Using strippath without modifying the xml

[robin-moss]

Intro

Hi!

I am a software engineer, using MuJoCo for Robotic Simulation

My setup

Python 3.10
mujoco 3.3.5
Ubuntu 24.04lts

My question

I was trying to avoid modifying the incoming XML (URDF) to include the compiler settings, and found that I cannot programmatically set strippath on MjSpec (and have it take affect).

What I've tried:

1. Setting strippath on MjSpec statically
2. Setting strippath on created MjSpec (causes an exception)
3. Passing strippath in as a kwarg for from_string/from_file (causes an exception)

Can you let me know if I've missed something, or if the only option for overriding strippath is via the compiler settings in the XML file itself?

Thanks

Minimal model and/or code that explain my question

from mujoco import MjSpec

URDF = """
<robot name="test_robot">
    <link name="base_link">
        <collision>
            <geometry>
                <mesh filename="path/to/my/mesh.stl" scale="1 1 1" />
            </geometry>
        </collision>
    </link>
</robot>
"""

URDF_WITH_COMPILER_SETTINGS = """
<robot name="test_robot">
  <mujoco>
    <compiler strippath="false" />
  </mujoco>
    <link name="base_link">
        <collision>
            <geometry>
                <mesh filename="path/to/my/mesh.stl" scale="1 1 1" />
            </geometry>
        </collision>
    </link>
</robot>
"""

MJCF = """
<?xml version="1.0" ?>
<mujoco model="RoboSim">
  <asset>
    <mesh name="my_mesh" content_type="model/stl" file="path/to/my/mesh.stl"/>
  </asset>
</mujoco>
"""


def run():
    MjSpec.strippath = False
    spec: MjSpec = MjSpec.from_string(URDF)
    # Stripppath is False, so the full path should be kept, but it isn't
    print(f"MjSpec.strippath = False;\t {spec.meshes[0].file}")

    spec: MjSpec = MjSpec.from_string(URDF_WITH_COMPILER_SETTINGS)
    # Works with compiler XML settings
    print(f"<compiler strippath=\"false\" />;\t {spec.meshes[0].file}")

    spec: MjSpec = MjSpec.from_string(MJCF)
    # Stripppath is default (true for mjcf), path isn't stripped when using MJCF
    print(f"MJCF default;\t {spec.meshes[0].file}")

    MjSpec.strippath = True
    spec: MjSpec = MjSpec.from_string(MJCF)
    # Stripppath is set to True, path isn't stripped
    print(f"MjSpec.strippath = True;\t {spec.meshes[0].file}")

if __name__ == "__main__":
    run()

Output:

MjSpec.strippath = False;	 mesh.stl
<compiler strippath="false" />;	 path/to/my/mesh.stl
MJCF default;	 path/to/my/mesh.stl
MjSpec.strippath = True;	 path/to/my/mesh.stl

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.