Version 2.1.2: Python bindings, OBJ assets support, bugfixes.

PiperOrigin-RevId: 434731612
Change-Id: I0cfda3e7a3d1c72036764986efc252ffa1b8c6b0

doc/changelog.rst

@@ -2,6 +2,83 @@
 Changelog
 =========
 
+Version 2.1.2 (Date TBD, 2022)
+------------------------------
+
+New modules
+^^^^^^^^^^^
+
+1. Added new :doc:`Python bindings<python>`, which can be installed via ``pip install mujoco``,
+   and imported as ``import mujoco``.
+#. Added new :doc:`Unity plug-in<unity>`.
+#. Added a new ``introspect`` module, which provides reflection-like capability for MuJoCo's public API, currently
+   describing functions and enums. While implemented in Python, this module is expected to be generally useful for
+   automatic code generation targeting multiple languages. (This is not shipped as part of the ``mujoco`` Python
+   bindings package.)
+
+API changes
+^^^^^^^^^^^
+
+4. Moved definition of ``mjtNum`` floating point type into a new header
+   `mjtnum.h <https://github.com/deepmind/mujoco/blob/main/include/mjtnum.h>`_.
+#. Renamed header `mujoco_export.h` to :ref:`mjexport.h<inHeader>`.
+#. Added ``mj_printFormattedData``, which accepts a format string for floating point numbers, for example to increase
+   precision.
+
+General
+^^^^^^^
+
+7. MuJoCo can load `OBJ <https://en.wikipedia.org/wiki/Wavefront_.obj_file>`_ mesh files.
+
+   a. Meshes containing polygons with more than 4 vertices are not supported.
+   #. In OBJ files containing multiple object groups, any groups after the first one will be ignored.
+
+#. Added optional frame-of-reference specification to :ref:`framepos<sensor-framepos>`,
+   :ref:`framequat<sensor-framequat>`, :ref:`framexaxis<sensor-framexaxis>`, :ref:`frameyaxis<sensor-frameyaxis>`,
+   :ref:`framezaxis<sensor-framezaxis>`, :ref:`framelinvel<sensor-framelinvel>`, and
+   :ref:`frameangvel<sensor-frameangvel>` sensors. The frame-of-reference is specified by new :at:`reftype` and
+   :at:`refname` attributes.
+
+#. Sizes of :ref:`user parameters <CUser>` are now automatically inferred.
+
+   a. Declarations of user parameters in the top-level :ref:`size <size>` clause (e.g. :at:`nuser_body`,
+      :at:`nuser_jnt`, etc.) now accept a value of -1, which is the default. This will automatically set the value to
+      the length of the maximum associated :at:`user` attribute defined in the model.
+   #. Setting a value smaller than -1 will lead to a compiler error (previously a segfault).
+   #. Setting a value to a length smaller than some :at:`user` attribute defined in the model will lead to an error
+      (previously additional values were ignored).
+
+#. Increased the maximum number of lights in an :ref:`mjvScene` from 8 to 100.
+
+#. Saved XML files only contain explicit :ref:`inertial <inertial>` elements if the original XML included them. Inertias
+   that were automatically inferred by the compiler's :ref:`inertiafromgeom <compiler>` mechanism remain unspecified.
+
+#. User-selected geoms are always rendered as opaque. This is useful in interactive visualizers.
+
+#. Static geoms now respect their :ref:`geom group<geom>` for visualisation. Until this change rendering of static geoms
+   could only be toggled using the :ref:`mjVIS_STATIC<mjtVisFlag>` visualisation flag . After this change, both the geom
+   group and the visualisation flag need to be enabled for the geom to be rendered.
+
+#. Pointer parameters in function declarations in :ref:`mujoco.h<inHeader>` that are supposed to represent fixed-length
+   arrays are now spelled as arrays with extents, e.g. ``mjtNum quat[4]`` rather than ``mjtNum* quat``. From the
+   perspective of C and C++, this is a non-change since array types in function signatures decay to pointer types.
+   However, it allows autogenerated code to be aware of expected input shapes.
+
+Bug Fixes
+^^^^^^^^^
+
+15. ``mj_loadXML`` and ``mj_saveLastXML`` are now locale-independent. The Unity plugin should now work correctly for
+    users whose system locales use commas as decimal separators.
+#.  XML assets in VFS no longer need to end in a null character. Instead, the file size is determined by the size
+    parameter of the corresponding VFS entry.
+#.  Fix a vertex buffer object memory leak in ``mjrContext`` when skins are used.
+#.  Camera quaternions are now normalized during XML compilation.
+
+Binary build
+^^^^^^^^^^^^
+
+18. Windows binaries are now built with Clang.
+
 Version 2.1.1 (Dec. 16, 2021)
 -----------------------------
 
@@ -45,7 +122,7 @@ Bug Fixes
    :ref:`weld <equality-weld>` constraints.
 
    .. note::
-      Forces generated by :ref:`spatial tendons <spatial>` which are outside the kinematic tree (i.e. between bodies
+      Forces generated by :ref:`spatial tendons <spatial>` which are outside the kinematic tree (i.e., between bodies
       which have no ancestral relationship) are still not taken into account by force and torque sensors. This remains a
       future work item.
 
@@ -118,7 +195,7 @@ New features
 General
 ^^^^^^^
 
-3. The pre-allocated sizes in the virtual file system (VFS) increased to 2000 and 1000, to allow for larger projects.
+3. The preallocated sizes in the virtual file system (VFS) increased to 2000 and 1000, to allow for larger projects.
 #. The C structs in the ``mjuiItem`` union are now named, for compatibility.
 #. Fixed: ``mjcb_contactfilter`` type is ``mjfConFilt`` (was ``mjfGeneric``).
 #. Fixed: The array of sensors in ``mjCModel`` was not cleared.