Applies packed colliders (see packMPMColliders) to velocity v at local point x, in place: inside a
collider, the velocity relative to it gets the Coulomb projection against the surface normal; with push, x also
moves out to the surface. Grid nodes use it without push, particles with it after advecting (as on the GPU).
Applies packed colliders (see packMPMColliders) to velocity
vat local pointx, in place: inside a collider, the velocity relative to it gets the Coulomb projection against the surface normal; withpush,xalso moves out to the surface. Grid nodes use it withoutpush, particles with it after advecting (as on the GPU).