[StafaH]

Description

Part 14 of the split of #7949. This PR cleans up sim authoring: the schema writers in isaaclab.sim.schemas, the spawners, and the mesh converter. It is rebased onto the current develop and ports only the parts of #7949 that still apply there. The authored USD is unchanged, and no public API changes.

Spawners and mesh converter

• spawners.utils (renamed from spawners._utils, see below) adds a helper:
  • apply_schema_props writes a spawner schema slot. It sends a fragment mapping to the fragment writer, one entry at a time and anchored at the spawned prim, and sends a legacy cfg to the legacy writer. The mesh and shape spawners, spawn_from_mesh, and MeshConverter repeated this branch for their collision, mass, and rigid-body slots; they now call the helper.
• Material paths are resolved inline at each call site (absolute paths are kept; relative names go under the spawned prim), replacing from_files._resolve_material_path.
• Existing-prim checks are left to create_prim, which already raises the same ValueError. The spawner bodies are shorter, and spawn_geom_from_prim_type / _spawn_mesh_geom_from_mesh return the prim they create.
• Mesh spawners share _axis_transform for the cylinder, capsule, and cone axis rotation.
• Light, sensor, ground plane, and multi-USD spawners:
  • The ground plane hides its light with set_prim_visibility.
  • spawn_multi_usd_file builds MultiAssetSpawnerCfg in one call and no longer runs a hasattr check that was always true.
• AssetConverterBase has a shorter USD-extension and hash-file check, and writes the config.yaml generation stamp with a single datetime.now() call. The stamp format is the same.

Schema writers

• apply_rigid_body_properties, apply_collision_properties, and apply_mass_properties now share _apply_api_fragments. Target matching, create_if_missing, the zero-target warning, and result aggregation are unchanged.
• The joint-drive writers share _write_drive_attributes, which converts angular stiffness and damping from per-radian to per-degree and maps drive_type to the USD type attribute. It is used by apply_drive, _ensure_drive_exists, apply_joint_drive_properties, and modify_joint_drive_properties. Joint-type detection reuses drive_instance_name, including in schemas_actuators.
• Other shared helpers:
  • _write_mesh_approximation writes and validates the physics:approximation token.
  • _tetrahedralize_surface holds the pytetwild call and the tet-winding fix, moved out of define_deformable_body_properties.
• Smaller cleanups:
  • activate_contact_sensors counts descendants with Usd.PrimRange.
  • schemas_actuators uses to_camel_case instead of a private camel-case regex.
  • Redundant pass statements are removed from the fragment marker classes.
  • Fragment appliers are called directly as cfg.func(cfg, prim_path, stage). @configclass already turns the func import string into a callable ResolvableString, so the callable(...) else string_to_callable(...) fallback (four schema writers and the physics-material spawner) never ran.

Reflection

• Replaced avoidable getattr/setattr/hasattr with direct attribute access or an isinstance check wherever the attribute is always defined for the configs that reach that code (actuator authoring, the USD-file and shape spawners, the camera spawner's intrinsics, the fragment annotation lookup). The remaining uses are dynamic by design: iterating dataclass fields, the deprecated alias forwarding, optional class metadata, and mixed config types in the multi-asset wrapper.

No underscore module names or cross-file private helpers in core

• Renamed the underscore modules: sim/spawners/_utils.py → utils.py, sim/schemas/_backend_hooks.py → backend_hooks.py, actuators/_compat.py → actuator_compat.py, benchmark/_cli.py → cli.py, cloner/_fabric_notices.py → fabric_notices.py, utils/_device.py → device.py. All importers in isaaclab, isaaclab_physx, isaaclab_newton, isaaclab_ov, the benchmark scripts, tests, and docs are updated.
• Dropped the _ prefix from module-level functions used from other files: limits_equal, resolve_limit_aliases, skip_joint_drive, articulation_root_companion_namespace, apply_namespaced_schemas, drive_instance_name, validate_newton_native_actuator_cfgs, author_actuator_prims, resave_checkpoint_with_metadata, deprecate_field_alias, deprecated_schema_cfg, spawn_from_usd_file, spawn_geom_from_prim_type. They are not added to the package exports.

Not ported from #7949

• The forwarding-shim refactors in schemas/__init__.py and schemas_cfg.py, the usd_api / physx_api deprecation properties, and the empty _usd_* metadata on deprecated cfgs. These are deprecation-only and will be removed.
• The _OVERRIDABLE_PROPS constant in the wrappers, a single-use constant.
• The import-only edits. develop already uses relative imports.

Type of change

• Refactor (no functional change). The only visible difference is that the ValueError for an unsupported deformable type is now one line, instead of a triple-quoted string with embedded indentation.

Verification

• USD authoring equivalence, comparing develop sources with this branch in Kit, one fresh stage per case. All 57 cases produce identical exported USDA, return values, and raised errors:
  • Sphere, cuboid, cylinder, capsule, and cone shapes; and sphere, cuboid, cylinder, capsule, cone, and rectangle meshes. Each is spawned plain, with legacy cfgs, and with fragments (including dict targets and absolute material paths).
  • The cable spawner, MeshFileCfg from a trimesh object and from an .obj file, and all five lights.
  • Pinhole and fisheye cameras, and the sensor frame.
  • UsdFileCfg with legacy cfgs and with fragments (articulation root, joint drives, contact sensors, semantics, materials), the compliant-contact spawner, and a ground plane asset.
  • MultiAssetSpawnerCfg and MultiUsdFileCfg, and a surface deformable.
  • The legacy define_/modify_ writers and the fragment apply_* writers, including ensure_drives_exist, the no-target case, mesh collision with an invalid approximation name, and fixed tendons.
  • A MeshConverter run with collision, mesh-collision, mass, and rigid props and make_instanceable, comparing the generated USD layers and config.yaml.
• Tests, run one file at a time; all pass:
  • Spawners: test_spawn_shapes, test_spawn_meshes, test_spawn_lights, test_spawn_sensors, test_spawn_from_files, test_spawn_wrappers, test_spawn_cable, test_spawn_materials, test_default_ground_plane, test_visual_materials_kitless.
  • Schemas: test_schemas, test_schemas_deprecation, test_schemas_shim, test_schemas_kitless_fixed_joint, test_schema_fragments, test_schema_fragment_parity, test_schema_writer_nested_targets, test_joint_drive_fragments, test_collision_fragments, test_mass_fragments, test_mesh_collision_fragments, test_articulation_fragments, test_material_fragments, test_tendon_fragments, test_tendon_fragments_codeless, test_deformable_backend_split.
  • Converter: test_mesh_converter.
  • Actuator authoring: source/isaaclab/test/actuators, test_newton_actuator_manager_authoring, test_newton_actuators_newton, test_newton_actuators_physx.
• After the renames, reflection pass, and review fixes, the 57-case USD comparison was rerun against the latest develop (0 differences), and the spawner, schema, fragment, converter, cloner (isaaclab and isaaclab_physx), benchmark CLI, device, Newton schema, and actuator authoring tests were rerun; all pass. Every renamed module and its importers in isaaclab_physx, isaaclab_newton, and isaaclab_ov import cleanly.
• One-line helpers are kept inline rather than wrapped in functions (e.g. the drive get-or-apply, the passive-drive check, the dataclass-field dict, material paths).
• After merging the latest develop (including [Core] Make tests backend-agnostic and start them with launch_test_simulation (3/3) #8102), the tests above were rerun and pass. isaaclab_physx/test/sim/test_spawn_meshes.py was run with the tetrahedralization extra, which covers _tetrahedralize_surface; it passes on this branch and on develop.
• ruff check and ruff format are clean.

Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added a changelog fragment under source/<package>/changelog.d/ for each changed package (see Changelog)
• If this is a user-visible change, the fragment clearly describes it

Release backport

• Backport this pull request to the active release branch after it merges into develop

[greptile-apps]

Confidence Score: 4/5

[Medium risk] Refactors spawner and schema utilities for cleaner code.

The PR appears safe to merge, with a non-blocking change to joint-drive no-target error handling worth correcting.

Findings

1.  No-target calls can raise ▶

Summary

This PR consolidates repeated schema-writing and spawner logic, simplifies prim creation and material-path handling, and extracts deformable-mesh and drive helpers.

• One joint-drive dispatch change makes a no-target call resolve fragment functions before it can return.

_{Reviews (1) · Last reviewed commit: "Share schema-writer and spawner helpers ..."}

[greptile-apps]

No-target calls can raise If a joint-drive fragment names a function in an unavailable module, this line raises before checking whether any joints match. Previously, a call with no matching joints returned False with a warning. This can turn an otherwise harmless asset spawn into an exception; resolve the functions only when there are targets.

Suggested change

	dispatchers = [_resolve_func(cfg) for cfg in fragments]
	# match revolute/prismatic joints not excluded by a backend-registered skip predicate;
	# non-joint matches (creation_candidates) are ignored silently since a subtree expression
	# matches every descendant
	# non-joint matches are ignored silently since a subtree expression matches every descendant
	targets, _, any_skipped = _match_fragment_targets(
	prim_path_expr,
	lambda p: (p.IsA(UsdPhysics.RevoluteJoint) or p.IsA(UsdPhysics.PrismaticJoint)) and not _skip_joint_drive(p),
	stage,
	prim_path_expr, lambda p: _drive_instance_name(p) is not None and not _skip_joint_drive(p), stage
	)
	# non-joint matches are ignored silently since a subtree expression matches every descendant
	targets, _, any_skipped = _match_fragment_targets(
	prim_path_expr, lambda p: _drive_instance_name(p) is not None and not _skip_joint_drive(p), stage
	)
	dispatchers = [_resolve_func(cfg) for cfg in fragments] if targets else []

[isaaclab-review-bot]

Isaac Lab Review Bot

Reviewed the sim-authoring deduplication across schema fragment dispatch, joint-drive authoring, mesh conversion, material-path resolution, and spawner creation paths. The patch consistently preserves the existing anchors, ordering, unit conversions, and legacy-writer routing shown in the changed code.

• Design and architecture: The shared _apply_api_fragments, apply_schema_props, drive-writing, mesh-approximation, and tetrahedralization helpers consolidate duplicated behavior without introducing a new public abstraction or changing backend ownership. Reusing _drive_instance_name and to_camel_case within the schema package is consistent with the existing utility layer.
• API: Public signatures and defaults remain intact. The fragment writers retain target matching, create_if_missing, warning, and result-aggregation behavior; joint-drive paths retain angular unit conversion and drive_type mapping. The internal geometry helpers now return their created prims, and their changed callers consume those returns consistently.
• Implementation: The changed producer and consumer paths for schema slots and material paths were traced across shape, mesh, file, and converter spawners. The proposed concern about omitting an explicit to_camel_case convention does not demonstrate a changed attribute name or concrete failure under the utility's current deterministic default, so it does not warrant pre-merge action.

No blocking issues. No inline issue met the actionable-evidence threshold; the assessment above records the review feedback.

Automated review; human maintainers own approval decisions.

[ooctipus]

I will inline this the resolve here makes no sense

[ooctipus]

i will also inline this there is only 2 caller, and one of the caller is going to be deprecated , it doesn't worth to refactor out

[StafaH]

run-ci

[StafaH]

run-ci

[StafaH]

run-ci

[isaaclab-bot]

Backported to release/3.0.0 as b8c1a6b.