Simple collision response between two equally massive objects (Assumed to be spherical)

gistfile1.cs

        internal static void bounce(Shape shape1, Shape shape2)
        {
            Vector2 displacement = shape1._position - shape2._position;
            Vector2 closingspeed = shape1._velocity - shape2._velocity;
            
            //check if they are already moving apart
            if(Vector2.Dot(displacement,closingspeed)>=0){
                return;// if moving apart, do nothing

            }
            displacement.Normalize();

            Vector2 bounce;
            
            //reverse the velocity vector in the direction of displacement
            bounce= Vector2.Dot(shape1._velocity, displacement) * displacement;

            shape1._velocity -= 2 * bounce;

            bounce = Vector2.Dot(shape2._velocity, displacement) * displacement;

            shape2._velocity -= 2 * bounce;


        }