Using PhysX 3.4 beta, I have found that modifying the target velocity for contact points yields different behaviour. Below is the behaviour with PhysX set to use the GPU processor:
Note that I am setting the target velocity to be orthogonal to both the contact position and the contact normal. The box is positioned at the origin. The behaviour shown above is what I would expect. However, when switching to use the CPU processor, the behaviour is different:
It’s as if all the contact points are receiving the same target velocity.