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Skip material randomization on physics backends that don't support it #5151

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Kripner wants to merge 3 commits into from
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Skip material randomization on physics backends that don't support it #5151

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e59b3c6
Skip material randomization on physics backends that don't support it
Kripner Apr 2, 2026
d272931
Update source/isaaclab/isaaclab/envs/mdp/events.py
Kripner Apr 2, 2026
96659d1
Update source/isaaclab/isaaclab/envs/mdp/events.py
Kripner Apr 2, 2026
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46 changes: 32 additions & 14 deletions source/isaaclab/isaaclab/envs/mdp/events.py
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Original file line number Diff line number Diff line change
Expand Up @@ -203,22 +203,36 @@ def __init__(self, cfg: EventTermCfg, env: ManagerBasedEnv):
f" with type: '{type(self.asset)}'."
)

# check if the physics backend supports material property randomization
self._supported = hasattr(self.asset.root_view, "get_material_properties")
if not self._supported:

logging.getLogger(__name__).warning(
"randomize_rigid_body_material: skipping because the current physics backend"
" does not support material property randomization."
)
self.num_shapes_per_body = None
return

# obtain number of shapes per body (needed for indexing the material properties correctly)
# note: this is a workaround since the Articulation does not provide a direct way to obtain the number of shapes
# per body. We use the physics simulation view to obtain the number of shapes per body.
if isinstance(self.asset, BaseArticulation) and self.asset_cfg.body_ids != slice(None):
self.num_shapes_per_body = []
for link_path in self.asset.root_view.link_paths[0]:
link_physx_view = self.asset._physics_sim_view.create_rigid_body_view(link_path) # type: ignore
self.num_shapes_per_body.append(link_physx_view.max_shapes)
# ensure the parsing is correct
num_shapes = sum(self.num_shapes_per_body)
expected_shapes = self.asset.root_view.max_shapes
if num_shapes != expected_shapes:
raise ValueError(
"Randomization term 'randomize_rigid_body_material' failed to parse the number of shapes per body."
f" Expected total shapes: {expected_shapes}, but got: {num_shapes}."
)
# check if the asset directly provides num_shapes_per_body (e.g. future backends that expose it)
if hasattr(self.asset, "num_shapes_per_body"):
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@isaaclab-review-bot isaaclab-review-bot Bot Apr 2, 2026

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[Medium] Missing validation: The PhysX path (lines 224-233) validates sum(num_shapes_per_body) == max_shapes. This Newton path trusts the backend property blindly. If it's ever wrong, materials will be assigned to incorrect shape indices.

Suggestion — add the same sanity check:

if hasattr(self.asset, "num_shapes_per_body"):
    self.num_shapes_per_body = self.asset.num_shapes_per_body
    # validate against max_shapes (same check as PhysX path)
    num_shapes = sum(self.num_shapes_per_body)
    expected_shapes = self.asset.root_view.max_shapes
    if num_shapes != expected_shapes:
        raise ValueError(
            "Randomization term 'randomize_rigid_body_material' failed to parse the number of shapes"
            f" per body. Expected total shapes: {expected_shapes}, but got: {num_shapes}."
        )

self.num_shapes_per_body = self.asset.num_shapes_per_body
else:
# PhysX workaround: use the simulation view to obtain the number of shapes per body
self.num_shapes_per_body = []
for link_path in self.asset.root_view.link_paths[0]:
link_physx_view = self.asset._physics_sim_view.create_rigid_body_view(link_path) # type: ignore
self.num_shapes_per_body.append(link_physx_view.max_shapes)
# ensure the parsing is correct
num_shapes = sum(self.num_shapes_per_body)
expected_shapes = self.asset.root_view.max_shapes
if num_shapes != expected_shapes:
raise ValueError(
"Randomization term 'randomize_rigid_body_material' failed to parse the number of shapes"
f" per body. Expected total shapes: {expected_shapes}, but got: {num_shapes}."
)
else:
# in this case, we don't need to do special indexing
self.num_shapes_per_body = None
Expand Down Expand Up @@ -252,6 +266,10 @@ def __call__(
asset_cfg: SceneEntityCfg,
make_consistent: bool = False,
):
# skip if backend doesn't support material randomization
if not self._supported:
return

# resolve environment ids
if env_ids is None:
env_ids = torch.arange(env.scene.num_envs, device="cpu", dtype=torch.int32)
Expand Down