"""Read delivered USD authoring without inferring simulation or real-world accuracy.""" from concurrent.futures import ThreadPoolExecutor import argparse import hashlib import json import math from pathlib import Path import sys import numpy as np from pxr import Usd, UsdGeom, UsdPhysics def inspect(path): stage = Usd.Stage.Open(str(path)) if not stage: raise ValueError('USD did not open: ' + str(path)) meters = UsdGeom.GetStageMetersPerUnit(stage) kg = UsdPhysics.GetStageKilogramsPerUnit(stage) axis = str(UsdGeom.GetStageUpAxis(stage)) xforms = UsdGeom.XformCache() lows, highs, bodies, joints, colliders = [], [], [], [], [] body_points = {} bad = [] visual_count = 0 for prim in stage.Traverse(): prim_path = str(prim.GetPath()) if prim.HasAPI(UsdPhysics.RigidBodyAPI): mass_api = UsdPhysics.MassAPI(prim) mass = mass_api.GetMassAttr().Get() inertia = mass_api.GetDiagonalInertiaAttr().Get() bodies.append({'path': prim_path, 'name': prim.GetName(), 'mass_kg': None if mass is None else float(mass) * kg, 'mass_authored': bool(mass_api.GetMassAttr().HasAuthoredValueOpinion()), 'enabled': bool(UsdPhysics.RigidBodyAPI(prim).GetRigidBodyEnabledAttr().Get()), 'kinematic': bool(UsdPhysics.RigidBodyAPI(prim).GetKinematicEnabledAttr().Get()), 'inertia_kg_m2': [float(v) * kg * meters ** 2 for v in inertia] if inertia is not None else None}) if prim.IsA(UsdPhysics.Joint): joint = UsdPhysics.Joint(prim) record = {'id': prim.GetName(), 'source_prim_path': prim_path, 'joint_type': prim.GetTypeName(), 'body0': [str(v) for v in joint.GetBody0Rel().GetTargets()], 'body1': [str(v) for v in joint.GetBody1Rel().GetTargets()], 'joint_enabled': bool(joint.GetJointEnabledAttr().Get())} for name in ('axis', 'lowerLimit', 'upperLimit', 'localPos0', 'localPos1', 'localRot0', 'localRot1'): attr = prim.GetAttribute('physics:' + name) value = attr.Get() if attr else None if value is not None: if isinstance(value, (int, float, str, bool)): record[name] = value elif hasattr(value, 'GetReal'): record[name] = [float(value.GetReal()), *map(float, value.GetImaginary())] else: record[name] = list(map(float, value)) dynamic_sides = 0 static_frames = [] for side in ('body0', 'body1'): if len(record[side]) > 1: bad.append('multiple joint body targets: ' + prim_path) for target in record[side]: body = stage.GetPrimAtPath(target) if not body: bad.append('joint target does not exist: ' + target) continue target_prim = body while body and not body.HasAPI(UsdPhysics.RigidBodyAPI): body = body.GetParent() if body and body.HasAPI(UsdPhysics.RigidBodyAPI): dynamic_sides += 1 elif target_prim.IsA(UsdGeom.Xformable): static_frames.append(target) else: bad.append('joint target is not a transformable frame: ' + target) if not dynamic_sides: bad.append('joint has no rigid body: ' + prim_path) record['static_frames'] = static_frames if record.get('lowerLimit', -float('inf')) > record.get('upperLimit', float('inf')): bad.append('reversed joint limits: ' + prim_path) joints.append(record) collision = prim.HasAPI(UsdPhysics.CollisionAPI) if collision: colliders.append({'path': prim_path, 'enabled': bool(UsdPhysics.CollisionAPI(prim).GetCollisionEnabledAttr().Get()), 'approximation': str(UsdPhysics.MeshCollisionAPI(prim).GetApproximationAttr().Get()) if prim.HasAPI(UsdPhysics.MeshCollisionAPI) else None}) if prim.IsA(UsdGeom.Mesh): mesh = UsdGeom.Mesh(prim) points = np.asarray(mesh.GetPointsAttr().Get(), dtype=np.float64) if points.size == 0 or not np.isfinite(points).all(): bad.append('empty or nonfinite mesh: ' + prim_path) continue imageable = UsdGeom.Imageable(prim) purpose = imageable.ComputePurpose() visible = imageable.ComputeVisibility() != UsdGeom.Tokens.invisible # Authored colliders may also be visible meshes; include these if # they belong to the default/render purpose and are visible. if visible and purpose in (UsdGeom.Tokens.default_, UsdGeom.Tokens.render): transformed = np.column_stack((points, np.ones(len(points)))) @ np.asarray(xforms.GetLocalToWorldTransform(prim)) world = transformed[:, :3] * meters lows.append(world.min(axis=0)); highs.append(world.max(axis=0)); visual_count += 1 body = prim while body and not body.HasAPI(UsdPhysics.RigidBodyAPI): body = body.GetParent() if body: body_points.setdefault(str(body.GetPath()), []).append((world.min(axis=0), world.max(axis=0))) if not lows: bad.append('no visible mesh bounds') bounds = None else: low = np.min(lows, axis=0); high = np.max(highs, axis=0) bounds = {'min': low.tolist(), 'max': high.tolist(), 'size': (high - low).tolist(), 'units': 'm'} for body in bodies: points = body_points.get(body['path']) if points: low = np.min([p[0] for p in points], axis=0); high = np.max([p[1] for p in points], axis=0) body['bounds'] = {'min': low.tolist(), 'max': high.tolist(), 'size': (high - low).tolist(), 'units': 'm'} if body['mass_kg'] is None or body['mass_kg'] <= 0 or not np.isfinite(body['mass_kg']): bad.append('missing/nonpositive authored body mass: ' + body['path']) return {'usd_sha256': hashlib.sha256(path.read_bytes()).hexdigest(), 'up_axis': axis, 'axis_authored': stage.HasAuthoredMetadata('upAxis'), 'meters_per_unit': meters, 'length_units_authored': UsdGeom.StageHasAuthoredMetersPerUnit(stage), 'kilograms_per_unit': kg, 'mass_units_authored': UsdPhysics.StageHasAuthoredKilogramsPerUnit(stage), 'bounds': bounds, 'visual_meshes': visual_count, 'bodies': bodies, 'joints': joints, 'colliders': colliders, 'total_mass_kg': sum(b['mass_kg'] or 0 for b in bodies), 'moving_joints': sum(j['joint_enabled'] and j['joint_type'] != 'PhysicsFixedJoint' for j in joints), 'errors': bad} if __name__ == '__main__': parser = argparse.ArgumentParser() parser.add_argument('usd', type=Path) args = parser.parse_args() def standard_json(value): if isinstance(value, dict): return {k: standard_json(v) for k, v in value.items()} if isinstance(value, list): return [standard_json(v) for v in value] if isinstance(value, float) and not math.isfinite(value): return 'Infinity' if value > 0 else '-Infinity' if value < 0 else 'NaN' return value print(json.dumps(standard_json(inspect(args.usd)), indent=2, allow_nan=False))