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Finalize built-in mesh example model and documentation

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PiperOrigin-RevId: 791227350
Change-Id: Ibdcdb8a4ee5b3f78c9ae93e1db2a9a2f9d55a80c
This commit is contained in:
Yuval Tassa
2025-08-05 08:31:46 -07:00
committed by Copybara-Service
parent 2f4375dda3
commit fde479736e
11 changed files with 283 additions and 55 deletions
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doc/computation/index.rst
+14 -15
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@@ -1603,9 +1603,6 @@ native pipeline
.. _coDistance:
Geom distance
^^^^^^^^^^^^^
.. image:: ../images/computation/ccd_light.gif
:width: 25%
:align: right
@@ -1616,28 +1613,30 @@ Geom distance
:align: right
:class: only-dark
Geom distance
^^^^^^^^^^^^^
The narrow-phase collision functions described :ref:`above<coChecking>` drive the :ref:`mj_geomDistance` function and
associated :ref:`collision-sensors`. Due to the limitations of MPR, the legacy pipeline will return incorrect values
(top) except at very small distances relative to the geom sizes, and is discouraged for this use case. In
contrast, the GJK-based native pipeline (bottom), computes the correct values at all distances.
.. _coDecomposition:
Convex decomposition
^^^^^^^^^^^^^^^^^^^^
In order to model a non-convex object other than a height field, the user must decompose it into a union of convex geoms
(which can be primitive shapes or meshes) and attach them to the same body. A height-field is essentially a shape that
is automatically-decomposed into prisms
(which can be primitive shapes or meshes) and attach them to the same body. The other exception to this rule (besides
height fields) are :ref:`Signed Distance Functions<exSDF>` (see documentation therein), which in certain cases (e.g.,
`analytic SDFs <https://github.com/google-deepmind/mujoco/blob/main/plugin/sdf/README.md#gear>`__) can be efficient, but
have other requirements and limitations.
Open mesh-decomposition tools like the
`CoACD library <https://github.com/SarahWeiii/CoACD>`__ can be used outside MuJoCo to automate this process. Finally,
all built-in collision functions can be replaced with custom callbacks. This can be used to incorporate a
general-purpose "triangle soup" collision detector for example. However we do not recommend such an approach.
Pre-processing the geometry and representing it as a union of convex geoms takes some work, but it pays off at runtime
and yields both faster and more stable simulation.
The exception to this rule are :ref:`SDF plugins<exSDF>` (see documentation therein), which in
`certain cases <https://github.com/google-deepmind/mujoco/blob/main/plugin/sdf/README.md#gear>`__ can be efficient,
but have other requirements and limitations.
Open source mesh-decomposition tools like the `CoACD library <https://github.com/SarahWeiii/CoACD>`__ can be used
outside MuJoCo to automate this process. Finally, all built-in collision functions can be replaced with custom
callbacks. This can be used to incorporate a general-purpose "triangle soup" collision detector for example. However we
do not recommend such an approach. Pre-processing the geometry and representing it as a union of convex geoms takes some
work, but it pays off at runtime and yields both faster and more stable simulation.
.. _Pipeline: