Clear self-collision filter pairs before finalizing shadow Newton model (#7505)

## Summary
- The PhysX-backend shadow Newton visualization model never runs
collision detection, but USD-authored self-collision filter pairs
(`physxArticulation:enabledSelfCollisions`) were still imported into it
and replicated across every cloned env.
- At real training env counts, this filter-pair set could reach billions
of entries, causing `ModelBuilder.finalize()` to run out of memory.
- Clears `builder.shape_collision_filter_pairs` before finalizing the
shadow model since it has no use for them.

## Test plan
- [x] `uv run python -m pytest
source/isaaclab/test/sim/test_newton_manager_visualization_state.py` —
23 passed, including new regression test
`test_ensure_visualization_model_clears_shape_collision_filter_pairs_before_finalize`
- [x] `uv run python -m pytest
source/isaaclab/test/sim/test_simulation_context_visualizers.py
source/isaaclab_newton/test/physics/test_newton_manager_abstraction.py`
— 200 passed
- [x] `uv run isaaclab -f`

## Release backport

- [x] <!-- backport-active-release --> Backport this pull request to the
active release branch after it merges into `develop`

---------

Co-authored-by: Octi Zhang <zhengyuz@nvidia.com>

Author: matthewtrepte

source/isaaclab/changelog.d/mtrepte-shadow-model-collision-filter-oom-test.skip

@@ -826,6 +826,10 @@ def test_clone_visualization_builder_ignores_non_env_deformables_on_world_import
     UsdGeom.Xform.Define(stage, "/World/envs/env_1")
 
     fake_builder = _FakeShadowBuilder(body_count=1, cloth_delta=3, track_usd=True)
+    fake_builder.shape_collision_filter_pairs = []
+    fake_builder.shape_collision_group = []
+    fake_builder.shape_count = 0
+    fake_builder.add_builder = lambda _builder: None
     clone_plan = SimpleNamespace(
         sources=("/World/envs/env_0",),
         destinations=("/World/envs/env_{}",),

source/isaaclab/test/sim/test_newton_manager_visualization_state.py

@@ -0,0 +1,5 @@
+Fixed
+^^^^^
+
+* Fixed PhysX-backend Newton visualization models replicating unused collision
+  filters and contact pairs, which could exhaust memory during ``ModelBuilder.finalize()``.

source/isaaclab_newton/changelog.d/fix-shadow-model-collision-filter-oom.rst

@@ -113,6 +113,8 @@ def build_visualization_builder_from_stage_envs(
         shadow_entities, registry_groups = add_shadow_deformables_to_builder(
             builder, stage, env_paths, device=device, entries=deformable_entries, clone_plan=clone_plan
         )
+        builder.shape_collision_filter_pairs = []
+        builder.shape_collision_group[:] = [0] * builder.shape_count
         return builder, (shadow_entities, registry_groups)
 
     if not env_paths:
@@ -147,6 +149,12 @@ def build_visualization_builder_from_stage_envs(
         schema_resolvers,
         ignore_paths=source_deformable_ignore_paths or None,
     )
+    global_builder = builder
+    builder = ModelBuilder(up_axis=up_axis)  # Preserve Newton's compact empty filter store.
+    for visual_builder in (global_builder, *source_builders.values()):
+        visual_builder.shape_collision_filter_pairs = []
+        visual_builder.shape_collision_group[:] = [0] * visual_builder.shape_count
+    builder.add_builder(global_builder)
     replicate_builder_mapping(builder, sources, mapping, positions, quaternions, source_builders, destinations, env_ids)
     shadow_entities, registry_groups = add_shadow_deformables_to_builder(
         builder, stage, env_paths, device=device, entries=deformable_entries, clone_plan=clone_plan

source/isaaclab_newton/isaaclab_newton/physics/visualization_builder.py

@@ -16,7 +16,7 @@
 from isaaclab_newton.physics import visualization_builder as visualization_builder_module
 from isaaclab_newton.physics import visualization_deformables as visualization_deformables_module
 
-from pxr import Usd, UsdGeom
+from pxr import Sdf, Usd, UsdGeom, UsdPhysics
 
 from isaaclab.cloner import ClonePlan
 from isaaclab.scene_data.deformable_discovery import DeformableStageEntry
@@ -40,6 +40,8 @@
 class _FakeVisualizationModelBuilder:
     def __init__(self, up_axis=None):
         self.up_axis = up_axis
+        self.shape_collision_filter_pairs = []
+        self.shape_collision_group = []
         for attr in _VIS_BUILTIN_LABEL_ATTRS:
             setattr(self, attr, [])
             setattr(self, attr.replace("_label", "_world"), [])
@@ -80,6 +82,7 @@ def add_usd(self, stage, root_path=None, ignore_paths=None, schema_resolvers=Non
         for attr in _VIS_BUILTIN_LABEL_ATTRS:
             getattr(self, attr).append(f"{root_path}/{_VIS_LABEL_SUFFIXES[attr]}")
             getattr(self, attr.replace("_label", "_world")).append(self._current_world or 0)
+        self.shape_collision_group.append(1)
         self.custom_attributes["mujoco:equality_constraint_label"].values.append(
             f"{root_path}/{_VIS_LABEL_SUFFIXES['equality_constraint_label']}"
         )
@@ -96,6 +99,7 @@ def add_builder(self, builder, xform=None):
             labels = getattr(builder, attr)
             getattr(self, attr).extend(labels)
             getattr(self, attr.replace("_label", "_world")).extend([self._current_world] * len(labels))
+        self.shape_collision_group.extend(builder.shape_collision_group)
         eq_labels = builder.custom_attributes["mujoco:equality_constraint_label"].values
         self.custom_attributes["mujoco:equality_constraint_label"].values.extend(eq_labels)
         self.custom_attributes["mujoco:equality_constraint_world"].values.extend([self._current_world] * len(eq_labels))
@@ -363,6 +367,9 @@ def test_visualization_builder_imports_standalone_stage_as_one_world(self):
         self._define_xform(stage, "/World")
         self._define_xform(stage, "/World/Robot")
         builder = mock.Mock()
+        builder.shape_collision_filter_pairs = []
+        builder.shape_collision_group = []
+        builder.shape_count = 0
         builder.add_usd.return_value = {"path_shape_map": {}}
 
         with (
@@ -380,6 +387,47 @@ def test_visualization_builder_imports_standalone_stage_as_one_world(self):
         self.assertEqual(registry_groups, [])
         builder.add_usd.assert_called_once_with(stage, schema_resolvers=["newton", "physx"], ignore_paths=None)
 
+    def test_visualization_builder_disables_collision_pairs(self):
+        stage = Usd.Stage.CreateInMemory()
+        robot_path = "/World/envs/env_0/Robot"
+        self._define_xform(stage, "/World")
+        self._define_xform(stage, "/World/envs")
+        self._define_xform(stage, "/World/envs/env_0")
+        self._define_xform(stage, "/World/envs/env_1", (2.0, 0.0, 0.0))
+        robot = UsdGeom.Xform.Define(stage, robot_path).GetPrim()
+        UsdPhysics.ArticulationRootAPI.Apply(robot)
+        robot.CreateAttribute("physxArticulation:enabledSelfCollisions", Sdf.ValueTypeNames.Bool).Set(False)
+        for name, translation in (("A", 0.0), ("B", 1.0)):
+            body_path = f"{robot_path}/{name}"
+            body = UsdGeom.Xform.Define(stage, body_path)
+            body.AddTranslateOp().Set((translation, 0.0, 0.0))
+            UsdPhysics.RigidBodyAPI.Apply(body.GetPrim())
+            collision = UsdGeom.Cube.Define(stage, f"{body_path}/Collision")
+            collision.CreateSizeAttr(0.2)
+            UsdPhysics.CollisionAPI.Apply(collision.GetPrim())
+        joint = UsdPhysics.RevoluteJoint.Define(stage, f"{robot_path}/Joint")
+        joint.CreateBody0Rel().SetTargets([Sdf.Path(f"{robot_path}/A")])
+        joint.CreateBody1Rel().SetTargets([Sdf.Path(f"{robot_path}/B")])
+
+        clone_plan = ClonePlan(
+            sources=(robot_path,),
+            destinations=("/World/envs/env_{}/Robot",),
+            clone_mask=torch.ones((1, 2), dtype=torch.bool),
+            env_ids=torch.arange(2),
+        )
+        for env_paths, plan, expected_shape_count in (
+            ([], None, 2),
+            ([(0, "/World/envs/env_0"), (1, "/World/envs/env_1")], clone_plan, 4),
+        ):
+            builder, _shadow_metadata = visualization_builder_module.build_visualization_builder_from_stage_envs(
+                stage, env_paths, plan
+            )
+            model = builder.finalize(device="cpu")
+
+            self.assertEqual(model.shape_count, expected_shape_count)
+            self.assertEqual(len(model.shape_collision_filter_pairs), 0)
+            self.assertEqual(model.shape_contact_pair_count, 0)
+
     def test_visualization_builder_rejects_clone_plan_without_environment_paths(self):
         """A cloned scene must not be cached as an incomplete single-world model."""
         stage = Usd.Stage.CreateInMemory()