Restore direct rigid collection spawning

Allow rigid object collections to fall back to prim_path when they are constructed outside InteractiveScene, while still honoring clone-planned spawn_path values.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: ooctipus

source/isaaclab_newton/changelog.d/octi-cloner_ordering.rst

@@ -1,6 +1,5 @@
 Changed
 ^^^^^^^
 
-* Changed rigid object collection spawning to require an explicit
-  ``spawn.spawn_path`` when a member has a spawner. Use ``spawn=None`` for
-  pre-authored prims that should only construct a view.
+* Changed rigid object collection spawning to honor planned ``spawn_path``
+  values while falling back to ``prim_path`` for direct construction.

source/isaaclab_newton/isaaclab_newton/assets/rigid_object_collection/rigid_object_collection.py

@@ -78,11 +78,9 @@ def __init__(self, cfg: RigidObjectCollectionCfg):
         for rigid_body_cfg in self.cfg.rigid_objects.values():
             # spawn the asset
             if rigid_body_cfg.spawn is not None:
-                # ``spawn=None`` means the prim already exists; otherwise the authoring path is explicit.
-                if rigid_body_cfg.spawn.spawn_path is None:
-                    raise RuntimeError(f"Missing spawn_path for rigid object '{rigid_body_cfg.prim_path}'.")
+                spawn_path = rigid_body_cfg.spawn.spawn_path or rigid_body_cfg.prim_path
                 rigid_body_cfg.spawn.func(
-                    rigid_body_cfg.spawn.spawn_path,
+                    spawn_path,
                     rigid_body_cfg.spawn,
                     translation=rigid_body_cfg.init_state.pos,
                     orientation=rigid_body_cfg.init_state.rot,

source/isaaclab_physx/changelog.d/octi-cloner_ordering.rst

@@ -1,6 +1,5 @@
 Changed
 ^^^^^^^
 
-* Changed rigid object collection spawning to require an explicit
-  ``spawn.spawn_path`` when a member has a spawner. Use ``spawn=None`` for
-  pre-authored prims that should only construct a view.
+* Changed rigid object collection spawning to honor planned ``spawn_path``
+  values while falling back to ``prim_path`` for direct construction.

source/isaaclab_physx/isaaclab_physx/assets/rigid_object_collection/rigid_object_collection.py

@@ -81,10 +81,9 @@ def __init__(self, cfg: RigidObjectCollectionCfg):
         for rigid_body_cfg in self.cfg.rigid_objects.values():
             # spawn the asset
             if rigid_body_cfg.spawn is not None:
-                if rigid_body_cfg.spawn.spawn_path is None:
-                    raise RuntimeError(f"Missing spawn_path for rigid object '{rigid_body_cfg.prim_path}'.")
+                spawn_path = rigid_body_cfg.spawn.spawn_path or rigid_body_cfg.prim_path
                 rigid_body_cfg.spawn.func(
-                    rigid_body_cfg.spawn.spawn_path,
+                    spawn_path,
                     rigid_body_cfg.spawn,
                     translation=rigid_body_cfg.init_state.pos,
                     orientation=rigid_body_cfg.init_state.rot,