Collision Response

float GetCollisionTime(Vector p1, Vector p2, PhysicsObject obj1, PhysicsObject obj2){ // Points p1, p2 are the collision points on the two objects, // after collision Vector relativeVelocity = obj2.Velocity - obj1.Velocity; float distanceAfter = DotProduct(p2 - p1, relativeVelocity); // 'Unmove' the collision points to find distance before // NB A better 'point unmove' is required if you have angular motion float distanceBefore = DotProduct(  (p2 - obj2.Velocity) - (p1 - obj1.Velocity),  relativeVelocity);  // Time that happened before collision return (distanceBefore / (distanceBefore + distanceAfter)) * lastFrameLength;}void Move(PhysicsObject obj1, PhysicsObject obj2, float time){ obj1.Position += obj1.Velocity * time; obj2.Position += obj2.Velocity * time;}void DoCollision(PhysicsObject obj1, PhysicsObject obj2){ // Get the collision point (you already know this) Vector[] points = GetCollisionPoints(obj1, obj2); float unmoveTime = GetCollisionTime(obj1, obj2, points[0], points[1]); // Negative move = unmove :) Move(obj1, obj2, -unmoveTime);  // Not listed DoCollisionResponse(obj1, obj2);  // Move the new velocities for the remainder of the frame, but // test for new collisions afterwards Move(obj1, obj2, lastFrameLength-unmoveTime);}