I am making the physics engine for a personal project, and one of the more important parts is that the collisions are detected and respond as accurately as possible. right now I'm in the preliminary phases of designing this, so I'm sticking to basic shapes, axis aligned boxes, axis aligned cylinders, and spheres. The problem I'm coming across is I have found how to deal with a single point collision, and two point collision, if an edge of something collides with a surface. But the one case I have not been able to at all figure out how to deal with, is if two surfaces completely collide with each other. IE if two boxes hit each other head on, the two faces will both smack right into each other. Anyone know how to resolve these kinds of collisions? Should I just compute a point that is at the center of the colliding faces and treat it as a single point collision? Ideally I would like this to include angular motion as well, but at this point in time I am only dealing with linear motion. Thanks in advance guys!