Bouncing. The object bounce when reach the screen borders.

Boucing

void bounce(){
  if ( (location.x > width) || (location.x < 0) ) {
    velocity.x = velocity.x * -1;
  }
  if ( (location.y > height) || (location.y < 0) ) {
    velocity.y = velocity.y * -1;
  }
}