first calculate approach velocity of the points on each object that collide:
uia = via + wia x ria
uib = vib + wib x rib
approach velocity = u = uia - uib
normal velocity component = u•n*n
tangential velocity component = u-(u•n*n)
Then in addition to calculating the impulse Jnorm to stop or reverse the normal approach velocity we also need to calculate the impulse Jtang to stop the tangential approach velocity
Then calculate the total impulse J which is made up from all of Jnorm + some of Jtang depending on the friction coefficient or collision parameter in the paper.
If we want to include sliding or continuous contact then we replace Jtang the
tangential impulse with a continuous tangential force. I think this makes things a lot more complicated as we need to know the contours of both objects along the sliding faces so there is not a formula that we can use if we have complex shapes.
