Real-Time Physics Simulation Forum

I'm reading Bridson's paper <Robust Treatment of Collisions, Contact and Friction for Cloth Animation>. I have question about the collision response order.

Jacobi iterative approach (parallel rather than sequential) ...a Gauss-Seidel iterative approach

, (These are in chapter 4

Limiting the Strain and Strain Rate

), I don't quite understand this. In my view, for example, there are two collision pair which are interacted. A Jacobi approach will update the two pair using their old state in parallel. A Gauss-Seidel approach will upate first pair , then update the second pair with first pair's newest state. Am i correct? In Gauss-Seidel approach which pair should I update first? Thank you very much!!!

No, you are only computing the collision response (an impulse) once, based on the current states of both objects. Once you have the impulse, you apply it positively to one object and negatively to the other, and the order is irrelevant.