Render Newton cables on all three renderers

.github/workflows/build.yaml

@@ -797,6 +797,7 @@ jobs:
           test_rendering_lift_kuka_homo.py,
           test_rendering_franka_cloth.py,
           test_rendering_franka_soft.py,
+          test_rendering_franka_cable.py,
           test_rendering_registered_tasks.py,
           test_rendering_shadow_hand.py
         test-node-ids-file: ${{ github.event_name == 'push' && '.github/test-subsets/postmerge-rendering.toml' || '' }}
@@ -843,6 +844,7 @@ jobs:
           test_rendering_lift_kuka_homo_kitless.py,
           test_rendering_franka_cloth_kitless.py,
           test_rendering_franka_soft_kitless.py,
+          test_rendering_franka_cable_kitless.py,
           test_rendering_shadow_hand_kitless.py
         test-k-expr: legacy
         test-node-ids-file: ${{ github.event_name == 'push' && '.github/test-subsets/postmerge-rendering.toml' || '' }}
@@ -887,6 +889,7 @@ jobs:
           test_rendering_lift_kuka_homo_kitless.py,
           test_rendering_franka_cloth_kitless.py,
           test_rendering_franka_soft_kitless.py,
+          test_rendering_franka_cable_kitless.py,
           test_rendering_shadow_hand_kitless.py
         test-k-expr: ovstage
         test-node-ids-file: ${{ github.event_name == 'push' && '.github/test-subsets/postmerge-rendering.toml' || '' }}

source/isaaclab_newton/changelog.d/jmart-cable-render-binding.minor.rst

@@ -0,0 +1,31 @@
+Added
+^^^^^
+
+* Added :meth:`~isaaclab_newton.physics.NewtonManager.collect_cable_segment_shapes`, which maps each
+  renderable cable prim path to its ordered Newton segment shape ids. It reads only the Newton model
+  and the USD stage, so kit-less renderers can drive cable points without a Fabric sync path.
+
+Changed
+^^^^^^^
+
+* Changed :meth:`~isaaclab_newton.physics.NewtonManager.sync_cables_to_usd` to select its Fabric
+  prims on the simulation device and run its kernel there, instead of mirroring the Newton model to
+  the host and running on the CPU. The host mirror existed because the RTX Hydra render delegate
+  could not read GPU-backed Fabric arrays for ``BasisCurves.points``; that gap is fixed upstream.
+  This removes a device-to-host copy of the whole model's ``body_q`` on every dirty render frame,
+  which scaled with total body count rather than with the number of cable segments actually read.
+
+Fixed
+^^^^^
+
+* Fixed the Fabric cable sync silently doing nothing for a whole session when the Fabric stage was
+  not yet available at ``start_simulation``. The stage handle was resolved exactly once and cached,
+  so cables simulated correctly and rendered frozen at their spawn pose. The cable sync now
+  re-acquires the stage on first use, and ``start_simulation`` warns instead of dereferencing a
+  handle it does not have.
+* Fixed cables rendering frozen under Kit-based renderers even when the Fabric write succeeded. The
+  sync writes ``points`` in place from a Warp kernel, which leaves a render delegate's cached curve
+  untouched, so each cable prim is now invalidated explicitly after the write.
+* Fixed :class:`~isaaclab_newton.physics.NewtonManager` being unimportable inside a Kit session
+  whose bundled Warp lags the one Newton's solvers require, by deferring a module-level
+  ``newton.solvers`` import.

source/isaaclab_newton/isaaclab_newton/assets/cable_object/cable_object.py

@@ -5,6 +5,7 @@
 
 from __future__ import annotations
 
+import re
 from collections.abc import Sequence
 from typing import TYPE_CHECKING
 
@@ -22,6 +23,7 @@
 from isaaclab.utils.warp import ProxyArray
 
 from isaaclab_newton.physics import NewtonManager as SimulationManager
+from isaaclab_newton.physics.newton_manager import CableRegistryEntry
 
 from .cable_object_data import CableObjectData
 from .kernels import (
@@ -215,12 +217,59 @@ def is_cable_curve(prim) -> bool:
         self._ALL_ENV_MASK = wp.ones((self.num_instances,), dtype=wp.bool, device=self.device)
 
         self._data = CableObjectData(self.root_view, self.device)
+        self._curve_path_expr = curve_path_expr
+        self._register_cable_render_entry()
         self._physics_ready_handle = SimulationManager.register_callback(
             self._rebind,
             PhysicsEvent.PHYSICS_READY,
             name=f"cable_object_rebind_{self.cfg.prim_path}",
         )
 
+    def _resolve_curve_path_for_env(self, env_idx: int) -> str:
+        """Resolve the per-env concrete BasisCurves path from the stored path expression."""
+        path = self._curve_path_expr
+        # Regex-style env wildcard (``env_.*``), matching deformable fabric registration.
+        resolved = re.sub(r"(?<=[Ee]nv_)\.\*", str(env_idx), path)
+        if resolved != path:
+            return resolved
+        # Glob-style env wildcard (``env_*``) returned by resolve_matching_prims_from_source.
+        resolved = re.sub(r"(?<=[Ee]nv_)\*", str(env_idx), path)
+        if resolved != path:
+            return resolved
+        if self.num_instances == 1:
+            return path
+        raise RuntimeError(
+            f"CableObject '{self.cfg.prim_path}' curve path '{self._curve_path_expr}' has no"
+            f" env wildcard but num_instances={self.num_instances}."
+        )
+
+    def _register_cable_render_entry(self) -> None:
+        """Publish this cable's curve prims and Newton segment shape ids for Fabric/OVRTX."""
+        shape_groups = SimulationManager._cable_shape_groups_from_model()
+        instance_curve_paths: list[str] = []
+        instance_segment_shape_ids: list[list[int]] = []
+        for env_idx in range(self.num_instances):
+            curve_path = self._resolve_curve_path_for_env(env_idx)
+            segments = shape_groups.get(curve_path)
+            if segments is None:
+                raise RuntimeError(
+                    f"CableObject '{self.cfg.prim_path}' could not resolve Newton segment shapes for"
+                    f" curve prim '{curve_path}' (env {env_idx})."
+                )
+            if set(segments) != set(range(self.num_segments)):
+                raise RuntimeError(f"CableObject '{curve_path}' requires {self.num_segments} ordered segment shapes.")
+            instance_curve_paths.append(curve_path)
+            instance_segment_shape_ids.append([segments[segment] for segment in range(self.num_segments)])
+
+        SimulationManager.register_cable_entry(
+            CableRegistryEntry(
+                curve_prim_path=self._curve_path_expr,
+                segments_per_cable=self.num_segments,
+                instance_curve_paths=instance_curve_paths,
+                instance_segment_shape_ids=instance_segment_shape_ids,
+            )
+        )
+
     def _resolve_env_ids(self, env_ids: Sequence[int] | torch.Tensor | wp.array(dtype=wp.int32) | None) -> wp.array(
         dtype=wp.int32
     ):
@@ -271,6 +320,7 @@ def _iter_states(self):
     def _rebind(self, _: object) -> None:
         """Rebind simulation arrays after a Newton model rebuild."""
         self._data._create_simulation_bindings()
+        self._register_cable_render_entry()
 
     def _clear_callbacks(self) -> None:
         """Clear all registered callbacks."""