   need help form someone who has implemented contact
  Assume I have two rigid bodies (for simplicity two identical boxes) with zero initial velocities in  resting contact. Body B cant be moved. Body A rests on the body B but is overbalanced and gravity should make it rotate and slide down. I have implemented a little frictionless contact algorithm following Baraff 1989/1994 papers but I am not sure as to how should my simulation proceed after the initial step. I have managed to get a sort of visualy feasible solution by getting first two steps to be contact steps and then doing impulse collision response. However this doesnt seem right.I have two major conceptual problems here.1. The alogorithm calculates forces to get non negative normal accelerations at the contact points. How is that of any use since the next frame will have different contact points with most likely negatvie normal velocities? Shouldnt the algorithm calucalate forces to get non negative normal acceleration at the next contact points? Getting proper velocity at the next contact points should get also feasible velocities at the current but it doesnt seem to be true the other way.2. The algorithm (at least mine implementation) applies forces caluculated at the beggining of the frame as if they were valid during the whole frame. No matter what model I try  this seems to produce rubbish even at the very first frame since the rotational acceleration should (?) be corrected by some kind of acceleration that is slighlty off the contact normal but obviously no such can be produced. I am not sure how to correct that.   