Hey all, not sure if this is the right place to post this, I apologise if it is not. I've created a basic Billiards simulation but there's a type of friction I lack with regards to ball rotation. Using an orthonormal basis to give an orientation: the surface of the Billiards table is aligned with the X-Z plane and the Y axis is perpendicular to the table's surface. My problem is that I don't know how to modelise friction for a ball's rotational velocity component around the Y axis. I understand the ball will be sitting in a sort of cup in the felt and its friction in this cup will slow it down, but I'm not sure how best to represent this friction and what sort of coefficients I'm dealing with. Any help with shedding some light on this would be greatly appreciated, thanks.