collider-non-uniform-scale#

Code

RB.COL.004

Validator

latest+

Compatibility

openusd

Tags

✅

Summary#

The collision shape scale must be uniform for the following geometries: Sphere, Capsule, Cylinder, Cone & Points.

Description#

Simulation does not support scale, hence simple geometries that are algorithmically defined like Sphere, Capsule, Cylinder, Cone must have their world transform matrix scale uniform in order to have a proper shape representation of the geometry in the simulation engine.

Why is it required?#

  • Assets with non-uniform world scale on the above UsdGeomGPrims won’t have correct collision behavior in simulation runtime.

Examples#

# Invalid: Non-Uniform scale on a Sphere
def Sphere "Sphere" (
   prepend apiSchemas = ["PhysicsCollisionAPI"]
) {
   float3 xformOp:scale = (1, 2, 3)
   uniform token[] xformOpOrder = ["xformOp:scale"]   
}

# Valid: Uniform scale on a Sphere
def Sphere "Sphere" (
   prepend apiSchemas = ["PhysicsCollisionAPI"]
) {
   float3 xformOp:scale = (2, 2, 2)
   uniform token[] xformOpOrder = ["xformOp:scale"]   
}

How to comply#

UsdPhysicsCollisionAPI can only be applied to a UsdGeomGPrim with non-uniform world scale for these types - Mesh & Cube. Other than these exceptions, the scale (world scale) must be uniform.

For More Information#