Fix PhysX D6 translational limit lookup

CHANGELOG.md

@@ -19,6 +19,7 @@
 ### Fixed
 
 - Fix MJCF, URDF, and USD imports rendering collision-only bodies as visuals when the asset authors visual geometry elsewhere. (#3291)
+- Fix `SchemaResolverPhysx` reading every D6 translational limit gain from the `linear` instance instead of its `transX`, `transY`, or `transZ` instance.
 - Fix `ViewerUSD` texture consumers observing partially written PNGs by publishing generated textures atomically (#3288)
 - Fix builder merging (`ModelBuilder.add_builder()`, `add_world()`, `replicate()`) offsetting negative reference sentinels in custom attribute values stored as NumPy or Warp integer scalars.
 - Fix `ModelBuilder.add_usd()` requiring the optional `mujoco` package when handling `MjcActuator` prims, including during default MJC equality conversion.

newton/_src/usd/schemas.py

@@ -346,13 +346,12 @@ class SchemaResolverPhysx(SchemaResolver):
         PrimType.JOINT: {
             "armature": SchemaAttribute("physxJoint:armature", 0.0),
             "velocity_limit": SchemaAttribute("physxJoint:maxJointVelocity", None),
-            # Per-axis linear limit aliases
-            "limit_transX_ke": SchemaAttribute("physxLimit:linear:stiffness", 0.0),
-            "limit_transY_ke": SchemaAttribute("physxLimit:linear:stiffness", 0.0),
-            "limit_transZ_ke": SchemaAttribute("physxLimit:linear:stiffness", 0.0),
-            "limit_transX_kd": SchemaAttribute("physxLimit:linear:damping", 0.0),
-            "limit_transY_kd": SchemaAttribute("physxLimit:linear:damping", 0.0),
-            "limit_transZ_kd": SchemaAttribute("physxLimit:linear:damping", 0.0),
+            "limit_transX_ke": SchemaAttribute("physxLimit:transX:stiffness", 0.0),
+            "limit_transY_ke": SchemaAttribute("physxLimit:transY:stiffness", 0.0),
+            "limit_transZ_ke": SchemaAttribute("physxLimit:transZ:stiffness", 0.0),
+            "limit_transX_kd": SchemaAttribute("physxLimit:transX:damping", 0.0),
+            "limit_transY_kd": SchemaAttribute("physxLimit:transY:damping", 0.0),
+            "limit_transZ_kd": SchemaAttribute("physxLimit:transZ:damping", 0.0),
             "limit_linear_ke": SchemaAttribute("physxLimit:linear:stiffness", 0.0),
             "limit_angular_ke": SchemaAttribute("physxLimit:angular:stiffness", 0.0),
             "limit_rotX_ke": SchemaAttribute("physxLimit:rotX:stiffness", 0.0),

newton/tests/test_schema_resolver.py

@@ -175,6 +175,20 @@ def test_physx_joint_velocity_limit(self):
         for vel_limit in velocity_limits_found:
             self.assertAlmostEqual(vel_limit, expected_velocity_limit, places=3)
 
+    def test_physx_d6_translational_limit_instances(self):
+        stage = Usd.Stage.CreateInMemory()
+        joint = stage.DefinePrim("/joint", "PhysicsJoint")
+        resolver = SchemaResolverPhysx()
+
+        for gain, property_name in (("ke", "stiffness"), ("kd", "damping")):
+            joint.CreateAttribute(f"physxLimit:linear:{property_name}", Sdf.ValueTypeNames.Float).Set(99.0)
+            for index, axis in enumerate(("transX", "transY", "transZ"), start=1):
+                expected = float(index + (3 if gain == "kd" else 0))
+                joint.CreateAttribute(f"physxLimit:{axis}:{property_name}", Sdf.ValueTypeNames.Float).Set(expected)
+
+                with self.subTest(axis=axis, gain=gain):
+                    self.assertEqual(resolver.get_value(joint, PrimType.JOINT, f"limit_{axis}_{gain}"), expected)
+
     def test_schema_attrs_collection(self):
         """
         Test solver-specific attribute collection from USD files.