# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved. # SPDX-License-Identifier: Apache-2.0 import numpy as np import omni from pxr import Usd, UsdGeom, UsdPhysics import robolab.core.utils.usd_utils as usd_utils def find_physics_material_in_children(parent_prim, stage: Usd.Stage) -> Usd.Prim: """Recursively search for physics material bound to mesh prims.""" for child_prim in parent_prim.GetAllChildren(): # Check if this child is a mesh if child_prim.IsA(UsdGeom.Mesh): # Check for physics material using relationship names relationship_names = [ "material:binding:physics", # USD Material binding for physics purpose "material:binding", # General material binding "physxMaterial:physicsMaterial", # NVIDIA Omniverse (PhysX) "physics:material:binding" # USD Physics Schema ] for rel_name in relationship_names: if child_prim.HasRelationship(rel_name): rel = child_prim.GetRelationship(rel_name) targets = rel.GetTargets() if targets: material_prim_path = targets[0].pathString potential_material = stage.GetPrimAtPath(material_prim_path) # Check if this material has physics properties if potential_material.IsValid() and potential_material.HasAPI(UsdPhysics.MaterialAPI): print(f"Physics material found via '{rel_name}': {potential_material.GetPath()}") return potential_material else: print(f"Material found via '{rel_name}' but no physics API: {material_prim_path}") print(f"No physics material bound to mesh: {child_prim.GetPath()}") # Recursively search in child's children result = find_physics_material_in_children(child_prim, stage) if result: return result return None def get_friction(prim: Usd.Prim, stage: Usd.Stage) -> dict: # Traverse all child prims to find meshes with bound physics materials material_prim = None material_prim = find_physics_material_in_children(prim, stage) if not material_prim: print(f"No physics material found at {prim.GetPath()}") return None material_api = UsdPhysics.MaterialAPI(material_prim) result = {'prim_path': material_prim.GetPath().pathString} static_attr = material_api.GetStaticFrictionAttr() if static_attr: result['static_friction'] = static_attr.Get() dynamic_attr = material_api.GetDynamicFrictionAttr() if dynamic_attr: result['dynamic_friction'] = dynamic_attr.Get() restitution_attr = material_api.GetRestitutionAttr() if restitution_attr: result['restitution'] = restitution_attr.Get() density_attr = material_api.GetDensityAttr() if density_attr: result['density'] = density_attr.Get() return result def update_friction(prim: Usd.Prim, stage: Usd.Stage, static_friction: float, dynamic_friction: float, restitution: float) -> None: material_prim = find_physics_material_in_children(prim, stage) if not material_prim: print(f"No physics material found at {prim.GetPath()}") return material_api = UsdPhysics.MaterialAPI(material_prim) if static_friction: old_static_friction = material_api.GetStaticFrictionAttr().Get() print(f"Updating static friction from {old_static_friction} to {static_friction}") material_api.GetStaticFrictionAttr().Set(static_friction) if dynamic_friction: old_dynamic_friction = material_api.GetDynamicFrictionAttr().Get() print(f"Updating dynamic friction from {old_dynamic_friction} to {dynamic_friction}") material_api.GetDynamicFrictionAttr().Set(dynamic_friction) if restitution: old_restitution = material_api.GetRestitutionAttr().Get() print(f"Updating restitution from {old_restitution} to {restitution}") material_api.GetRestitutionAttr().Set(restitution) def add_friction(static_friction: float=5.0, dynamic_friction: float=5.0, restitution: float=0.25, root_prim_path: str=None, ) -> dict: """ 0.8 is rubber like restitution is the amount of "bounce". 1.0 means that it always return to the original bounce position. PhysX default is 0.25. We will set to 0. Friction combination is by default 'average' (between the two physics_materials interacting with each other). This is not exposed here to be modified. """ from omni.physx.scripts.physicsUtils import add_physics_material_to_prim from pxr import Usd, UsdGeom stage = omni.usd.get_context().get_stage() root_prim, root_prim_path = usd_utils.get_root_prim_path(root_prim_path) data_dict = {} from isaacsim.core.api.materials.physics_material import PhysicsMaterial material = PhysicsMaterial( prim_path=root_prim_path + "/physics_material", name=f"physics_material", static_friction=static_friction, dynamic_friction=dynamic_friction, restitution=restitution,) for prim in Usd.PrimRange(root_prim): if prim.IsA(UsdGeom.Mesh): print(f"\tStatic friction: {static_friction} Dynamic friction: {dynamic_friction} Restitution: {restitution}") add_physics_material_to_prim(stage, prim, material.prim_path) data_dict[root_prim_path] = {'static': static_friction, 'dynamic':dynamic_friction, 'restitution': restitution, 'physics_material': material.prim_path} return data_dict def add_mass_api(mass: float, root_prim_path: str=None) -> dict: from pxr import Usd, UsdGeom, UsdPhysics root_prim, root_prim_path = usd_utils.get_root_prim_path(root_prim_path) if mass <= 0: raise ValueError(f"Cannot set mass to <= 0: {mass}") data_dict = {} # Total mass is applied to the root Xform only. if root_prim.IsA(UsdGeom.Xform): print(f"\tAdd mass: {mass} to root prim: {root_prim}") massAPI = UsdPhysics.MassAPI.Apply(root_prim) massAPI.CreateMassAttr(mass) data_dict[root_prim_path] = mass # Automatically compute mass for the rest of the meshes. for prim in Usd.PrimRange(root_prim): if prim.IsA(UsdGeom.Mesh): massAPI = UsdPhysics.MassAPI.Apply(prim) data_dict[root_prim_path] = "auto" return data_dict def get_rigid_body_collider(prim: Usd.Prim, stage: Usd.Stage) -> dict: from pxr import UsdGeom, UsdPhysics result = {} rigid_body_api = UsdPhysics.RigidBodyAPI(prim) if rigid_body_api: kin_attr = rigid_body_api.GetKinematicEnabledAttr() kin = kin_attr.Get() if kin_attr else None result['kinematic'] = kin # Traverse all prims in the stage starting at this path for subprim in Usd.PrimRange(prim): print(f"Processing prim: {subprim.GetPath()}") # Only process shapes and meshes if ( subprim.IsA(UsdGeom.Cylinder) or subprim.IsA(UsdGeom.Capsule) or subprim.IsA(UsdGeom.Cone) or subprim.IsA(UsdGeom.Sphere) or subprim.IsA(UsdGeom.Cube) or subprim.IsA(UsdGeom.Mesh) ): # Check standard USD Physics collider collision_api = UsdPhysics.CollisionAPI(subprim) if collision_api: enabled_attr = collision_api.GetCollisionEnabledAttr() enabled = enabled_attr.Get() if enabled_attr else None print(f" UsdPhysics Collider found. Enabled: {enabled}") result['usd_collision_enabled'] = enabled # Check PhysX collider (if running in Isaac/Omniverse) try: from pxr import PhysxSchema physx_collision_api = PhysxSchema.PhysxCollisionAPI(subprim) if physx_collision_api: approx_attr = physx_collision_api.GetApproximationAttr() approx = approx_attr.Get() if approx_attr else None print(f" PhysxSchema Collider found. Approximation: {approx}") result['physx_approximation'] = approx except ImportError: pass # PhysxSchema not available if not result: print(f"No rigid body collider (or collision API) found at {prim.GetPath()}") return None return result def update_rigid_body_collider( prim: Usd.Prim, contact_offset: float = 0.02, rest_offset: float = 0.01, enable_ccd: bool = True, kinematic: bool = False ) -> None: from pxr import Usd, UsdGeom, UsdPhysics # Check base prim for RigidBodyAPI rigid_body_api = UsdPhysics.RigidBodyAPI(prim) if rigid_body_api: kin_attr = rigid_body_api.GetKinematicEnabledAttr() kin = kin_attr.Get() if kin_attr else None print(f"Base prim {prim.GetPath()} has RigidBodyAPI (kinematic: {kin})") if kin != kinematic: print(f"Updating kinematic from {kin} to {kinematic}") rigid_body_api.GetKinematicEnabledAttr().Set(kinematic) else: print(f"Base prim {prim.GetPath()} has no RigidBodyAPI.") rigid_body_collider_params = {'approximation': 'convexDecomposition', 'kinematic': False, 'attributes': { 'physxConvexDecompositionCollision:maxConvexHulls': 256, 'physxConvexDecompositionCollision:shrinkWrap': 1, 'physxConvexDecompositionCollision:errorPercentage': 1, }, } attributes_dict = rigid_body_collider_params.get('attributes') approximation = rigid_body_collider_params.get('approximation') # Recursively traverse all children/shapes/meshes from omni.physx.scripts import utils for child_prim in Usd.PrimRange(prim): if ( child_prim.IsA(UsdGeom.Cylinder) or child_prim.IsA(UsdGeom.Capsule) or child_prim.IsA(UsdGeom.Cone) or child_prim.IsA(UsdGeom.Sphere) or child_prim.IsA(UsdGeom.Cube) or child_prim.IsA(UsdGeom.Mesh) ): print(f"Processing child prim: {child_prim.GetPath()}") # Remove UsdPhysics.CollisionAPI if UsdPhysics.CollisionAPI(child_prim): print(f" Removing UsdPhysics.CollisionAPI from {child_prim.GetPath()}") UsdPhysics.CollisionAPI(child_prim).GetPrim().RemoveAPI(UsdPhysics.CollisionAPI) # Remove PhysxSchema.PhysxCollisionAPI if present try: from pxr import PhysxSchema if PhysxSchema.PhysxCollisionAPI(child_prim): print(f" Removing PhysxSchema.PhysxCollisionAPI from {child_prim.GetPath()}") PhysxSchema.PhysxCollisionAPI(child_prim).GetPrim().RemoveAPI(PhysxSchema.PhysxCollisionAPI) except ImportError: pass # Apply new PhysxSchema Collider add_rigid_body_collider(child_prim, approximation=approximation, kinematic=kinematic, attributes=attributes_dict, contact_offset=contact_offset, rest_offset=rest_offset, enable_ccd=enable_ccd) print("Collider update complete.") def add_rigid_body_collider(prim: Usd.Prim, approximation: str = "convexDecomposition", kinematic: bool = False, attributes: dict= { 'physxConvexDecompositionCollision:maxConvexHulls': 256, 'physxConvexDecompositionCollision:shrinkWrap': 1, 'physxConvexDecompositionCollision:errorPercentage': 1, }, contact_offset: float = 0.02, rest_offset: float = 0.01, enable_ccd: bool=True,): from omni.physx.scripts import utils from pxr import PhysxSchema, Usd, UsdGeom # Add RigidBodyAPI to base prim if prim.IsA(UsdGeom.Xform): utils.setPhysics(prim, kinematic=kinematic) physx_rigid_body = PhysxSchema.PhysxRigidBodyAPI.Apply(prim) physx_rigid_body.CreateEnableCCDAttr().Set(enable_ccd) # Enable CCD - dynamically increases the contact offset based on the object's velocity print(f"\tAdding rigidBodyAPI to: {prim.GetPath()}") print(f"\tEnable CCD '{enable_ccd}' to: {prim.GetPath()}") else: print(f"\t[WARNING] {prim.GetPath()} is NOT a Xform ({prim.GetPrimTypeInfo().GetTypeName()}). Not adding rigid body physics.") # Traverse all prims in the stage starting at this path for prim in Usd.PrimRange(prim): # only process shapes and meshes if ( prim.IsA(UsdGeom.Cylinder) or prim.IsA(UsdGeom.Capsule) or prim.IsA(UsdGeom.Cone) or prim.IsA(UsdGeom.Sphere) or prim.IsA(UsdGeom.Cube) ): # use a ConvexHull for regular prims utils.setCollider(prim, approximationShape="convexHull") elif prim.IsA(UsdGeom.Mesh): # "None" will use the base triangle mesh if available # Can also use "convexDecomposition", "convexHull", "boundingSphere", "boundingCube" print(f"\tAdding collider '{approximation}' to: {prim.GetPath()}") utils.setCollider(prim, approximationShape=approximation) if attributes is not None: for attribute, value in attributes.items(): prim.GetAttribute(attribute).Set(value) collision_api = PhysxSchema.PhysxCollisionAPI.Apply(prim) if contact_offset: collision_api.GetContactOffsetAttr().Set(contact_offset) if rest_offset: collision_api.GetRestOffsetAttr().Set(rest_offset) if approximation == "sdf": # set sdf resolution to 256 meshCollision = PhysxSchema.PhysxSDFMeshCollisionAPI.Apply(prim) meshCollision.CreateSdfResolutionAttr().Set(256) # Increase the contact offset physxCollisionApi = PhysxSchema.PhysxCollisionAPI.Apply(prim) physxCollisionApi.CreateContactOffsetAttr().Set(0.25) # Increase the contact offset for better collision detection, especially for fast moving objects rigidBodyApi = PhysxSchema.PhysxRigidBodyAPI.Apply(prim) rigidBodyApi.CreateSolverPositionIterationCountAttr().Set(30) # Increase position iterations for better solver convergence rigidBodyApi.CreateMaxDepenetrationVelocityAttr().Set(100) # Reduce depenetration velocity to avoid violent collision responses rigidBodyApi.CreateEnableSpeculativeCCDAttr().Set(True) # Enable speculative CCD - dynamically increases the contact offset based on the object's velocity rigidBodyApi.CreateEnableCCDAttr().Set(enable_ccd) # Enable CCD - dynamically increases the contact offset based on the object's velocity # for attribute, value in attributes_dict.items(): # prim.GetAttribute(attribute).Set(value) else: continue return def create_str_attribute_to_prim(prim, attribute_name: str): """Creates attribute for a prim that holds a string. See: https://openusd.org/release/api/class_usd_prim.html See: https://docs.omniverse.nvidia.com/kit/docs/omni.usd/latest/omni.usd.commands/omni.usd.commands.CreateUsdAttributeCommand.html Args: prim (Usd.Prim): A Prim for holding the attribute. attribute_name (str): The name of the attribute to create. Returns: Usd.Attribute: An attribute created at specific prim. """ from pxr import Sdf, Usd omni.kit.commands.execute( "CreateUsdAttributeCommand", prim=prim, attr_name=attribute_name, attr_type=Sdf.ValueTypeNames.String, ) attr: Usd.Attribute = prim.GetAttribute(attribute_name) return attr def set_str_attribute_to_prim(prim, name: str, value: str): attribute = create_str_attribute_to_prim(prim, attribute_name=name) attribute.Set(value) def add_attributes_to_prim(attribute_dict: dict, root_prim_path: str=None) -> dict: """ Add attribute to the meshes attached to this partiular prim """ data_dict = {} from pxr import UsdGeom root_prim, root_prim_path = usd_utils.get_root_prim_path(root_prim_path) print(f"Adding attributes to {root_prim_path}") # Add attribute to only the root prim if root_prim.IsA(UsdGeom.Xform): for name, value in attribute_dict.items(): set_str_attribute_to_prim(root_prim, name, value) print(f"\tAttribute '{name}': '{value}'") data_dict[root_prim_path] = attribute_dict # Traverse all prims in the stage starting at this path # for prim in Usd.PrimRange(root_prim): # if prim.IsA(UsdGeom.Mesh): # for name, value in attribute_dict.items(): # set_str_attribute_to_prim(prim, name, value) # print(f"Set {prim} {name} to: {value}") return data_dict def add_semantics_to_prim(semantic_labels: dict, root_prim_path=None) -> dict: from omni.isaac.core.utils.semantics import add_update_semantics, get_semantics from pxr import Sdf, UsdGeom data_dict={} root_prim, root_prim_path = usd_utils.get_root_prim_path(root_prim_path) # Apply semantic label to the root of the xform. if root_prim.IsA(UsdGeom.Xform): i = 0 for type, label in semantic_labels.items(): add_update_semantics(root_prim, semantic_label=label, type_label=type, suffix=f"{i}") i += 1 semantics = get_semantics(root_prim) print(f"Added semantics to {root_prim}, semantics: {semantics}") data_dict[root_prim_path] = semantic_labels # for prim in Usd.PrimRange(root_prim): # if prim.IsA(UsdGeom.Mesh): # for type, label in semantic_labels.items(): # add_update_semantics(prim, semantic_label=label, type_label=type) # semantics = get_semantics(prim) # print(f"Added semantics to {prim}, semantics: {semantics}") return data_dict def transform_mesh_prim(position_offset=None, scale: float | np.ndarray | list=None, root_prim_path: str=None) -> dict: from omni.physx.scripts import physicsUtils from pxr import Gf, Usd, UsdGeom data_dict = {} if position_offset is None and scale is None: return data_dict root_prim, root_prim_path = usd_utils.get_root_prim_path(root_prim_path) if root_prim.IsA(UsdGeom.Xform): xform = UsdGeom.Xformable(root_prim) if scale is not None: if isinstance(scale, float): scale = [scale, scale, scale] elif isinstance(scale, np.ndarray): scale = scale.tolist() elif isinstance(scale, list): pass physicsUtils.set_or_add_scale_op(xform, scale=scale) if position_offset is not None: physicsUtils.set_or_add_translate_op(xform, [-position_offset[0],-position_offset[1],-position_offset[2]]) root_prim.GetAttribute('xformOp:translate').Set(-position_offset[0],-position_offset[1],-position_offset[2]) data_dict[root_prim_path] = { 'translate':position_offset} # for prim in Usd.PrimRange(root_prim): # # Only process mesh # if prim.IsA(UsdGeom.Mesh): # xform = UsdGeom.Xformable(prim) # if scale is not None: # scaleOp = xform.AddScaleOp() # scaleOp.Set(Gf.Vec3d(scale,scale,scale)) # # if position_offset is not None: # # print(f"\tTranslation: '{position_offset}'") # # translateOp = xform.AddTranslateOp() # # translateOp.Set(Gf.Vec3d(-position_offset[0],-position_offset[1],-position_offset[2])) # data_dict[root_prim_path] = {'scale': scale, # } return data_dict