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check friction in io.put_model #978

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Merged
thowell merged 1 commit into from
Jan 12, 2026
Merged

check friction in io.put_model #978

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41 changes: 21 additions & 20 deletions mujoco_warp/_src/collision_driver_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -882,26 +882,27 @@ def test_hfield_maxconpair(self):
np.testing.assert_equal(d.nacon.numpy()[0], 4)

def test_min_friction(self):
_, _, _, d = test_data.fixture(
xml="""
<mujoco>
<worldbody>
<body>
<geom type="sphere" size=".1" friction="0 0 0"/>
<joint type="slide"/>
</body>
<body>
<geom type="sphere" size=".1" friction="0 0 0"/>
<joint type="slide"/>
</body>
</worldbody>
<keyframe>
<key qpos="0 .1"/>
</keyframe>
</mujoco>
""",
keyframe=0,
)
with self.assertWarns(UserWarning):
_, _, _, d = test_data.fixture(
xml="""
<mujoco>
<worldbody>
<body>
<geom type="sphere" size=".1" friction="0 0 0"/>
<joint type="slide"/>
</body>
<body>
<geom type="sphere" size=".1" friction="0 0 0"/>
<joint type="slide"/>
</body>
</worldbody>
<keyframe>
<key qpos="0 .1"/>
</keyframe>
</mujoco>
""",
keyframe=0,
)

self.assertEqual(d.nacon.numpy()[0], 1)
np.testing.assert_allclose(d.contact.friction.numpy()[0], types.MJ_MINMU)
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16 changes: 16 additions & 0 deletions mujoco_warp/_src/io.py
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
# ==============================================================================

import dataclasses
import warnings
from typing import Any, Optional, Sequence, Union

import mujoco
Expand Down Expand Up @@ -153,6 +154,21 @@ def not_implemented(objtype, objid, geomtype):
if not_implemented(objtype, objid, types.GeomType.BOX) and not_implemented(reftype, refid, types.GeomType.BOX):
raise NotImplementedError(f"Collision sensors with box-box collisions are not implemented.")

def _check_friction(name: str, id_: int, condim: int, friction, checks):
for min_condim, indices in checks:
if condim >= min_condim:
for idx in indices:
if friction[idx] < types.MJ_MINMU:
warnings.warn(
f"{name} {id_}: friction[{idx}] ({friction[idx]}) < MJ_MINMU ({types.MJ_MINMU}) with condim={condim} may cause NaN"
)

for geomid in range(mjm.ngeom):
_check_friction("geom", geomid, mjm.geom_condim[geomid], mjm.geom_friction[geomid], [(3, [0]), (4, [1]), (6, [2])])

for pairid in range(mjm.npair):
_check_friction("pair", pairid, mjm.pair_dim[pairid], mjm.pair_friction[pairid], [(3, [0]), (4, [1, 2]), (6, [3, 4])])

# create opt
opt_kwargs = {f.name: getattr(mjm.opt, f.name, None) for f in dataclasses.fields(types.Option)}
if hasattr(mjm.opt, "impratio"):
Expand Down
37 changes: 37 additions & 0 deletions mujoco_warp/_src/io_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -582,6 +582,43 @@ def test_contact_sensor_maxmatch(self):

self.assertEqual(m.opt.contact_sensor_maxmatch, 5)

@parameterized.parameters(
'<worldbody><geom type="sphere" size=".1" condim="3" friction="0 0.1 0.1"/></worldbody>',
'<worldbody><geom type="sphere" size=".1" condim="4" friction="1 0 0.1"/></worldbody>',
'<worldbody><geom type="sphere" size=".1" condim="6" friction="1 1 0"/></worldbody>',
"""
<worldbody>
<geom name="g1" type="sphere" size=".1"/>
<geom name="g2" type="sphere" size=".1" pos="0.5 0 0"/>
</worldbody>
<contact>
<pair geom1="g1" geom2="g2" condim="3" friction="0 1 1 1 1"/>
</contact>
""",
"""
<worldbody>
<geom name="g1" type="sphere" size=".1"/>
<geom name="g2" type="sphere" size=".1" pos="0.5 0 0"/>
</worldbody>
<contact>
<pair geom1="g1" geom2="g2" condim="4" friction="1 0 0 1 1"/>
</contact>
""",
"""
<worldbody>
<geom name="g1" type="sphere" size=".1"/>
<geom name="g2" type="sphere" size=".1" pos="0.5 0 0"/>
</worldbody>
<contact>
<pair geom1="g1" geom2="g2" condim="6" friction="1 1 1 0 0"/>
</contact>
""",
)
def test_small_friction_warning(self, xml):
"""Tests that a warning is raised for small friction values."""
with self.assertWarns(UserWarning):
mjwarp.put_model(mujoco.MjModel.from_xml_string(f"<mujoco>{xml}</mujoco>"))

@parameterized.product(active=["true", "false"], make_data=[True, False])
def test_eq_active(self, active, make_data):
mjm, mjd, m, d = test_data.fixture(
Expand Down
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