Xform

A transform-only prim. It carries no geometry, so it can be a rigid body or an articulation root but never a collider; colliders live on Gprim children whose world transform composes through it. Plain Xforms with no physics API still get rows when they are ancestors of physics prims.

• Type chain: Xformable

• Applicable APIs: MaterialBindingAPI, PhysicsArticulationRootAPI, PhysicsFilteredPairsAPI, PhysicsMassAPI, PhysicsRigidBodyAPI, PhysxArticulationAPI, PhysxContactReportAPI, PhysxRigidBodyAPI, PhysxSplinesSurfaceVelocityAPI, PhysxSurfaceVelocityAPI

• Transform columns: yes, Xformable

• Uses blocks: prim

What USD population writes

Published when it applies a physics API, or as an ancestor of any physics prim. In the ancestor case it carries only usd-prim-type, usd-schemas if any, omni:xform and omni:resetXformStack. No Xform-specific attributes exist; xformOp:* and xformOpOrder are never published, they are folded into omni:xform.

Interactions

• PhysicsCollisionAPI: Not applicable: the collision API needs a Gprim. Applying it to an Xform enumerates the prim as a collider whose shape is then skipped.

• PhysicsRigidBodyAPI: A rigid body on an Xform gathers colliders from descendant Gprims; each child shape’s local pose is the child’s transform relative to this prim.

• prim: Every ancestor Xform in the chain above a physics prim must have a row with omni:xform, or the consumer’s world-transform composition stops short.