extents=(3,),
+                 ),
+                 doc='separator title',
+             ),
+             StructFieldDecl(
+                 name='separator2',
+                 type=ArrayType(
+                     inner_type=ValueType(name='float'),
+                     extents=(3,),
+                 ),
+                 doc='separator title: bottom color',
+             ),
              StructFieldDecl(
                  name='shortcut',
                  type=ArrayType(
@@ -11602,6 +11526,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='int'),
                  doc='id of item within section',
              ),
+             StructFieldDecl(
+                 name='userid',
+                 type=ValueType(name='int'),
+                 doc='user-supplied id (for event handling)',
+             ),
              AnonymousUnionDecl(
                  fields=(
                      StructFieldDecl(
@@ -11631,6 +11560,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='mjrRect'),
                  doc='rectangle occupied by item',
              ),
+             StructFieldDecl(
+                 name='skip',
+                 type=ValueType(name='int'),
+                 doc='item skipped due to closed separator',
+             ),
          ),
      )),
     ('mjuiSection',
@@ -11649,7 +11583,7 @@ STRUCTS: Mapping[str, StructDecl] = dict([
              StructFieldDecl(
                  name='state',
                  type=ValueType(name='int'),
-                 doc='0: closed, 1: open',
+                 doc='section state (mjtSection)',
              ),
              StructFieldDecl(
                  name='modifier',
@@ -11661,6 +11595,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='int'),
                  doc='shortcut key; 0: undefined',
              ),
+             StructFieldDecl(
+                 name='checkbox',
+                 type=ValueType(name='int'),
+                 doc='0: none, 1: hidden, 2: unchecked, 2: checked',
+             ),
              StructFieldDecl(
                  name='nitem',
                  type=ValueType(name='int'),
@@ -11684,6 +11623,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='mjrRect'),
                  doc='rectangle occupied by content',
              ),
+             StructFieldDecl(
+                 name='lastclick',
+                 type=ValueType(name='int'),
+                 doc='last mouse click over this section',
+             ),
          ),
      )),
     ('mjUI',
@@ -11763,6 +11707,16 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='int'),
                  doc='help button down: print shortcuts',
              ),
+             StructFieldDecl(
+                 name='mouseclicks',
+                 type=ValueType(name='int'),
+                 doc='number of mouse clicks over UI',
+             ),
+             StructFieldDecl(
+                 name='mousesectcheck',
+                 type=ValueType(name='int'),
+                 doc='0: none, otherwise 1+section',
+             ),
              StructFieldDecl(
                  name='editsect',
                  type=ValueType(name='int'),
@@ -11851,6 +11805,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='string with type-specific properties',
              ),
+             StructFieldDecl(
+                 name='otherint',
+                 type=ValueType(name='int'),
+                 doc='int with type-specific properties',
+             ),
          ),
      )),
 ])

mjx/requirements.txt

@@ -32,9 +32,7 @@ jaxlib==0.4.18; python_version >= '3.9' \
     --hash=sha256:f7787a5531d226d6cc9ec2baa7141260bb713435e1cfc053cb9f5cefa9756ac3 \
     --hash=sha256:6cb20bbbdafd90e71ad0deb9295519a0175c108c8c557b84fb9fe94f751daee4 \
     --hash=sha256:116a0d6aedd3e856b52493d7e392fb1b40952b84fb72448fde1c1ab5687db667 \
-    --hash=sha256:9593ff69f424947567e206f3e356b2a2df55ca68e6d815d5adc6cae308e8f652 \
+    --hash=sha256:9593ff69f424947567e206f3e356b2a2df55ca68e6d815d5adc6cae308e8f652
-    --hash=sha256:2b17b3f05b3bbf8e0ddb85fba339525ac03bac21c9f26d0f83dcea1b1654353e \
-    --hash=sha256:b35ec08984e2aa5e96ba3f3f8b88e90dee0283649e037f213dec8e85638fa17d
 pip==23.3.1 \
     --hash=sha256:55eb67bb6171d37447e82213be585b75fe2b12b359e993773aca4de9247a052b
 pytest==7.4.2 \

mjx/training_apg.ipynb

@@ -1,39 +1,39 @@
 {
  "cells": [
   {
-    "cell_type": "markdown",
+   "cell_type": "markdown",
-    "metadata": {
+   "metadata": {
-     "id": "MpkYHwCqk7W-"
+    "id": "MpkYHwCqk7W-"
-    },
-    "source": [
-     "![MuJoCo banner](https://raw.githubusercontent.com/google-deepmind/mujoco/main/banner.png)\n",
-     "\n",
-     "# <h1><center>Tutorial  <a href=\"https://colab.research.google.com/github/google-deepmind/mujoco/blob/main/mjx/training_apg.ipynb\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" width=\"140\" align=\"center\"/></a></center></h1>\n",
-     "\n",
-     "This notebook provides a tutorial for differentiable physics for policy learning in [**MuJoCo XLA (MJX)**](https://github.com/google-deepmind/mujoco/blob/main/mjx), a JAX-based implementation of MuJoCo.\n",
-     "\n",
-     "**A Colab runtime with GPU acceleration is required.** If you're using a CPU-only runtime, you can switch using the menu \"Runtime > Change runtime type\".\n",
-     "\n",
-     "\n",
-     "This notebook was written by [Jing Yuan Luo](https://github.com/Andrew-Luo1).\n",
-     "\n",
-     "\u003c!-- Copyright 2021 DeepMind Technologies Limited\n",
-     "\n",
-     "     Licensed under the Apache License, Version 2.0 (the \"License\");\n",
-     "     you may not use this file except in compliance with the License.\n",
-     "     You may obtain a copy of the License at\n",
-     "\n",
-     "         http://www.apache.org/licenses/LICENSE-2.0\n",
-     "\n",
-     "     Unless required by applicable law or agreed to in writing, software\n",
-     "     distributed under the License is distributed on an \"AS IS\" BASIS,\n",
-     "     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n",
-     "     See the License for the specific language governing permissions and\n",
-     "     limitations under the License.\n",
-     "--\u003e"
-    ]
    },
-   {
+   "source": [
+    "![MuJoCo banner](https://raw.githubusercontent.com/google-deepmind/mujoco/main/banner.png)\n",
+    "\n",
+    "# <h1><center>Tutorial  <a href=\"https://colab.research.google.com/github/google-deepmind/mujoco/blob/main/mjx/training_apg.ipynb\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" width=\"140\" align=\"center\"/></a></center></h1>\n",
+    "\n",
+    "This notebook provides a tutorial for differentiable physics for policy learning in [**MuJoCo XLA (MJX)**](https://github.com/google-deepmind/mujoco/blob/main/mjx), a JAX-based implementation of MuJoCo.\n",
+    "\n",
+    "**A Colab runtime with GPU acceleration is required.** If you're using a CPU-only runtime, you can switch using the menu \"Runtime > Change runtime type\".\n",
+    "\n",
+    "\n",
+    "This notebook was written by [Jing Yuan Luo](https://github.com/Andrew-Luo1).\n",
+    "\n",
+    "<!-- Copyright 2021 DeepMind Technologies Limited\n",
+    "\n",
+    "     Licensed under the Apache License, Version 2.0 (the \"License\");\n",
+    "     you may not use this file except in compliance with the License.\n",
+    "     You may obtain a copy of the License at\n",
+    "\n",
+    "         http://www.apache.org/licenses/LICENSE-2.0\n",
+    "\n",
+    "     Unless required by applicable law or agreed to in writing, software\n",
+    "     distributed under the License is distributed on an \"AS IS\" BASIS,\n",
+    "     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n",
+    "     See the License for the specific language governing permissions and\n",
+    "     limitations under the License.\n",
+    "-->"
+   ]
+  },
+  {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
@@ -106,12 +106,97 @@
     "## Setup: Imports and installations"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": 0,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Install MuJoCo, MJX, and Brax\n",
+    "!pip install mujoco\n",
+    "!pip install mujoco_mjx\n",
+    "!pip install brax"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 0,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#@title Check if MuJoCo installation was successful\n",
+    "\n",
+    "# Set up GPU rendering.\n",
+    "from google.colab import files\n",
+    "import distutils.util\n",
+    "import os\n",
+    "import subprocess\n",
+    "if subprocess.run('nvidia-smi').returncode:\n",
+    "  raise RuntimeError(\n",
+    "      'Cannot communicate with GPU. '\n",
+    "      'Make sure you are using a GPU Colab runtime. '\n",
+    "      'Go to the Runtime menu and select Choose runtime type.')\n",
+    "\n",
+    "# Add an ICD config so that glvnd can pick up the Nvidia EGL driver.\n",
+    "# This is usually installed as part of an Nvidia driver package, but the Colab\n",
+    "# kernel doesn't install its driver via APT, and as a result the ICD is missing.\n",
+    "# (https://github.com/NVIDIA/libglvnd/blob/master/src/EGL/icd_enumeration.md)\n",
+    "NVIDIA_ICD_CONFIG_PATH = '/usr/share/glvnd/egl_vendor.d/10_nvidia.json'\n",
+    "if not os.path.exists(NVIDIA_ICD_CONFIG_PATH):\n",
+    "  with open(NVIDIA_ICD_CONFIG_PATH, 'w') as f:\n",
+    "    f.write(\"\"\"{\n",
+    "    \"file_format_version\" : \"1.0.0\",\n",
+    "    \"ICD\" : {\n",
+    "        \"library_path\" : \"libEGL_nvidia.so.0\"\n",
+    "    }\n",
+    "}\n",
+    "\"\"\")\n",
+    "\n",
+    "# Configure MuJoCo to use the EGL rendering backend (requires GPU)\n",
+    "print('Setting environment variable to use GPU rendering:')\n",
+    "%env MUJOCO_GL=egl\n",
+    "\n",
+    "# Check if installation was succesful.\n",
+    "try:\n",
+    "  print('Checking that the installation succeeded:')\n",
+    "  import mujoco\n",
+    "  mujoco.MjModel.from_xml_string('<mujoco/>')\n",
+    "except Exception as e:\n",
+    "  raise e from RuntimeError(\n",
+    "      'Something went wrong during installation. Check the shell output above '\n",
+    "      'for more information.\\n'\n",
+    "      'If using a hosted Colab runtime, make sure you enable GPU acceleration '\n",
+    "      'by going to the Runtime menu and selecting \"Choose runtime type\".')\n",
+    "\n",
+    "print('Installation successful.')\n",
+    "\n",
+    "# Other imports and helper functions\n",
+    "import time\n",
+    "import itertools\n",
+    "import numpy as np\n",
+    "\n",
+    "# Graphics and plotting.\n",
+    "print('Installing mediapy:')\n",
+    "!command -v ffmpeg >/dev/null || (apt update && apt install -y ffmpeg)\n",
+    "!pip install -q mediapy\n",
+    "import mediapy as media\n",
+    "import matplotlib.pyplot as plt\n",
+    "\n",
+    "# More legible printing from numpy.\n",
+    "np.set_printoptions(precision=3, suppress=True, linewidth=100)\n",
+    "\n",
+    "from IPython.display import clear_output\n",
+    "clear_output()"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 1,
    "metadata": {},
    "outputs": [],
    "source": [
+    "#@title Import MuJoCo, MJX, and Brax\n",
+    "\n",
     "import os\n",
     "os.environ[\"XLA_PYTHON_CLIENT_MEM_FRACTION\"] = \"0.8\" # 0.9 causes too much lag. \n",
     "from datetime import datetime\n",
@@ -162,7 +247,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 0,
    "metadata": {},
    "outputs": [],
    "source": [

model/hammock/humanoid_body.xml

@@ -25,7 +25,7 @@
   <asset>
     <texture type="skybox" builtin="gradient" rgb1=".3 .5 .7" rgb2="0 0 0" width="512" height="512"/>
     <texture name="body" type="cube" builtin="flat" mark="cross" width="128" height="128"
-             rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1" random="0.01"/>
+             rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1"/>
     <material name="body" texture="body" texuniform="true" rgba="0.8 0.6 .4 1"/>
     <texture name="grid" type="2d" builtin="checker" width="512" height="512" rgb1=".1 .2 .3" rgb2=".2 .3 .4"/>
     <material name="grid" texture="grid" texrepeat="1 1" texuniform="true" reflectance=".2"/>

model/humanoid/22_humanoids.xml

@@ -21,7 +21,7 @@
   <asset>
     <texture type="skybox" builtin="gradient" rgb1=".3 .5 .7" rgb2="0 0 0" width="512" height="512"/>
     <texture name="body" type="cube" builtin="flat" mark="cross" width="128" height="128"
-             rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1" random="0.01"/>
+             rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1"/>
     <material name="body" texture="body" texuniform="true" rgba="0.8 0.6 .4 1"/>
     <texture name="grid" type="2d" builtin="checker" width="512" height="512" rgb1=".1 .2 .3" rgb2=".2 .3 .4"/>
     <material name="grid" texture="grid" texrepeat="1 1" texuniform="true" reflectance=".2"/>

model/humanoid/humanoid.xml

@@ -26,7 +26,7 @@
 
   <asset>
     <texture type="skybox" builtin="gradient" rgb1=".3 .5 .7" rgb2="0 0 0" width="32" height="512"/>
-    <texture name="body" type="cube" builtin="flat" mark="cross" width="128" height="128" rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1" random="0.01"/>
+    <texture name="body" type="cube" builtin="flat" mark="cross" width="128" height="128" rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1"/>
     <material name="body" texture="body" texuniform="true" rgba="0.8 0.6 .4 1"/>
     <texture name="grid" type="2d" builtin="checker" width="512" height="512" rgb1=".1 .2 .3" rgb2=".2 .3 .4"/>
     <material name="grid" texture="grid" texrepeat="1 1" texuniform="true" reflectance=".2"/>

model/humanoid100/humanoid_body.xml

@@ -25,7 +25,7 @@
   <asset>
     <texture type="skybox" builtin="gradient" rgb1=".3 .5 .7" rgb2="0 0 0" width="512" height="512"/>
     <texture name="body" type="cube" builtin="flat" mark="cross" width="128" height="128"
-             rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1" random="0.01"/>
+             rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" markrgb="1 1 1"/>
     <material name="body" texture="body" texuniform="true" rgba="0.8 0.6 .4 1"/>
     <texture name="grid" type="2d" builtin="checker" width="512" height="512" rgb1=".1 .2 .3" rgb2=".2 .3 .4"/>
     <material name="grid" texture="grid" texrepeat="1 1" texuniform="true" reflectance=".2"/>

plugin/sdf/bolt.cc

@@ -148,7 +148,7 @@ void Bolt::RegisterPlugin() {
     delete reinterpret_cast<Bolt*>(d->plugin_data[instance]);
     d->plugin_data[instance] = 0;
   };
-  plugin.reset = +[](const mjModel* m, double* plugin_state, void* plugin_data,
+  plugin.reset = +[](const mjModel* m, mjtNum* plugin_state, void* plugin_data,
                      int instance) {
     auto sdf = reinterpret_cast<Bolt*>(plugin_data);
     sdf->Reset();

plugin/sdf/bowl.cc

@@ -146,7 +146,7 @@ void Bowl::RegisterPlugin() {
     delete reinterpret_cast<Bowl*>(d->plugin_data[instance]);
     d->plugin_data[instance] = 0;
   };
-  plugin.reset = +[](const mjModel* m, double* plugin_state, void* plugin_data,
+  plugin.reset = +[](const mjModel* m, mjtNum* plugin_state, void* plugin_data,
                      int instance) {
     auto sdf = reinterpret_cast<Bowl*>(plugin_data);
     sdf->Reset();

plugin/sdf/gear.cc

@@ -232,7 +232,7 @@ void Gear::RegisterPlugin() {
     delete reinterpret_cast<Gear*>(d->plugin_data[instance]);
     d->plugin_data[instance] = 0;
   };
-  plugin.reset = +[](const mjModel* m, double* plugin_state, void* plugin_data,
+  plugin.reset = +[](const mjModel* m, mjtNum* plugin_state, void* plugin_data,
                      int instance) {
     auto sdf = reinterpret_cast<Gear*>(plugin_data);
     sdf->Reset();

plugin/sdf/nut.cc

@@ -148,7 +148,7 @@ void Nut::RegisterPlugin() {
     delete reinterpret_cast<Nut*>(d->plugin_data[instance]);
     d->plugin_data[instance] = 0;
   };
-  plugin.reset = +[](const mjModel* m, double* plugin_state, void* plugin_data,
+  plugin.reset = +[](const mjModel* m, mjtNum* plugin_state, void* plugin_data,
                      int instance) {
     auto sdf = reinterpret_cast<Nut*>(plugin_data);
     sdf->Reset();

plugin/sdf/sdflib.cc

@@ -180,7 +180,7 @@ void SdfLib::RegisterPlugin() {
     delete reinterpret_cast<SdfLib*>(d->plugin_data[instance]);
     d->plugin_data[instance] = 0;
   };
-  plugin.reset = +[](const mjModel* m, double* plugin_state, void* plugin_data,
+  plugin.reset = +[](const mjModel* m, mjtNum* plugin_state, void* plugin_data,
                      int instance) {
     auto sdf = reinterpret_cast<SdfLib*>(plugin_data);
     sdf->Reset();

plugin/sdf/torus.cc

@@ -95,7 +95,7 @@ void Torus::RegisterPlugin() {
     delete reinterpret_cast<Torus*>(d->plugin_data[instance]);
     d->plugin_data[instance] = 0;
   };
-  plugin.reset = +[](const mjModel* m, double* plugin_state, void* plugin_data,
+  plugin.reset = +[](const mjModel* m, mjtNum* plugin_state, void* plugin_data,
                      int instance) {
     // do nothing
   };

python/MANIFEST.in

@@ -1,3 +1,3 @@
 include LICENSE *.md
-recursive-include mujoco *.h *.cc *.mm CMakeLists.txt *.cmake
+recursive-include mujoco *.h *.cc *.cc.inc *.mm CMakeLists.txt *.cmake
 recursive-include mujoco/mjpython mjpython.* Info.plist

python/make_sdist.sh

@@ -44,6 +44,8 @@ python "${package_dir}"/mujoco/codegen/generate_enum_traits.py > \
     mujoco/enum_traits.h
 python "${package_dir}"/mujoco/codegen/generate_function_traits.py > \
     mujoco/function_traits.h
+python "${package_dir}"/mujoco/codegen/generate_spec_bindings.py > \
+    mujoco/specs.cc.inc
 export PYTHONPATH="${old_pythonpath}"
 
 # Copy over the LICENSE file.

python/mujoco/CMakeLists.txt

@@ -405,6 +405,29 @@ target_link_libraries(
           structs_header
 )
 
+if(NOT EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/specs.cc.inc)
+  add_custom_command(
+    OUTPUT specs.cc.inc
+    COMMAND ${CMAKE_COMMAND} -E env PYTHONPATH=${mujoco_SOURCE_DIR}/mujoco ${Python3_EXECUTABLE}
+            ${CMAKE_CURRENT_SOURCE_DIR}/codegen/generate_spec_bindings.py > specs.cc.inc
+    DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/codegen/generate_spec_bindings.py
+  )
+endif()
+
+mujoco_pybind11_module(
+  _specs
+  specs.cc
+  specs.cc.inc
+)
+target_link_libraries(
+  _specs
+  PRIVATE mujoco
+          Eigen3::Eigen
+          errors_header
+          raw
+          structs_header
+)
+
 mujoco_pybind11_module(_simulate simulate.cc)
 target_link_libraries(
   _simulate
@@ -424,6 +447,7 @@ set(LIBRARIES_FOR_WHEEL
     "$<TARGET_FILE:_render>"
     "$<TARGET_FILE:_rollout>"
     "$<TARGET_FILE:_simulate>"
+    "$<TARGET_FILE:_specs>"
     "$<TARGET_FILE:_structs>"
     "$<TARGET_FILE:mujoco>"
 )
@@ -459,6 +483,7 @@ if(MUJOCO_PYTHON_MAKE_WHEEL)
     _render
     _rollout
     _simulate
+    _specs
     _structs
     mujoco
   )

python/mujoco/__init__.py

@@ -43,6 +43,7 @@ from mujoco._enums import *
 from mujoco._errors import *
 from mujoco._functions import *
 from mujoco._render import *
+from mujoco._specs import *
 from mujoco._structs import *
 from mujoco.gl_context import *
 from mujoco.renderer import Renderer

python/mujoco/bindings_test.py

@@ -409,19 +409,6 @@ class MuJoCoBindingsTest(parameterized.TestCase):
     np.testing.assert_array_equal(self.model.geom_size[1], [0.5, 0.5, 0.5])
     np.testing.assert_array_equal(model_copy.geom_size[1], [0.1, 0.1, 0.1])
 
-  def test_assets_array_filename_too_long(self):
-    # Longest allowed filename (excluding null byte)
-    limit = mujoco.mjMAXVFSNAME - 1
-    contents = b'<mujoco/>'
-    valid_filename = 'a' * limit
-    mujoco.MjModel.from_xml_path(valid_filename, {valid_filename: contents})
-    invalid_filename = 'a' * (limit + 1)
-    expected_message = (
-        f'Filename length 1000 exceeds 999 character limit: {invalid_filename}')
-    with self.assertRaisesWithLiteralMatch(ValueError, expected_message):
-      mujoco.MjModel.from_xml_path(invalid_filename,
-                                   {invalid_filename: contents})
-
   def test_mjdata_can_copy(self):
     self.data.qpos = [0, 0, 0.1*np.sqrt(2) - 0.001,
                       np.cos(np.pi/8), np.sin(np.pi/8), 0, 0, 0,
@@ -856,9 +843,6 @@ Return the current version of MuJoCo as a null-terminated string.
 Euler integrator, semi-implicit in velocity.
 """)
 
-  def test_int_constant(self):
-    self.assertEqual(mujoco.mjMAXVFSNAME, 1000)
-
   def test_float_constant(self):
     self.assertEqual(mujoco.mjMAXVAL, 1e10)
     self.assertEqual(mujoco.mjMINVAL, 1e-15)

python/mujoco/codegen/generate_spec_bindings.py

@@ -0,0 +1,221 @@
+# Copyright 2024 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Generates the bindings for the MuJoCo specs."""
+
+from collections.abc import Sequence
+
+from absl import app
+
+from introspect import ast_nodes
+from introspect import structs
+
+
+SCALAR_TYPES = {'int', 'double', 'float', 'mjtByte', 'mjtNum'}
+
+
+def _value_binding_code(
+    field: ast_nodes.ValueType, classname: str = '', varname: str = ''
+) -> str:
+  """Creates a string that defines Python bindings for a value type."""
+  fulltype = field.name
+  if field.name not in SCALAR_TYPES:
+    fulltype += '&'
+  fullvarname = varname
+  rawclassname = classname.replace('mjs', 'raw::Mjs')
+  if classname == 'mjSpec':  # raw mjSpec has a wrapper
+    rawclassname = classname.replace('mjS', 'MjS')
+    fullvarname = 'ptr->' + varname
+  if field.name.startswith('mjs'):  # all other mjs are raw structs
+    fulltype = field.name.replace('mjs', 'raw::Mjs')
+    if field.name != 'mjsPlugin' and field.name != 'mjsOrientation':
+      fulltype = fulltype + '*'  # plugin and orientation are pointers
+
+  def_property_args = (
+      f'"{varname}"',
+      f"""[]({rawclassname}& self) -> {fulltype} {{
+        return self.{fullvarname};
+      }}""",
+      f"""[]({rawclassname}& self, {fulltype} {varname}) {{
+        self.{fullvarname} = {varname};
+      }}""",
+  )
+
+  if field.name not in SCALAR_TYPES:
+    def_property_args += ('py::return_value_policy::reference_internal',)
+
+  return f'{classname}.def_property({",".join(def_property_args)});'
+
+
+def _array_binding_code(
+    field: ast_nodes.ArrayType, classname: str = '', varname: str = ''
+) -> str:
+  """Creates a string that declares Python bindings for an array type."""
+  if len(field.extents) > 1:
+    raise NotImplementedError()
+  innertype = field.inner_type.decl()
+  rawclassname = classname.replace('mjs', 'raw::Mjs')
+  fullvarname = varname
+  if classname == 'mjSpec':  # raw mjSpec has a wrapper
+    rawclassname = classname.replace('mjS', 'MjS')
+    fullvarname = 'ptr->' + varname
+  if innertype == 'double' or innertype == 'mjtNum':
+    innertype = 'MjDouble'  # custom Eigen type
+  elif innertype == 'float':
+    innertype = 'MjFloat'  # custom Eigen type
+  elif innertype == 'int':
+    innertype = 'MjInt'  # custom Eigen type
+  elif innertype == 'char':
+    # char array special case
+    return f"""\
+  {classname}.def_property(
+    "{varname}",
+    []({rawclassname}& self) -> py::array_t<char> {{
+      return py::array_t<char>({field.extents[0]}, self.{fullvarname});
+    }},
+    []({rawclassname}& self, py::object rhs) {{
+      int i = 0;
+      for (auto val : rhs) {{
+        self.{fullvarname}[i++] = py::cast<char>(val);
+      }}
+    }}, py::return_value_policy::reference_internal);"""
+  # all other array types
+  return f"""\
+  {classname}.def_property(
+      "{varname}",
+      []({rawclassname}& self) -> {innertype}{field.extents[0]} {{
+        return {innertype}{field.extents[0]}(self.{fullvarname});
+    }},
+      []({rawclassname}& self, {innertype}Ref{field.extents[0]} {varname}) {{
+        {innertype}{field.extents[0]}(self.{fullvarname}) = {varname};
+    }}, py::return_value_policy::reference_internal);"""
+
+
+def _ptr_binding_code(
+    field: ast_nodes.PointerType, classname: str = '', varname: str = ''
+) -> str:
+  """Creates a string that declares Python bindings for a pointer type."""
+  vartype = field.inner_type.decl()
+  rawclassname = classname.replace('mjs', 'raw::Mjs')
+  fullvarname = varname
+  if classname == 'mjSpec':  # raw mjSpec has a wrapper
+    rawclassname = classname.replace('mjS', 'MjS')
+    fullvarname = 'ptr->' + varname
+  if vartype == 'mjsElement':  # this is ignored by the caller
+    return 'mjsElement'
+  if vartype.startswith('mjs'):  # for structs, use the value case
+    return _value_binding_code(field.inner_type, classname, varname)
+  elif vartype == 'mjString':  # C++ string -> Python string
+    return f"""\
+  {classname}.def_property(
+      "{varname}",
+      []({rawclassname}& self) -> std::string_view {{
+        return *self.{fullvarname};
+      }},
+      []({rawclassname}& self, std::string_view {varname}) {{
+        *(self.{fullvarname}) = {varname};
+    }});"""
+  elif (  # C++ vectors of values -> Python array
+      vartype == 'mjDoubleVec'
+      or vartype == 'mjFloatVec'
+      or vartype == 'mjIntVec'
+    ):
+    vartype = vartype.replace('mj', '').replace('Vec', '').lower()
+    return f"""\
+  {classname}.def_property(
+    "{varname}",
+    []({rawclassname}& self) -> py::array_t<{vartype}> {{
+        return py::array_t<{vartype}>(self.{fullvarname}->size(),
+                                      self.{fullvarname}->data());
+      }},
+    []({rawclassname}& self, py::object rhs) {{
+        self.{fullvarname}->clear();
+        self.{fullvarname}->reserve(py::len(rhs));
+        for (auto val : rhs) {{
+          self.{fullvarname}->push_back(py::cast<{vartype}>(val));
+      }}
+    }}, py::return_value_policy::reference_internal);"""
+  elif vartype == 'mjStringVec':  # C++ vector of strings -> Python list
+    return f"""\
+  {classname}.def_property(
+    "{varname}",
+    []({rawclassname}& self) -> py::list {{
+        py::list list;
+        for (auto val : *self.{fullvarname}) {{
+          list.append(val);
+        }}
+        return list;
+      }},
+    []({rawclassname}& self, py::object rhs) {{
+        self.{fullvarname}->clear();
+        self.{fullvarname}->reserve(py::len(rhs));
+        for (auto val : rhs) {{
+          self.{fullvarname}->push_back(py::cast<std::string>(val));
+      }}
+    }}, py::return_value_policy::reference_internal);"""
+  elif 'VecVec' in vartype:  # C++ vector of vectors -> Python list of lists
+    vartype = vartype.replace('mj', '').replace('VecVec', '').lower()
+    return f"""\
+  {classname}.def_property(
+    "{varname}",
+    []({rawclassname}& self) -> py::list {{
+        py::list list;
+        for (auto inner_vec : *self.{fullvarname}) {{
+          py::list inner_list;
+          for (auto val : inner_vec) {{
+            inner_list.append(val);
+          }}
+          list.append(inner_list);
+        }}
+        return list;
+      }},
+    []({rawclassname}& self, py::object rhs) {{
+        self.{fullvarname}->clear();
+        self.{fullvarname}->reserve(py::len(rhs));
+        for (auto inner_list : rhs) {{
+          auto inner_vec = py::cast<std::vector<{vartype}>>(inner_list);
+          self.{fullvarname}->push_back(inner_vec);
+        }}
+    }}, py::return_value_policy::reference_internal);"""
+
+  raise NotImplementedError()
+
+
+def _binding_code(field: ast_nodes.StructFieldDecl, key: str) -> str:
+  if isinstance(field.type, ast_nodes.ValueType):
+    return _value_binding_code(field.type, key, field.name)
+  elif isinstance(field.type, ast_nodes.PointerType):
+    return _ptr_binding_code(field.type, key, field.name)
+  elif isinstance(field.type, ast_nodes.ArrayType):
+    return _array_binding_code(field.type, key, field.name)
+  return ''
+
+
+def generate() -> None:
+  for key in structs.STRUCTS.keys():
+    if (key.startswith('mjs') or key == 'mjSpec') and key != 'mjsElement':
+      print('\n  // ' + key)
+      for field in structs.STRUCTS[key].fields:
+        code = _binding_code(field, key)
+        if code != 'mjsElement':
+          print(code)
+
+
+def main(argv: Sequence[str]) -> None:
+  if len(argv) > 1:
+    raise app.UsageError('Too many command-line arguments.')
+  generate()
+
+if __name__ == '__main__':
+  app.run(main)

python/mujoco/constants.cc

@@ -57,8 +57,6 @@ PYBIND11_MODULE(_constants, pymodule) {
   X(mjMINIMP);
   X(mjMAXIMP);
   X(mjMAXCONPAIR);
-  X(mjMAXVFS);
-  X(mjMAXVFSNAME);
   X(mjNEQDATA);
   X(mjNDYN);
   X(mjNGAIN);

python/mujoco/functions.cc

@@ -17,7 +17,6 @@
 #include <array>
 #include <cstdint>
 #include <memory>
-#include <sstream>
 #include <string>
 #include <optional>
 
@@ -29,6 +28,7 @@
 #include "functions.h"
 #include "private.h"
 #include "raw.h"
+#include "structs.h"
 #include <pybind11/eigen.h>
 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h>
@@ -108,9 +108,10 @@ PYBIND11_MODULE(_functions, pymodule) {
   // Skipped: mj_copyModel (have MjModel.__copy__, memory managed by MjModel)
   pymodule.def(
       "mj_saveModel",
-      [](const MjModelWrapper& m, const std::optional<std::string>& filename = std::nullopt,
+      [](const MjModelWrapper& m,
-         std::optional<
+         const std::optional<std::string>& filename = std::nullopt,
-             Eigen::Ref<Eigen::Vector<std::uint8_t, Eigen::Dynamic>>> buffer = std::nullopt) {
+         std::optional<Eigen::Ref<Eigen::Vector<std::uint8_t, Eigen::Dynamic>>>
+             buffer = std::nullopt) {
         void* buffer_ptr = nullptr;
         int buffer_sz = 0;
         if (buffer.has_value()) {
@@ -122,8 +123,7 @@ PYBIND11_MODULE(_functions, pymodule) {
             buffer_ptr, buffer_sz);
       },
       py::arg("m"), py::arg_v("filename", std::nullopt),
-      py::arg_v("buffer", std::nullopt),
+      py::arg_v("buffer", std::nullopt), py::doc(traits::mj_saveModel::doc),
-      py::doc(traits::mj_saveModel::doc),
       py::call_guard<py::gil_scoped_release>());
   // Skipped: mj_loadModel (have MjModel.from_binary_path)
   // Skipped: mj_deleteModel (have MjModel.__del__)
@@ -700,8 +700,8 @@ PYBIND11_MODULE(_functions, pymodule) {
   Def<traits::mju_dist3>(pymodule);
   Def<traits::mju_mulMatVec3>(pymodule);
   Def<traits::mju_mulMatTVec3>(pymodule);
-  Def<traits::mju_rotVecMat>(pymodule);
+  // skipped: mju_rotVecMat
-  Def<traits::mju_rotVecMatT>(pymodule);
+  // skipped: mju_rotVecMatT
   Def<traits::mju_cross>(pymodule);
   Def<traits::mju_zero4>(pymodule);
   Def<traits::mju_unit4>(pymodule);

python/mujoco/indexer_xmacro.h

@@ -168,7 +168,7 @@
   X( float,   light_, specular,      nlight,  3 )
 
 #define MJMODEL_MATERIAL                   \
-  X( int,     mat_, texid,       nmat, 1 ) \
+  X( int,     mat_, texid,       nmat, mjNTEXMAT ) \
   X( mjtByte, mat_, texuniform,  nmat, 1 ) \
   X( float,   mat_, texrepeat,   nmat, 2 ) \
   X( float,   mat_, emission,    nmat, 1 ) \

python/mujoco/memory_leak_test.py

@@ -0,0 +1,69 @@
+# Copyright 2024 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Test that copying mujoco.MjData multiple times doesn't leak memory."""
+
+import copy
+import textwrap
+
+from absl.testing import absltest
+import mujoco
+
+
+class MemoryLeakTest(absltest.TestCase):
+
+  # Regression test for https://github.com/google-deepmind/mujoco/issues/1572
+  def test_deepcopy_mjdata_leak(self):
+    # MuJoCo model with textures that take up significant memory.
+    model_xml = textwrap.dedent("""
+    <mujoco>
+      <asset>
+        <material name="body"/>
+        <texture name="grid" type="2d" builtin="checker"
+            width="1024" height="1024" rgb1="0 0 0" rgb2="1 1 1"/>
+        <material name="grid" texture="grid" texrepeat="1 1"
+            texuniform="true" reflectance=".2"/>
+      </asset>
+      <worldbody>
+          <geom size="0 0 .05" type="plane" material="grid"/>
+      </worldbody>
+    </mujoco>
+    """)
+    limit = self._memory_limit(4 * 2**30)
+    try:
+      model = mujoco.MjModel.from_xml_string(model_xml)
+      data = mujoco.MjData(model)
+      total = 0
+      for _ in range(1000):
+        mujoco.mj_step(model, data)
+        last_data = copy.deepcopy(data)
+        total += last_data.time
+    finally:
+      self._memory_limit(limit)
+
+  def _memory_limit(self, limit_in_bytes: int) -> int:
+    """Limits max memory usage, and returns previous limit."""
+    soft = -1
+    try:
+      import resource  # pylint: disable=g-import-not-at-top
+      soft, hard = resource.getrlimit(resource.RLIMIT_AS)
+      resource.setrlimit(resource.RLIMIT_AS, (limit_in_bytes, hard))
+    except (ImportError, ValueError):
+      # On Windows or systems where setting resource limits fails, do nothing.
+      pass
+    return soft
+
+
+if __name__ == '__main__':
+  absltest.main()

python/mujoco/raw.h

@@ -18,6 +18,7 @@
 #include <mujoco/mjdata.h>
 #include <mujoco/mjmodel.h>
 #include <mujoco/mjrender.h>
+#include <mujoco/mjspec.h>
 #include <mujoco/mjvisualize.h>
 
 // Type aliases for MuJoCo C structs to allow us refer to consistently refer
@@ -28,6 +29,35 @@ using MjContact = ::mjContact;
 using MjData = ::mjData;
 using MjLROpt = ::mjLROpt;
 using MjModel = ::mjModel;
+using MjSpec = ::mjSpec;
+using MjsElement = ::mjsElement;
+using MjsOrientation = ::mjsOrientation;
+using MjsPlugin = ::mjsPlugin;
+using MjsBody = ::mjsBody;
+using MjsFrame = ::mjsFrame;
+using MjsJoint = ::mjsJoint;
+using MjsGeom = ::mjsGeom;
+using MjsSite = ::mjsSite;
+using MjsCamera = ::mjsCamera;
+using MjsLight = ::mjsLight;
+using MjsFlex = ::mjsFlex;
+using MjsMesh = ::mjsMesh;
+using MjsHField = ::mjsHField;
+using MjsSkin = ::mjsSkin;
+using MjsTexture = ::mjsTexture;
+using MjsMaterial = ::mjsMaterial;
+using MjsPair = ::mjsPair;
+using MjsExclude = ::mjsExclude;
+using MjsEquality = ::mjsEquality;
+using MjsTendon = ::mjsTendon;
+using MjsWrap = ::mjsWrap;
+using MjsActuator = ::mjsActuator;
+using MjsSensor = ::mjsSensor;
+using MjsNumeric = ::mjsNumeric;
+using MjsText = ::mjsText;
+using MjsTuple = ::mjsTuple;
+using MjsKey = ::mjsKey;
+using MjsDefault = ::mjsDefault;
 using MjOption = ::mjOption;
 using MjSolverStat = ::mjSolverStat;
 using MjStatistic = ::mjStatistic;

python/mujoco/render.cc

@@ -54,6 +54,9 @@ class MjWrapper<raw::MjrContext> : public WrapperBase<raw::MjrContext> {
   X(auxFBO_r);
   X(auxColor);
   X(auxColor_r);
+  X(mat_texid);
+  X(mat_texuniform);
+  X(mat_texrepeat);
   X(textureType);
   X(texture);
   X(skinvertVBO);
@@ -95,6 +98,9 @@ MjrContextWrapper::MjWrapper()
       X(auxFBO_r),
       X(auxColor),
       X(auxColor_r),
+      X(mat_texid),
+      X(mat_texuniform),
+      X(mat_texrepeat),
       X(textureType),
       X(texture),
       X_SKIN(skinvertVBO),
@@ -119,6 +125,9 @@ MjrContextWrapper::MjWrapper(const MjModelWrapper& model, int fontscale)
       X(auxFBO_r),
       X(auxColor),
       X(auxColor_r),
+      X(mat_texid),
+      X(mat_texuniform),
+      X(mat_texrepeat),
       X(textureType),
       X(texture),
       X_SKIN(skinvertVBO),
@@ -238,6 +247,9 @@ PYBIND11_MODULE(_render, pymodule) {
   X(auxFBO_r);
   X(auxColor);
   X(auxColor_r);
+  X(mat_texid);
+  X(mat_texuniform);
+  X(mat_texrepeat);
   X(textureType);
   X(texture);
   X(skinvertVBO);

python/mujoco/simulate.cc

@@ -123,6 +123,9 @@ class SimulateWrapper {
 
   mujoco::Simulate* simulate() { return simulate_; }
 
+  py::object GetModel() const { return m_; }
+  py::object GetData() const { return d_; }
+
  private:
   mujoco::Simulate* simulate_;
   std::atomic_int destroyed_ = 0;
@@ -222,6 +225,8 @@ PYBIND11_MODULE(_simulate, pymodule) {
       .def("lock", GetIfNotNull(&mujoco::Simulate::mtx),
            py::call_guard<py::gil_scoped_release>(),
            py::return_value_policy::reference_internal)
+      .def_property_readonly("m", &SimulateWrapper::GetModel)
+      .def_property_readonly("d", &SimulateWrapper::GetData)
       .def_property_readonly("ctrl_noise_std",
                              GetIfNotNull(&mujoco::Simulate::ctrl_noise_std),
                              py::call_guard<py::gil_scoped_release>())

python/mujoco/specs.cc

@@ -0,0 +1,954 @@
+// Copyright 2024 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <array>
+#include <cstddef>  // IWYU pragma: keep
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <string_view>  // IWYU pragma: keep
+#include <vector>       // IWYU pragma: keep
+
+#include <Eigen/Core>
+#include <Eigen/Eigen>
+#include <mujoco/mjspec.h>  // IWYU pragma: keep
+#include <mujoco/mujoco.h>
+#include "errors.h"
+#include "indexers.h"  // IWYU pragma: keep
+#include "raw.h"
+#include "structs.h"  // IWYU pragma: keep
+#include <pybind11/cast.h>
+#include <pybind11/eigen.h>
+#include <pybind11/eigen/matrix.h>
+#include <pybind11/pybind11.h>
+#include <pybind11/pytypes.h>
+#include <pybind11/stl.h>
+
+namespace py = ::pybind11;
+
+namespace mujoco::python {
+using MjInt2 = Eigen::Map<Eigen::Vector2i>;
+using MjInt3 = Eigen::Map<Eigen::Vector3i>;
+using MjFloat2 = Eigen::Map<Eigen::Vector2f>;
+using MjFloat3 = Eigen::Map<Eigen::Vector3f>;
+using MjFloat4 = Eigen::Map<Eigen::Vector4f>;
+using MjDouble2 = Eigen::Map<Eigen::Vector2d>;
+using MjDouble3 = Eigen::Map<Eigen::Vector3d>;
+using MjDouble4 = Eigen::Map<Eigen::Vector4d>;
+using MjDouble5 = Eigen::Map<Eigen::Matrix<double, 5, 1>>;
+using MjDouble6 = Eigen::Map<Eigen::Matrix<double, 6, 1>>;
+using MjDouble10 = Eigen::Map<Eigen::Matrix<double, 10, 1>>;
+using MjDouble11 = Eigen::Map<Eigen::Matrix<double, 11, 1>>;
+using MjDoubleVec = Eigen::Map<Eigen::VectorXd>;
+
+using MjIntRef2 = Eigen::Ref<const Eigen::Vector2i>;
+using MjIntRef3 = Eigen::Ref<const Eigen::Vector3i>;
+using MjFloatRef2 = Eigen::Ref<const Eigen::Vector2f>;
+using MjFloatRef3 = Eigen::Ref<const Eigen::Vector3f>;
+using MjFloatRef4 = Eigen::Ref<const Eigen::Vector4f>;
+using MjDoubleRef2 = Eigen::Ref<const Eigen::Vector2d>;
+using MjDoubleRef3 = Eigen::Ref<const Eigen::Vector3d>;
+using MjDoubleRef4 = Eigen::Ref<const Eigen::Vector4d>;
+using MjDoubleRef5 = Eigen::Ref<const Eigen::Matrix<double, 5, 1>>;
+using MjDoubleRef6 = Eigen::Ref<const Eigen::Matrix<double, 6, 1>>;
+using MjDoubleRef10 = Eigen::Ref<const Eigen::Matrix<double, 10, 1>>;
+using MjDoubleRef11 = Eigen::Ref<const Eigen::Matrix<double, 11, 1>>;
+using MjDoubleRefVec = Eigen::Ref<const Eigen::VectorXd>;
+
+struct MjSpec {
+  MjSpec() : ptr(mj_makeSpec()) {}
+  ~MjSpec() { mj_deleteSpec(ptr); }
+  raw::MjSpec* ptr;
+};
+
+PYBIND11_MODULE(_specs, m) {
+  auto structs_m = py::module::import("mujoco._structs");
+  py::function mjmodel_from_spec_ptr =
+      structs_m.attr("MjModel").attr("_from_spec_ptr");
+  py::function mjmodel_mjdata_from_spec_ptr =
+      structs_m.attr("_recompile_spec_addr");
+
+  py::class_<MjSpec> mjSpec(m, "MjSpec");
+  py::class_<raw::MjsElement> mjsElement(m, "MjsElement");
+  py::class_<raw::MjsDefault> mjsDefault(m, "MjsDefault");
+  py::class_<raw::MjsBody> mjsBody(m, "MjsBody");
+  py::class_<raw::MjsFrame> mjsFrame(m, "MjsFrame");
+  py::class_<raw::MjsGeom> mjsGeom(m, "MjsGeom");
+  py::class_<raw::MjsJoint> mjsJoint(m, "MjsJoint");
+  py::class_<raw::MjsLight> mjsLight(m, "MjsLight");
+  py::class_<raw::MjsMaterial> mjsMaterial(m, "MjsMaterial");
+  py::class_<raw::MjsSite> mjsSite(m, "MjsSite");
+  py::class_<raw::MjsMesh> mjsMesh(m, "MjsMesh");
+  py::class_<raw::MjsSkin> mjsSkin(m, "MjsSkin");
+  py::class_<raw::MjsTexture> mjsTexture(m, "MjsTexture");
+  py::class_<raw::MjsText> mjsText(m, "MjsText");
+  py::class_<raw::MjsTuple> mjsTuple(m, "MjsTuple");
+  py::class_<raw::MjsCamera> mjsCamera(m, "MjsCamera");
+  py::class_<raw::MjsFlex> mjsFlex(m, "MjsFlex");
+  py::class_<raw::MjsHField> mjsHField(m, "MjsHField");
+  py::class_<raw::MjsKey> mjsKey(m, "MjsKey");
+  py::class_<raw::MjsNumeric> mjsNumeric(m, "MjsNumeric");
+  py::class_<raw::MjsPair> mjsPair(m, "MjsPair");
+  py::class_<raw::MjsExclude> mjsExclude(m, "MjsExclude");
+  py::class_<raw::MjsEquality> mjsEquality(m, "MjsEquality");
+  py::class_<raw::MjsTendon> mjsTendon(m, "MjsTendon");
+  py::class_<raw::MjsSensor> mjsSensor(m, "MjsSensor");
+  py::class_<raw::MjsActuator> mjsActuator(m, "MjsActuator");
+  py::class_<raw::MjsPlugin> mjsPlugin(m, "MjsPlugin");
+  py::class_<raw::MjsOrientation> mjsOrientation(m, "MjsOrientation");
+  py::class_<raw::MjsWrap> mjsWrap(m, "MjsWrap");
+
+  // ============================= MJSPEC =====================================
+  mjSpec.def(py::init<>());
+  mjSpec.def("recompile", [mjmodel_mjdata_from_spec_ptr](
+                              const MjSpec& self, py::object m, py::object d) {
+    return mjmodel_mjdata_from_spec_ptr(reinterpret_cast<uintptr_t>(self.ptr),
+                                        m, d);
+  });
+  mjSpec.def(
+      "copy",
+      [](const MjSpec& self) -> raw::MjSpec* { return mj_copySpec(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "worldbody",
+      [](MjSpec& self) -> raw::MjsBody* {
+        return mjs_findBody(self.ptr, "world");
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "find_body",
+      [](MjSpec& self, std::string& name) -> raw::MjsBody* {
+        return mjs_findBody(self.ptr, name.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "find_mesh",
+      [](MjSpec& self, std::string& name) -> raw::MjsMesh* {
+        return mjs_findMesh(self.ptr, name.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "find_frame",
+      [](MjSpec& self, std::string& name) -> raw::MjsFrame* {
+        return mjs_findFrame(self.ptr, name.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "find_keyframe",
+      [](MjSpec& self, std::string& name) -> raw::MjsKey* {
+        return mjs_findKeyframe(self.ptr, name.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "find_default",
+      [](MjSpec& self, std::string& classname) -> raw::MjsDefault* {
+        return mjs_findDefault(self.ptr, classname.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def("compile", [mjmodel_from_spec_ptr](MjSpec& self) {
+    return mjmodel_from_spec_ptr(reinterpret_cast<uintptr_t>(self.ptr));
+  });
+  mjSpec.def(
+      "copy_back",
+      [](MjSpec& self, raw::MjModel& model) {
+        return mj_copyBack(self.ptr, &model);
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def("to_xml", [](MjSpec& self) -> std::string {
+    int size = mj_saveXMLString(self.ptr, nullptr, 0, nullptr, 0);
+    std::unique_ptr<char[]> buf(new char[size + 1]);
+    std::array<char, 1024> err;
+    buf[0] = '\0';
+    err[0] = '\0';
+    mj_saveXMLString(self.ptr, buf.get(), size + 1, err.data(), err.size());
+    if (err[0] != '\0') {
+      throw FatalError(std::string(err.data()));
+    }
+    return std::string(buf.get());
+  });
+  mjSpec.def("from_file", [](MjSpec& self, std::string& filename) -> void {
+    std::array<char, 1024> err;
+    err[0] = '\0';
+    mj_deleteSpec(self.ptr);
+    self.ptr = mj_parseXML(filename.c_str(), 0, err.data(), err.size());
+    if (!self.ptr) {
+      throw FatalError(std::string(err.data()));
+    }
+  });
+  mjSpec.def("from_string", [](MjSpec& self, std::string& xml) -> void {
+    std::array<char, 1024> err;
+    err[0] = '\0';
+    mj_deleteSpec(self.ptr);
+    self.ptr = mj_parseXMLString(xml.c_str(), 0, err.data(), err.size());
+    if (!self.ptr) {
+      throw FatalError(std::string(err.data()));
+    }
+  });
+  mjSpec.def(
+      "add_default",
+      [](MjSpec* spec, std::string& classname,
+         raw::MjsDefault* parent) -> raw::MjsDefault* {
+        return mjs_addDefault(spec->ptr, classname.c_str(), parent);
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "default",
+      [](MjSpec& self) -> raw::MjsDefault* {
+        return mjs_getSpecDefault(self.ptr);
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_material",
+      [](MjSpec& self, raw::MjsDefault* default_) -> raw::MjsMaterial* {
+        return mjs_addMaterial(self.ptr, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_mesh",
+      [](MjSpec& self, raw::MjsDefault* default_) -> raw::MjsMesh* {
+        return mjs_addMesh(self.ptr, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_skin",
+      [](MjSpec& self) -> raw::MjsSkin* { return mjs_addSkin(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_texture",
+      [](MjSpec& self) -> raw::MjsTexture* { return mjs_addTexture(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_text",
+      [](MjSpec& self) -> raw::MjsText* { return mjs_addText(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_tuple",
+      [](MjSpec& self) -> raw::MjsTuple* { return mjs_addTuple(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_flex",
+      [](MjSpec& self) -> raw::MjsFlex* { return mjs_addFlex(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_hfield",
+      [](MjSpec& self) -> raw::MjsHField* { return mjs_addHField(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_key",
+      [](MjSpec& self) -> raw::MjsKey* { return mjs_addKey(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_numeric",
+      [](MjSpec& self) -> raw::MjsNumeric* { return mjs_addNumeric(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_pair",
+      [](MjSpec& self, raw::MjsDefault* default_) -> raw::MjsPair* {
+        return mjs_addPair(self.ptr, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_exclude",
+      [](MjSpec& self) -> raw::MjsExclude* { return mjs_addExclude(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_equality",
+      [](MjSpec& self, raw::MjsDefault* default_) -> raw::MjsEquality* {
+        return mjs_addEquality(self.ptr, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_tendon",
+      [](MjSpec& self, raw::MjsDefault* default_) -> raw::MjsTendon* {
+        return mjs_addTendon(self.ptr, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_sensor",
+      [](MjSpec& self) -> raw::MjsSensor* { return mjs_addSensor(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_actuator",
+      [](MjSpec& self, raw::MjsDefault* default_) -> raw::MjsActuator* {
+        return mjs_addActuator(self.ptr, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjSpec.def(
+      "add_plugin",
+      [](MjSpec& self) -> raw::MjsPlugin* { return mjs_addPlugin(self.ptr); },
+      py::return_value_policy::reference_internal);
+  mjSpec.def("detach_body", [](MjSpec& self, raw::MjsBody& body) {
+    mjs_detachBody(self.ptr, &body);
+  });
+  mjSpec.def_property_readonly(
+      "actuators",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_ACTUATOR);
+        while (el) {
+          list.append(mjs_asActuator(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "sensors",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SENSOR);
+        while (el) {
+          list.append(mjs_asSensor(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "flexes",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_FLEX);
+        while (el) {
+          list.append(mjs_asFlex(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "pairs",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_PAIR);
+        while (el) {
+          list.append(mjs_asPair(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "equality",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EQUALITY);
+        while (el) {
+          list.append(mjs_asEquality(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "excludes",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EXCLUDE);
+        while (el) {
+          list.append(mjs_asExclude(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "tendons",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TENDON);
+        while (el) {
+          list.append(mjs_asTendon(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "numeric",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_NUMERIC);
+        while (el) {
+          list.append(mjs_asNumeric(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "text",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXT);
+        while (el) {
+          list.append(mjs_asText(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "tuple",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TUPLE);
+        while (el) {
+          list.append(mjs_asTuple(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "key",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_KEY);
+        while (el) {
+          list.append(mjs_asKey(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "mesh",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MESH);
+        while (el) {
+          list.append(mjs_asMesh(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "hfield",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_HFIELD);
+        while (el) {
+          list.append(mjs_asHField(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "skin",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SKIN);
+        while (el) {
+          list.append(mjs_asSkin(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "texture",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXTURE);
+        while (el) {
+          list.append(mjs_asTexture(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+  mjSpec.def_property_readonly(
+      "material",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MATERIAL);
+        while (el) {
+          list.append(mjs_asMaterial(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSBODY =====================================
+  mjsBody.def_property_readonly(
+      "id", [](raw::MjsBody& self) -> int { return mjs_getId(self.element); });
+  mjsBody.def("delete", [](raw::MjsBody& self) { mjs_delete(self.element); });
+  mjsBody.def(
+      "add_body",
+      [](raw::MjsBody& self, raw::MjsDefault* default_) -> raw::MjsBody* {
+        return mjs_addBody(&self, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_frame",
+      [](raw::MjsBody& self, raw::MjsFrame* parentframe_) -> raw::MjsFrame* {
+        return mjs_addFrame(&self, parentframe_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_geom",
+      [](raw::MjsBody& self, raw::MjsDefault* default_) -> raw::MjsGeom* {
+        return mjs_addGeom(&self, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_joint",
+      [](raw::MjsBody& self, raw::MjsDefault* default_) -> raw::MjsJoint* {
+        return mjs_addJoint(&self, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_freejoint",
+      [](raw::MjsBody& self) -> raw::MjsJoint* {
+        return mjs_addFreeJoint(&self);
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_light",
+      [](raw::MjsBody& self, raw::MjsDefault* default_) -> raw::MjsLight* {
+        return mjs_addLight(&self, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_site",
+      [](raw::MjsBody& self, raw::MjsDefault* default_) -> raw::MjsSite* {
+        return mjs_addSite(&self, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "add_camera",
+      [](raw::MjsBody& self, raw::MjsDefault* default_) -> raw::MjsCamera* {
+        return mjs_addCamera(&self, default_);
+      },
+      py::arg_v("default", nullptr),
+      py::return_value_policy::reference_internal);
+  mjsBody.def("set_frame",
+              [](raw::MjsBody& self, raw::MjsFrame& frame) -> void {
+                mjs_setFrame(self.element, &frame);
+              });
+  mjsBody.def("set_default",
+              [](raw::MjsBody& self, raw::MjsDefault& default_) -> void {
+                mjs_setDefault(self.element, &default_);
+              });
+  mjsBody.def(
+      "default",
+      [](raw::MjsBody& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "find_child",
+      [](raw::MjsBody& self, std::string& name) -> raw::MjsBody* {
+        return mjs_findChild(&self, name.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_body",
+      [](raw::MjsBody& self) -> raw::MjsBody* {
+        return mjs_asBody(mjs_firstChild(&self, mjOBJ_BODY));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_body",
+      [](raw::MjsBody& self, raw::MjsBody& child) -> raw::MjsBody* {
+        return mjs_asBody(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_camera",
+      [](raw::MjsBody& self) -> raw::MjsCamera* {
+        return mjs_asCamera(mjs_firstChild(&self, mjOBJ_CAMERA));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_camera",
+      [](raw::MjsBody& self, raw::MjsCamera& child) -> raw::MjsCamera* {
+        return mjs_asCamera(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_light",
+      [](raw::MjsBody& self) -> raw::MjsLight* {
+        return mjs_asLight(mjs_firstChild(&self, mjOBJ_LIGHT));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_light",
+      [](raw::MjsBody& self, raw::MjsLight& child) -> raw::MjsLight* {
+        return mjs_asLight(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_joint",
+      [](raw::MjsBody& self) -> raw::MjsJoint* {
+        return mjs_asJoint(mjs_firstChild(&self, mjOBJ_JOINT));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_joint",
+      [](raw::MjsBody& self, raw::MjsJoint& child) -> raw::MjsJoint* {
+        return mjs_asJoint(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_geom",
+      [](raw::MjsBody& self) -> raw::MjsGeom* {
+        return mjs_asGeom(mjs_firstChild(&self, mjOBJ_GEOM));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_geom",
+      [](raw::MjsBody& self, raw::MjsGeom& child) -> raw::MjsGeom* {
+        return mjs_asGeom(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_site",
+      [](raw::MjsBody& self) -> raw::MjsSite* {
+        return mjs_asSite(mjs_firstChild(&self, mjOBJ_SITE));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_site",
+      [](raw::MjsBody& self, raw::MjsSite& child) -> raw::MjsSite* {
+        return mjs_asSite(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "first_frame",
+      [](raw::MjsBody& self) -> raw::MjsFrame* {
+        return mjs_asFrame(mjs_firstChild(&self, mjOBJ_FRAME));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "next_frame",
+      [](raw::MjsBody& self, raw::MjsFrame& child) -> raw::MjsFrame* {
+        return mjs_asFrame(mjs_nextChild(&self, child.element));
+      },
+      py::return_value_policy::reference_internal);
+  mjsBody.def(
+      "spec",
+      [](raw::MjsBody& self) -> raw::MjSpec* { return mjs_getSpec(&self); },
+      py::return_value_policy::reference_internal);
+  mjsBody.def("attach_frame",
+              [](raw::MjsBody& self, raw::MjsFrame& frame, std::string& prefix,
+                 std::string& suffix) -> void {
+                mjs_attachFrame(&self, &frame, prefix.c_str(), suffix.c_str());
+              });
+
+  // ============================= MJSFRAME ====================================
+  mjsFrame.def_property_readonly(
+      "id", [](raw::MjsFrame& self) -> int { return mjs_getId(self.element); });
+  mjsFrame.def("delete", [](raw::MjsFrame& self) { mjs_delete(self.element); });
+  mjsFrame.def("set_frame", [](raw::MjsFrame& self, raw::MjsFrame& frame) {
+    mjs_setFrame(self.element, &frame);
+  });
+  mjsFrame.def("attach_body", [](raw::MjsFrame& self, raw::MjsBody& body,
+                                 std::string& prefix, std::string& suffix) {
+    mjs_attachBody(&self, &body, prefix.c_str(), suffix.c_str());
+  });
+
+  // ============================= MJSGEOM =====================================
+  mjsGeom.def_property_readonly(
+      "id", [](raw::MjsGeom& self) -> int { return mjs_getId(self.element); });
+  mjsGeom.def("delete", [](raw::MjsGeom& self) { mjs_delete(self.element); });
+  mjsGeom.def("set_frame", [](raw::MjsGeom& self, raw::MjsFrame& frame) {
+    mjs_setFrame(self.element, &frame);
+  });
+  mjsGeom.def("set_default", [](raw::MjsGeom& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsGeom.def(
+      "default",
+      [](raw::MjsGeom& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSJOINT ====================================
+  mjsJoint.def_property_readonly(
+      "id", [](raw::MjsJoint& self) -> int { return mjs_getId(self.element); });
+  mjsJoint.def("delete", [](raw::MjsJoint& self) { mjs_delete(self.element); });
+  mjsJoint.def("set_frame", [](raw::MjsJoint& self, raw::MjsFrame& frame) {
+    mjs_setFrame(self.element, &frame);
+  });
+  mjsJoint.def("set_default", [](raw::MjsJoint& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsJoint.def(
+      "default",
+      [](raw::MjsJoint& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSSITE =====================================
+  mjsSite.def_property_readonly(
+      "id", [](raw::MjsSite& self) -> int { return mjs_getId(self.element); });
+  mjsSite.def("delete", [](raw::MjsSite& self) { mjs_delete(self.element); });
+  mjsSite.def("set_frame", [](raw::MjsSite& self, raw::MjsFrame& frame) {
+    mjs_setFrame(self.element, &frame);
+  });
+  mjsSite.def("set_default", [](raw::MjsSite& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsSite.def(
+      "default",
+      [](raw::MjsSite& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSCAMERA ===================================
+  mjsCamera.def_property_readonly("id", [](raw::MjsCamera& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsCamera.def("delete",
+                [](raw::MjsCamera& self) { mjs_delete(self.element); });
+  mjsCamera.def("set_frame", [](raw::MjsCamera& self, raw::MjsFrame& frame) {
+    mjs_setFrame(self.element, &frame);
+  });
+  mjsCamera.def("set_default", [](raw::MjsCamera& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsCamera.def(
+      "default",
+      [](raw::MjsCamera& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSLIGHT ====================================
+  mjsLight.def_property_readonly(
+      "id", [](raw::MjsLight& self) -> int { return mjs_getId(self.element); });
+  mjsLight.def("delete", [](raw::MjsLight& self) { mjs_delete(self.element); });
+  mjsLight.def("set_frame", [](raw::MjsLight& self, raw::MjsFrame& frame) {
+    mjs_setFrame(self.element, &frame);
+  });
+  mjsLight.def("set_default", [](raw::MjsLight& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsLight.def(
+      "default",
+      [](raw::MjsLight& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSMATERIAL =================================
+  mjsMaterial.def_property_readonly("id", [](raw::MjsMaterial& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsMaterial.def("delete",
+                  [](raw::MjsMaterial& self) { mjs_delete(self.element); });
+  mjsMaterial.def("set_default",
+                  [](raw::MjsMaterial& self, raw::MjsDefault& def) {
+                    mjs_setDefault(self.element, &def);
+                  });
+  mjsMaterial.def(
+      "default",
+      [](raw::MjsMaterial& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSMESH =====================================
+  mjsMesh.def_property_readonly(
+      "id", [](raw::MjsMesh& self) -> int { return mjs_getId(self.element); });
+  mjsMesh.def("delete", [](raw::MjsMesh& self) { mjs_delete(self.element); });
+  mjsMesh.def("set_default", [](raw::MjsMesh& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsMesh.def(
+      "default",
+      [](raw::MjsMesh& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSPAIR =====================================
+  mjsPair.def_property_readonly(
+      "id", [](raw::MjsPair& self) -> int { return mjs_getId(self.element); });
+  mjsPair.def("delete", [](raw::MjsPair& self) { mjs_delete(self.element); });
+  mjsPair.def("set_default", [](raw::MjsPair& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsPair.def(
+      "default",
+      [](raw::MjsPair& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSEQUAL ====================================
+  mjsEquality.def_property_readonly("id", [](raw::MjsEquality& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsEquality.def("delete",
+                  [](raw::MjsEquality& self) { mjs_delete(self.element); });
+  mjsEquality.def("set_default",
+                  [](raw::MjsEquality& self, raw::MjsDefault& def) {
+                    mjs_setDefault(self.element, &def);
+                  });
+  mjsEquality.def(
+      "default",
+      [](raw::MjsEquality& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSACTUATOR =================================
+  mjsActuator.def_property_readonly("id", [](raw::MjsActuator& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsActuator.def("delete",
+                  [](raw::MjsActuator& self) { mjs_delete(self.element); });
+  mjsActuator.def("set_default",
+                  [](raw::MjsActuator& self, raw::MjsDefault& def) {
+                    mjs_setDefault(self.element, &def);
+                  });
+  mjsActuator.def(
+      "default",
+      [](raw::MjsActuator& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSTENDON ===================================
+  mjsTendon.def_property_readonly("id", [](raw::MjsTendon& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsTendon.def("delete",
+                [](raw::MjsTendon& self) { mjs_delete(self.element); });
+  mjsTendon.def("set_default", [](raw::MjsTendon& self, raw::MjsDefault& def) {
+    mjs_setDefault(self.element, &def);
+  });
+  mjsTendon.def(
+      "default",
+      [](raw::MjsTendon& self) -> raw::MjsDefault* {
+        return mjs_getDefault(self.element);
+      },
+      py::return_value_policy::reference_internal);
+  mjsTendon.def(
+      "wrap_site",
+      [](raw::MjsTendon& self, std::string& name) {
+        return mjs_wrapSite(&self, name.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjsTendon.def(
+      "wrap_geom",
+      [](raw::MjsTendon& self, std::string& name, std::string& sidesite) {
+        return mjs_wrapGeom(&self, name.c_str(), sidesite.c_str());
+      },
+      py::return_value_policy::reference_internal);
+  mjsTendon.def(
+      "wrap_joint",
+      [](raw::MjsTendon& self, std::string& name, double coef) {
+        return mjs_wrapJoint(&self, name.c_str(), coef);
+      },
+      py::return_value_policy::reference_internal);
+  mjsTendon.def(
+      "wrap_pulley",
+      [](raw::MjsTendon& self, double divisor) {
+        return mjs_wrapPulley(&self, divisor);
+      },
+      py::return_value_policy::reference_internal);
+
+  // ============================= MJSSENSOR ===================================
+  mjsSensor.def_property_readonly("id", [](raw::MjsSensor& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsSensor.def("delete",
+                [](raw::MjsSensor& self) { mjs_delete(self.element); });
+
+  // ============================= MJSFLEX =====================================
+  mjsFlex.def_property_readonly(
+      "id", [](raw::MjsFlex& self) -> int { return mjs_getId(self.element); });
+  mjsFlex.def("delete", [](raw::MjsFlex& self) { mjs_delete(self.element); });
+
+  // ============================= MJSHFIELD ===================================
+  mjsHField.def_property_readonly("id", [](raw::MjsHField& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsHField.def("delete",
+                [](raw::MjsHField& self) { mjs_delete(self.element); });
+
+  // ============================= MJSSKIN =====================================
+  mjsSkin.def_property_readonly(
+      "id", [](raw::MjsSkin& self) -> int { return mjs_getId(self.element); },
+      py::return_value_policy::reference_internal);
+  mjsSkin.def("delete", [](raw::MjsSkin& self) { mjs_delete(self.element); });
+
+  // ============================= MJSTEXTURE ==================================
+  mjsTexture.def_property_readonly("id", [](raw::MjsTexture& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsTexture.def("delete",
+                 [](raw::MjsTexture& self) { mjs_delete(self.element); });
+
+  // ============================= MJSKEY ======================================
+  mjsKey.def_property_readonly(
+      "id", [](raw::MjsKey& self) -> int { return mjs_getId(self.element); });
+  mjsKey.def("delete", [](raw::MjsKey& self) { mjs_delete(self.element); });
+
+  // ============================= MJSTEXT =====================================
+  mjsText.def_property_readonly(
+      "id", [](raw::MjsText& self) -> int { return mjs_getId(self.element); });
+  mjsText.def("delete", [](raw::MjsText& self) { mjs_delete(self.element); });
+
+  // ============================= MJSNUMERIC ==================================
+  mjsNumeric.def_property_readonly("id", [](raw::MjsNumeric& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsNumeric.def("delete",
+                 [](raw::MjsNumeric& self) { mjs_delete(self.element); });
+
+  // ============================= MJSEXCLUDE ==================================
+  mjsExclude.def_property_readonly("id", [](raw::MjsExclude& self) -> int {
+    return mjs_getId(self.element);
+  });
+  mjsExclude.def("delete",
+                 [](raw::MjsExclude& self) { mjs_delete(self.element); });
+
+  // ============================= MJSTUPLE ====================================
+  mjsTuple.def_property_readonly(
+      "id", [](raw::MjsTuple& self) -> int { return mjs_getId(self.element); });
+  mjsTuple.def("delete", [](raw::MjsTuple& self) { mjs_delete(self.element); });
+
+  // ============================= MJSPLUGIN ===================================
+  mjsPlugin.def_property_readonly("id", [](raw::MjsPlugin& self) -> int {
+    return mjs_getId(self.instance);
+  });
+  mjsPlugin.def("delete",
+                [](raw::MjsPlugin& self) { mjs_delete(self.instance); });
+
+#include "specs.cc.inc"
+}  // PYBIND11_MODULE // NOLINT
+}  // namespace mujoco::python

python/mujoco/specs_test.py

@@ -0,0 +1,237 @@
+# Copyright 2024 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Tests for mjSpec bindings."""
+
+import inspect
+import textwrap
+
+from absl.testing import absltest
+import mujoco
+import numpy as np
+
+
+def get_linenumber():
+  cf = inspect.currentframe()
+  return cf.f_back.f_lineno
+
+
+class SpecsTest(absltest.TestCase):
+
+  def test_basic(self):
+    # Create a spec.
+    spec = mujoco.MjSpec()
+
+    # Check that euler sequence order is set correctly.
+    self.assertEqual(spec.eulerseq[0], ord('x'))
+    spec.eulerseq = ['z', 'y', 'x']
+    self.assertEqual(spec.eulerseq[0], ord('z'))
+
+    # Add a body, check that it has default orientation.
+    body = spec.worldbody.add_body()
+    self.assertEqual(body.name, '')
+    np.testing.assert_array_equal(body.quat, [1, 0, 0, 0])
+
+    # Change the name of the body and read it back twice.
+    body.name = 'foobar'
+    self.assertEqual(body.name, 'foobar')
+    body.name = 'baz'
+    self.assertEqual(body.name, 'baz')
+
+    # Change the position of the body and read it back.
+    body.pos = [1, 2, 3]
+    np.testing.assert_array_equal(body.pos, [1, 2, 3])
+    self.assertEqual(body.pos.shape, (3,))
+
+    # Change the orientation of the body and read it back.
+    body.quat = [0, 1, 0, 0]
+    np.testing.assert_array_equal(body.quat, [0, 1, 0, 0])
+    self.assertEqual(body.quat.shape, (4,))
+
+    # Add a site to the body with user data and read it back.
+    site = body.add_site()
+    site.name = 'sitename'
+    site.userdata = [1, 2, 3, 4, 5, 6]
+    self.assertEqual(site.name, 'sitename')
+    np.testing.assert_array_equal(site.userdata, [1, 2, 3, 4, 5, 6])
+
+    # Check that the site and body have no id before compilation.
+    self.assertEqual(body.id, -1)
+    self.assertEqual(site.id, -1)
+
+    # Compile the spec and check for expected values in the model.
+    model = spec.compile()
+    self.assertEqual(spec.worldbody.id, 0)
+    self.assertEqual(body.id, 1)
+    self.assertEqual(site.id, 0)
+    self.assertEqual(model.nbody, 2)  # 2 bodies, including the world body
+    np.testing.assert_array_equal(model.body_pos[1], [1, 2, 3])
+    np.testing.assert_array_equal(model.body_quat[1], [0, 1, 0, 0])
+    self.assertEqual(model.nsite, 1)
+    self.assertEqual(model.nuser_site, 6)
+    np.testing.assert_array_equal(model.site_user[0], [1, 2, 3, 4, 5, 6])
+
+    self.assertEqual(spec.to_xml(), textwrap.dedent("""\
+        <mujoco model="MuJoCo Model">
+          <compiler angle="radian"/>
+
+          <size nuser_site="6"/>
+
+          <worldbody>
+            <body name="baz" pos="1 2 3" quat="0 1 0 0">
+              <site name="sitename" pos="0 0 0" user="1 2 3 4 5 6"/>
+            </body>
+          </worldbody>
+        </mujoco>
+    """),)
+
+  def test_compile_errors_with_line_info(self):
+    spec = mujoco.MjSpec()
+
+    added_on_line = get_linenumber() + 1
+    geom = spec.worldbody.add_geom()
+    geom.name = 'MyGeom'
+    geom.info = f'geom added on line {added_on_line}'
+
+    # Try to compile, get error.
+    expected_error = (
+        'Error: size 0 must be positive in geom\n'
+        + f'Element name \'MyGeom\', id 0, geom added on line {added_on_line}'
+    )
+    with self.assertRaisesRegex(ValueError, expected_error):
+      spec.compile()
+
+  def test_recompile(self):
+    # Create a spec.
+    spec = mujoco.MjSpec()
+
+    # Add movable body1.
+    body1 = spec.worldbody.add_body()
+    geom = body1.add_geom()
+    geom.size[0] = 1
+    geom.pos = [1, 1, 0]
+    joint = body1.add_joint()
+    joint.type = mujoco.mjtJoint.mjJNT_BALL
+
+    # Compile model, make data.
+    model = spec.compile()
+    data = mujoco.MjData(model)
+
+    # Simulate for 1 second.
+    while data.time < 1:
+      mujoco.mj_step(model, data)
+
+    # Add movable body2.
+    body2 = spec.worldbody.add_body()
+    body2.pos[1] = 3
+    geom = body2.add_geom()
+    geom.size[0] = 1
+    geom.pos = [0, 1, 0]
+    joint = body2.add_joint()
+    joint.type = mujoco.mjtJoint.mjJNT_BALL
+
+    # Recompile model and data while maintaining the state.
+    model_new, data_new = spec.recompile(model, data)
+
+    # Check that the state is preserved.
+    np.testing.assert_array_equal(model_new.body_pos[1], model.body_pos[1])
+    np.testing.assert_array_equal(data_new.qpos[:4], data.qpos)
+    np.testing.assert_array_equal(data_new.qvel[:3], data.qvel)
+
+  def test_uncompiled_spec_cannot_be_written(self):
+    spec = mujoco.MjSpec()
+
+    # Cannot write XML of an uncompiled spec.
+    expected_error = 'XML Write error: Only compiled model can be written'
+    with self.assertRaisesWithLiteralMatch(mujoco.FatalError, expected_error):
+      spec.to_xml()
+
+  def test_modelname_default_class(self):
+    spec = mujoco.MjSpec()
+    spec.modelname = 'test'
+
+    main = spec.default()
+    main.geom.size[0] = 2
+
+    def1 = spec.add_default('def1', main)
+    def1.geom.size[0] = 3
+
+    spec.worldbody.add_geom(def1)
+    spec.worldbody.add_geom(main)
+
+    spec.compile()
+    self.assertEqual(spec.to_xml(), textwrap.dedent("""\
+        <mujoco model="test">
+          <compiler angle="radian"/>
+
+          <default>
+            <geom size="2 0 0"/>
+            <default class="def1">
+              <geom size="3 0 0"/>
+            </default>
+          </default>
+
+          <worldbody>
+            <geom class="def1"/>
+            <geom/>
+          </worldbody>
+        </mujoco>
+    """))
+    spec = mujoco.MjSpec()
+    spec.modelname = 'test'
+
+    main = spec.default()
+    main.geom.size[0] = 2
+
+    def1 = spec.add_default('def1', main)
+    def1.geom.size[0] = 3
+
+    spec.worldbody.add_geom(def1)
+    spec.worldbody.add_geom(main)
+
+    spec.compile()
+    self.assertEqual(spec.to_xml(), textwrap.dedent("""\
+        <mujoco model="test">
+          <compiler angle="radian"/>
+
+          <default>
+            <geom size="2 0 0"/>
+            <default class="def1">
+              <geom size="3 0 0"/>
+            </default>
+          </default>
+
+          <worldbody>
+            <geom class="def1"/>
+            <geom/>
+          </worldbody>
+        </mujoco>
+    """))
+
+  def test_element_list(self):
+    spec = mujoco.MjSpec()
+    sensor1 = spec.add_sensor()
+    sensor2 = spec.add_sensor()
+    sensor3 = spec.add_sensor()
+    sensor1.name = 'sensor1'
+    sensor2.name = 'sensor2'
+    sensor3.name = 'sensor3'
+    self.assertLen(spec.sensors, 3)
+    self.assertEqual(spec.sensors[0].name, 'sensor1')
+    self.assertEqual(spec.sensors[1].name, 'sensor2')
+    self.assertEqual(spec.sensors[2].name, 'sensor3')
+
+
+if __name__ == '__main__':
+  absltest.main()

python/mujoco/structs.cc

@@ -28,6 +28,7 @@
 #include <sstream>
 #include <string>
 #include <string_view>
+#include <tuple>
 #include <type_traits>
 #include <unordered_map>
 #include <utility>
@@ -316,24 +317,22 @@ static raw::MjModel* LoadModelFileImpl(
     const std::string& filename,
     const std::vector<VfsAsset>& assets,
     LoadFunc&& loadfunc) {
-  std::unique_ptr<mjVFS, void(*)(mjVFS*)> vfs(nullptr, [](mjVFS*){});
+  mjVFS vfs;
+  mjVFS* vfs_ptr = nullptr;
   if (!assets.empty()) {
-    // mjVFS should be allocated on the heap, because it's ~2MB
+    mj_defaultVFS(&vfs);
-    vfs = decltype(vfs)(new mjVFS, [](mjVFS* vfs) {
+    vfs_ptr = &vfs;
-      mj_deleteVFS(vfs);
-      delete vfs;
-    });
-    mj_defaultVFS(vfs.get());
     for (const auto& asset : assets) {
       const int vfs_error = InterceptMjErrors(mj_addBufferVFS)(
-          vfs.get(), asset.name, asset.content, asset.content_size);
+          vfs_ptr, asset.name, asset.content, asset.content_size);
       if (vfs_error) {
         throw py::value_error("assets dict is too big");
       }
     }
   }
 
-  raw::MjModel* model = loadfunc(filename.c_str(), vfs.get());
+  raw::MjModel* model = loadfunc(filename.c_str(), vfs_ptr);
+  mj_deleteVFS(vfs_ptr);
   if (model && !model->buffer) {
     mj_deleteModel(model);
     model = nullptr;
@@ -350,12 +349,6 @@ ConvertAssetsDict(
   std::vector<VfsAsset> out;
   if (assets.has_value()) {
     for (const auto& [name, content] : *assets) {
-      if (name.length() >= mjMAXVFSNAME) {
-        std::ostringstream error;
-        error << "Filename length " << name.length() << " exceeds "
-              << mjMAXVFSNAME - 1 << " character limit: " << name;
-        throw py::value_error(error.str());
-      }
       out.emplace_back(name.c_str(), PYBIND11_BYTES_AS_STRING(content.ptr()),
                        py::len(content));
     }
@@ -430,6 +423,27 @@ MjModelWrapper MjModelWrapper::LoadXML(
   return MjModelWrapper(model);
 }
 
+MjModelWrapper MjModelWrapper::CompileSpec(raw::MjSpec* spec) {
+  auto m = mj_compile(spec, nullptr);
+  if (!m || mjs_isWarning(spec)) {
+    throw py::value_error(mjs_getError(spec));
+  }
+  return MjModelWrapper(m);
+}
+
+py::tuple RecompileSpec(raw::MjSpec* spec, const MjModelWrapper& old_m,
+                        const MjDataWrapper& old_d) {
+  raw::MjModel* m = static_cast<raw::MjModel*>(mju_malloc(sizeof(mjModel)));
+  m->buffer = nullptr;
+  raw::MjData* d = mj_copyData(nullptr, old_m.get(), old_d.get());
+  mj_recompile(spec, nullptr, m, d);
+
+  py::object m_pyobj = py::cast((MjModelWrapper(m)));
+  py::object d_pyobj =
+      py::cast((MjDataWrapper(py::cast<MjModelWrapper*>(m_pyobj), d)));
+  return py::make_tuple(m_pyobj, d_pyobj);
+}
+
 namespace {
 // A byte at the start of serialized mjModel structs, which can be incremented
 // when we change the serialization logic to reject pickles from an unsupported
@@ -1056,7 +1070,6 @@ MjvGLCameraWrapper::MjWrapper(const MjvGLCameraWrapper& other)
 #define X(var) var(InitPyArray(ptr_->var, owner_))
 MjvGeomWrapper::MjWrapper()
     : WrapperBase(new raw::MjvGeom{}),
-      X(texrepeat),
       X(size),
       X(pos),
       mat([this]() {
@@ -1069,7 +1082,6 @@ MjvGeomWrapper::MjWrapper()
 
 MjvGeomWrapper::MjWrapper(raw::MjvGeom* ptr, py::handle owner)
     : WrapperBase(ptr, owner),
-      X(texrepeat),
       X(size),
       X(pos),
       mat([this]() {
@@ -1557,6 +1569,11 @@ PYBIND11_MODULE(_structs, m) {
       py::arg("xml"), py::arg_v("assets", py::none()),
       py::doc(
 R"(Loads an MjModel from an XML string and an optional assets dictionary.)"));
+  mjModel.def_static(
+      "_from_spec_ptr", [](uintptr_t addr) {
+        return MjModelWrapper::CompileSpec(
+            reinterpret_cast<raw::MjSpec*>(addr));
+      });
   mjModel.def_static(
       "from_xml_path", &MjModelWrapper::LoadXMLFile,
       py::arg("filename"), py::arg_v("assets", py::none()),
@@ -1907,9 +1924,11 @@ This is useful for example when the MJB is not available as a file on disk.)"));
   mjData.def("__copy__", [](const MjDataWrapper& other) {
     return MjDataWrapper(other);
   });
-  mjData.def("__deepcopy__", [](const MjDataWrapper& other, py::dict) {
+  mjData.def("__deepcopy__", [](const MjDataWrapper& other, py::dict memo) {
-    MjModelWrapper* model_copy = new MjModelWrapper(other.model());
+    // Use copy.deepcopy(model) to make a model that Python is aware of.
-    return MjDataWrapper(other, model_copy);
+    py::object new_model_py =
+        py::cast(other.model()).attr("__deepcopy__")(memo);
+    return MjDataWrapper(other, new_model_py.cast<MjModelWrapper*>());
   });
   mjData.def(py::pickle(
       [](const MjDataWrapper& d) {  // __getstate__
@@ -2185,8 +2204,7 @@ This is useful for example when the MJB is not available as a file on disk.)"));
   X(objtype);
   X(objid);
   X(category);
-  X(texid);
+  X(matid);
-  X(texuniform);
   X(texcoord);
   X(segid);
   X(emission);
@@ -2199,7 +2217,6 @@ This is useful for example when the MJB is not available as a file on disk.)"));
 #undef X
 
 #define X(var) DefinePyArray(mjvGeom, #var, &MjvGeomWrapper::var)
-  X(texrepeat);
   X(size);
   X(pos);
   X(mat);
@@ -2404,5 +2421,12 @@ This is useful for example when the MJB is not available as a file on disk.)"));
       },
       py::arg("cam1"), py::arg("cam2"),
       py::doc(python_traits::mjv_averageCamera::doc));
+
+  m.def(
+      "_recompile_spec_addr",
+      [](uintptr_t spec_addr, const MjModelWrapper& m, const MjDataWrapper& d) {
+        return RecompileSpec(reinterpret_cast<raw::MjSpec*>(spec_addr), m, d);
+      }
+  );
 }  // PYBIND11_MODULE NOLINT(readability/fn_size)
 }  // namespace mujoco::python::_impl

python/mujoco/structs.h

@@ -462,6 +462,10 @@ class MjWrapper<raw::MjModel> : public WrapperBase<raw::MjModel> {
  public:
   MjWrapper(const MjWrapper&);
   MjWrapper(MjWrapper&&);
+
+  // Takes ownership of the raw mjModel pointer.
+  explicit MjWrapper(raw::MjModel* ptr);
+
   ~MjWrapper();
 
   MjModelIndexer& indexer() { return indexer_; }
@@ -485,6 +489,8 @@ class MjWrapper<raw::MjModel> : public WrapperBase<raw::MjModel> {
       const std::optional<
           std::unordered_map<std::string, pybind11::bytes>>& assets);
 
+  static MjWrapper CompileSpec(raw::MjSpec* spec);
+
   static constexpr char kFromRawPointer[] =
       "__MUJOCO_STRUCTS_MJMODELWRAPPER_LOOKUP";
   static MjWrapper* FromRawPointer(raw::MjModel* m) noexcept;
@@ -502,8 +508,6 @@ class MjWrapper<raw::MjModel> : public WrapperBase<raw::MjModel> {
   pybind11::bytes paths_bytes;
 
  protected:
-  explicit MjWrapper(raw::MjModel* ptr);
-
   MjModelIndexer indexer_;
 };
 
@@ -591,8 +595,14 @@ class MjWrapper<raw::MjData>: public WrapperBase<raw::MjData> {
   explicit MjWrapper(MjModelWrapper* model);
   MjWrapper(const MjWrapper& other);
   MjWrapper(MjWrapper&&);
+
   // Used for deepcopy
   MjWrapper(const MjWrapper& other, MjModelWrapper* model);
+
+  // Internal constructor which takes ownership of given mjData pointer.
+  // Used for deserialization and recompile.
+  explicit MjWrapper(MjModelWrapper* model, raw::MjData* d);
+
   ~MjWrapper();
 
   const MjModelWrapper& model() const { return *model_; }
@@ -622,9 +632,6 @@ class MjWrapper<raw::MjData>: public WrapperBase<raw::MjData> {
   py_array_or_tuple_t<mjtNum> energy;
 
  protected:
-  // Internal constructor which takes ownership of given mjData pointer.
-  // Used for deserialization.
-  explicit MjWrapper(MjModelWrapper* model, raw::MjData* d);
   raw::MjData* Copy() const;
 
   // A reference to the model that was used to create this mjData.
@@ -727,7 +734,7 @@ class MjWrapper<raw::MjvGeom> : public WrapperBase<raw::MjvGeom> {
     py_array_or_tuple_t<                                        \
         std::remove_all_extents_t<decltype(raw::MjvGeom::var)>> \
         var
-  X(texrepeat);
+  X(matid);
   X(size);
   X(pos);
   X(mat);

python/mujoco/usd/exporter.py

@@ -247,7 +247,11 @@ class USDExporter:
 
     assert geom_name not in self.geom_names
 
-    texture_file = self.texture_files[geom.texid] if geom.texid != -1 else None
+    texture_file = (
+        self.texture_files[self.model.mat_texid[mujoco.mjNTEXMAT*geom.matid]]
+        if geom.matid != -1
+        else None
+    )
 
     # handling meshes in our scene
     if geom.type == mujoco.mjtGeom.mjGEOM_MESH:

python/mujoco/viewer.py

@@ -94,6 +94,20 @@ class Handle:
   def user_scn(self):
     return self._user_scn
 
+  @property
+  def m(self):
+    sim = self._sim()
+    if sim is not None:
+      return sim.m
+    return None
+
+  @property
+  def d(self):
+    sim = self._sim()
+    if sim is not None:
+      return sim.d
+    return None
+
   def close(self):
     sim = self._sim()
     if sim is not None:

python/setup.py

@@ -347,6 +347,7 @@ setuptools.setup(
         CMakeExtension('mujoco._render'),
         CMakeExtension('mujoco._rollout'),
         CMakeExtension('mujoco._simulate'),
+        CMakeExtension('mujoco._specs'),
         CMakeExtension('mujoco._structs'),
     ],
     scripts=[

python/tutorial.ipynb

@@ -420,8 +420,8 @@
     "data = mujoco.MjData(model)\n",
     "\n",
     "# Make renderer, render and show the pixels\n",
-    "renderer = mujoco.Renderer(model)\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -445,10 +445,11 @@
    },
    "outputs": [],
    "source": [
-    "mujoco.mj_forward(model, data)\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "renderer.update_scene(data)\n",
+    "  mujoco.mj_forward(model, data)\n",
+    "  renderer.update_scene(data)\n",
     "\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -480,11 +481,11 @@
     "model = mujoco.MjModel.from_xml_string(xml)\n",
     "data = mujoco.MjData(model)\n",
     "\n",
-    "renderer = mujoco.Renderer(model)\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "mujoco.mj_forward(model, data)\n",
+    "  mujoco.mj_forward(model, data)\n",
-    "renderer.update_scene(data)\n",
+    "  renderer.update_scene(data)\n",
     "\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -508,9 +509,10 @@
    "source": [
     "# Run this cell multiple times for different colors\n",
     "model.geom('red_box').rgba[:3] = np.random.rand(3)\n",
-    "renderer.update_scene(data)\n",
+    "with mujoco.Renderer(model) as renderer:\n",
+    "  renderer.update_scene(data)\n",
     "\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -540,12 +542,13 @@
     "# Simulate and display video.\n",
     "frames = []\n",
     "mujoco.mj_resetData(model, data)  # Reset state and time.\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "  mujoco.mj_step(model, data)\n",
+    "  while data.time < duration:\n",
-    "  if len(frames) < data.time * framerate:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    renderer.update_scene(data)\n",
+    "    if len(frames) < data.time * framerate:\n",
-    "    pixels = renderer.render()\n",
+    "      renderer.update_scene(data)\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=framerate)"
    ]
@@ -583,7 +586,6 @@
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(xml)\n",
     "data = mujoco.MjData(model)\n",
-    "renderer = mujoco.Renderer(model)\n",
     "\n",
     "# enable joint visualization option:\n",
     "scene_option = mujoco.MjvOption()\n",
@@ -595,12 +597,13 @@
     "# Simulate and display video.\n",
     "frames = []\n",
     "mujoco.mj_resetData(model, data)\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "  mujoco.mj_step(model, data)\n",
+    "  while data.time < duration:\n",
-    "  if len(frames) < data.time * framerate:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    renderer.update_scene(data, scene_option=scene_option)\n",
+    "    if len(frames) < data.time * framerate:\n",
-    "    pixels = renderer.render()\n",
+    "      renderer.update_scene(data, scene_option=scene_option)\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=framerate)"
    ]
@@ -651,12 +654,13 @@
     "# Simulate and display video.\n",
     "frames = []\n",
     "mujoco.mj_resetData(model, data)\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "  mujoco.mj_step(model, data)\n",
+    "  while data.time < duration:\n",
-    "  if len(frames) < data.time * framerate:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    renderer.update_scene(data, scene_option=scene_option)\n",
+    "    if len(frames) < data.time * framerate:\n",
-    "    pixels = renderer.render()\n",
+    "      renderer.update_scene(data, scene_option=scene_option)\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=60)"
    ]
@@ -760,12 +764,12 @@
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(tippe_top)\n",
     "data = mujoco.MjData(model)\n",
-    "renderer = mujoco.Renderer(model)\n",
     "\n",
     "mujoco.mj_forward(model, data)\n",
-    "renderer.update_scene(data, camera=\"closeup\")\n",
+    "with mujoco.Renderer(model) as renderer:\n",
+    "  renderer.update_scene(data, camera=\"closeup\")\n",
     "\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -821,12 +825,13 @@
     "# Simulate and display video.\n",
     "frames = []\n",
     "mujoco.mj_resetDataKeyframe(model, data, 0)  # Reset the state to keyframe 0\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "  mujoco.mj_step(model, data)\n",
+    "  while data.time < duration:\n",
-    "  if len(frames) < data.time * framerate:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    renderer.update_scene(data, \"closeup\")\n",
+    "    if len(frames) < data.time * framerate:\n",
-    "    pixels = renderer.render()\n",
+    "      renderer.update_scene(data, \"closeup\")\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=framerate)"
    ]
@@ -939,12 +944,14 @@
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(chaotic_pendulum)\n",
     "data = mujoco.MjData(model)\n",
-    "renderer = mujoco.Renderer(model, 480, 640)\n",
+    "height = 480\n",
+    "width = 640\n",
     "\n",
-    "mujoco.mj_forward(model, data)\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "renderer.update_scene(data, camera=\"fixed\")\n",
+    "  mujoco.mj_forward(model, data)\n",
+    "  renderer.update_scene(data, camera=\"fixed\")\n",
     "\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -970,7 +977,8 @@
     "framerate = 30  # Hz\n",
     "n_frames = int(n_seconds * framerate)\n",
     "frames = []\n",
-    "renderer = mujoco.Renderer(model, 240, 320)\n",
+    "height = 240\n",
+    "width = 320\n",
     "\n",
     "# set initial state\n",
     "mujoco.mj_resetData(model, data)\n",
@@ -981,17 +989,18 @@
     "sim_time = 0\n",
     "render_time = 0\n",
     "n_steps = 0\n",
-    "for i in range(n_frames):\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "  while data.time * framerate < i:\n",
+    "  for i in range(n_frames):\n",
+    "    while data.time * framerate < i:\n",
+    "      tic = time.time()\n",
+    "      mujoco.mj_step(model, data)\n",
+    "      sim_time += time.time() - tic\n",
+    "      n_steps += 1\n",
     "    tic = time.time()\n",
-    "    mujoco.mj_step(model, data)\n",
+    "    renderer.update_scene(data, \"fixed\")\n",
-    "    sim_time += time.time() - tic\n",
+    "    frame = renderer.render()\n",
-    "    n_steps += 1\n",
+    "    render_time += time.time() - tic\n",
-    "  tic = time.time()\n",
+    "    frames.append(frame)\n",
-    "  renderer.update_scene(data, \"fixed\")\n",
-    "  frame = renderer.render()\n",
-    "  render_time += time.time() - tic\n",
-    "  frames.append(frame)\n",
     "\n",
     "# print timing and play video\n",
     "step_time = 1e6*sim_time/n_steps\n",
@@ -1233,12 +1242,14 @@
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(free_body_MJCF)\n",
     "data = mujoco.MjData(model)\n",
-    "renderer = mujoco.Renderer(model, 400, 600)\n",
+    "height = 400\n",
+    "width = 600\n",
     "\n",
-    "mujoco.mj_forward(model, data)\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "renderer.update_scene(data, \"fixed\")\n",
+    "  mujoco.mj_forward(model, data)\n",
+    "  renderer.update_scene(data, \"fixed\")\n",
     "\n",
-    "media.show_image(renderer.render())"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -1262,7 +1273,6 @@
     "height = 240\n",
     "width = 320\n",
     "frames = []\n",
-    "renderer = mujoco.Renderer(model, height, width)\n",
     "\n",
     "# visualize contact frames and forces, make body transparent\n",
     "options = mujoco.MjvOption()\n",
@@ -1282,12 +1292,13 @@
     "data.qvel[3:6] = 5*np.random.randn(3)\n",
     "\n",
     "# Simulate and display video.\n",
-    "for i in range(n_frames):\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "  while data.time < i/120.0: #1/4x real time\n",
+    "  for i in range(n_frames):\n",
-    "    mujoco.mj_step(model, data)\n",
+    "    while data.time < i/120.0: #1/4x real time\n",
-    "  renderer.update_scene(data, \"track\", options)\n",
+    "      mujoco.mj_step(model, data)\n",
-    "  frame = renderer.render()\n",
+    "    renderer.update_scene(data, \"track\", options)\n",
-    "  frames.append(frame)\n",
+    "    frame = renderer.render()\n",
+    "    frames.append(frame)\n",
     "\n",
     "media.show_video(frames, fps=30)"
    ]
@@ -1440,16 +1451,16 @@
     "# load\n",
     "model = mujoco.MjModel.from_xml_string(MJCF)\n",
     "data = mujoco.MjData(model)\n",
-    "renderer = mujoco.Renderer(model, height, width)\n",
     "\n",
     "# Simulate and display video.\n",
-    "mujoco.mj_resetData(model, data)\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "for i in range(n_frames):\n",
+    "  mujoco.mj_resetData(model, data)\n",
-    "  while data.time < i/30.0:\n",
+    "  for i in range(n_frames):\n",
-    "    mujoco.mj_step(model, data)\n",
+    "    while data.time < i/30.0:\n",
-    "  renderer.update_scene(data, \"y\")\n",
+    "      mujoco.mj_step(model, data)\n",
-    "  frame = renderer.render()\n",
+    "    renderer.update_scene(data, \"y\")\n",
-    "  frames.append(frame)\n",
+    "    frame = renderer.render()\n",
+    "    frames.append(frame)\n",
     "\n",
     "media.show_video(frames, fps=30)"
    ]
@@ -1520,12 +1531,14 @@
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(MJCF)\n",
     "data = mujoco.MjData(model)\n",
-    "renderer = mujoco.Renderer(model, 480, 480)\n",
+    "height = 480\n",
+    "width = 480\n",
     "\n",
-    "mujoco.mj_forward(model, data)\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "renderer.update_scene(data, \"fixed\")\n",
+    "  mujoco.mj_forward(model, data)\n",
+    "  renderer.update_scene(data, \"fixed\")\n",
     "\n",
-    "media.show_image(renderer.render())\n"
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -1553,21 +1566,20 @@
     "times = []\n",
     "sensordata = []\n",
     "\n",
-    "renderer = mujoco.Renderer(model, height, width)\n",
-    "\n",
     "# constant actuator signal\n",
     "mujoco.mj_resetData(model, data)\n",
     "data.ctrl = 20\n",
     "\n",
     "# Simulate and display video.\n",
-    "for i in range(n_frames):\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "  while data.time < i/fps:\n",
+    "  for i in range(n_frames):\n",
-    "    mujoco.mj_step(model, data)\n",
+    "    while data.time < i/fps:\n",
-    "    times.append(data.time)\n",
+    "      mujoco.mj_step(model, data)\n",
-    "    sensordata.append(data.sensor('accelerometer').data.copy())\n",
+    "      times.append(data.time)\n",
-    "  renderer.update_scene(data, \"fixed\")\n",
+    "      sensordata.append(data.sensor('accelerometer').data.copy())\n",
-    "  frame = renderer.render()\n",
+    "    renderer.update_scene(data, \"fixed\")\n",
-    "  frames.append(frame)\n",
+    "    frame = renderer.render()\n",
+    "    frames.append(frame)\n",
     "\n",
     "media.show_video(frames, fps=fps)"
    ]
@@ -1644,12 +1656,12 @@
     "</mujoco>\n",
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(xml)\n",
-    "renderer = mujoco.Renderer(model)\n",
     "data = mujoco.MjData(model)\n",
     "\n",
-    "mujoco.mj_forward(model, data)\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "renderer.update_scene(data)\n",
+    "  mujoco.mj_forward(model, data)\n",
-    "media.show_image(renderer.render())"
+    "  renderer.update_scene(data)\n",
+    "  media.show_image(renderer.render())"
    ]
   },
   {
@@ -1664,9 +1676,10 @@
     "\n",
     "scene_option.frame = mujoco.mjtFrame.mjFRAME_GEOM\n",
     "scene_option.flags[mujoco.mjtVisFlag.mjVIS_TRANSPARENT] = True\n",
-    "renderer.update_scene(data, scene_option=scene_option)\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "frame = renderer.render()\n",
+    "  renderer.update_scene(data, scene_option=scene_option)\n",
-    "media.show_image(frame)"
+    "  frame = renderer.render()\n",
+    "  media.show_image(frame)"
    ]
   },
   {
@@ -1679,25 +1692,24 @@
    "source": [
     "#@title Depth rendering {vertical-output: true}\n",
     "\n",
-    "# update renderer to render depth\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "renderer.enable_depth_rendering()\n",
+    "  # update renderer to render depth\n",
+    "  renderer.enable_depth_rendering()\n",
     "\n",
-    "# reset the scene\n",
+    "  # reset the scene\n",
-    "renderer.update_scene(data)\n",
+    "  renderer.update_scene(data)\n",
     "\n",
-    "# depth is a float array, in meters.\n",
+    "  # depth is a float array, in meters.\n",
-    "depth = renderer.render()\n",
+    "  depth = renderer.render()\n",
     "\n",
-    "# Shift nearest values to the origin.\n",
+    "  # Shift nearest values to the origin.\n",
-    "depth -= depth.min()\n",
+    "  depth -= depth.min()\n",
-    "# Scale by 2 mean distances of near rays.\n",
+    "  # Scale by 2 mean distances of near rays.\n",
-    "depth /= 2*depth[depth <= 1].mean()\n",
+    "  depth /= 2*depth[depth <= 1].mean()\n",
-    "# Scale to [0, 255]\n",
+    "  # Scale to [0, 255]\n",
-    "pixels = 255*np.clip(depth, 0, 1)\n",
+    "  pixels = 255*np.clip(depth, 0, 1)\n",
     "\n",
-    "media.show_image(pixels.astype(np.uint8))\n",
+    "  media.show_image(pixels.astype(np.uint8))"
-    "\n",
-    "renderer.disable_depth_rendering()"
    ]
   },
   {
@@ -1710,25 +1722,26 @@
    "source": [
     "#@title Segmentation rendering {vertical-output: true}\n",
     "\n",
-    "# update renderer to render segmentation\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "renderer.enable_segmentation_rendering()\n",
+    "  renderer.disable_depth_rendering()\n",
     "\n",
-    "# reset the scene\n",
+    "  # update renderer to render segmentation\n",
-    "renderer.update_scene(data)\n",
+    "  renderer.enable_segmentation_rendering()\n",
     "\n",
-    "seg = renderer.render()\n",
+    "  # reset the scene\n",
+    "  renderer.update_scene(data)\n",
     "\n",
-    "# Display the contents of the first channel, which contains object\n",
+    "  seg = renderer.render()\n",
-    "# IDs. The second channel, seg[:, :, 1], contains object types.\n",
-    "geom_ids = seg[:, :, 0]\n",
-    "# Infinity is mapped to -1\n",
-    "geom_ids = geom_ids.astype(np.float64) + 1\n",
-    "# Scale to [0, 1]\n",
-    "geom_ids = geom_ids / geom_ids.max()\n",
-    "pixels = 255*geom_ids\n",
-    "media.show_image(pixels.astype(np.uint8))\n",
     "\n",
-    "renderer.disable_segmentation_rendering()"
+    "  # Display the contents of the first channel, which contains object\n",
+    "  # IDs. The second channel, seg[:, :, 1], contains object types.\n",
+    "  geom_ids = seg[:, :, 0]\n",
+    "  # Infinity is mapped to -1\n",
+    "  geom_ids = geom_ids.astype(np.float64) + 1\n",
+    "  # Scale to [0, 1]\n",
+    "  geom_ids = geom_ids / geom_ids.max()\n",
+    "  pixels = 255*geom_ids\n",
+    "  media.show_image(pixels.astype(np.uint8))"
    ]
   },
   {
@@ -1792,37 +1805,39 @@
    "source": [
     "#@title Project from world to camera coordinates {vertical-output: true}\n",
     "\n",
-    "# reset the scene\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "renderer.update_scene(data)\n",
+    "  renderer.disable_segmentation_rendering()\n",
+    "  # reset the scene\n",
+    "  renderer.update_scene(data)\n",
     "\n",
-    "# Get the world coordinates of the box corners\n",
+    "  # Get the world coordinates of the box corners\n",
-    "box_pos = data.geom_xpos[model.geom('red_box').id]\n",
+    "  box_pos = data.geom_xpos[model.geom('red_box').id]\n",
-    "box_mat = data.geom_xmat[model.geom('red_box').id].reshape(3, 3)\n",
+    "  box_mat = data.geom_xmat[model.geom('red_box').id].reshape(3, 3)\n",
-    "box_size = model.geom_size[model.geom('red_box').id]\n",
+    "  box_size = model.geom_size[model.geom('red_box').id]\n",
-    "offsets = np.array([-1, 1]) * box_size[:, None]\n",
+    "  offsets = np.array([-1, 1]) * box_size[:, None]\n",
-    "xyz_local = np.stack(list(itertools.product(*offsets))).T\n",
+    "  xyz_local = np.stack(list(itertools.product(*offsets))).T\n",
-    "xyz_global = box_pos[:, None] + box_mat @ xyz_local\n",
+    "  xyz_global = box_pos[:, None] + box_mat @ xyz_local\n",
     "\n",
-    "# Camera matrices multiply homogenous [x, y, z, 1] vectors.\n",
+    "  # Camera matrices multiply homogenous [x, y, z, 1] vectors.\n",
-    "corners_homogeneous = np.ones((4, xyz_global.shape[1]), dtype=float)\n",
+    "  corners_homogeneous = np.ones((4, xyz_global.shape[1]), dtype=float)\n",
-    "corners_homogeneous[:3, :] = xyz_global\n",
+    "  corners_homogeneous[:3, :] = xyz_global\n",
     "\n",
-    "# Get the camera matrix.\n",
+    "  # Get the camera matrix.\n",
-    "m = compute_camera_matrix(renderer, data)\n",
+    "  m = compute_camera_matrix(renderer, data)\n",
     "\n",
-    "# Project world coordinates into pixel space. See:\n",
+    "  # Project world coordinates into pixel space. See:\n",
-    "# https://en.wikipedia.org/wiki/3D_projection#Mathematical_formula\n",
+    "  # https://en.wikipedia.org/wiki/3D_projection#Mathematical_formula\n",
-    "xs, ys, s = m @ corners_homogeneous\n",
+    "  xs, ys, s = m @ corners_homogeneous\n",
-    "# x and y are in the pixel coordinate system.\n",
+    "  # x and y are in the pixel coordinate system.\n",
-    "x = xs / s\n",
+    "  x = xs / s\n",
-    "y = ys / s\n",
+    "  y = ys / s\n",
     "\n",
-    "# Render the camera view and overlay the projected corner coordinates.\n",
+    "  # Render the camera view and overlay the projected corner coordinates.\n",
-    "pixels = renderer.render()\n",
+    "  pixels = renderer.render()\n",
-    "fig, ax = plt.subplots(1, 1)\n",
+    "  fig, ax = plt.subplots(1, 1)\n",
-    "ax.imshow(pixels)\n",
+    "  ax.imshow(pixels)\n",
-    "ax.plot(x, y, '+', c='w')\n",
+    "  ax.plot(x, y, '+', c='w')\n",
-    "ax.set_axis_off()"
+    "  ax.set_axis_off()"
    ]
   },
   {
@@ -1894,17 +1909,18 @@
     "mujoco.mj_resetData(model, data)\n",
     "mujoco.mj_forward(model, data)\n",
     "\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model) as renderer:\n",
-    "  # append data to the traces\n",
+    "  while data.time < duration:\n",
-    "  positions.append(data.geom_xpos[data.geom(\"green_sphere\").id].copy())\n",
+    "    # append data to the traces\n",
-    "  times.append(data.time)\n",
+    "    positions.append(data.geom_xpos[data.geom(\"green_sphere\").id].copy())\n",
-    "  speeds.append(get_geom_speed(model, data, \"green_sphere\"))\n",
+    "    times.append(data.time)\n",
-    "  mujoco.mj_step(model, data)\n",
+    "    speeds.append(get_geom_speed(model, data, \"green_sphere\"))\n",
-    "  if len(frames) < data.time * framerate:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    renderer.update_scene(data)\n",
+    "    if len(frames) < data.time * framerate:\n",
-    "    modify_scene(renderer.scene)\n",
+    "      renderer.update_scene(data)\n",
-    "    pixels = renderer.render()\n",
+    "      modify_scene(renderer.scene)\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=framerate)"
    ]
@@ -2018,8 +2034,7 @@
     "</mujoco>\n",
     "\"\"\"\n",
     "model = mujoco.MjModel.from_xml_string(dominos_xml)\n",
-    "data = mujoco.MjData(model)\n",
+    "data = mujoco.MjData(model)\n"
-    "renderer = mujoco.Renderer(model, height=1024, width=1440)"
    ]
   },
   {
@@ -2035,16 +2050,19 @@
     "\n",
     "duration = 2.5  # (seconds)\n",
     "framerate = 60  # (Hz)\n",
+    "height = 1024\n",
+    "width = 1440\n",
     "\n",
     "# Simulate and display video.\n",
     "frames = []\n",
     "mujoco.mj_resetData(model, data)  # Reset state and time.\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "  mujoco.mj_step(model, data)\n",
+    "  while data.time < duration:\n",
-    "  if len(frames) < data.time * framerate:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    renderer.update_scene(data, camera='top')\n",
+    "    if len(frames) < data.time * framerate:\n",
-    "    pixels = renderer.render()\n",
+    "      renderer.update_scene(data, camera='top')\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=framerate)"
    ]
@@ -2061,6 +2079,8 @@
     "#@title Render from moving camera\n",
     "\n",
     "duration = 3  # (seconds)\n",
+    "height = 1024\n",
+    "width = 1440\n",
     "\n",
     "# find time when box is thrown (speed > 2cm/s)\n",
     "throw_time = 0.0\n",
@@ -2115,13 +2135,14 @@
     "slowdown = 4    # 4x slow-down\n",
     "mujoco.mj_resetData(model, data)\n",
     "frames = []\n",
-    "while data.time < duration:\n",
+    "with mujoco.Renderer(model, height, width) as renderer:\n",
-    "  mujoco.mj_step(model, data)\n",
+    "  while data.time < duration:\n",
-    "  if len(frames) < data.time * framerate * slowdown:\n",
+    "    mujoco.mj_step(model, data)\n",
-    "    cam.distance, cam.azimuth, cam.elevation, cam.lookat = cam_motion()\n",
+    "    if len(frames) < data.time * framerate * slowdown:\n",
-    "    renderer.update_scene(data, cam)\n",
+    "      cam.distance, cam.azimuth, cam.elevation, cam.lookat = cam_motion()\n",
-    "    pixels = renderer.render()\n",
+    "      renderer.update_scene(data, cam)\n",
-    "    frames.append(pixels)\n",
+    "      pixels = renderer.render()\n",
+    "      frames.append(pixels)\n",
     "\n",
     "media.show_video(frames, fps=framerate)"
    ]

sample/Makefile

@@ -1,12 +0,0 @@
-# This Makefile assumes that you have GLFW libraries and headers installed on,
-# which is commonly available through your distro's package manager.
-# On Debian and Ubuntu, GLFW can be installed via `apt install libglfw3-dev`.
-
-COMMON=-O2 -I../include -L../lib -std=c++17 -pthread -Wl,-no-as-needed -Wl,-rpath,'$$ORIGIN'/../lib
-
-.PHONY: all
-all:
-	$(CXX) $(COMMON) testspeed.cc          -lmujoco          -o ../bin/testspeed
-	$(CXX) $(COMMON) compile.cc            -lmujoco          -o ../bin/compile
-	$(CXX) $(COMMON) basic.cc              -lmujoco -lglfw   -o ../bin/basic
-	$(CXX) $(COMMON) record.cc             -lmujoco -lglfw   -o ../bin/record

sample/Makefile.macos

@@ -1,18 +0,0 @@
-# This Makefile assumes that GLFW is installed via Homebrew.
-# If your setup is different, you will need to set GLFWROOT manually.
-
-# This Makefile also assumes that MuJoCo.app is present in /Applications.
-
-GLFWROOT?=$(shell brew --prefix)
-MUJOCOPATH?=/Applications/MuJoCo.app/Contents/Frameworks
-
-CFLAGS=-O2 -F$(MUJOCOPATH) -I$(GLFWROOT)/include -pthread
-CXXFLAGS=$(CFLAGS) -std=c++17 -stdlib=libc++
-ALLFLAGS=$(CXXFLAGS) -L$(GLFWROOT)/lib -Wl,-rpath,$(MUJOCOPATH)
-
-.PHONY: all
-all:
-	clang++ $(ALLFLAGS)    testspeed.cc  -framework mujoco        -o testspeed
-	clang++ $(ALLFLAGS)    compile.cc    -framework mujoco        -o compile
-	clang++ $(ALLFLAGS)    basic.cc      -framework mujoco -lglfw -o basic
-	clang++ $(ALLFLAGS)    record.cc     -framework mujoco -lglfw -o record

sample/Makefile.windows

@@ -1,17 +0,0 @@
-# A copy of the GLFW library is required to build some sample programs.
-# If this is not already installed on your system, download the WIN64 archive
-# from https://github.com/glfw/glfw/releases, and copy files as follows:
-# - Copy the entire `include/GLFW` subdirectory to `mujoco/include/GLFW`.
-# - Copy glfw3dll.lib from the subdirectory corresponding into your compiler
-#   choice to `mujoco/lib/glfw3dll.lib`.
-# - Copy glfw3.dll from the same subdirectory into `mujoco/bin/glfw3.dll`.
-
-COMMON=/O2 /MT /EHsc /arch:AVX /I../include /Fe../bin/
-
-.PHONY: all
-all:
-	cl $(COMMON) testspeed.cc                              ../lib/mujoco.lib
-	cl $(COMMON) compile.cc                                ../lib/mujoco.lib
-	cl $(COMMON) basic.cc              ../lib/glfw3dll.lib ../lib/mujoco.lib
-	cl $(COMMON) record.cc             ../lib/glfw3dll.lib ../lib/mujoco.lib
-	del *.obj

sample/cmake/SampleOptions.cmake

@@ -104,6 +104,10 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang
   endif()
 endif()
 
+if(NOT CMAKE_INTERPROCEDURAL_OPTIMIZATION AND (CMAKE_BUILD_TYPE AND NOT CMAKE_BUILD_TYPE STREQUAL "Debug"))
+  set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
+endif()
+
 include(MujocoHarden)
 set(EXTRA_COMPILE_OPTIONS ${EXTRA_COMPILE_OPTIONS} ${MUJOCO_HARDEN_COMPILE_OPTIONS})
 set(EXTRA_LINK_OPTIONS ${EXTRA_LINK_OPTIONS} ${MUJOCO_HARDEN_LINK_OPTIONS})

sample/testspeed.cc

@@ -34,18 +34,17 @@ mjData* d[maxthread];
 // per-thread statistics
 int contacts[maxthread];
 int constraints[maxthread];
-double simtime[maxthread];
+mjtNum simtime[maxthread];
-
 
 // timer
-std::chrono::steady_clock::time_point tm_start;
 mjtNum gettm(void) {
-  std::chrono::duration<double, std::micro> elapsed;
+  using std::chrono::steady_clock;
-  elapsed = std::chrono::steady_clock::now() - tm_start;
+  using Microseconds = std::chrono::duration<double, std::micro>;
+  static steady_clock::time_point tm_start = steady_clock::now();
+  auto elapsed = Microseconds(steady_clock::now() - tm_start);
   return elapsed.count();
 }
 
-
 // deallocate and print message
 int finish(const char* msg = NULL, mjModel* m = NULL) {
   // deallocate model
@@ -87,7 +86,7 @@ void simulate(int id, int nstep, mjtNum* ctrl) {
   constraints[id] = 0;
 
   // run and time
-  double start = gettm();
+  mjtNum start = gettm();
   for (int i=0; i < nstep; i++) {
     // inject pseudo-random control noise
     mju_copy(d[id]->ctrl, ctrl + i*m->nu, m->nu);
@@ -126,7 +125,7 @@ int main(int argc, char** argv) {
   // read arguments
   int nstep = 10000, nthread = 0, npoolthread = 0;
   // inject small noise by default, to avoid fixed contact state
-  mjtNum ctrlnoise = 0.01;
+  double ctrlnoise = 0.01;
   if (argc > 2 && (std::sscanf(argv[2], "%d", &nstep) != 1 || nstep <= 0)) {
     return finish("Invalid nstep argument");
   }
@@ -149,7 +148,7 @@ int main(int argc, char** argv) {
 
   // get filename, determine file type
   std::string filename(argv[1]);
-  bool binary = (filename.find(".mjb") != std::string::npos);
+  bool binary = (filename.find(".mjb") != std::string::npos);  // NOLINT
 
   // load model
   char error[1000] = "Could not load binary model";
@@ -191,8 +190,11 @@ int main(int argc, char** argv) {
               nstep,
               nthread > 1 ? " per thread" : "",
               m->opt.timestep);
+  if (sizeof(mjtNum) == 4) {
+    std::printf(", using single-precision");
+  }
   if (npoolthread > 1) {
-    std::printf(", using %d threads for engine-internal threadpool", npoolthread);
+    std::printf(", using %d threads", npoolthread);
   }
   std::printf("...\n\n");
 

simulate/Makefile

@@ -1,11 +0,0 @@
-# This Makefile assumes that you have GLFW libraries and headers installed on,
-# which is commonly available through your distro's package manager.
-# On Debian and Ubuntu, GLFW can be installed via `apt install libglfw3-dev`.
-
-COMMON=-O2 -I../include -L../lib -pthread -Wl,-no-as-needed -Wl,-rpath,'$$ORIGIN'/../lib
-
-all:
-	$(CXX) $(COMMON) -std=c++17 -c simulate.cc
-	$(CC)  $(COMMON) -std=c11   -c uitools.c
-	$(CXX) $(COMMON) -std=c++17 main.cc simulate.o uitools.o -lmujoco -lglfw -o ../bin/simulate
-	rm uitools.o simulate.o

simulate/Makefile.macos

@@ -1,18 +0,0 @@
-# This Makefile assumes that GLFW is installed via Homebrew.
-# If your setup is different, you will need to set GLFWROOT manually.
-
-# This Makefile also assumes that MuJoCo.app is present in /Applications.
-
-GLFWROOT?=$(shell brew --prefix)
-MUJOCOPATH?=/Applications/MuJoCo.app/Contents/Frameworks
-
-CFLAGS=-O2 -F$(MUJOCOPATH) -I$(GLFWROOT)/include -pthread
-CXXFLAGS=$(CFLAGS) -std=c++17 -stdlib=libc++
-ALLFLAGS=$(CXXFLAGS) -L$(GLFWROOT)/lib -Wl,-rpath,$(MUJOCOPATH)
-
-all:
-	clang++ $(CXXFLAGS)      -c macos_gui.mm
-	clang++ $(CXXFLAGS)      -c simulate.cc
-	clang $(CFLAGS) -std=c11 -c uitools.c
-	clang++ $(CXXFLAGS) main.cc macos_gui.o simulate.o uitools.o  -framework mujoco -framework Cocoa -lglfw -o simulate
-	rm *.o

simulate/Makefile.windows

@@ -1,13 +0,0 @@
-# A copy of the GLFW library is required to build some sample programs.
-# If this is not already installed on your system, download the WIN64 archive
-# from https://github.com/glfw/glfw/releases, and copy files as follows:
-# - Copy the entire `include/GLFW` subdirectory to `mujoco/include/GLFW`.
-# - Copy glfw3dll.lib from the subdirectory corresponding into your compiler
-#   choice to `mujoco/lib/glfw3dll.lib`.
-# - Copy glfw3.dll from the same subdirectory into `mujoco/bin/glfw3.dll`.
-
-COMMON=/O2 /MT /EHsc /arch:AVX /I../include /Fe../bin/
-
-all:
-	cl $(COMMON) main.cc simulate.cc uitools.c ../lib/glfw3dll.lib ../lib/mujoco.lib
-	del *.obj

simulate/cmake/SimulateOptions.cmake

@@ -104,6 +104,10 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang
   endif()
 endif()
 
+if(NOT CMAKE_INTERPROCEDURAL_OPTIMIZATION AND (CMAKE_BUILD_TYPE AND NOT CMAKE_BUILD_TYPE STREQUAL "Debug"))
+  set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
+endif()
+
 include(MujocoHarden)
 set(EXTRA_COMPILE_OPTIONS ${EXTRA_COMPILE_OPTIONS} ${MUJOCO_HARDEN_COMPILE_OPTIONS})
 set(EXTRA_LINK_OPTIONS ${EXTRA_LINK_OPTIONS} ${MUJOCO_HARDEN_LINK_OPTIONS})

simulate/main.cc

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <cerrno>
 #include <chrono>
 #include <cstdint>
 #include <cstdio>
@@ -334,7 +335,7 @@ void PhysicsLoop(mj::Simulate& sim) {
 
           // misalignment condition: distance from target sim time is bigger than syncmisalign
           bool misaligned =
-              mju_abs(Seconds(elapsedCPU).count()/slowdown - elapsedSim) > syncMisalign;
+              std::abs(Seconds(elapsedCPU).count()/slowdown - elapsedSim) > syncMisalign;
 
           // out-of-sync (for any reason): reset sync times, step
           if (elapsedSim < 0 || elapsedCPU.count() < 0 || syncCPU.time_since_epoch().count() == 0 ||

simulate/simulate.cc

@@ -117,13 +117,13 @@ enum {
 
 // file section of UI
 const mjuiDef defFile[] = {
-  {mjITEM_SECTION,   "File",          1, nullptr,                    "AF"},
+  {mjITEM_SECTION,   "File",          mjPRESERVE, nullptr, "AF"},
-  {mjITEM_BUTTON,    "Save xml",      2, nullptr,                    ""},
+  {mjITEM_BUTTON,    "Save xml",      2, nullptr, ""},
-  {mjITEM_BUTTON,    "Save mjb",      2, nullptr,                    ""},
+  {mjITEM_BUTTON,    "Save mjb",      2, nullptr, ""},
-  {mjITEM_BUTTON,    "Print model",   2, nullptr,                    "CM"},
+  {mjITEM_BUTTON,    "Print model",   2, nullptr, "CM"},
-  {mjITEM_BUTTON,    "Print data",    2, nullptr,                    "CD"},
+  {mjITEM_BUTTON,    "Print data",    2, nullptr, "CD"},
-  {mjITEM_BUTTON,    "Quit",          1, nullptr,                    "CQ"},
+  {mjITEM_BUTTON,    "Quit",          1, nullptr, "CQ"},
-  {mjITEM_BUTTON,    "Screenshot",    2, nullptr,                    "CP"},
+  {mjITEM_BUTTON,    "Screenshot",    2, nullptr, "CP"},
   {mjITEM_END}
 };
 
@@ -674,15 +674,15 @@ void UpdateWatch(mj::Simulate* sim, const mjModel* m, const mjData* d) {
 //---------------------------------- UI construction -----------------------------------------------
 
 // make physics section of UI
-void MakePhysicsSection(mj::Simulate* sim, int oldstate) {
+void MakePhysicsSection(mj::Simulate* sim) {
   mjOption* opt = sim->is_passive_ ? &sim->scnstate_.model.opt : &sim->m_->opt;
   mjuiDef defPhysics[] = {
-    {mjITEM_SECTION,   "Physics",       oldstate, nullptr,           "AP"},
+    {mjITEM_SECTION,   "Physics",       mjPRESERVE, nullptr,          "AP"},
     {mjITEM_SELECT,    "Integrator",    2, &(opt->integrator),        "Euler\nRK4\nimplicit\nimplicitfast"},
     {mjITEM_SELECT,    "Cone",          2, &(opt->cone),              "Pyramidal\nElliptic"},
     {mjITEM_SELECT,    "Jacobian",      2, &(opt->jacobian),          "Dense\nSparse\nAuto"},
     {mjITEM_SELECT,    "Solver",        2, &(opt->solver),            "PGS\nCG\nNewton"},
-    {mjITEM_SEPARATOR, "Algorithmic Parameters", 1},
+    {mjITEM_SEPARATOR, "Algorithmic Parameters", mjPRESERVE},
     {mjITEM_EDITNUM,   "Timestep",      2, &(opt->timestep),          "1 0 1"},
     {mjITEM_EDITINT,   "Iterations",    2, &(opt->iterations),        "1 0 1000"},
     {mjITEM_EDITNUM,   "Tolerance",     2, &(opt->tolerance),         "1 0 1"},
@@ -695,22 +695,22 @@ void MakePhysicsSection(mj::Simulate* sim, int oldstate) {
     {mjITEM_EDITNUM,   "API Rate",      2, &(opt->apirate),           "1 0 1000"},
     {mjITEM_EDITINT,   "SDF Iter",      2, &(opt->sdf_iterations),    "1 1 20"},
     {mjITEM_EDITINT,   "SDF Init",      2, &(opt->sdf_initpoints),    "1 1 100"},
-    {mjITEM_SEPARATOR, "Physical Parameters", 1},
+    {mjITEM_SEPARATOR, "Physical Parameters", mjPRESERVE},
     {mjITEM_EDITNUM,   "Gravity",       2, opt->gravity,              "3"},
     {mjITEM_EDITNUM,   "Wind",          2, opt->wind,                 "3"},
     {mjITEM_EDITNUM,   "Magnetic",      2, opt->magnetic,             "3"},
     {mjITEM_EDITNUM,   "Density",       2, &(opt->density),           "1"},
     {mjITEM_EDITNUM,   "Viscosity",     2, &(opt->viscosity),         "1"},
     {mjITEM_EDITNUM,   "Imp Ratio",     2, &(opt->impratio),          "1"},
-    {mjITEM_SEPARATOR, "Disable Flags", 1},
+    {mjITEM_SEPARATOR, "Disable Flags", mjPRESERVE},
     {mjITEM_END}
   };
   mjuiDef defEnableFlags[] = {
-    {mjITEM_SEPARATOR, "Enable Flags", 1},
+    {mjITEM_SEPARATOR, "Enable Flags", mjPRESERVE},
     {mjITEM_END}
   };
   mjuiDef defOverride[] = {
-    {mjITEM_SEPARATOR, "Contact Override", 1},
+    {mjITEM_SEPARATOR, "Contact Override", mjPRESERVE},
     {mjITEM_EDITNUM,   "Margin",        2, &(opt->o_margin),          "1"},
     {mjITEM_EDITNUM,   "Sol Imp",       2, &(opt->o_solimp),          "5"},
     {mjITEM_EDITNUM,   "Sol Ref",       2, &(opt->o_solref),          "2"},
@@ -718,7 +718,7 @@ void MakePhysicsSection(mj::Simulate* sim, int oldstate) {
     {mjITEM_END}
   };
   mjuiDef defDisableActuator[] = {
-    {mjITEM_SEPARATOR, "Actuator Group Enable", 1},
+    {mjITEM_SEPARATOR, "Actuator Group Enable", mjPRESERVE},
     {mjITEM_CHECKBYTE,  "Act Group 0",  2, sim->enableactuator+0,     ""},
     {mjITEM_CHECKBYTE,  "Act Group 1",  2, sim->enableactuator+1,     ""},
     {mjITEM_CHECKBYTE,  "Act Group 2",  2, sim->enableactuator+2,     ""},
@@ -752,57 +752,39 @@ void MakePhysicsSection(mj::Simulate* sim, int oldstate) {
 
   // add actuator group enable/disable
   mjui_add(&sim->ui0, defDisableActuator);
+
+  // make some subsections closed by default
+  for (int i=0; i < sim->ui0.sect[SECT_PHYSICS].nitem; i++) {
+    mjuiItem* it = sim->ui0.sect[SECT_PHYSICS].item + i;
+
+    // close less useful subsections
+    if (it->type == mjITEM_SEPARATOR) {
+      if (mju::strcmp_arr(it->name, "Actuator Group Enable") &&
+          mju::strcmp_arr(it->name, "Contact Override")  &&
+          mju::strcmp_arr(it->name, "Physical Parameters")) {
+        it->state = mjSEPCLOSED+1;
+      }
+    }
+  }
 }
 
 
 
 // make rendering section of UI
-void MakeRenderingSection(mj::Simulate* sim, const mjModel* m, int oldstate) {
+void MakeRenderingSection(mj::Simulate* sim, const mjModel* m) {
   mjuiDef defRendering[] = {
-    {
+    {mjITEM_SECTION, "Rendering", mjPRESERVE, nullptr, "AR"},
-      mjITEM_SECTION,
+    {mjITEM_SELECT, "Camera", 2, &(sim->camera), "Free\nTracking"},
-      "Rendering",
+    {mjITEM_SELECT, "Label", 2, &(sim->opt.label),
-      oldstate,
-      nullptr,
-      "AR"
-    },
-    {
-      mjITEM_SELECT,
-      "Camera",
-      2,
-      &(sim->camera),
-      "Free\nTracking"
-    },
-    {
-      mjITEM_SELECT,
-      "Label",
-      2,
-      &(sim->opt.label),
       "None\nBody\nJoint\nGeom\nSite\nCamera\nLight\nTendon\n"
       "Actuator\nConstraint\nFlex\nSkin\nSelection\nSel Pnt\nContact\nForce\nIsland"
     },
-    {
+    {mjITEM_SELECT, "Frame", 2, &(sim->opt.frame),
-      mjITEM_SELECT,
-      "Frame",
-      2,
-      &(sim->opt.frame),
       "None\nBody\nGeom\nSite\nCamera\nLight\nContact\nWorld"
     },
-    {
+    {mjITEM_BUTTON, "Copy camera", 2, nullptr, ""},
-      mjITEM_BUTTON,
+    {mjITEM_SEPARATOR, "Model Elements", 1},
-      "Copy camera",
+    {mjITEM_END}
-      2,
-      nullptr,
-      ""
-    },
-    {
-      mjITEM_SEPARATOR,
-      "Model Elements",
-      1
-    },
-    {
-      mjITEM_END
-    }
   };
   mjuiDef defOpenGL[] = {
     {mjITEM_SEPARATOR, "OpenGL Effects", 1},
@@ -876,18 +858,18 @@ void MakeRenderingSection(mj::Simulate* sim, const mjModel* m, int oldstate) {
 }
 
 // make visualization section of UI
-void MakeVisualizationSection(mj::Simulate* sim, const mjModel* m, int oldstate) {
+void MakeVisualizationSection(mj::Simulate* sim, const mjModel* m) {
   mjStatistic* stat = sim->is_passive_ ? &sim->scnstate_.model.stat : &sim->m_->stat;
   mjVisual* vis = sim->is_passive_ ? &sim->scnstate_.model.vis : &sim->m_->vis;
 
   mjuiDef defVisualization[] = {
-    {mjITEM_SECTION,   "Visualization", oldstate, nullptr, "AV"},
+    {mjITEM_SECTION,   "Visualization", mjPRESERVE, nullptr, "AV"},
     {mjITEM_SEPARATOR, "Headlight",  1},
     {mjITEM_RADIO,     "Active",          5, &(vis->headlight.active),     "Off\nOn"},
     {mjITEM_EDITFLOAT, "Ambient",         2, &(vis->headlight.ambient),    "3"},
     {mjITEM_EDITFLOAT, "Diffuse",         2, &(vis->headlight.diffuse),    "3"},
     {mjITEM_EDITFLOAT, "Specular",        2, &(vis->headlight.specular),   "3"},
-    {mjITEM_SEPARATOR, "Free Camera",  1},
+    {mjITEM_SEPARATOR, "Free Camera", 1},
     {mjITEM_RADIO,     "Orthographic",    2, &(vis->global.orthographic),  "No\nYes"},
     {mjITEM_EDITFLOAT, "Field of view",   2, &(vis->global.fovy),          "1"},
     {mjITEM_EDITNUM,   "Center",          2, &(stat->center),              "3"},
@@ -911,8 +893,8 @@ void MakeVisualizationSection(mj::Simulate* sim, const mjModel* m, int oldstate)
     {mjITEM_EDITFLOAT, "Haze",            2, &(vis->map.haze),             "1"},
     {mjITEM_EDITFLOAT, "Shadow clip",     2, &(vis->map.shadowclip),       "1"},
     {mjITEM_EDITFLOAT, "Shadow scale",    2, &(vis->map.shadowscale),      "1"},
-    {mjITEM_SEPARATOR, "Scale",  1},
+    {mjITEM_SEPARATOR, "Scale", mjPRESERVE},
-    {mjITEM_EDITNUM,   "All [meansize]",  2, &(stat->meansize),            "1"},
+    {mjITEM_EDITNUM,   "All (meansize)",  2, &(stat->meansize),            "1"},
     {mjITEM_EDITFLOAT, "Force width",     2, &(vis->scale.forcewidth),     "1"},
     {mjITEM_EDITFLOAT, "Contact width",   2, &(vis->scale.contactwidth),   "1"},
     {mjITEM_EDITFLOAT, "Contact height",  2, &(vis->scale.contactheight),  "1"},
@@ -929,17 +911,43 @@ void MakeVisualizationSection(mj::Simulate* sim, const mjModel* m, int oldstate)
     {mjITEM_EDITFLOAT, "Frame width",     2, &(vis->scale.framewidth),     "1"},
     {mjITEM_EDITFLOAT, "Constraint",      2, &(vis->scale.constraint),     "1"},
     {mjITEM_EDITFLOAT, "Slider-crank",    2, &(vis->scale.slidercrank),    "1"},
+    {mjITEM_SEPARATOR, "RGBA", mjPRESERVE},
+    {mjITEM_EDITFLOAT, "fog",             2, &(vis->rgba.fog),              "4"},
+    {mjITEM_EDITFLOAT, "haze",            2, &(vis->rgba.haze),             "4"},
+    {mjITEM_EDITFLOAT, "force",           2, &(vis->rgba.force),            "4"},
+    {mjITEM_EDITFLOAT, "inertia",         2, &(vis->rgba.inertia),          "4"},
+    {mjITEM_EDITFLOAT, "joint",           2, &(vis->rgba.joint),            "4"},
+    {mjITEM_EDITFLOAT, "actuator",        2, &(vis->rgba.actuator),         "4"},
+    {mjITEM_EDITFLOAT, "actnegative",     2, &(vis->rgba.actuatornegative), "4"},
+    {mjITEM_EDITFLOAT, "actpositive",     2, &(vis->rgba.actuatorpositive), "4"},
+    {mjITEM_EDITFLOAT, "com",             2, &(vis->rgba.com),              "4"},
+    {mjITEM_EDITFLOAT, "camera",          2, &(vis->rgba.camera),           "4"},
+    {mjITEM_EDITFLOAT, "light",           2, &(vis->rgba.light),            "4"},
+    {mjITEM_EDITFLOAT, "selectpoint",     2, &(vis->rgba.selectpoint),      "4"},
+    {mjITEM_EDITFLOAT, "connect",         2, &(vis->rgba.connect),          "4"},
+    {mjITEM_EDITFLOAT, "contactpoint",    2, &(vis->rgba.contactpoint),     "4"},
+    {mjITEM_EDITFLOAT, "contactforce",    2, &(vis->rgba.contactforce),     "4"},
+    {mjITEM_EDITFLOAT, "contactfriction", 2, &(vis->rgba.contactfriction),  "4"},
+    {mjITEM_EDITFLOAT, "contacttorque",   2, &(vis->rgba.contacttorque),    "4"},
+    {mjITEM_EDITFLOAT, "contactgap",      2, &(vis->rgba.contactgap),       "4"},
+    {mjITEM_EDITFLOAT, "rangefinder",     2, &(vis->rgba.rangefinder),      "4"},
+    {mjITEM_EDITFLOAT, "constraint",      2, &(vis->rgba.constraint),       "4"},
+    {mjITEM_EDITFLOAT, "slidercrank",     2, &(vis->rgba.slidercrank),      "4"},
+    {mjITEM_EDITFLOAT, "crankbroken",     2, &(vis->rgba.crankbroken),      "4"},
+    {mjITEM_EDITFLOAT, "frustum",         2, &(vis->rgba.frustum),          "4"},
+    {mjITEM_EDITFLOAT, "bv",              2, &(vis->rgba.bv),               "4"},
+    {mjITEM_EDITFLOAT, "bvactive",        2, &(vis->rgba.bvactive),         "4"},
     {mjITEM_END}
   };
 
-  // add rendering standard
+  // add visualization section
   mjui_add(&sim->ui0, defVisualization);
 }
 
 // make group section of UI
-void MakeGroupSection(mj::Simulate* sim, int oldstate) {
+void MakeGroupSection(mj::Simulate* sim) {
   mjuiDef defGroup[] = {
-    {mjITEM_SECTION,    "Group enable",     oldstate, nullptr,          "AG"},
+    {mjITEM_SECTION,    "Group enable",     mjPRESERVE, nullptr,            "AG"},
     {mjITEM_SEPARATOR,  "Geom groups",  1},
     {mjITEM_CHECKBYTE,  "Geom 0",           2, sim->opt.geomgroup,          " 0"},
     {mjITEM_CHECKBYTE,  "Geom 1",           2, sim->opt.geomgroup+1,        " 1"},
@@ -997,9 +1005,9 @@ void MakeGroupSection(mj::Simulate* sim, int oldstate) {
 }
 
 // make joint section of UI
-void MakeJointSection(mj::Simulate* sim, int oldstate) {
+void MakeJointSection(mj::Simulate* sim) {
   mjuiDef defJoint[] = {
-    {mjITEM_SECTION, "Joint", oldstate, nullptr, "AJ"},
+    {mjITEM_SECTION, "Joint", mjPRESERVE, nullptr, "AJ"},
     {mjITEM_END}
   };
   mjuiDef defSlider[] = {
@@ -1050,9 +1058,9 @@ void MakeJointSection(mj::Simulate* sim, int oldstate) {
 }
 
 // make control section of UI
-void MakeControlSection(mj::Simulate* sim, int oldstate) {
+void MakeControlSection(mj::Simulate* sim) {
   mjuiDef defControl[] = {
-    {mjITEM_SECTION, "Control", oldstate, nullptr, "AC"},
+    {mjITEM_SECTION, "Control", mjPRESERVE, nullptr, "AC"},
     {mjITEM_BUTTON,  "Clear all", 2},
     {mjITEM_END}
   };
@@ -1107,35 +1115,17 @@ void MakeControlSection(mj::Simulate* sim, int oldstate) {
 
 // make model-dependent UI sections
 void MakeUiSections(mj::Simulate* sim, const mjModel* m, const mjData* d) {
-  // get section open-close state, UI 0
-  int oldstate0[NSECT0];
-  for (int i=0; i<NSECT0; i++) {
-    oldstate0[i] = 0;
-    if (sim->ui0.nsect>i) {
-      oldstate0[i] = sim->ui0.sect[i].state;
-    }
-  }
-
-  // get section open-close state, UI 1
-  int oldstate1[NSECT1];
-  for (int i=0; i<NSECT1; i++) {
-    oldstate1[i] = 0;
-    if (sim->ui1.nsect>i) {
-      oldstate1[i] = sim->ui1.sect[i].state;
-    }
-  }
-
   // clear model-dependent sections of UI
   sim->ui0.nsect = SECT_PHYSICS;
   sim->ui1.nsect = 0;
 
   // make
-  MakePhysicsSection(sim, oldstate0[SECT_PHYSICS]);
+  MakePhysicsSection(sim);
-  MakeRenderingSection(sim, m, oldstate0[SECT_RENDERING]);
+  MakeRenderingSection(sim, m);
-  MakeVisualizationSection(sim, m, oldstate0[SECT_VISUALIZATION]);
+  MakeVisualizationSection(sim, m);
-  MakeGroupSection(sim, oldstate0[SECT_GROUP]);
+  MakeGroupSection(sim);
-  MakeJointSection(sim, oldstate1[SECT_JOINT]);
+  MakeJointSection(sim);
-  MakeControlSection(sim, oldstate1[SECT_CONTROL]);
+  MakeControlSection(sim);
 }
 
 //---------------------------------- utility functions ---------------------------------------------
@@ -1165,7 +1155,9 @@ void CopyPose(mj::Simulate* sim, const mjModel* m, const mjData* d) {
 
 // millisecond timer, for MuJoCo built-in profiler
 mjtNum Timer() {
-  return Milliseconds(mj::Simulate::Clock::now().time_since_epoch()).count();
+  static auto start = mj::Simulate::Clock::now();
+  auto elapsed = Milliseconds(mj::Simulate::Clock::now() - start);
+  return elapsed.count();
 }
 
 // clear all times
@@ -1263,7 +1255,7 @@ int ComputeFontScale(const mj::PlatformUIAdapter& platform_ui) {
     fs = 150;
   }
   fs = mju_round(fs * 0.02) * 50;
-  fs = mjMIN(250, mjMAX(100, fs));
+  fs = mjMIN(300, mjMAX(100, fs));
 
   return fs;
 }
@@ -1320,9 +1312,22 @@ void UiLayout(mjuiState* state) {
   rect[3].height = rect[0].height;
 }
 
+// modify UI
 void UiModify(mjUI* ui, mjuiState* state, mjrContext* con) {
   mjui_resize(ui, con);
-  mjr_addAux(ui->auxid, ui->width, ui->maxheight, ui->spacing.samples, con);
+
+  // remake aux buffer only if missing or different
+  int id = ui->auxid;
+  if (con->auxFBO[id] == 0 ||
+      con->auxFBO_r[id] == 0 ||
+      con->auxColor[id] == 0 ||
+      con->auxColor_r[id] == 0 ||
+      con->auxWidth[id] != ui->width ||
+      con->auxHeight[id] != ui->maxheight ||
+      con->auxSamples[id] != ui->spacing.samples) {
+    mjr_addAux(id, ui->width, ui->maxheight, ui->spacing.samples, con);
+  }
+
   UiLayout(state);
   mjui_update(-1, -1, ui, state, con);
 }
@@ -1502,7 +1507,7 @@ void UiEvent(mjuiState* state) {
       // remake joint section if joint group changed
       if (it->name[0]=='J' && it->name[1]=='o') {
         sim->ui1.nsect = SECT_JOINT;
-        MakeJointSection(sim, sim->ui1.sect[SECT_JOINT].state);
+        MakeJointSection(sim);
         sim->ui1.nsect = NSECT1;
         UiModify(&sim->ui1, state, &sim->platform_ui->mjr_context());
       }
@@ -2455,7 +2460,7 @@ void Simulate::Render() {
   if (pending_.ui_remake_ctrl) {
     if (this->ui1_enable && this->ui1.sect[SECT_CONTROL].state) {
       this->ui1.nsect = SECT_CONTROL;
-      MakeControlSection(this, this->ui1.sect[SECT_CONTROL].state);
+      MakeControlSection(this);
       this->ui1.nsect = NSECT1;
       UiModify(&this->ui1, &this->uistate, &this->platform_ui->mjr_context());
     }
@@ -2643,12 +2648,15 @@ void Simulate::RenderLoop() {
   this->platform_ui->SetEventCallback(UiEvent);
   this->platform_ui->SetLayoutCallback(UiLayout);
 
-  // populate uis with standard sections
+  // populate uis with standard sections, open some sections initially
   this->ui0.userdata = this;
   this->ui1.userdata = this;
   mjui_add(&this->ui0, defFile);
   mjui_add(&this->ui0, this->def_option);
   mjui_add(&this->ui0, this->def_simulation);
+  this->ui0.sect[0].state = 1;
+  this->ui0.sect[1].state = 1;
+  this->ui0.sect[2].state = 1;
   mjui_add(&this->ui0, this->def_watch);
   UiModify(&this->ui0, &this->uistate, &this->platform_ui->mjr_context());
   UiModify(&this->ui1, &this->uistate, &this->platform_ui->mjr_context());

simulate/simulate.h

@@ -265,7 +265,7 @@ class Simulate {
   // Constant arrays needed for the option section of UI and the UI interface
   // TODO setting the size here is not ideal
   const mjuiDef def_option[13] = {
-    {mjITEM_SECTION,  "Option",        1, nullptr,           "AO"},
+    {mjITEM_SECTION,  "Option",        mjPRESERVE, nullptr,  "AO"},
     {mjITEM_CHECKINT, "Help",          2, &this->help,       " #290"},
     {mjITEM_CHECKINT, "Info",          2, &this->info,       " #291"},
     {mjITEM_CHECKINT, "Profiler",      2, &this->profiler,   " #292"},
@@ -287,7 +287,7 @@ class Simulate {
 
   // simulation section of UI
   const mjuiDef def_simulation[14] = {
-    {mjITEM_SECTION,   "Simulation",    1, nullptr,              "AS"},
+    {mjITEM_SECTION,   "Simulation",    mjPRESERVE, nullptr,     "AS"},
     {mjITEM_RADIO,     "",              5, &this->run,           "Pause\nRun"},
     {mjITEM_BUTTON,    "Reset",         2, nullptr,              " #259"},
     {mjITEM_BUTTON,    "Reload",        5, nullptr,              "CL"},
@@ -306,7 +306,7 @@ class Simulate {
 
   // watch section of UI
   const mjuiDef def_watch[5] = {
-    {mjITEM_SECTION,   "Watch",         0, nullptr,              "AW"},
+    {mjITEM_SECTION,   "Watch",         mjPRESERVE, nullptr,     "AW"},
     {mjITEM_EDITTXT,   "Field",         2, this->field,          "qpos"},
     {mjITEM_EDITINT,   "Index",         2, &this->index,         "1"},
     {mjITEM_STATIC,    "Value",         2, nullptr,              " "},

src/engine/CMakeLists.txt

@@ -21,6 +21,8 @@ set(MUJOCO_ENGINE_SRCS
     engine_collision_convex.h
     engine_collision_driver.c
     engine_collision_driver.h
+    engine_collision_gjk.c
+    engine_collision_gjk.h
     engine_collision_primitive.c
     engine_collision_primitive.h
     engine_collision_sdf.c
@@ -45,6 +47,8 @@ set(MUJOCO_ENGINE_SRCS
     engine_io.c
     engine_io.h
     engine_macro.h
+    engine_name.c
+    engine_name.h
     engine_passive.c
     engine_passive.h
     engine_plugin.cc

src/engine/engine_collision_box.c

@@ -806,8 +806,8 @@ int mjc_BoxBox(const mjModel* M, const mjData* D, mjContact* con, int g1, int g2
   if (q2) {
     mju_mulMatMatT3(r, rotmore, rot);
 
-    // mju_rotVecMat(p,pos12,rotmore);
+    // mju_mulMatVec3(p,rotmore,pos12);
-    // mju_rotVecMat(tmp1,size2,rotmore);
+    // mju_mulMatVec3(tmp1,rotmore,size2);
 
     rotaxis(p, pos12);
     rotaxis(tmp1, size2);
@@ -818,8 +818,8 @@ int mjc_BoxBox(const mjModel* M, const mjData* D, mjContact* con, int g1, int g2
 
     rotmatx(r, rot);
 
-    // mju_rotVecMat(p,pos21,rotmore);
+    // mju_mulMatVec3(p,rotmore,pos21);
-    // mju_rotVecMat(tmp1,size1,rotmore);
+    // mju_mulMatVec3(tmp1,rotmore,size1);
 
     rotaxis(p, pos21);
     rotaxis(tmp1, size1);
@@ -1074,8 +1074,8 @@ edgeedge:
     f2 = -1;
   }
 
-  // mju_rotVecMat(p,pos21,rotmore);
+  // mju_mulMatVec3(p,rotmore,pos21);
-  // mju_rotVecMat(rnorm,clnorm,rotmore);
+  // mju_mulMatVec3(rnorm,rotmore,clnorm);
   rotaxis(p, pos21);
   rotaxis(rnorm, clnorm);
 

src/engine/engine_collision_convex.c

@@ -34,25 +34,31 @@
 
 // ccd center function
 void mjccd_center(const void *obj, ccd_vec3_t *center) {
-  const mjtCCD* ccd = (const mjtCCD*)obj;
+  mjc_center(center->v, (const mjCCDObj*) obj);
-  int g = ccd->geom;
+}
-  int f = ccd->flex;
+
-  int e = ccd->elem;
+
-  int v = ccd->vert;
+
+// center function for convex collision algorithms
+void mjc_center(mjtNum res[3], const mjCCDObj *obj) {
+  int g = obj->geom;
+  int f = obj->flex;
+  int e = obj->elem;
+  int v = obj->vert;
 
   // return geom position
   if (g >= 0) {
-    mju_copy3(center->v, ccd->data->geom_xpos + 3*g);
+    mju_copy3(res, obj->data->geom_xpos + 3*g);
   }
 
   // return flex element position
   else if (e >= 0) {
-    mju_copy3(center->v, ccd->data->flexelem_aabb + 6*(ccd->model->flex_elemadr[f]+e));
+    mju_copy3(res, obj->data->flexelem_aabb + 6*(obj->model->flex_elemadr[f]+e));
   }
 
   // return flex vertex position
   else {
-    mju_copy3(center->v, ccd->data->flexvert_xpos + 3*(ccd->model->flex_vertadr[f]+v));
+    mju_copy3(res, obj->data->flexvert_xpos + 3*(obj->model->flex_vertadr[f]+v));
   }
 }
 
@@ -60,21 +66,25 @@ void mjccd_center(const void *obj, ccd_vec3_t *center) {
 
 // ccd support function
 void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
-  const mjtCCD* ccd = (const mjtCCD*)obj;
+  mjc_support(vec->v, (mjCCDObj*) obj, _dir->v);
-  const mjModel* m = ccd->model;
+}
-  const mjData* d = ccd->data;
+
-  int g = ccd->geom;
+
+
+// support function for convex collision algorithms
+void mjc_support(mjtNum res[3], mjCCDObj* obj, const mjtNum dir[3]) {
+  const mjModel* m = obj->model;
+  const mjData* d = obj->data;
+  int g = obj->geom;
 
   //-------------------------- flex element or vertex -----------------------------
   if (g < 0) {
-    int f = ccd->flex;
+    int f = obj->flex;
     int dim = m->flex_dim[f];
-    mjtNum *res = vec->v;
-    const mjtNum *dir = _dir->v;
 
     // flex element
-    if (ccd->elem >= 0) {
+    if (obj->elem >= 0) {
-      int e = ccd->elem;
+      int e = obj->elem;
       const int* edata = m->flex_elem + m->flex_elemdataadr[f] + e*(dim+1);
       const mjtNum* vert = d->flexvert_xpos + 3*m->flex_vertadr[f];
 
@@ -92,14 +102,14 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
       }
 
       // add radius and margin/2
-      mju_addToScl3(res, dir, m->flex_radius[f] + 0.5*ccd->margin);
+      mju_addToScl3(res, dir, m->flex_radius[f] + 0.5*obj->margin);
       return;
     }
 
     // flex vertex
     else {
-      const mjtNum* vert = d->flexvert_xpos + 3*(m->flex_vertadr[f] + ccd->vert);
+      const mjtNum* vert = d->flexvert_xpos + 3*(m->flex_vertadr[f] + obj->vert);
-      mju_addScl3(res, vert, dir, m->flex_radius[f] + 0.5*ccd->margin);
+      mju_addScl3(res, vert, dir, m->flex_radius[f] + 0.5*obj->margin);
       return;
     }
   }
@@ -111,30 +121,29 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
   mjtNum tmp, vdot;
 
   const mjtNum* size = m->geom_size+3*g;  // geom sizes
-  mjtNum dir[3];                          // direction in geom local frame
+  mjtNum local_dir[3];                    // direction in geom local frame
-  mjtNum res[3];                          // result in geom local frame
 
   // rotate dir to geom local frame
-  mju_mulMatTVec3(dir, d->geom_xmat+9*g, _dir->v);
+  mju_mulMatTVec3(local_dir, d->geom_xmat+9*g, dir);
 
   // compute result according to geom type
   switch ((mjtGeom) m->geom_type[g]) {
   case mjGEOM_SPHERE:
-    mju_scl3(res, dir, size[0]);
+    mju_scl3(res, local_dir, size[0]);
     break;
 
   case mjGEOM_CAPSULE:
     // start with sphere
-    mju_scl3(res, dir, size[0]);
+    mju_scl3(res, local_dir, size[0]);
 
     // add cylinder contribution
-    res[2] += mju_sign(dir[2]) * size[1];
+    res[2] += mju_sign(local_dir[2]) * size[1];
     break;
 
   case mjGEOM_ELLIPSOID:
     // find support point on unit sphere: scale dir by ellipsoid sizes and renormalize
     for (int i=0; i < 3; i++) {
-      res[i] = dir[i] * size[i];
+      res[i] = local_dir[i] * size[i];
     }
     mju_normalize3(res);
 
@@ -146,21 +155,21 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
 
   case mjGEOM_CYLINDER:
     // set result in XY plane: support on circle
-    tmp = mju_sqrt(dir[0]*dir[0] + dir[1]*dir[1]);
+    tmp = mju_sqrt(local_dir[0]*local_dir[0] + local_dir[1]*local_dir[1]);
     if (tmp > mjMINVAL) {
-      res[0] = dir[0]/tmp*size[0];
+      res[0] = local_dir[0]/tmp*size[0];
-      res[1] = dir[1]/tmp*size[0];
+      res[1] = local_dir[1]/tmp*size[0];
     } else {
       res[0] = res[1] = 0;
     }
 
     // set result in Z direction
-    res[2] = mju_sign(dir[2]) * size[1];
+    res[2] = mju_sign(local_dir[2]) * size[1];
     break;
 
   case mjGEOM_BOX:
     for (int i=0; i < 3; i++) {
-      res[i] = mju_sign(dir[i]) * size[i];
+      res[i] = mju_sign(local_dir[i]) * size[i];
     }
     break;
 
@@ -176,9 +185,9 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
       // search all vertices, find best
       for (int i=0; i < m->mesh_vertnum[m->geom_dataid[g]]; i++) {
         // vdot = dot(vertex, dir)
-        vdot = dir[0] * (mjtNum)vertdata[3*i] +
+        vdot = local_dir[0] * (mjtNum)vertdata[3*i] +
-               dir[1] * (mjtNum)vertdata[3*i+1] +
+               local_dir[1] * (mjtNum)vertdata[3*i+1] +
-               dir[2] * (mjtNum)vertdata[3*i+2];
+               local_dir[2] * (mjtNum)vertdata[3*i+2];
 
         // update best
         if (vdot > tmp) {
@@ -188,7 +197,7 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
       }
 
       // record best vertex index, in globalid format
-      ((mjtCCD*)ccd)->meshindex = ibest;
+      obj->meshindex = ibest;
     }
 
     // hill-climb using graph data
@@ -202,9 +211,9 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
 
       // init with first vertex in convex hull
       ibest = 0;
-      tmp = dir[0] * (mjtNum)vertdata[3*vert_globalid[0]] +
+      tmp = local_dir[0] * (mjtNum)vertdata[3*vert_globalid[0]] +
-            dir[1] * (mjtNum)vertdata[3*vert_globalid[0]+1] +
+            local_dir[1] * (mjtNum)vertdata[3*vert_globalid[0]+1] +
-            dir[2] * (mjtNum)vertdata[3*vert_globalid[0]+2];
+            local_dir[2] * (mjtNum)vertdata[3*vert_globalid[0]+2];
 
       // hill-climb until no change
       change = 1;
@@ -213,10 +222,10 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
         change = 0;
         int i = vert_edgeadr[ibest];
         while ((locid=edge_localid[i]) >= 0) {
-          // vdot = dot(vertex, dir)
+          // vdot = dot(vertex, local_dir)
-          vdot = dir[0] * (mjtNum)vertdata[3*vert_globalid[locid]] +
+          vdot = local_dir[0] * (mjtNum)vertdata[3*vert_globalid[locid]] +
-                 dir[1] * (mjtNum)vertdata[3*vert_globalid[locid]+1] +
+                 local_dir[1] * (mjtNum)vertdata[3*vert_globalid[locid]+1] +
-                 dir[2] * (mjtNum)vertdata[3*vert_globalid[locid]+2];
+                 local_dir[2] * (mjtNum)vertdata[3*vert_globalid[locid]+2];
 
           // update best
           if (vdot > tmp) {
@@ -231,7 +240,7 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
       }
 
       // record best vertex index, in locid format
-      ((mjtCCD*)ccd)->meshindex = ibest;
+      obj->meshindex = ibest;
 
       // map best index to globalid
       ibest = vert_globalid[ibest];
@@ -255,16 +264,16 @@ void mjccd_support(const void *obj, const ccd_vec3_t *_dir, ccd_vec3_t *vec) {
     mjERROR("ccd support function is undefined for geom type %d", m->geom_type[g]);
   }
 
-  // add dir*margin/2 to result
+  // add local_dir*margin/2 to result
   for (int i=0; i < 3; i++) {
-    res[i] += dir[i] * ccd->margin/2;
+    res[i] += local_dir[i] * obj->margin/2;
   }
 
   // rotate result to global frame
-  mju_mulMatVec3(vec->v, d->geom_xmat+9*g, res);
+  mju_mulMatVec3(res, d->geom_xmat+9*g, res);
 
   // add geom position
-  mju_addTo3(vec->v, d->geom_xpos+3*g);
+  mju_addTo3(res, d->geom_xpos+3*g);
 }
 
 
@@ -280,7 +289,7 @@ static void mjc_initCCD(ccd_t* ccd, const mjModel* m) {
 
 
 // find single convex-convex collision, using libccd
-static int mjc_MPRIteration(mjtCCD* obj1, mjtCCD* obj2, const ccd_t* ccd,
+static int mjc_MPRIteration(mjCCDObj* obj1, mjCCDObj* obj2, const ccd_t* ccd,
                             const mjModel* m, const mjData* d,
                             mjContact* con, mjtNum margin) {
   ccd_vec3_t dir, pos;
@@ -351,8 +360,8 @@ static void mju_rotateFrame(const mjtNum origin[3], const mjtNum rot[9],
 int mjc_Convex(const mjModel* m, const mjData* d,
                mjContact* con, int g1, int g2, mjtNum margin) {
   ccd_t ccd;
-  mjtCCD obj1 = {m, d, g1, -1, -1, -1, -1, margin, {1, 0, 0, 0}};
+  mjCCDObj obj1 = {m, d, g1, -1, -1, -1, -1, margin, {1, 0, 0, 0}, {0, 0, 0}};
-  mjtCCD obj2 = {m, d, g2, -1, -1, -1, -1, margin, {1, 0, 0, 0}};
+  mjCCDObj obj2 = {m, d, g2, -1, -1, -1, -1, margin, {1, 0, 0, 0}, {0, 0, 0}};
 
   // init ccd structure
   mjc_initCCD(&ccd, m);
@@ -480,7 +489,7 @@ int mjc_PlaneConvex(const mjModel* m, const mjData* d,
   mjGETINFO
   mjtNum dist, dif[3], normal[3] = {mat1[2], mat1[5], mat1[8]};
   ccd_vec3_t dir, vec;
-  mjtCCD obj = {m, d, g2, -1, -1, -1, -1, 0, {1, 0, 0, 0}};
+  mjCCDObj obj = {m, d, g2, -1, -1, -1, -1, 0, {1, 0, 0, 0}, {0, 0, 0}};
 
   // get support point in -normal direction
   ccdVec3Set(&dir, -mat1[2], -mat1[5], -mat1[8]);
@@ -661,7 +670,7 @@ int mjc_ConvexHField(const mjModel* m, const mjData* d,
   // ccd-related
   ccd_vec3_t dirccd, vecccd;
   ccd_real_t depth;
-  mjtCCD obj = {m, d, g2, -1, -1, -1, -1, 0, {1, 0, 0, 0}};
+  mjCCDObj obj = {m, d, g2, -1, -1, -1, -1, 0, {1, 0, 0, 0}, {0, 0, 0}};
   ccd_t ccd;
 
   // point size1 to hfield size instead of geom1 size
@@ -1094,8 +1103,8 @@ void mjc_fixNormal(const mjModel* m, const mjData* d, mjContact* con, int g1, in
 int mjc_ConvexElem(const mjModel* m, const mjData* d, mjContact* con,
                    int g1, int f1, int e1, int v1, int f2, int e2, mjtNum margin) {
   ccd_t ccd;
-  mjtCCD obj1 = {m, d, g1, -1, f1, e1, v1, margin, {1, 0, 0, 0}};
+  mjCCDObj obj1 = {m, d, g1, -1, f1, e1, v1, margin, {1, 0, 0, 0}, {0, 0, 0}};
-  mjtCCD obj2 = {m, d, -1, -1, f2, e2, -1, margin, {1, 0, 0, 0}};
+  mjCCDObj obj2 = {m, d, -1, -1, f2, e2, -1, margin, {1, 0, 0, 0}, {0, 0, 0}};
 
   // init ccd structure
   mjc_initCCD(&ccd, m);
@@ -1142,7 +1151,7 @@ int mjc_HFieldElem(const mjModel* m, const mjData* d, mjContact* con,
   // ccd-related
   ccd_vec3_t dirccd, vecccd;
   ccd_real_t depth;
-  mjtCCD obj = {m, d, -1, -1, f, e, -1, margin, {1, 0, 0, 0}};
+  mjCCDObj obj = {m, d, -1, -1, f, e, -1, margin, {1, 0, 0, 0}, {0, 0, 0}};
   ccd_t ccd;
 
   //------------------------------------- AABB computation, box-box test

src/engine/engine_collision_convex.h

@@ -23,8 +23,10 @@
 
 #include <ccd/vec3.h>
 
+#include <mujoco/mjexport.h>
 #include <mujoco/mjdata.h>
 #include <mujoco/mjmodel.h>
+#include <mujoco/mjtnum.h>
 
 #define mjGETINFO_HFIELD \
     const mjtNum* pos1  = d->geom_xpos + 3*g1; \
@@ -38,8 +40,8 @@
 extern "C" {
 #endif
 
-// ccd general object type
+// internal object type for convex collision detection
-struct _mjtCCD {
+struct _mjCCDObj {
   const mjModel* model;
   const mjData* data;
   int geom;
@@ -49,14 +51,19 @@ struct _mjtCCD {
   int vert;
   mjtNum margin;
   mjtNum rotate[4];
+  mjtNum x0[3];  // initial guess of the witness point
 };
-typedef struct _mjtCCD mjtCCD;
+typedef struct _mjCCDObj mjCCDObj;
 
+// support function for convex collision algorithms
+MJAPI void mjc_support(mjtNum res[3], mjCCDObj* obj, const mjtNum dir[3]);
+
+// center function for convex collision algorithms
+MJAPI void mjc_center(mjtNum res[3], const mjCCDObj *obj);
 
 // ccd support function
 void mjccd_support(const void *obj, const ccd_vec3_t *dir, ccd_vec3_t *vec);
 
-
 // pairwise geom collision functions using ccd
 int mjc_PlaneConvex   (const mjModel* m, const mjData* d,
                        mjContact* con, int g1, int g2, mjtNum margin);

src/engine/engine_collision_gjk.c

@@ -0,0 +1,475 @@
+// Copyright 2024 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "engine/engine_collision_gjk.h"
+
+#include <stddef.h>
+
+#include <mujoco/mjtnum.h>
+#include <mujoco/mjmodel.h>
+#include "engine/engine_util_blas.h"
+#include "engine/engine_util_spatial.h"
+#include "engine/engine_collision_convex.h"
+
+// Computes the shortest distance between the origin and an n-simplex (n <= 3) and returns the
+// barycentric coordinates of the closest point in the simplex. This is the so called distance
+// sub-algorithm of the original 1988 GJK algorithm.
+//
+//  We have adapted the Signed Volume method for our approach from the paper:
+//     Improving the GJK Algorithm for Faster and More Reliable Distance Queries Between Two
+//     Convex Objects, Montanari et al, ToG 2017.
+static void signedVolume(mjtNum lambda[4], const mjtNum simplex[12], int n);
+
+// these internal functions compute the barycentric coordinates of the closest point
+// to the origin in the n-simplex, where n = 3, 2, 1 respectively
+static void S3D(mjtNum lambda[4], const mjtNum simplex[12]);
+static void S2D(mjtNum lambda[3], const mjtNum simplex[9]);
+static void S1D(mjtNum lambda[2], const mjtNum simplex[6]);
+
+// helper function to compute the support point in the Minkowski difference
+static void support(mjtNum s1[3], mjtNum s2[3], mjCCDObj* obj1, mjCCDObj* obj2,
+                    const mjtNum x_k[3]);
+
+// linear algebra utility functions
+static mjtNum det3(const mjtNum v1[3], const mjtNum v2[3], const mjtNum v3[3]);
+static void lincomb(mjtNum res[3], const mjtNum* coef, const mjtNum* v, int n);
+
+// returns the distance between the two objects. The witness points are
+// recoverable from x_0 in obj1 and obj2.
+mjtNum mj_gjk(const mjCCDConfig* config, mjCCDObj* obj1, mjCCDObj* obj2) {
+  mjtNum simplex[12];  // our current simplex with max 4 vertices due to only 3 dimensions
+  int n = 0;           // number of vertices in the simplex
+  mjtNum x_k[3];       // the kth approximation point with initial value x_0
+
+  // segregated simplices and points for the two objects to recover witness points
+  mjtNum simplex1[12], simplex2[12];
+  mjtNum* x1_k = obj1->x0;
+  mjtNum* x2_k = obj2->x0;
+  mju_sub3(x_k, x1_k, x2_k);
+
+  int N = config->max_iterations;
+  for (size_t k = 0; k < N; k++) {
+    mjtNum s1[3], s2[3];  // the support points in obj1 and obj2
+    mjtNum s_k[3];        // the kth support point of Minkowski difference
+    mjtNum lambda[4];     // barycentric coordinates for x_k
+
+    // compute the kth support point
+    support(s1, s2, obj1, obj2, x_k);
+    mju_sub3(s_k, s1, s2);
+
+    // the stopping criteria relies on the Frank-Wolfe duality gap given by
+    //  f(x_k) - f(x_min) <= < grad f(x_k), (x_k - s_k) >
+    mjtNum diff[3];
+    mju_sub3(diff, x_k, s_k);
+    if (2*mju_dot3(x_k, diff) < config->tolerance) {
+      return mju_norm3(x_k);
+    }
+
+    // TODO(kylebayes): signedVolume has been written to assume the first vertex is the latest
+    // support to be added. Once the logic has been updated, then this hack should be removed.
+    for (int i = n; i > 0; i--) {
+      // shift the simplex vertices to the right
+      mju_copy3(simplex  + 3*i, simplex  + 3*(i-1));
+      mju_copy3(simplex1 + 3*i, simplex1 + 3*(i-1));
+      mju_copy3(simplex2 + 3*i, simplex2 + 3*(i-1));
+    }
+
+    // copy new support point into the simplex
+    mju_copy3(simplex, s_k);
+
+    // copy new support point into the individual simplexes
+    mju_copy3(simplex1, s1);
+    mju_copy3(simplex2, s2);
+
+    // run the distance subalgorithm to compute the barycentric coordinates
+    // of the closest point to the origin in the simplex
+    signedVolume(lambda, simplex, ++n);
+    lincomb(x_k, lambda, simplex, 4);
+
+    // compute the approximate witness points
+    lincomb(x1_k, lambda, simplex1, 4);
+    lincomb(x2_k, lambda, simplex2, 4);
+
+    // for lambda[i] == 0, remove the ith vertex from the simplex
+    n = 0;
+    for (int i = 0; i < 4; i++) {
+      if (lambda[i] == 0) continue;
+      // recover simplex for the two objects
+      mju_copy3(simplex1 + 3*n, simplex1 + 3*i);
+      mju_copy3(simplex2 + 3*n, simplex2 + 3*i);
+
+      // simplex in Minkowski difference
+      mju_copy3(simplex + 3*n++, simplex + 3*i);
+    }
+  }
+  return mju_norm3(x_k);
+}
+
+
+
+// computes the support points in obj1 and obj2 for the kth approximation point
+static void support(mjtNum s1[3], mjtNum s2[3], mjCCDObj* obj1, mjCCDObj* obj2,
+                    const mjtNum x_k[3]) {
+  mjtNum dir[3], dir_neg[3];
+  mju_copy3(dir_neg, x_k);
+  mju_normalize3(dir_neg);  // mjc_support assumes a normalized direction
+  mju_scl3(dir, dir_neg, -1);
+
+  // compute S_{A-B}(dir) = S_A(dir) - S_B(-dir)
+  mjc_support(s1, obj1, dir);
+  mjc_support(s2, obj2, dir_neg);
+}
+
+
+
+// linear combination of n 3D vectors:
+//   res = coef[0]*v[0] + ... + coef[n-1]*v[3*(n-1)]
+static void lincomb(mjtNum res[3], const mjtNum* coef, const mjtNum* v, int n) {
+  mju_zero3(res);
+  for (int i = 0; i < n; i++) {
+    if (coef[i] == 0) continue;
+    res[0] += coef[i] * v[3*i + 0];
+    res[1] += coef[i] * v[3*i + 1];
+    res[2] += coef[i] * v[3*i + 2];
+  }
+}
+
+
+
+// returns determinant of the 3x3 matrix with columns v1, v2, v3
+static mjtNum det3(const mjtNum v1[3], const mjtNum v2[3], const mjtNum v3[3]) {
+  mjtNum temp[3];
+  mju_cross(temp, v2, v3);
+  return mju_dot3(v1, temp);
+}
+
+
+
+// returns true only when a and b are both strictly positive or both strictly negative
+static int compareSigns(mjtNum a, mjtNum b) {
+  if (a > 0 && b > 0) return 1;
+  if (a < 0 && b < 0) return 1;
+  return 0;
+}
+
+
+
+// computes the barycentric coordinates of the closest point to the origin in the n-simplex
+void signedVolume(mjtNum lambda[4], const mjtNum simplex[12], int n) {
+  int r = n - 1;  // spatial dimension of the simplex
+  mju_zero4(lambda);
+
+  if (r == 3) {
+    S3D(lambda, simplex);
+  } else if (r == 2) {
+    S2D(lambda, simplex);
+  } else if (r == 1) {
+    S1D(lambda, simplex);
+  } else {
+    lambda[0] = 1;
+  }
+}
+
+
+
+static void S3D(mjtNum lambda[4], const mjtNum simplex[12]) {
+  // the four vertices of the 3-simplex that correspond to 4 support points
+  const mjtNum* s1 = simplex;
+  const mjtNum* s2 = simplex + 3;
+  const mjtNum* s3 = simplex + 6;
+  const mjtNum* s4 = simplex + 9;
+
+  // the matrix M is given by
+  //  [[ s1_x, s2_x, s3_x, s4_x ],
+  //   [ s1_y, s2_y, s3_y, s4_y ],
+  //   [ s1_z, s2_z, s3_z, s4_z ],
+  //   [ 1,    1,    1,    1    ]]
+  // we want to solve M*lambda = P, where P = [p_x, p_y, p_z, 1] with [p_x, p_y, p_z] is the
+  // origin projected onto the simplex
+
+  // compute cofactors to find det(M)
+  mjtNum C41 = -det3(s2, s3, s4);
+  mjtNum C42 =  det3(s1, s3, s4);
+  mjtNum C43 = -det3(s1, s2, s4);
+  mjtNum C44 =  det3(s1, s2, s3);
+
+  // note that m_det = 6*SignVol(simplex) with C4i corresponding to the volume of the 3-simplex
+  // with vertices {s1, s2, s3, 0} - si
+  mjtNum m_det = C41 + C42 + C43 + C44;
+
+  int comp1 = compareSigns(m_det, C41),
+      comp2 = compareSigns(m_det, C42),
+      comp3 = compareSigns(m_det, C43),
+      comp4 = compareSigns(m_det, C44);
+
+  // if all signs are the same then the origin is inside the simplex
+  if (comp1 && comp2 && comp3 && comp4) {
+    lambda[0] = C41 / m_det;
+    lambda[1] = C42 / m_det;
+    lambda[2] = C43 / m_det;
+    lambda[3] = C44 / m_det;
+    return;
+  }
+
+  // find the smallest distance, and use the corresponding barycentric coordinates
+  mjtNum dist = mjMAXVAL;
+
+  if (!comp2) {
+    mjtNum lambda_2d[3], verts[9], x[3];
+    mju_copy3(verts, s1);
+    mju_copy3(verts + 3, s3);
+    mju_copy3(verts + 6, s4);
+    S2D(lambda_2d, verts);
+    lincomb(x, lambda_2d, verts, 3);
+    mjtNum d = mju_norm3(x);
+    lambda[0] = lambda_2d[0];
+    lambda[1] = 0;
+    lambda[2] = lambda_2d[1];
+    lambda[3] = lambda_2d[2];
+    dist = d;
+  }
+
+  if (!comp3) {
+    mjtNum lambda_2d[3], verts[9], x[3];
+    mju_copy3(verts, s1);
+    mju_copy3(verts + 3, s2);
+    mju_copy3(verts + 6, s4);
+    S2D(lambda_2d, verts);
+    lincomb(x, lambda_2d, verts, 3);
+    mjtNum d = mju_norm3(x);
+    if (d < dist) {
+      lambda[0] = lambda_2d[0];
+      lambda[1] = lambda_2d[1];
+      lambda[2] = 0;
+      lambda[3] = lambda_2d[2];
+      dist = d;
+    }
+  }
+
+  if (!comp4) {
+    mjtNum lambda_2d[3], verts[9], x[3];
+    mju_copy3(verts, s1);
+    mju_copy3(verts + 3, s2);
+    mju_copy3(verts + 6, s3);
+    S2D(lambda_2d, verts);
+    lincomb(x, lambda_2d, verts, 3);
+    mjtNum d = mju_norm3(x);
+    if (d < dist) {
+      lambda[0] = lambda_2d[0];
+      lambda[1] = lambda_2d[1];
+      lambda[2] = lambda_2d[2];
+      lambda[3] = 0;
+      dist = d;
+    }
+  }
+
+  if (!comp1) {
+    mjtNum lambda_2d[3], verts[9], x[3];
+    mju_copy3(verts, s2);
+    mju_copy3(verts + 3, s3);
+    mju_copy3(verts + 6, s4);
+    S2D(lambda_2d, verts);
+    lincomb(x, lambda_2d, verts, 3);
+    mjtNum d = mju_norm3(x);
+    if (d < dist) {
+      lambda[0] = 0;
+      lambda[1] = lambda_2d[0];
+      lambda[2] = lambda_2d[1];
+      lambda[3] = lambda_2d[2];
+      dist = d;
+    }
+  }
+}
+
+
+
+static void S2D(mjtNum lambda[3], const mjtNum simplex[9]) {
+  // the three vertices of the 2-simplex that correspond to 3 support points
+  const mjtNum* s1 = simplex;
+  const mjtNum* s2 = simplex + 3;
+  const mjtNum* s3 = simplex + 6;
+
+  // compute normal
+  mjtNum diff1[3], diff2[3], n[3];
+  mju_sub3(diff1, s2, s1);
+  mju_sub3(diff2, s3, s1);
+  mju_cross(n, diff1, diff2);
+
+  // project origin
+  mjtNum p_o[3];
+  mju_scl3(p_o, n, mju_dot3(n, s1) / mju_dot3(n, n));
+
+  mjtNum mu_max = 0;
+
+  //  Below are the minors M_i4 of the matrix M given by
+  //  [[ s1_x, s2_x, s3_x, s4_x ],
+  //   [ s1_y, s2_y, s3_y, s4_y ],
+  //   [ s1_z, s2_z, s3_z, s4_z ],
+  //   [ 1,    1,    1,    1    ]]
+  mjtNum M_14 = s2[1]*s3[2] - s2[2]*s3[1] - s1[1]*s3[2] + s1[2]*s3[1] + s1[1]*s2[2] - s1[2]*s2[1];
+  mjtNum M_24 = s2[0]*s3[2] - s2[2]*s3[0] - s1[0]*s3[2] + s1[2]*s3[0] + s1[0]*s2[2] - s1[2]*s2[0];
+  mjtNum M_34 = s2[0]*s3[1] - s2[1]*s3[0] - s1[0]*s3[1] + s1[1]*s3[0] + s1[0]*s2[1] - s1[1]*s2[0];
+
+  // exclude one of the axes with the largest projection of the simplex using the computed minors
+  mjtNum s1_2D[2], s2_2D[2], s3_2D[2], p_o_2D[2];
+  mjtNum mu1 = mju_abs(M_14), mu2 = mju_abs(M_24), mu3 = mju_abs(M_34);
+  if (mu1 >= mu2 && mu1 >= mu3) {
+    mu_max = mu1;
+    s1_2D[0] = s1[1];
+    s1_2D[1] = s1[2];
+
+    s2_2D[0] = s2[1];
+    s2_2D[1] = s2[2];
+
+    s3_2D[0] = s3[1];
+    s3_2D[1] = s3[2];
+
+    p_o_2D[0] = p_o[1];
+    p_o_2D[1] = p_o[2];
+  } else if (mu2 >= mu3) {
+    mu_max = mu2;
+    s1_2D[0] = s1[0];
+    s1_2D[1] = s1[2];
+
+    s2_2D[0] = s2[0];
+    s2_2D[1] = s2[2];
+
+    s3_2D[0] = s3[0];
+    s3_2D[1] = s3[2];
+
+    p_o_2D[0] = p_o[0];
+    p_o_2D[1] = p_o[2];
+  } else {
+    mu_max = mu3;
+    s1_2D[0] = s1[0];
+    s1_2D[1] = s1[1];
+
+    s2_2D[0] = s2[0];
+    s2_2D[1] = s2[1];
+
+    s3_2D[0] = s3[0];
+    s3_2D[1] = s3[1];
+
+    p_o_2D[0] = p_o[0];
+    p_o_2D[1] = p_o[1];
+  }
+
+  // substitute p_o as a vertex in simplex
+  mjtNum C1 = p_o_2D[0]*s2_2D[1] + p_o_2D[1]*s3_2D[0] + s2_2D[0]*s3_2D[1]
+            - p_o_2D[0]*s3_2D[1] - p_o_2D[1]*s2_2D[0] - s3_2D[0]*s2_2D[1];
+
+  mjtNum C2 = p_o_2D[0]*s3_2D[1] + p_o_2D[1]*s1_2D[0] + s3_2D[0]*s1_2D[1]
+            - p_o_2D[0]*s1_2D[1] - p_o_2D[1]*s3_2D[0] - s1_2D[0]*s3_2D[1];
+
+  mjtNum C3 = p_o_2D[0]*s1_2D[1] + p_o_2D[1]*s2_2D[0] + s1_2D[0]*s2_2D[1]
+            - p_o_2D[0]*s2_2D[1] - p_o_2D[1]*s1_2D[0] - s2_2D[0]*s1_2D[1];
+
+  int comp1 = compareSigns(mu_max, C1),
+      comp2 = compareSigns(mu_max, C2),
+      comp3 = compareSigns(mu_max, C3);
+
+  // inside the simplex
+  if (comp1 && comp2 && comp3) {
+    lambda[0] = C1 / mu_max;
+    lambda[1] = C2 / mu_max;
+    lambda[2] = C3 / mu_max;
+    return;
+  }
+
+  // find the smallest distance, and use the corresponding barycentric coordinates
+  mjtNum dist = mjMAXVAL;
+
+  if (!comp2) {
+    mjtNum lambda_1d[2], verts[6], x[3];
+    mju_copy3(verts, s1);
+    mju_copy3(verts + 3, s3);
+    S1D(lambda_1d, verts);
+    lincomb(x, lambda_1d, verts, 2);
+    mjtNum d = mju_norm3(x);
+    lambda[0] = lambda_1d[0];
+    lambda[1] = 0;
+    lambda[2] = lambda_1d[1];
+    dist = d;
+  }
+
+  if (!comp3) {
+    mjtNum lambda_1d[2], verts[6], x[3];
+    mju_copy3(verts, s1);
+    mju_copy3(verts + 3, s2);
+    S1D(lambda_1d, verts);
+    lincomb(x, lambda_1d, verts, 2);
+    mjtNum d = mju_norm3(x);
+    if (d < dist) {
+      lambda[0] = lambda_1d[0];
+      lambda[1] = lambda_1d[1];
+      lambda[2] = 0;
+      dist = d;
+    }
+  }
+
+  if (!comp1) {
+    mjtNum lambda_1d[2], verts[6], x[3];
+    mju_copy3(verts, s2);
+    mju_copy3(verts + 3, s3);
+    S1D(lambda_1d, verts);
+    lincomb(x, lambda_1d, verts, 2);
+    mjtNum d = mju_norm3(x);
+    if (d < dist) {
+      lambda[1] = lambda_1d[0];
+      lambda[2] = lambda_1d[1];
+      lambda[0] = 0;
+      dist = d;
+    }
+  }
+}
+
+
+
+static void S1D(mjtNum lambda[2], const mjtNum simplex[6]) {
+  // the two vertices of the 1-simplex correspond to 2 support points
+  const mjtNum* s1 = simplex;
+  const mjtNum* s2 = simplex + 3;
+
+  // find projection of origin onto the 1-simplex:
+  //   p_o = s2 - <s2, s2 - s1> / <s2 - s1, s2 - s1> * (s2 - s1)
+  mjtNum p_o[3];
+  mjtNum diff[3];
+  mju_sub3(diff, s2, s1);
+  mjtNum temp1 = mju_dot3(s2, diff);
+  mjtNum temp2 = mju_dot3(diff, diff);
+  mju_addScl3(p_o, s2, diff, - temp1 / temp2);
+
+  // find the axis with the largest projection "shadow" of the simplex
+  mjtNum mu_max = 0;
+  int index;
+  for (int i = 0; i < 3; i++) {
+    mjtNum mu = s1[i] - s2[i];
+    if (mju_abs(mu) >= mju_abs(mu_max)) {
+      mu_max = mu;
+      index = i;
+    }
+  }
+
+  mjtNum C1 = p_o[index] - s2[index];
+  mjtNum C2 = s1[index] - p_o[index];
+
+  // inside the simplex
+  if (compareSigns(mu_max, C1) && compareSigns(mu_max, C2)) {
+    lambda[0] = C1 / mu_max;
+    lambda[1] = C2 / mu_max;
+  } else {
+    lambda[0] = 1;
+    lambda[1] = 0;
+  }
+}

src/engine/engine_collision_gjk.h

@@ -0,0 +1,41 @@
+// Copyright 2024 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef MUJOCO_SRC_ENGINE_ENGINE_COLLISION_GJK_H_
+#define MUJOCO_SRC_ENGINE_ENGINE_COLLISION_GJK_H_
+
+#include <mujoco/mjexport.h>
+#include <mujoco/mjtnum.h>
+#include "engine/engine_collision_convex.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// internal configuration for convex collision detection
+struct _mjCCDConfig {
+  int max_iterations;
+  mjtNum tolerance;
+};
+typedef struct _mjCCDConfig mjCCDConfig;
+
+// Returns the distance between the two objects. The witness points are
+// recoverable from x_0 in obj1 and obj2.
+MJAPI mjtNum mj_gjk(const mjCCDConfig* config, mjCCDObj* obj1, mjCCDObj* obj2);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // MUJOCO_SRC_ENGINE_ENGINE_COLLISION_GJK_H_

src/engine/engine_core_constraint.c

@@ -35,9 +35,9 @@
 #endif
 
 #ifdef mjUSEPLATFORMSIMD
-  #if defined(__AVX__) && defined(mjUSEDOUBLE)
+  #if defined(__AVX__) && !defined(mjUSESINGLE)
     #define mjUSEAVX
-  #endif  // defined(__AVX__) && defined(mjUSEDOUBLE)
+  #endif  // defined(__AVX__) && !defined(mjUSESINGLE)
 #endif  // mjUSEPLATFORMSIMD
 
 
@@ -818,7 +818,10 @@ void mj_instantiateLimit(const mjModel* m, mjData* d) {
       // BALL joint
       else if (m->jnt_type[i] == mjJNT_BALL) {
         // convert joint quaternion to axis-angle
-        mju_quat2Vel(angleAxis, d->qpos+m->jnt_qposadr[i], 1);
+        int adr = m->jnt_qposadr[i];
+        mjtNum quat[4] = {d->qpos[adr], d->qpos[adr+1], d->qpos[adr+2], d->qpos[adr+3]};
+        mju_normalize4(quat);
+        mju_quat2Vel(angleAxis, quat, 1);
 
         // get rotation angle, normalize
         value = mju_normalize3(angleAxis);
@@ -1767,7 +1770,10 @@ static int mj_nl(const mjModel* m, const mjData* d, int *nnz) {
     }
     else if (m->jnt_type[i] == mjJNT_BALL) {
       mjtNum angleAxis[3];
-      mju_quat2Vel(angleAxis, d->qpos+m->jnt_qposadr[i], 1);
+      int adr = m->jnt_qposadr[i];
+      mjtNum quat[4] = {d->qpos[adr], d->qpos[adr+1], d->qpos[adr+2], d->qpos[adr+3]};
+      mju_normalize4(quat);
+      mju_quat2Vel(angleAxis, quat, 1);
       value = mju_normalize3(angleAxis);
       dist = mju_max(m->jnt_range[2*i], m->jnt_range[2*i+1]) - value;
       if (dist < margin) {

src/engine/engine_core_smooth.c

@@ -44,14 +44,6 @@ void mj_kinematics(const mjModel* m, mjData* d) {
   d->xmat[0] = d->xmat[4] = d->xmat[8] = 1;
   d->ximat[0] = d->ximat[4] = d->ximat[8] = 1;
 
-  // normalize all quaternions in qpos
-  mj_normalizeQuat(m, d->qpos);
-
-  // normalize mocap quaternions
-  for (int i=0; i < m->nmocap; i++) {
-    mju_normalize4(d->mocap_quat+4*i);
-  }
-
   // compute global cartesian positions and orientations of all bodies
   for (int i=1; i < m->nbody; i++) {
     mjtNum xpos[3], xquat[4];
@@ -66,6 +58,7 @@ void mj_kinematics(const mjModel* m, mjData* d) {
       // copy pos and quat from qpos
       mju_copy3(xpos, d->qpos+qadr);
       mju_copy4(xquat, d->qpos+qadr+3);
+      mju_normalize4(xquat);
 
       // assign xanchor and xaxis
       mju_copy3(d->xanchor+3*jntadr, xpos);
@@ -77,10 +70,12 @@ void mj_kinematics(const mjModel* m, mjData* d) {
       int pid = m->body_parentid[i];
 
       // get body pos and quat: from model or mocap
-      mjtNum *bodypos, *bodyquat;
+      mjtNum *bodypos, *bodyquat, quat[4];
       if (m->body_mocapid[i] >= 0) {
         bodypos = d->mocap_pos + 3*m->body_mocapid[i];
-        bodyquat = d->mocap_quat + 4*m->body_mocapid[i];
+        mju_copy4(quat, d->mocap_quat + 4*m->body_mocapid[i]);
+        mju_normalize4(quat);
+        bodyquat = quat;
       } else {
         bodypos = m->body_pos+3*i;
         bodyquat = m->body_quat+4*i;
@@ -125,6 +120,7 @@ void mj_kinematics(const mjModel* m, mjData* d) {
             mjtNum qloc[4];
             if (jtype == mjJNT_BALL) {
               mju_copy4(qloc, d->qpos+qadr);
+              mju_normalize4(qloc);
             } else {
               mju_axisAngle2Quat(qloc, m->jnt_axis+3*jid, d->qpos[qadr] - m->qpos0[qadr]);
             }
@@ -890,13 +886,15 @@ void mj_transmission(const mjModel* m, mjData* d) {
         int j = m->jnt_qposadr[id];
 
         // axis: expmap representation of quaternion
-        mju_quat2Vel(axis, d->qpos+j, 1);
+        mju_copy4(quat, d->qpos+j);
+        mju_normalize4(quat);
+        mju_quat2Vel(axis, quat, 1);
 
         // gearAxis: rotate to parent frame if necessary
         if (m->actuator_trntype[i] == mjTRN_JOINT) {
           mju_copy3(gearAxis, gear);
         } else {
-          mju_negQuat(quat, d->qpos+j);
+          mju_negQuat(quat, quat);
           mju_rotVecQuat(gearAxis, gear, quat);
         }
 
@@ -923,12 +921,15 @@ void mj_transmission(const mjModel* m, mjData* d) {
 
         // axis: expmap representation of quaternion
         mju_quat2Vel(axis, d->qpos+j+3, 1);
+        mju_copy4(quat, d->qpos+j+3);
+        mju_normalize4(quat);
+        mju_quat2Vel(axis, quat, 1);
 
         // gearAxis: rotate to world frame if necessary
         if (m->actuator_trntype[i] == mjTRN_JOINT) {
           mju_copy3(gearAxis, gear+3);
         } else {
-          mju_negQuat(quat, d->qpos+j+3);
+          mju_negQuat(quat, quat);
           mju_rotVecQuat(gearAxis, gear+3, quat);
         }
 

src/engine/engine_name.c

@@ -0,0 +1,284 @@
+// Copyright 2021 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "engine/engine_name.h"
+
+#include <stdint.h>
+#include <string.h>
+
+#include <mujoco/mjmodel.h>
+#include "engine/engine_crossplatform.h"
+#include "engine/engine_io.h"
+
+
+
+//-------------------------- name functions --------------------------------------------------------
+// get number of objects and name addresses for given object type
+static int _getnumadr(const mjModel* m, mjtObj type, int** padr, int* mapadr) {
+  int num = -1;
+  // map address starts at the end, subtract with explicit switch fallthrough below
+  *mapadr = m->nnames_map;
+
+  // get address list and size for object type
+  switch (type) {
+  case mjOBJ_BODY:
+  case mjOBJ_XBODY:
+    *mapadr -= mjLOAD_MULTIPLE*m->nbody;
+    *padr = m->name_bodyadr;
+    num = m->nbody;
+    mjFALLTHROUGH;
+
+  case mjOBJ_JOINT:
+    *mapadr -= mjLOAD_MULTIPLE*m->njnt;
+    if (num < 0) {
+      *padr = m->name_jntadr;
+      num = m->njnt;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_GEOM:
+    *mapadr -= mjLOAD_MULTIPLE*m->ngeom;
+    if (num < 0) {
+      *padr = m->name_geomadr;
+      num = m->ngeom;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_SITE:
+    *mapadr -= mjLOAD_MULTIPLE*m->nsite;
+    if (num < 0) {
+      *padr = m->name_siteadr;
+      num = m->nsite;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_CAMERA:
+    *mapadr -= mjLOAD_MULTIPLE*m->ncam;
+    if (num < 0) {
+      *padr = m->name_camadr;
+      num = m->ncam;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_LIGHT:
+    *mapadr -= mjLOAD_MULTIPLE*m->nlight;
+    if (num < 0) {
+      *padr = m->name_lightadr;
+      num = m->nlight;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_FLEX:
+    *mapadr -= mjLOAD_MULTIPLE*m->nflex;
+    if (num < 0) {
+      *padr = m->name_flexadr;
+      num =  m->nflex;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_MESH:
+    *mapadr -= mjLOAD_MULTIPLE*m->nmesh;
+    if (num < 0) {
+      *padr = m->name_meshadr;
+      num =  m->nmesh;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_SKIN:
+    *mapadr -= mjLOAD_MULTIPLE*m->nskin;
+    if (num < 0) {
+      *padr = m->name_skinadr;
+      num = m->nskin;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_HFIELD:
+    *mapadr -= mjLOAD_MULTIPLE*m->nhfield;
+    if (num < 0) {
+      *padr = m->name_hfieldadr;
+      num = m->nhfield;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_TEXTURE:
+    *mapadr -= mjLOAD_MULTIPLE*m->ntex;
+    if (num < 0) {
+      *padr = m->name_texadr;
+      num = m->ntex;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_MATERIAL:
+    *mapadr -= mjLOAD_MULTIPLE*m->nmat;
+    if (num < 0) {
+      *padr = m->name_matadr;
+      num = m->nmat;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_PAIR:
+    *mapadr -= mjLOAD_MULTIPLE*m->npair;
+    if (num < 0) {
+      *padr = m->name_pairadr;
+      num = m->npair;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_EXCLUDE:
+    *mapadr -= mjLOAD_MULTIPLE*m->nexclude;
+    if (num < 0) {
+      *padr = m->name_excludeadr;
+      num = m->nexclude;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_EQUALITY:
+    *mapadr -= mjLOAD_MULTIPLE*m->neq;
+    if (num < 0) {
+      *padr = m->name_eqadr;
+      num = m->neq;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_TENDON:
+    *mapadr -= mjLOAD_MULTIPLE*m->ntendon;
+    if (num < 0) {
+      *padr = m->name_tendonadr;
+      num = m->ntendon;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_ACTUATOR:
+    *mapadr -= mjLOAD_MULTIPLE*m->nu;
+    if (num < 0) {
+      *padr = m->name_actuatoradr;
+      num = m->nu;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_SENSOR:
+    *mapadr -= mjLOAD_MULTIPLE*m->nsensor;
+    if (num < 0) {
+      *padr = m->name_sensoradr;
+      num = m->nsensor;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_NUMERIC:
+    *mapadr -= mjLOAD_MULTIPLE*m->nnumeric;
+    if (num < 0) {
+      *padr = m->name_numericadr;
+      num = m->nnumeric;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_TEXT:
+    *mapadr -= mjLOAD_MULTIPLE*m->ntext;
+    if (num < 0) {
+      *padr = m->name_textadr;
+      num = m->ntext;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_TUPLE:
+    *mapadr -= mjLOAD_MULTIPLE*m->ntuple;
+    if (num < 0) {
+      *padr = m->name_tupleadr;
+      num = m->ntuple;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_KEY:
+    *mapadr -= mjLOAD_MULTIPLE*m->nkey;
+    if (num < 0) {
+      *padr = m->name_keyadr;
+      num = m->nkey;
+    }
+    mjFALLTHROUGH;
+
+  case mjOBJ_PLUGIN:
+    *mapadr -= mjLOAD_MULTIPLE*m->nplugin;
+    if (num < 0) {
+      *padr = m->name_pluginadr;
+      num = m->nplugin;
+    }
+    mjFALLTHROUGH;
+
+  default:
+    if (num < 0) {
+      *padr = 0;
+      num = 0;
+    }
+  }
+
+  return num;
+}
+
+// get string hash, see http://www.cse.yorku.ca/~oz/hash.html
+uint64_t mj_hashString(const char* s, uint64_t n) {
+  uint64_t h = 5381;
+  int c;
+  while ((c = *s++)) {
+    h = ((h << 5) + h) ^ c;
+  }
+  return h % n;
+}
+
+// get id of object with the specified mjtObj type and name,
+// returns -1 if id not found
+int mj_name2id(const mjModel* m, int type, const char* name) {
+  int mapadr;
+  int* adr = 0;
+
+  // get number of objects and name addresses
+  int num = mjLOAD_MULTIPLE*_getnumadr(m, type, &adr, &mapadr);
+
+  // search
+  if (num) {    // look up at hash address
+    uint64_t hash = mj_hashString(name, num);
+    uint64_t i = hash;
+
+    do {
+      int j = m->names_map[mapadr + i];
+      if (j < 0) {
+        return -1;
+      }
+
+      if (!strncmp(name, m->names+adr[j], m->nnames-adr[j])) {
+        return j;
+      }
+      if ((++i) == num)i = 0;
+    } while (i != hash);
+  }
+  return -1;
+}
+
+
+
+// get name of object with the specified mjtObj type and id,
+// returns NULL if name not found
+const char* mj_id2name(const mjModel* m, int type, int id) {
+  int mapadr;
+  int* adr = 0;
+
+  // get number of objects and name addresses
+  int num = _getnumadr(m, type, &adr, &mapadr);
+
+  // id is in [0, num) and the found name is not the empty string "\0"
+  if (id >= 0 && id < num && m->names[adr[id]]) {
+    return m->names+adr[id];
+  }
+
+  return NULL;
+}

src/engine/engine_name.h

@@ -0,0 +1,41 @@
+// Copyright 2021 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef MUJOCO_SRC_ENGINE_ENGINE_NAME_H_
+#define MUJOCO_SRC_ENGINE_ENGINE_NAME_H_
+
+#include <stdint.h>
+
+#include <mujoco/mjexport.h>
+#include <mujoco/mjmodel.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//-------------------------- name functions --------------------------------------------------------
+
+// get string hash, see http://www.cse.yorku.ca/~oz/hash.html
+uint64_t mj_hashString(const char* s, uint64_t n);
+
+// get id of object with the specified mjtObj type and name, returns -1 if id not found
+MJAPI int mj_name2id(const mjModel* m, int type, const char* name);
+
+// get name of object with the specified mjtObj type and id, returns NULL if name not found
+MJAPI const char* mj_id2name(const mjModel* m, int type, int id);
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // MUJOCO_SRC_ENGINE_ENGINE_NAME_H_

src/engine/engine_passive.c

@@ -64,9 +64,11 @@ static void mj_springdamper(const mjModel* m, mjData* d) {
 
     case mjJNT_BALL:
       {
-        mjtNum dif[3];
         // convert quatertion difference into angular "velocity"
-        mju_subQuat(dif, d->qpos + padr, m->qpos_spring + padr);
+        mjtNum dif[3], quat[4];
+        mju_copy4(quat, d->qpos+padr);
+        mju_normalize4(quat);
+        mju_subQuat(dif, quat, m->qpos_spring + padr);
 
         // apply torque
         d->qfrc_spring[dadr+0] = -stiffness*dif[0];

src/engine/engine_print.c

@@ -25,6 +25,7 @@
 #include <mujoco/mjxmacro.h>
 #include "engine/engine_core_constraint.h"
 #include "engine/engine_io.h"
+#include "engine/engine_name.h"
 #include "engine/engine_support.h"
 #include "engine/engine_util_errmem.h"
 #include "engine/engine_util_misc.h"

src/engine/engine_resource.c

@@ -14,6 +14,7 @@
 
 #include "engine/engine_resource.h"
 
+#include <errno.h>
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -41,7 +42,6 @@ static void* _fileToMemory(FILE* fp, const char* filename, size_t* filesize);
 
 // file buffer used internally for the OS filesystem
 typedef struct {
-  FILE* fp;         // file handle
   int is_read;      // set to nonzero if buffer was read into
   uint8_t* buffer;  // raw bytes from file
   size_t nbuffer;   // size of buffer in bytes
@@ -100,20 +100,16 @@ mjResource* mju_openResource(const char* name, char* error, size_t error_sz) {
   spec->is_read = 0;
   spec->buffer = NULL;
   spec->nbuffer = 0;
-  spec->fp = fopen(name, "rb");
-  if (!spec->fp) {
-    if (error) {
-      snprintf(error, error_sz,
-               "resource not found via provider or OS filesystem: '%s'", name);
-    }
-    mju_closeResource(resource);
-    return NULL;
-  }
   struct stat file_stat;
+  errno = 0;
   if (stat(name, &file_stat) == 0) {
     memcpy(&spec->mtime, &file_stat.st_mtime, sizeof(time_t));
   } else {
-    memset(&spec->mtime, 0, sizeof(time_t));
+    if (error) {
+      snprintf(error, error_sz, "Error opening file '%s': %s", name, strerror(errno));
+    }
+    mju_closeResource(resource);
+    return NULL;
   }
   mju_encodeBase64(resource->timestamp, (uint8_t*) &spec->mtime, sizeof(time_t));
   return resource;
@@ -157,17 +153,12 @@ int mju_readResource(mjResource* resource, const void** buffer) {
     return resource->provider->read(resource, buffer);
   }
 
-
   // if provider is NULL, then OS filesystem is used
   file_spec* spec = (file_spec*) resource->data;
-  if (!spec->fp && !spec->is_read) {
-     mjERROR("internal error FILE pointer undefined");  // should not occur
-  }
 
   // only read once from file
   if (!spec->is_read) {
-    spec->buffer = _fileToMemory(spec->fp, resource->name, &(spec->nbuffer));
+    spec->buffer = mju_fileToMemory(resource->name, &(spec->nbuffer));
-    spec->fp = NULL;  // closed by _fileToMemory
     spec->is_read = 1;
   }
   *buffer = spec->buffer;

src/engine/engine_sensor.c

@@ -281,6 +281,7 @@ void mj_sensorPos(const mjModel* m, mjData* d) {
 
       case mjSENS_BALLQUAT:                               // ballquat
         mju_copy4(d->sensordata+adr, d->qpos+m->jnt_qposadr[objid]);
+        mju_normalize4(d->sensordata+adr);
         break;
 
       case mjSENS_JOINTLIMITPOS:                          // jointlimitpos
@@ -899,7 +900,7 @@ void mj_sensorAcc(const mjModel* m, mjData* d) {
 // position-dependent energy (potential)
 void mj_energyPos(const mjModel* m, mjData* d) {
   int padr;
-  mjtNum dif[3], stiffness;
+  mjtNum dif[3], quat[4], stiffness;
 
   // disabled: clear and return
   if (!mjENABLED(mjENBL_ENERGY)) {
@@ -923,7 +924,9 @@ void mj_energyPos(const mjModel* m, mjData* d) {
 
       switch ((mjtJoint) m->jnt_type[i]) {
       case mjJNT_FREE:
-        mju_sub3(dif, d->qpos+padr, m->qpos_spring+padr);
+        mju_copy4(quat, d->qpos+padr);
+        mju_normalize4(quat);
+        mju_sub3(dif, quat, m->qpos_spring+padr);
         d->energy[0] += 0.5*stiffness*mju_dot3(dif, dif);
 
         // continue with rotations
@@ -932,6 +935,8 @@ void mj_energyPos(const mjModel* m, mjData* d) {
 
       case mjJNT_BALL:
         // covert quatertion difference into angular "velocity"
+        mju_copy4(quat, d->qpos+padr);
+        mju_normalize4(quat);
         mju_subQuat(dif, d->qpos + padr, m->qpos_spring + padr);
         d->energy[0] += 0.5*stiffness*mju_dot3(dif, dif);
         break;

src/engine/engine_support.c

@@ -15,7 +15,6 @@
 #include "engine/engine_support.h"
 
 #include <stddef.h>
-#include <stdint.h>
 #include <string.h>
 
 #include <mujoco/mjdata.h>
@@ -31,7 +30,7 @@
 #include "engine/engine_util_spatial.h"
 
 #ifdef mjUSEPLATFORMSIMD
-  #if defined(__AVX__) && defined(mjUSEDOUBLE)
+  #if defined(__AVX__) && !defined(mjUSESINGLE)
     #define mjUSEAVX
     #include "immintrin.h"
   #endif
@@ -868,269 +867,6 @@ void mj_angmomMat(const mjModel* m, mjData* d, mjtNum* mat, int body) {
 
 
 
-//-------------------------- name functions --------------------------------------------------------
-
-// get number of objects and name addresses for given object type
-static int _getnumadr(const mjModel* m, mjtObj type, int** padr, int* mapadr) {
-  int num = -1;
-  // map address starts at the end, subtract with explicit switch fallthrough below
-  *mapadr = m->nnames_map;
-
-  // get address list and size for object type
-  switch (type) {
-  case mjOBJ_BODY:
-  case mjOBJ_XBODY:
-    *mapadr -= mjLOAD_MULTIPLE*m->nbody;
-    *padr = m->name_bodyadr;
-    num = m->nbody;
-    mjFALLTHROUGH;
-
-  case mjOBJ_JOINT:
-    *mapadr -= mjLOAD_MULTIPLE*m->njnt;
-    if (num < 0) {
-      *padr = m->name_jntadr;
-      num = m->njnt;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_GEOM:
-    *mapadr -= mjLOAD_MULTIPLE*m->ngeom;
-    if (num < 0) {
-      *padr = m->name_geomadr;
-      num = m->ngeom;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_SITE:
-    *mapadr -= mjLOAD_MULTIPLE*m->nsite;
-    if (num < 0) {
-      *padr = m->name_siteadr;
-      num = m->nsite;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_CAMERA:
-    *mapadr -= mjLOAD_MULTIPLE*m->ncam;
-    if (num < 0) {
-      *padr = m->name_camadr;
-      num = m->ncam;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_LIGHT:
-    *mapadr -= mjLOAD_MULTIPLE*m->nlight;
-    if (num < 0) {
-      *padr = m->name_lightadr;
-      num = m->nlight;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_FLEX:
-    *mapadr -= mjLOAD_MULTIPLE*m->nflex;
-    if (num < 0) {
-      *padr = m->name_flexadr;
-      num =  m->nflex;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_MESH:
-    *mapadr -= mjLOAD_MULTIPLE*m->nmesh;
-    if (num < 0) {
-      *padr = m->name_meshadr;
-      num =  m->nmesh;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_SKIN:
-    *mapadr -= mjLOAD_MULTIPLE*m->nskin;
-    if (num < 0) {
-      *padr = m->name_skinadr;
-      num = m->nskin;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_HFIELD:
-    *mapadr -= mjLOAD_MULTIPLE*m->nhfield;
-    if (num < 0) {
-      *padr = m->name_hfieldadr;
-      num = m->nhfield;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_TEXTURE:
-    *mapadr -= mjLOAD_MULTIPLE*m->ntex;
-    if (num < 0) {
-      *padr = m->name_texadr;
-      num = m->ntex;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_MATERIAL:
-    *mapadr -= mjLOAD_MULTIPLE*m->nmat;
-    if (num < 0) {
-      *padr = m->name_matadr;
-      num = m->nmat;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_PAIR:
-    *mapadr -= mjLOAD_MULTIPLE*m->npair;
-    if (num < 0) {
-      *padr = m->name_pairadr;
-      num = m->npair;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_EXCLUDE:
-    *mapadr -= mjLOAD_MULTIPLE*m->nexclude;
-    if (num < 0) {
-      *padr = m->name_excludeadr;
-      num = m->nexclude;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_EQUALITY:
-    *mapadr -= mjLOAD_MULTIPLE*m->neq;
-    if (num < 0) {
-      *padr = m->name_eqadr;
-      num = m->neq;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_TENDON:
-    *mapadr -= mjLOAD_MULTIPLE*m->ntendon;
-    if (num < 0) {
-      *padr = m->name_tendonadr;
-      num = m->ntendon;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_ACTUATOR:
-    *mapadr -= mjLOAD_MULTIPLE*m->nu;
-    if (num < 0) {
-      *padr = m->name_actuatoradr;
-      num = m->nu;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_SENSOR:
-    *mapadr -= mjLOAD_MULTIPLE*m->nsensor;
-    if (num < 0) {
-      *padr = m->name_sensoradr;
-      num = m->nsensor;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_NUMERIC:
-    *mapadr -= mjLOAD_MULTIPLE*m->nnumeric;
-    if (num < 0) {
-      *padr = m->name_numericadr;
-      num = m->nnumeric;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_TEXT:
-    *mapadr -= mjLOAD_MULTIPLE*m->ntext;
-    if (num < 0) {
-      *padr = m->name_textadr;
-      num = m->ntext;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_TUPLE:
-    *mapadr -= mjLOAD_MULTIPLE*m->ntuple;
-    if (num < 0) {
-      *padr = m->name_tupleadr;
-      num = m->ntuple;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_KEY:
-    *mapadr -= mjLOAD_MULTIPLE*m->nkey;
-    if (num < 0) {
-      *padr = m->name_keyadr;
-      num = m->nkey;
-    }
-    mjFALLTHROUGH;
-
-  case mjOBJ_PLUGIN:
-    *mapadr -= mjLOAD_MULTIPLE*m->nplugin;
-    if (num < 0) {
-      *padr = m->name_pluginadr;
-      num = m->nplugin;
-    }
-    mjFALLTHROUGH;
-
-  default:
-    if (num < 0) {
-      *padr = 0;
-      num = 0;
-    }
-  }
-
-  return num;
-}
-
-// get string hash, see http://www.cse.yorku.ca/~oz/hash.html
-uint64_t mj_hashString(const char* s, uint64_t n) {
-  uint64_t h = 5381;
-  int c;
-  while ((c = *s++)) {
-    h = ((h << 5) + h) ^ c;
-  }
-  return h % n;
-}
-
-// get id of object with the specified mjtObj type and name,
-// returns -1 if id not found
-int mj_name2id(const mjModel* m, int type, const char* name) {
-  int mapadr;
-  int* adr = 0;
-
-  // get number of objects and name addresses
-  int num = mjLOAD_MULTIPLE*_getnumadr(m, type, &adr, &mapadr);
-
-  // search
-  if (num) {    // look up at hash address
-    uint64_t hash = mj_hashString(name, num);
-    uint64_t i = hash;
-
-    do {
-      int j = m->names_map[mapadr + i];
-      if (j < 0) {
-        return -1;
-      }
-
-      if (!strncmp(name, m->names+adr[j], m->nnames-adr[j])) {
-        return j;
-      }
-      if ((++i) == num)i = 0;
-    } while (i != hash);
-  }
-  return -1;
-}
-
-
-
-// get name of object with the specified mjtObj type and id,
-// returns NULL if name not found
-const char* mj_id2name(const mjModel* m, int type, int id) {
-  int mapadr;
-  int* adr = 0;
-
-  // get number of objects and name addresses
-  int num = _getnumadr(m, type, &adr, &mapadr);
-
-  // id is in [0, num) and the found name is not the empty string "\0"
-  if (id >= 0 && id < num && m->names[adr[id]]) {
-    return m->names+adr[id];
-  }
-
-  return NULL;
-}
-
-
-
 //-------------------------- inertia functions -----------------------------------------------------
 
 // convert sparse inertia matrix M into full matrix

src/engine/engine_support.h

@@ -15,8 +15,6 @@
 #ifndef MUJOCO_SRC_ENGINE_ENGINE_SUPPORT_H_
 #define MUJOCO_SRC_ENGINE_ENGINE_SUPPORT_H_
 
-#include <stdint.h>
-
 #include <mujoco/mjdata.h>
 #include <mujoco/mjexport.h>
 #include <mujoco/mjmodel.h>
@@ -113,18 +111,6 @@ int mj_jacSum(const mjModel* m, mjData* d, int* chain,
 MJAPI void mj_angmomMat(const mjModel* m, mjData* d, mjtNum* mat, int body);
 
 
-//-------------------------- name functions --------------------------------------------------------
-
-// get string hash, see http://www.cse.yorku.ca/~oz/hash.html
-uint64_t mj_hashString(const char* s, uint64_t n);
-
-// get id of object with the specified mjtObj type and name, returns -1 if id not found
-MJAPI int mj_name2id(const mjModel* m, int type, const char* name);
-
-// get name of object with the specified mjtObj type and id, returns NULL if name not found
-MJAPI const char* mj_id2name(const mjModel* m, int type, int id);
-
-
 //-------------------------- inertia functions -----------------------------------------------------
 
 // convert sparse inertia matrix M into full matrix

src/engine/engine_util_blas.c

@@ -19,7 +19,7 @@
 #include <mujoco/mjtnum.h>
 
 #ifdef mjUSEPLATFORMSIMD
-  #if defined(__AVX__) && defined(mjUSEDOUBLE)
+  #if defined(__AVX__) && !defined(mjUSESINGLE)
     #define mjUSEAVX
     #include "immintrin.h"
   #endif
@@ -609,7 +609,7 @@ void mju_addToScl(mjtNum* res, const mjtNum* vec, mjtNum scl, int n) {
 void mju_addScl(mjtNum* res, const mjtNum* vec1, const mjtNum* vec2, mjtNum scl, int n) {
   int i = 0;
 
-#if defined(__AVX__) && defined(mjUSEAVX)  && defined(mjUSEDOUBLE)
+#if defined(__AVX__) && defined(mjUSEAVX)  && !defined(mjUSESINGLE)
   int n_4 = n - 4;
 
   // vector part

src/engine/engine_util_blas.h

@@ -26,7 +26,7 @@ extern "C" {
 
 //------------------------------ standard library functions ----------------------------------------
 
-#ifdef mjUSEDOUBLE
+#if !defined(mjUSESINGLE)
   #define mju_sqrt    sqrt
   #define mju_exp     exp
   #define mju_sin     sin
@@ -59,7 +59,7 @@ extern "C" {
   #define mju_log10   log10f
   #define mju_floor   floorf
   #define mju_ceil    ceilf
-#endif
+#endif  // !defined(mjUSESINGLE)
 
 
 //------------------------------ 3D vector and matrix-vector operations ----------------------------

src/engine/engine_util_misc.c

@@ -1407,51 +1407,6 @@ char* mju_strncpy(char *dst, const char *src, int n) {
 
 
 
-// assemble full filename from directory and filename, return 0 on success
-int mju_makefullname(char* full, size_t nfull, const char* dir, const char* file) {
-  int dirlen = (!dir) ? 0 : strlen(dir);
-  int filelen = (!file) ? 0 : strlen(file);
-  char* filepos = full + dirlen;
-
-  // missing filename
-  if (!filelen) {
-    return -1;
-  }
-
-  // no directory then just copy filename over
-  if (!dirlen) {
-    // make sure full has space
-    if (filelen >= nfull) {
-      return -1;
-    }
-    strcpy(full, file);
-    return 0;
-  }
-
-  // make sure full has space
-  if (dirlen + filelen >= nfull) {
-    return -1;
-  }
-
-  // dir doesn't end with a slash
-  if (dir[dirlen - 1] != '\\' && dir[dirlen - 1] != '/') {
-    // need extra space for forward slash
-    if ((dirlen + filelen + 1) >= nfull) {
-      return -1;
-    }
-
-    // add forward slash
-    *filepos++ = '/';
-  }
-
-  // copy directory and file over
-  memcpy(full, dir, sizeof(char) * dirlen);
-  strcpy(filepos, file);
-  return 0;
-}
-
-
-
 // sigmoid function over 0<=x<=1 using quintic polynomial
 mjtNum mju_sigmoid(mjtNum x) {
   // fast return

src/engine/engine_util_misc.h

@@ -164,10 +164,6 @@ MJAPI mjtNum mju_Halton(int index, int base);
 // call strncpy, then set dst[n-1] = 0
 MJAPI char* mju_strncpy(char *dst, const char *src, int n);
 
-// assemble full filename from directory and filename, return 0 on success
-MJAPI int mju_makefullname(char* full, size_t nfull,
-                           const char* dir, const char* file);
-
 // sigmoid function over 0<=x<=1 using quintic polynomial
 MJAPI mjtNum mju_sigmoid(mjtNum x);
 

src/engine/engine_util_sparse_avx.h

@@ -16,7 +16,7 @@
 #define MUJOCO_SRC_ENGINE_ENGINE_UTIL_SPARSE_AVX_H_
 
 #ifdef mjUSEPLATFORMSIMD
-#if defined(__AVX__) && defined(mjUSEDOUBLE)
+#if defined(__AVX__) && !defined(mjUSESINGLE)
 
 #define mjUSEAVX
 
@@ -315,7 +315,7 @@ int mju_compare_avx(const int* vec1, const int* vec2, int n) {
   return !memcmp(vec1+i, vec2+i, (n-i)*sizeof(int));
 }
 
-#endif  // defined(__AVX__) && defined(mjUSEDOUBLE)
+#endif  // defined(__AVX__) && !defined(mjUSESINGLE)
 
 #endif  // mjUSEPLATFORMSIMD
 

src/engine/engine_util_spatial.c

@@ -247,8 +247,8 @@ void mju_quatIntegrate(mjtNum quat[4], const mjtNum vel[3], mjtNum scale) {
   mju_copy3(tmp, vel);
   angle = scale * mju_normalize3(tmp);
   mju_axisAngle2Quat(qrot, tmp, angle);
-  mju_mulQuat(quat, quat, qrot);
   mju_normalize4(quat);
+  mju_mulQuat(quat, quat, qrot);
 }
 
 

src/engine/engine_vis_visualize.c

@@ -23,6 +23,7 @@
 #include <mujoco/mjvisualize.h>
 #include "engine/engine_array_safety.h"
 #include "engine/engine_io.h"
+#include "engine/engine_name.h"
 #include "engine/engine_plugin.h"
 #include "engine/engine_support.h"
 #include "engine/engine_util_blas.h"
@@ -301,21 +302,13 @@ static void setMaterial(const mjModel* m, mjvGeom* geom, int matid, const float*
                         const mjtByte* flags) {
   // set material properties if given
   if (matid >= 0) {
-    f2f(geom->texrepeat, m->mat_texrepeat + 2*matid, 2);
     f2f(geom->rgba, m->mat_rgba + 4*matid, 4);
-    geom->texuniform = m->mat_texuniform[matid];
     geom->emission = m->mat_emission[matid];
     geom->specular = m->mat_specular[matid];
     geom->shininess = m->mat_shininess[matid];
     geom->reflectance = m->mat_reflectance[matid];
   }
 
-  // otherwise clear texrepeat
-  else {
-    geom->texrepeat[0] = 0;
-    geom->texrepeat[1] = 0;
-  }
-
   // use rgba if different from default, or no material given
   if (rgba[0] != 0.5f || rgba[1] != 0.5f || rgba[2] != 0.5f || rgba[3] != 1.0f || matid < 0) {
     f2f(geom->rgba, rgba, 4);
@@ -323,7 +316,7 @@ static void setMaterial(const mjModel* m, mjvGeom* geom, int matid, const float*
 
   // set texture
   if (flags[mjVIS_TEXTURE] && matid >= 0) {
-    geom->texid = m->mat_texid[matid];
+    geom->matid = matid;
   }
 
   // scale alpha for dynamic geoms only
@@ -457,11 +450,8 @@ void mjv_initGeom(mjvGeom* geom, int type, const mjtNum* size,
 
   // set defaults that cannot be assigned via this function
   geom->dataid       = -1;
-  geom->texid        = -1;
+  geom->matid        = -1;
-  geom->texuniform   = 0;
   geom->texcoord     = 0;
-  geom->texrepeat[0] = 1;
-  geom->texrepeat[1] = 1;
   geom->emission     = 0;
   geom->specular     = 0.5;
   geom->shininess    = 0.5;
@@ -570,7 +560,7 @@ void mjv_addGeoms(const mjModel* m, mjData* d, const mjvOption* vopt,
           thisgeom->texcoord = 1;
         }
         else {
-          thisgeom->texid = -1;
+          thisgeom->matid = -1;
         }
 
         // glow flex if selected

src/render/render_context.c

@@ -1294,6 +1294,43 @@ static void makeFont(mjrContext* con, int fontscale) {
   }
 }
 
+// make materials, just for those that have textures
+static void makeMaterial(const mjModel* m, mjrContext* con) {
+  memset(con->mat_texid, -1, sizeof(con->mat_texid));
+  memset(con->mat_texuniform, 0, sizeof(con->mat_texuniform));
+  memset(con->mat_texrepeat, 0, sizeof(con->mat_texrepeat));
+  if (!m->nmat || !m->ntex) {
+    return;
+  }
+
+  if (m->nmat >= mjMAXMATERIAL-1) {
+    mju_error("Maximum number of materials is %d", mjMAXMATERIAL);
+  }
+  for (int i=0; i < m->nmat; i++) {
+    if (m->mat_texid[i*mjNTEXMAT] >= 0) {
+      for (int j=0; j < mjNTEXMAT; j++) {
+        con->mat_texid[i*mjNTEXMAT + j] = m->mat_texid[i*mjNTEXMAT + j];
+      }
+      con->mat_texuniform[i] = m->mat_texuniform[i];
+      con->mat_texrepeat[2*i] = m->mat_texrepeat[2*i];
+      con->mat_texrepeat[2*i+1] = m->mat_texrepeat[2*i+1];
+    }
+  }
+  // find skybox texture
+  for (int i=0; i < m->ntex; i++) {
+    if (m->tex_type[i] == mjTEXTURE_SKYBOX) {
+      if (m->nmat >= mjMAXMATERIAL-2) {
+        mju_error("With skybox, maximum number of materials is %d", mjMAXMATERIAL);
+      }
+      con->mat_texid[mjNTEXMAT * (mjMAXMATERIAL-1)] = i;
+      for (int j=1; j < mjNTEXMAT; j++) {
+        con->mat_texid[mjNTEXMAT * (mjMAXMATERIAL-1) + j] = -1;
+      }
+
+      break;
+    }
+  }
+}
 
 
 // make textures
@@ -1585,6 +1622,7 @@ void mjr_makeContext_offSize(const mjModel* m, mjrContext* con, int fontscale,
   // make everything
   makeOff(con);
   makeShadow(m, con);
+  makeMaterial(m, con);
   makeTexture(m, con);
   makePlane(m, con);
   makeMesh(m, con);

src/render/render_gl3.c

@@ -61,6 +61,10 @@ enum {
 // enable/disable texture mapping
 static void settexture(int type, int state, const mjrContext* con, const mjvGeom* geom) {
   float plane[4], scl[2];
+  int texid = -1;
+  if (geom) {
+    texid = (geom->matid == -1) ? -1 : con->mat_texid[mjNTEXMAT * geom->matid];
+  }
 
   // shadow
   if (type == mjtexSHADOW) {
@@ -92,7 +96,7 @@ static void settexture(int type, int state, const mjrContext* con, const mjvGeom
     if (state) {
       glActiveTexture(GL_TEXTURE0);
       glEnable(GL_TEXTURE_2D);
-      glBindTexture(GL_TEXTURE_2D, con->texture[geom->texid]);
+      glBindTexture(GL_TEXTURE_2D, con->texture[texid]);
     }
 
     // disable
@@ -103,18 +107,18 @@ static void settexture(int type, int state, const mjrContext* con, const mjvGeom
   }
 
   // 2D
-  else if (type == mjtexREGULAR && con->textureType[geom->texid] == mjTEXTURE_2D) {
+  else if (type == mjtexREGULAR && con->textureType[texid] == mjTEXTURE_2D) {
     // enable
     if (state) {
       glActiveTexture(GL_TEXTURE0);
       glEnable(GL_TEXTURE_2D);
       glEnable(GL_TEXTURE_GEN_S);
       glEnable(GL_TEXTURE_GEN_T);
-      glBindTexture(GL_TEXTURE_2D, con->texture[geom->texid]);
+      glBindTexture(GL_TEXTURE_2D, con->texture[texid]);
 
       // determine scaling, adjust for pre-scaled geoms
-      scl[0] = geom->texrepeat[0];
+      scl[0] = con->mat_texrepeat[geom->matid*2];
-      scl[1] = geom->texrepeat[1];
+      scl[1] = con->mat_texrepeat[geom->matid*2+1];
       if (geom->dataid >= 0) {
         if (geom->size[0] > 0) {
           scl[0] = scl[0] / mju_max(mjMINVAL, geom->size[0]);
@@ -126,7 +130,7 @@ static void settexture(int type, int state, const mjrContext* con, const mjvGeom
       }
 
       // uniform: repeat relative to spatial units rather than object
-      if (geom->texuniform) {
+      if (con->mat_texuniform[geom->matid]) {
         if (geom->size[0] > 0) {
           scl[0] = scl[0] * geom->size[0];
         }
@@ -161,15 +165,15 @@ static void settexture(int type, int state, const mjrContext* con, const mjvGeom
       glEnable(GL_TEXTURE_GEN_S);
       glEnable(GL_TEXTURE_GEN_T);
       glEnable(GL_TEXTURE_GEN_R);
-      glBindTexture(GL_TEXTURE_CUBE_MAP, con->texture[geom->texid]);
+      glBindTexture(GL_TEXTURE_CUBE_MAP, con->texture[texid]);
 
       // set mapping : cube
       if (type == mjtexREGULAR) {
-        mjr_setf4(plane, geom->texuniform ? geom->size[0] : 1, 0, 0, 0);
+        mjr_setf4(plane, con->mat_texuniform[geom->matid] ? geom->size[0] : 1, 0, 0, 0);
         glTexGenfv(GL_S, GL_OBJECT_PLANE, plane);
-        mjr_setf4(plane, 0, geom->texuniform ? geom->size[1] : 1, 0, 0);
+        mjr_setf4(plane, 0, con->mat_texuniform[geom->matid] ? geom->size[1] : 1, 0, 0);
         glTexGenfv(GL_T, GL_OBJECT_PLANE, plane);
-        mjr_setf4(plane, 0, 0, geom->texuniform ? geom->size[2] : 1, 0);
+        mjr_setf4(plane, 0, 0, con->mat_texuniform[geom->matid] ? geom->size[2] : 1, 0);
         glTexGenfv(GL_R, GL_OBJECT_PLANE, plane);
       }
 
@@ -232,7 +236,7 @@ static void renderGeom(const mjvGeom* geom, int mode, const float* headpos,
   behind = isBehind(headpos, geom->pos, geom->mat);
 
   // enable texture in normal and shadowmap mode
-  if (geom->texid >= 0 && con->ntexture > 0 &&
+  if (geom->matid >= 0 &&
       (mode == mjrRND_NORMAL || mode == mjrRND_SHADOWMAP)) {
     settexture(mjtexREGULAR, 1, con, geom);
   }
@@ -515,14 +519,14 @@ static void renderGeom(const mjvGeom* geom, int mode, const float* headpos,
       glEnableClientState(GL_NORMAL_ARRAY);
       glVertexPointer(3, GL_FLOAT, 0, scn->flexface + 9*scn->flexfaceadr[geom->objid]);
       glNormalPointer(GL_FLOAT, 0, scn->flexnormal + 9*scn->flexfaceadr[geom->objid]);
-      if (geom->texcoord && geom->texid>=0) {
+      if (geom->texcoord && geom->matid>=0) {
         glEnableClientState(GL_TEXTURE_COORD_ARRAY);
         glTexCoordPointer(2, GL_FLOAT, 0, scn->flextexcoord + 6*scn->flexfaceadr[geom->objid]);
       }
       glDrawArrays(GL_TRIANGLES, 0, 3*scn->flexfaceused[geom->objid]);
       glDisableClientState(GL_VERTEX_ARRAY);
       glDisableClientState(GL_NORMAL_ARRAY);
-      if (geom->texcoord && geom->texid>=0) {
+      if (geom->texcoord && geom->matid>=0) {
         glDisableClientState(GL_TEXTURE_COORD_ARRAY);
       }
     }
@@ -568,7 +572,7 @@ static void renderGeom(const mjvGeom* geom, int mode, const float* headpos,
   glPopMatrix();
 
   // disable texture if enabled
-  if (geom->texid >= 0 && con->ntexture > 0 &&
+  if (geom->matid >= 0 &&
       (mode == mjrRND_NORMAL || mode == mjrRND_SHADOWMAP)) {
     settexture(mjtexREGULAR, 0, con, geom);
   }
@@ -1268,7 +1272,7 @@ void mjr_render(mjrRect viewport, mjvScene* scn, const mjrContext* con) {
         if (con->textureType[i] == mjTEXTURE_SKYBOX) {
           // save first skybox texture id in tempgeom
           memset(&tempgeom, 0, sizeof(mjvGeom));
-          tempgeom.texid = i;
+          tempgeom.matid = mjMAXMATERIAL - 1;
 
           // modify settings
           glDisable(GL_LIGHTING);

src/user/CMakeLists.txt

@@ -29,7 +29,7 @@ set(MUJOCO_USER_SRCS
     user_objects.h
     user_util.cc
     user_util.h
-    user_vfs.c
+    user_vfs.cc
     user_vfs.h
 )
 

src/user/user_api.cc

@@ -437,10 +437,11 @@ mjsPlugin* mjs_addPlugin(mjSpec* s) {
 
 
 // add default to model
-mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, int parentid, int* id) {
+mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, const mjsDefault* parent) {
   mjCModel* modelC = static_cast<mjCModel*>(s->element);
-  *id = (int)modelC->NumDefaults();
+  mjCDef* parentC = parent ? static_cast<mjCDef*>(parent->element) :
-  mjCDef* def = modelC->AddDefault(classname, parentid);
+                             static_cast<mjCModel*>(s->element)->Defaults(0);
+  mjCDef* def = modelC->AddDefault(classname, parentC);
   if (def) {
     return &def->spec;
   } else {
@@ -529,6 +530,15 @@ mjsFrame* mjs_findFrame(mjSpec* s, const char* name) {
 
 
 
+// find keyframe by name
+mjsKey* mjs_findKeyframe(mjSpec* s, const char* name) {
+  mjCModel* model = static_cast<mjCModel*>(s->element);
+  mjCKey* key = (mjCKey*)model->FindObject(mjOBJ_KEY, std::string(name));
+  return key ? &(static_cast<mjCKey*>(key)->spec) : nullptr;
+}
+
+
+
 // set frame
 void mjs_setFrame(mjsElement* dest, mjsFrame* frame) {
   if (!frame) {
@@ -580,6 +590,183 @@ mjsElement* mjs_nextChild(mjsBody* body, mjsElement* child) {
 
 
 
+// return spec's first element of selected type
+mjsElement* mjs_firstElement(mjSpec* s, mjtObj type) {
+  mjCModel* modelC = static_cast<mjCModel*>(s->element);
+  return modelC->NextObject(NULL, type);
+}
+
+
+
+// return spec's next element; return NULL if element is last
+mjsElement* mjs_nextElement(mjSpec* s, mjsElement* element) {
+  mjCModel* modelC = static_cast<mjCModel*>(s->element);
+  return modelC->NextObject(element);
+}
+
+
+
+// return body given mjsElement
+mjsBody* mjs_asBody(mjsElement* element) {
+  return element->elemtype == mjOBJ_BODY ? &(static_cast<mjCBody*>(element)->spec) : nullptr;
+}
+
+
+
+// return geom given mjsElement
+mjsGeom* mjs_asGeom(mjsElement* element) {
+  return element->elemtype == mjOBJ_GEOM ? &(static_cast<mjCGeom*>(element)->spec) : nullptr;
+}
+
+
+
+// return joint given mjsElement
+mjsJoint* mjs_asJoint(mjsElement* element) {
+  return element->elemtype == mjOBJ_JOINT ? &(static_cast<mjCJoint*>(element)->spec) : nullptr;
+}
+
+
+
+// Return site given mjsElement
+mjsSite* mjs_asSite(mjsElement* element) {
+  return element->elemtype == mjOBJ_SITE ? &(static_cast<mjCSite*>(element)->spec) : nullptr;
+}
+
+
+
+// return camera given mjsElement
+mjsCamera* mjs_asCamera(mjsElement* element) {
+  return element->elemtype == mjOBJ_CAMERA ? &(static_cast<mjCCamera*>(element)->spec) : nullptr;
+}
+
+
+
+// return light given mjsElement
+mjsLight* mjs_asLight(mjsElement* element) {
+  return element->elemtype == mjOBJ_LIGHT ? &(static_cast<mjCLight*>(element)->spec) : nullptr;
+}
+
+
+
+// return frame given mjsElement
+mjsFrame* mjs_asFrame(mjsElement* element) {
+  return element->elemtype == mjOBJ_FRAME ? &(static_cast<mjCFrame*>(element)->spec) : nullptr;
+}
+
+
+
+// return actuator given mjsElement
+mjsActuator* mjs_asActuator(mjsElement* element) {
+  return element->elemtype == mjOBJ_ACTUATOR ? &(static_cast<mjCActuator*>(element)->spec) : nullptr;
+}
+
+
+
+// return sensor given mjsElement
+mjsSensor* mjs_asSensor(mjsElement* element) {
+  return element->elemtype == mjOBJ_SENSOR ? &(static_cast<mjCSensor*>(element)->spec) : nullptr;
+}
+
+
+
+// return flex given mjsElement
+mjsFlex* mjs_asFlex(mjsElement* element) {
+  return element->elemtype == mjOBJ_FLEX ? &(static_cast<mjCFlex*>(element)->spec) : nullptr;
+}
+
+
+
+// return pair given mjsElement
+mjsPair* mjs_asPair(mjsElement* element) {
+  return element->elemtype == mjOBJ_PAIR ? &(static_cast<mjCPair*>(element)->spec) : nullptr;
+}
+
+
+
+// return equality given mjsElement
+mjsEquality* mjs_asEquality(mjsElement* element) {
+  return element->elemtype == mjOBJ_EQUALITY ? &(static_cast<mjCEquality*>(element)->spec) : nullptr;
+}
+
+
+
+// return exclude given mjsElement
+mjsExclude* mjs_asExclude(mjsElement* element) {
+  return element->elemtype == mjOBJ_EXCLUDE ? &(static_cast<mjCBodyPair*>(element)->spec) : nullptr;
+}
+
+
+
+// return tendon given mjsElement
+mjsTendon* mjs_asTendon(mjsElement* element) {
+  return element->elemtype == mjOBJ_TENDON ? &(static_cast<mjCTendon*>(element)->spec) : nullptr;
+}
+
+
+
+// return numeric given mjsElement
+mjsNumeric* mjs_asNumeric(mjsElement* element) {
+  return element->elemtype == mjOBJ_NUMERIC ? &(static_cast<mjCNumeric*>(element)->spec) : nullptr;
+}
+
+
+
+// return text given mjsElement
+mjsText* mjs_asText(mjsElement* element) {
+  return element->elemtype == mjOBJ_TEXT ? &(static_cast<mjCText*>(element)->spec) : nullptr;
+}
+
+
+
+// return tuple given mjsElement
+mjsTuple* mjs_asTuple(mjsElement* element) {
+  return element->elemtype == mjOBJ_TUPLE ? &(static_cast<mjCTuple*>(element)->spec) : nullptr;
+}
+
+
+
+// return key given mjsElement
+mjsKey* mjs_asKey(mjsElement* element) {
+  return element->elemtype == mjOBJ_KEY ? &(static_cast<mjCKey*>(element)->spec) : nullptr;
+}
+
+
+
+// return mesh given mjsElement
+mjsMesh* mjs_asMesh(mjsElement* element) {
+  return element->elemtype == mjOBJ_MESH ? &(static_cast<mjCMesh*>(element)->spec) : nullptr;
+}
+
+
+
+// return hfield given mjsElement
+mjsHField* mjs_asHField(mjsElement* element) {
+  return element->elemtype == mjOBJ_HFIELD ? &(static_cast<mjCHField*>(element)->spec) : nullptr;
+}
+
+
+
+// return skin given mjsElement
+mjsSkin* mjs_asSkin(mjsElement* element) {
+  return element->elemtype == mjOBJ_SKIN ? &(static_cast<mjCSkin*>(element)->spec) : nullptr;
+}
+
+
+
+// return texture given mjsElement
+mjsTexture* mjs_asTexture(mjsElement* element) {
+  return element->elemtype == mjOBJ_TEXTURE ? &(static_cast<mjCTexture*>(element)->spec) : nullptr;
+}
+
+
+
+// return material given mjsElement
+mjsMaterial* mjs_asMaterial(mjsElement* element) {
+  return element->elemtype == mjOBJ_MATERIAL ? &(static_cast<mjCMaterial*>(element)->spec) : nullptr;
+}
+
+
+
 // set string
 void mjs_setString(mjString* dest, const char* text) {
   std::string* str = static_cast<std::string*>(dest);
@@ -696,13 +883,6 @@ void mjs_setActivePlugins(mjSpec* s, void* activeplugins) {
 
 
 
-// compute full inertia
-const char* mjs_fullInertia(double quat[4], double inertia[3], const double fullinertia[6]) {
-  return FullInertia(quat, inertia, fullinertia);
-}
-
-
-
 // -------------------------- GLOBAL ASSET CACHE -------------------------------
 
 void mj_setCacheSize(mjCache cache, std::size_t size) {

src/user/user_api.h

@@ -156,7 +156,7 @@ MJAPI mjsKey* mjs_addKey(mjSpec* s);
 MJAPI mjsPlugin* mjs_addPlugin(mjSpec* s);
 
 // Add default.
-MJAPI mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, int parentid, int* id);
+MJAPI mjsDefault* mjs_addDefault(mjSpec* s, const char* classname, const mjsDefault* parent);
 
 
 //---------------------------------- Add assets ----------------------------------------------------
@@ -194,6 +194,9 @@ MJAPI mjsMesh* mjs_findMesh(mjSpec* s, const char* name);
 // Find frame by name.
 MJAPI mjsFrame* mjs_findFrame(mjSpec* s, const char* name);
 
+// Find keyframe by name.
+MJAPI mjsKey* mjs_findKeyframe(mjSpec* s, const char* name);
+
 // Get default corresponding to an element.
 MJAPI mjsDefault* mjs_getDefault(mjsElement* element);
 
@@ -215,6 +218,81 @@ MJAPI mjsElement* mjs_firstChild(mjsBody* body, mjtObj type);
 // Return body's next child of the same type; return NULL if child is last.
 MJAPI mjsElement* mjs_nextChild(mjsBody* body, mjsElement* child);
 
+// Return spec's first element of selected type.
+MJAPI mjsElement* mjs_firstElement(mjSpec* s, mjtObj type);
+
+// Return spec's next element; return NULL if element is last.
+MJAPI mjsElement* mjs_nextElement(mjSpec* s, mjsElement* element);
+
+// Safely cast an element as mjsBody, or return NULL if the element is not an mjsBody.
+MJAPI mjsBody* mjs_asBody(mjsElement* element);
+
+// Safely cast an element as mjsGeom, or return NULL if the element is not an mjsGeom.
+MJAPI mjsGeom* mjs_asGeom(mjsElement* element);
+
+// Safely cast an element as mjsJoint, or return NULL if the element is not an mjsJoint.
+MJAPI mjsJoint* mjs_asJoint(mjsElement* element);
+
+// Safely cast an element as mjsSite, or return NULL if the element is not an mjsSite.
+MJAPI mjsSite* mjs_asSite(mjsElement* element);
+
+// Safely cast an element as mjsCamera, or return NULL if the element is not an mjsCamera.
+MJAPI mjsCamera* mjs_asCamera(mjsElement* element);
+
+// Safely cast an element as mjsLight, or return NULL if the element is not an mjsLight.
+MJAPI mjsLight* mjs_asLight(mjsElement* element);
+
+// Safely cast an element as mjsFrame, or return NULL if the element is not an mjsFrame.
+MJAPI mjsFrame* mjs_asFrame(mjsElement* element);
+
+// Safely cast an element as mjsActuator, or return NULL if the element is not an mjsActuator.
+MJAPI mjsActuator* mjs_asActuator(mjsElement* element);
+
+// Safely cast an element as mjsSensor, or return NULL if the element is not an mjsSensor.
+MJAPI mjsSensor* mjs_asSensor(mjsElement* element);
+
+// Safely cast an element as mjsFlex, or return NULL if the element is not an mjsFlex.
+MJAPI mjsFlex* mjs_asFlex(mjsElement* element);
+
+// Safely cast an element as mjsPair, or return NULL if the element is not an mjsPair.
+MJAPI mjsPair* mjs_asPair(mjsElement* element);
+
+// Safely cast an element as mjsEquality, or return NULL if the element is not an mjsEquality.
+MJAPI mjsEquality* mjs_asEquality(mjsElement* element);
+
+// Safely cast an element as mjsExclude, or return NULL if the element is not an mjsExclude.
+MJAPI mjsExclude* mjs_asExclude(mjsElement* element);
+
+// Safely cast an element as mjsTendon, or return NULL if the element is not an mjsTendon.
+MJAPI mjsTendon* mjs_asTendon(mjsElement* element);
+
+// Safely cast an element as mjsNumeric, or return NULL if the element is not an mjsNumeric.
+MJAPI mjsNumeric* mjs_asNumeric(mjsElement* element);
+
+// Safely cast an element as mjsText, or return NULL if the element is not an mjsText.
+MJAPI mjsText* mjs_asText(mjsElement* element);
+
+// Safely cast an element as mjsTuple, or return NULL if the element is not an mjsTuple.
+MJAPI mjsTuple* mjs_asTuple(mjsElement* element);
+
+// Safely cast an element as mjsKey, or return NULL if the element is not an mjsKey.
+MJAPI mjsKey* mjs_asKey(mjsElement* element);
+
+// Safely cast an element as mjsMesh, or return NULL if the element is not an mjsMesh.
+MJAPI mjsMesh* mjs_asMesh(mjsElement* element);
+
+// Safely cast an element as mjsHField, or return NULL if the element is not an mjsHField.
+MJAPI mjsHField* mjs_asHField(mjsElement* element);
+
+// Safely cast an element as mjsSkin, or return NULL if the element is not an mjsSkin.
+MJAPI mjsSkin* mjs_asSkin(mjsElement* element);
+
+// Safely cast an element as mjsTexture, or return NULL if the element is not an mjsTexture.
+MJAPI mjsTexture* mjs_asTexture(mjsElement* element);
+
+// Safely cast an element as mjsMaterial, or return NULL if the element is not an mjsMaterial.
+MJAPI mjsMaterial* mjs_asMaterial(mjsElement* element);
+
 
 //---------------------------------- Attribute setters ---------------------------------------------
 
@@ -273,9 +351,6 @@ MJAPI void mjs_setFrame(mjsElement* dest, mjsFrame* frame);
 MJAPI const char* mjs_resolveOrientation(double quat[4], mjtByte degree, const char* sequence,
                                          const mjsOrientation* orientation);
 
-// Compute quat and diag inertia from full inertia matrix, return error if any.
-MJAPI const char* mjs_fullInertia(double quat[4], double inertia[3], const double fullinertia[6]);
-
 
 //---------------------------------- Initialization  -----------------------------------------------
 

src/user/user_composite.cc

@@ -31,7 +31,6 @@
 #include <mujoco/mujoco.h>
 #include "cc/array_safety.h"
 #include "engine/engine_io.h"
-#include "engine/engine_util_blas.h"
 #include "engine/engine_util_errmem.h"
 #include "engine/engine_util_misc.h"
 #include "user/user_model.h"
@@ -428,12 +427,12 @@ bool mjCComposite::MakeParticle(mjCModel* model, mjsBody* body, char* error, int
   }
 
   // compute volume
-  std::vector<mjtNum> volume(uservert.size()/3);
+  std::vector<double> volume(uservert.size()/3);
-  mjtNum t = 1;
+  double thickness = 1;
   if (dim == 2 && plugin.active) {
     try {
       mjCPlugin* pplugin = static_cast<mjCPlugin*>(plugin.instance);
-      t = std::stod(pplugin->config_attribs["thickness"], nullptr);
+      thickness = std::stod(pplugin->config_attribs["thickness"], nullptr);
     } catch (const std::invalid_argument& e) {
       return comperr(error, "Invalid thickness attribute", error_sz);
     }
@@ -441,9 +440,9 @@ bool mjCComposite::MakeParticle(mjCModel* model, mjsBody* body, char* error, int
   if (!userface.empty()) {
     face = mjXUtil::String2Vector<int>(userface);
     for (int j=0; j<face.size()/3; j++) {
-      mjtNum area[3];
+      double area[3];
-      mjtNum edge1[3];
+      double edge1[3];
-      mjtNum edge2[3];
+      double edge2[3];
 
       for (int i=0; i<3; i++) {
         edge1[i] = uservert[3*face[3*j+1]+i] - uservert[3*face[3*j]+i];
@@ -452,12 +451,12 @@ bool mjCComposite::MakeParticle(mjCModel* model, mjsBody* body, char* error, int
 
       mjuu_crossvec(area, edge1, edge2);
       for (int i=0; i<3; i++) {
-        volume[face[3*j+i]] += sqrt(mjuu_dot3(area, area)) / 2 * t;
+        volume[face[3*j+i]] += sqrt(mjuu_dot3(area, area)) / 2 * thickness;
       }
     }
   } else {
     for (int i=0; i<uservert.size()/3; i++) {
-      volume[i] = 6 * spacing * spacing / 2 * t;
+      volume[i] = 6 * spacing * spacing / 2 * thickness;
     }
   }
 
@@ -754,7 +753,7 @@ bool mjCComposite::MakeCable(mjCModel* model, mjsBody* body, char* error, int er
   }
 
   // create frame
-  mjtNum normal[3], prev_quat[4];
+  double normal[3], prev_quat[4];
   mjuu_setvec(normal, 0, 1, 0);
   mjuu_setvec(prev_quat, 1, 0, 0, 0);
 
@@ -780,10 +779,11 @@ bool mjCComposite::MakeCable(mjCModel* model, mjsBody* body, char* error, int er
 
 
 
-mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix, mjtNum normal[3], mjtNum prev_quat[4]) {
+mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix,
+                                    double normal[3], double prev_quat[4]) {
   char txt_geom[100], txt_site[100], txt_slide[100];
   char this_body[100], next_body[100], this_joint[100];
-  mjtNum dquat[4], this_quat[4];
+  double dquat[4], this_quat[4];
 
   // set flags
   int lastidx = count[0]-2;
@@ -792,7 +792,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix, mjtN
   bool secondlast = ix==lastidx-1;
 
   // compute edge and tangent vectors
-  mjtNum edge[3], tprev[3], tnext[3], length_prev = 0;
+  double edge[3], tprev[3], tnext[3], length_prev = 0;
   mjuu_setvec(edge, uservert[3*(ix+1)+0]-uservert[3*ix+0],
                     uservert[3*(ix+1)+1]-uservert[3*ix+1],
                     uservert[3*(ix+1)+2]-uservert[3*ix+2]);
@@ -810,7 +810,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix, mjtN
   }
 
   // update moving frame
-  mjtNum length = mju_updateFrame(this_quat, normal, edge, tprev, tnext, first);
+  double length = mjuu_updateFrame(this_quat, normal, edge, tprev, tnext, first);
 
   // create body, joint, and geom names
   if (first) {
@@ -845,7 +845,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix, mjtN
     mjuu_copyvec(body->quat, this_quat, 4);
   } else {
     mjuu_setvec(body->pos, length_prev, 0, 0);
-    mjtNum negquat[4] = {prev_quat[0], -prev_quat[1], -prev_quat[2], -prev_quat[3]};
+    double negquat[4] = {prev_quat[0], -prev_quat[1], -prev_quat[2], -prev_quat[3]};
     mjuu_mulquat(dquat, negquat, this_quat);
     mjuu_copyvec(body->quat, dquat, 4);
   }
@@ -1091,7 +1091,7 @@ void mjCComposite::BoxProject(double* pos) {
 
   // cylinder
   else if (type==mjCOMPTYPE_CYLINDER) {
-    double L0 = mju_max(mju_abs(pos[0]), mju_abs(pos[1]));
+    double L0 = std::max(std::abs(pos[0]), std::abs(pos[1]));
     mjuu_normvec(pos, 2);
     pos[0] *= size[0]*L0;
     pos[1] *= size[1]*L0;
@@ -1156,6 +1156,7 @@ bool mjCComposite::MakeBox(mjCModel* model, mjsBody* body, char* error, int erro
           BoxProject(b->pos);
 
           // reorient body
+          b->alt.type = mjORIENTATION_ZAXIS;
           mjuu_copyvec(b->alt.zaxis, b->pos, 3);
           mjuu_normvec(b->alt.zaxis, 3);
 

src/user/user_composite.h

@@ -107,7 +107,7 @@ class mjCComposite {
   std::string initial;            // root boundary type
   std::vector<float> uservert;    // user-specified vertex positions
   std::string userface;           // connectivity
-  mjtNum size[3];                 // rope size (meaning depends on the shape)
+  double size[3];                 // rope size (meaning depends on the shape)
   mjtCompShape curve[3];          // geometric shape
 
   // body names used in the skin
@@ -137,7 +137,7 @@ class mjCComposite {
 
  private:
   mjsBody* AddRopeBody(mjCModel* model, mjsBody* body, int ix, int ix1);
-  mjsBody* AddCableBody(mjCModel* model, mjsBody* body, int ix, mjtNum normal[3], mjtNum prev_quat[4]);
+  mjsBody* AddCableBody(mjCModel* model, mjsBody* body, int ix, double normal[3], double prev_quat[4]);
 
   // temporary skin vectors
   void CopyIntoSkin(mjsSkin* skin);

src/user/user_flexcomp.cc

@@ -14,6 +14,7 @@
 
 #include <algorithm>
 #include <climits>
+#include <cmath>
 #include <cstddef>
 #include <cstdio>
 #include <cstring>
@@ -26,13 +27,11 @@
 #include <mujoco/mjmodel.h>
 #include <mujoco/mjtnum.h>
 #include <mujoco/mjplugin.h>
+#include <mujoco/mujoco.h>
 #include "cc/array_safety.h"
 #include "engine/engine_crossplatform.h"
 #include "engine/engine_resource.h"
-#include "engine/engine_util_blas.h"
 #include "engine/engine_util_errmem.h"
-#include "engine/engine_util_misc.h"
-#include "engine/engine_util_spatial.h"
 #include "user/user_flexcomp.h"
 #include <mujoco/mjspec.h>
 #include "user/user_model.h"
@@ -147,7 +146,7 @@ bool mjCFlexcomp::Make(mjSpec* spec, mjsBody* body, char* error, int error_sz) {
   }
 
   // compute orientation
-  const char* alterr = mjs_resolveOrientation(quat, model->spec.degree, model->spec.euler, &alt);
+  const char* alterr = mjs_resolveOrientation(quat, model->spec.degree, model->spec.eulerseq, &alt);
   if (alterr) {
     return comperr(error, alterr, error_sz);
   }
@@ -250,12 +249,9 @@ bool mjCFlexcomp::Make(mjSpec* spec, mjsBody* body, char* error, int error_sz) {
   }
 
   // apply pose transform to points
-  mjtNum posn[3], quatn[4];
-  mju_d2n(posn, pos, 3);
-  mju_d2n(quatn, quat, 4);
   for (int i=0; i < npnt; i++) {
-    mjtNum newp[3], oldp[3] = {point[3*i], point[3*i+1], point[3*i+2]};
+    double newp[3], oldp[3] = {point[3*i], point[3*i+1], point[3*i+2]};
-    mju_trnVecPose(newp, posn, quatn, oldp);
+    mjuu_trnVecPose(newp, pos, quat, oldp);
     point[3*i] = newp[0];
     point[3*i+1] = newp[1];
     point[3*i+2] = newp[2];
@@ -570,7 +566,7 @@ bool mjCFlexcomp::MakeGrid(char* error, int error_sz) {
         int quad2tri[2][3] = {{0, 1, 2}, {0, 2, 3}};
 
         // add point
-        mjtNum pos[2] = {spacing[0]*(ix - 0.5*(count[0]-1)),
+        double pos[2] = {spacing[0]*(ix - 0.5*(count[0]-1)),
                          spacing[1]*(iy - 0.5*(count[1]-1))};
         point.push_back(pos[0]);
         point.push_back(pos[1]);
@@ -578,8 +574,8 @@ bool mjCFlexcomp::MakeGrid(char* error, int error_sz) {
 
         // add texture coordinates, if not specified explicitly
         if (!hastex) {
-          texcoord.push_back(ix/(mjtNum)mjMAX(count[0]-1, 1));
+          texcoord.push_back(ix/(double)std::max(count[0]-1, 1));
-          texcoord.push_back(iy/(mjtNum)mjMAX(count[1]-1, 1));
+          texcoord.push_back(iy/(double)std::max(count[1]-1, 1));
         }
 
         // flip triangles if radial projection is requested
@@ -713,7 +709,7 @@ void mjCFlexcomp::BoxProject(double* pos, int ix, int iy, int iz) {
 
   // cylinder
   else if (type==mjFCOMPTYPE_CYLINDER) {
-    double L0 = mjMAX(mju_abs(pos[0]), mju_abs(pos[1]));
+    double L0 = std::max(std::abs(pos[0]), std::abs(pos[1]));
     mjuu_normvec(pos, 2);
     pos[0] *= size[0]*L0;
     pos[1] *= size[1]*L0;
@@ -749,8 +745,8 @@ bool mjCFlexcomp::MakeSquare(char* error, int error_sz) {
     };
 
     for (int i=0; i < point.size()/3; i++) {
-      mjtNum* pos = point.data() + i*3;
+      double* pos = point.data() + i*3;
-      double L0 = mjMAX(mju_abs(pos[0]), mju_abs(pos[1]));
+      double L0 = std::max(std::abs(pos[0]), std::abs(pos[1]));
       mjuu_normvec(pos, 2);
       pos[0] *= size[0]*L0;
       pos[1] *= size[1]*L0;
@@ -904,7 +900,7 @@ bool mjCFlexcomp::MakeMesh(mjCModel* model, char* error, int error_sz) {
   }
 
   // load resource
-  std::string filename = mjuu_makefullname(mjs_getString(model->spec.modelfiledir),
+  std::string filename = mjuu_combinePaths(mjs_getString(model->spec.modelfiledir),
                                            mjs_getString(model->spec.meshdir), file);
   mjResource* resource = nullptr;
 
@@ -952,10 +948,10 @@ bool mjCFlexcomp::MakeMesh(mjCModel* model, char* error, int error_sz) {
   // copy faces
   element = mesh.face_;
 
-  // copy vertices, convert from float to mjtNum
+  // copy vertices, convert from float to double
-  point = vector<mjtNum> (mesh.nvert()*3);
+  point = vector<double> (mesh.nvert()*3);
   for (int i=0; i < mesh.nvert()*3; i++) {
-    point[i] = (mjtNum) mesh.vert_[i];
+    point[i] = (double) mesh.vert_[i];
   }
 
   return true;
@@ -1003,7 +999,7 @@ bool mjCFlexcomp::MakeGMSH(mjCModel* model, char* error, int error_sz) {
   }
 
   // open resource
-  std::string filename = mjuu_makefullname(mjs_getString(model->spec.modelfiledir),
+  std::string filename = mjuu_combinePaths(mjs_getString(model->spec.modelfiledir),
                                            mjs_getString(model->spec.meshdir), file);
   mjResource* resource = nullptr;