function update() {
            ctx.strokeStyle = ctx.fillStyle = '#fff';
            UpdatePhysics(loop.physicsStep);
            Collide(bodyA, bodyB, BodiesCollided);

            // Run this after all collision request
            // have been done.
            UpdateCollisions();

            if (bodyA.position.y < 0) {
                bodyA.position.x = canvas.width / 2;
                bodyA.position.y = canvas.height;
                bodyA.velocity.x = 0;
                bodyA.velocity.y = 0;
            }
            if (bodyB.position.y > 512) {
                bodyB.position.x = canvas.width / 2;
                bodyB.position.y = -bodyB.collider.height;
                bodyB.velocity.x = 0;
                bodyB.velocity.y = 0;
            }
        }
 function update() {
     UpdatePhysics(loop.physicsStep);
 }