rigid-body-no-instancing-f1#

Code	RB.005
Validator	latest+
Compatibility	openusd
Tags	✅

Summary#

Rigid bodies cannot be part of a scene graph instance.

Description#

Since UsdPhysicsRigidBodyAPI has to be able to modify the xformOp attributes in simulation, it cannot be part of a scene graph instance (because instanceable prims prohibit changes to their internal prims).

Note

The root prim of a rigid body hierarchy can be instanced.

Why is it required?#

Assets with UsdPhysicsRigidBodyAPI define rigid bodies for the simulator. Prims with this API will have their xformOp attributes updated after each simulation step hence they can’t be part of a scene graph instance that prohibits changes.

Examples#

# Invalid: Rigid body part of a scene graph instance
def Xform "Xform"
{
   def Cube "cube" (
      prepend apiSchemas = ["PhysicsRigidBodyAPI", "PhysicsCollisionAPI"]
   ) {
   }
}

def Xform "Xform_01" (
   instanceable = true
   references = </World/Xform>
)
{
}

# Valid: Rigid body applied to the scene graph instance, while collision (does not change) is applied to geometry in the scene graph instance
def Xform "Xform"
{
   def Cube "cube" (
      prepend apiSchemas = ["PhysicsCollisionAPI"]
   ) {
   }
}

def Xform "Xform_01" (
   instanceable = true
   references = </World/Xform>
   prepend apiSchemas = ["PhysicsRigidBodyAPI"]
)
{
}

How to comply#

The UsdPhysicsRigidBodyAPI schema cannot be part of a scene graph instance.

For More Information#