Flexcomp seems to ignore the VFS #2805
Description
Intro
Dear MuJoCo-team,
thank you for providing and maintaining such a great simulator. Currently, I am working as an SDE intern at Amazon robotics, using MuJoCo for large-scale simulations. Within our software stack, we are also using flexcomp elements.
My setup
- Python 3.10
- MuJoCo: 3.3.5 & 3.3.4
- macOS: Sequoia 15.6
What's happening? What did you expect?
When loading a stl-file inside a flexcomp tag, I would expect the file to be resolved by the VFS. Instead mujoco expects the file to be in the current working directory.
In the MWE below this is not a big problem, but for more complex setups and files downloaded via custom plugins, this is very tedious or even impossible respectively.
Steps for reproduction
- Download a mesh, e.g.
scad-p35.stlfrom https://www.printables.com/model/358708-nonconvex-regularization-examples/files - Run the MWE below:
- If the stl-file is in the same folder as the python-file, everything works.
- If the file is only in
/meshesand in the VFS, but not in the cwd, the model compilation fails.
Minimal model for reproduction
minimal XML
<mujoco>
<worldbody>
<body name="flex_body" pos="0 0 1">
<flexcomp name="flex_object" type="mesh" file="scad-p35.stl" rigid="true">
<contact contype="1" conaffinity="1"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
Code required for reproduction
import mujoco
# example stl-file taken from https://www.printables.com/model/358708-nonconvex-regularization-examples/files
meshname = "scad-p35.stl"
xml_model = f"""
<mujoco>
<!-- with or without assets yields the same outcome -->
<asset>
<mesh name="mesh" file="{meshname}"/>
</asset>
<worldbody>
<body name="flex_body" pos="0 0 1">
<flexcomp name="flex_object" type="mesh" file="{meshname}" rigid="true">
<contact contype="1" conaffinity="1"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
"""
with open(f"./meshes/{meshname}", "rb") as f:
stl_data = f.read()
vfs = {}
vfs[meshname] = stl_data
# works, if scad-p35.stl is in the same folder
# fails, if scad-p35.stl is only in meshes/
model = mujoco.MjModel.from_xml_string(xml_model, vfs)
data = mujoco.MjData(model)
mujoco.mj_step(model, data)
print("Model compiled and stepped successfully")
# visualize
import mujoco.viewer
mujoco.viewer.launch(model)Confirmations
- I searched the latest documentation thoroughly before posting.
- I searched previous Issues and Discussions, I am certain this has not been raised before.