No Mesh-mesh collision in mujoco-mjx #2759
Description
Intro
I am using mujoco-mjx 3.3.4 and found that mesh-mesh collisions are not available. Two meshes will penetrate each other. The mesh-primitive collision is working fine.
Here is a video of the penetration: video
You can reproduce with the code from this dropbox link
My setup
I pre-processed the mesh files so that each stl doesn't contain too many vertices, and all of them are convex.
My xml file:
<mujoco model="stage">
<option gravity="0 0 -1"/>
<asset>
<mesh name="violin_body_1" file="violin/fingerboard-only-decomp-worst/mesh/body_1.stl" />
<mesh name="violin_body_2" file="violin/fingerboard-only-decomp-worst/mesh/body_2.stl" />
<mesh name="violin_body_3" file="violin/fingerboard-only-decomp-worst/mesh/body_3.stl" />
<mesh name="violin_body_4" file="violin/fingerboard-only-decomp-worst/mesh/body_4.stl" />
<mesh name="violin_visual" file="violin/raw_stl/violin1-coarse.stl"/>
<mesh name="bow_body_0" file="bow/bow-convex-hull-worst/bow.stl" />
</asset>
<worldbody>
<!-- Ground plane at z=0 -->
<geom name="ground" type="plane" pos="0 0 -0.3" size="5 5 0.1" rgba="0.8 0.8 0.8 1"/>
<!-- Side camera -->
<camera name="front" pos="0 -0.8 0.8" xyaxes="1 0 0 0 1 1"/>
<!-- <camera name="side" pos="-1.0 0 0.5" xyaxes="0 1 2 1 0 0"/> -->
<!-- Overhead white light -->
<light name="overhead" pos="0 0 3" dir="0 0 -1" diffuse="1 1 1" specular="0.3 0.3 0.3" />
<!-- Warm side light -->
<light name="side_warm" pos="3 3 1.5" dir="-1 -1 -0.5" diffuse="1 0.8 0.6" specular="0.2 0.2 0.1" />
<!-- Cool back light -->
<light name="back_cool" pos="-3 -3 4" dir="1 1 -1" diffuse="0.6 0.8 1" specular="0.1 0.2 0.3" />
<body name="violin_on_stage" pos="0 0 0">
<geom name="violin_body_1" pos="0 0 0" euler="0 0 0" contype="1" conaffinity="2" type="mesh" mesh="violin_body_1" />
<geom name="violin_body_2" pos="0 0 0" euler="0 0 0" contype="1" conaffinity="2" type="mesh" mesh="violin_body_2" />
<geom name="violin_body_3" pos="0 0 0" euler="0 0 0" contype="1" conaffinity="2" type="mesh" mesh="violin_body_3" />
<geom name="violin_body_4" pos="0 0 0" euler="0 0 0" contype="1" conaffinity="2" type="mesh" mesh="violin_body_4" />
<freejoint/>
</body>
<body name="bow_on_stage" pos="0.0 0.3 .2" euler="0 90 0">
<geom name="bow_body_0" pos="0 0 0" euler="0 0 0" contype="2" conaffinity="1" type="mesh" mesh="bow_body_0" />
<freejoint/>
</body>
</worldbody>
<visual>
<global offwidth="1920" offheight="1080"/>
</visual>
</mujoco>
The dependencies:
Package Version
-------------------- -----------
absl-py 2.3.1
asttokens 3.0.0
blinker 1.9.0
brax 0.12.4
build 1.2.2.post1
chex 0.1.89
click 8.2.1
cloudpickle 3.1.1
coacd 1.0.7
contourpy 1.3.2
cycler 0.12.1
decorator 5.2.1
etils 1.13.0
exceptiongroup 1.3.0
executing 2.2.0
Farama-Notifications 0.0.4
Flask 3.1.1
flask-cors 6.0.1
flax 0.10.7
fonttools 4.59.0
fsspec 2025.7.0
glfw 2.9.0
gymnasium 1.2.0
humanize 4.12.3
importlib_resources 6.5.2
ipdb 0.13.13
ipython 8.37.0
itsdangerous 2.2.0
jax 0.5.2
jaxlib 0.5.1
jaxopt 0.8.5
jedi 0.19.2
Jinja2 3.1.6
kiwisolver 1.4.8
markdown-it-py 3.0.0
MarkupSafe 3.0.2
matplotlib 3.10.3
matplotlib-inline 0.1.7
mdurl 0.1.2
mediapy 1.2.4
ml_collections 1.1.0
ml_dtypes 0.5.1
msgpack 1.1.1
mujoco 3.3.4
mujoco-mjx 3.3.4
nest-asyncio 1.6.0
numpy 2.2.6
opt_einsum 3.4.0
optax 0.2.5
orbax-checkpoint 0.11.19
packaging 25.0
parso 0.8.4
pexpect 4.9.0
pillow 11.3.0
pip 25.1
prompt_toolkit 3.0.51
protobuf 6.31.1
ptyprocess 0.7.0
pure_eval 0.2.3
Pygments 2.19.2
PyOpenGL 3.1.9
pyparsing 3.2.3
pyproject_hooks 1.2.0
python-dateutil 2.9.0.post0
PyYAML 6.0.2
rich 14.0.0
scipy 1.15.3
setuptools 78.1.1
simplejson 3.20.1
six 1.17.0
stack-data 0.6.3
tensorboardX 2.6.4
tensorstore 0.1.76
tomli 2.2.1
toolz 1.0.0
traitlets 5.14.3
treescope 0.1.9
trimesh 4.7.0
typing_extensions 4.14.1
wcwidth 0.2.13
Werkzeug 3.1.3
wheel 0.45.1
zipp 3.23.0What's happening? What did you expect?
The two bodies penetrated each other. I expect them to have collisions.
Steps for reproduction
Unzip the zip file from the dropbox link.
Run main_mjx.py in the folder.
Minimal model for reproduction
No response
Code required for reproduction
No response
Confirmations
- I searched the latest documentation thoroughly before posting.
- I searched previous Issues and Discussions, I am certain this has not been raised before.