private void AddBullet()
{
//clear out all the bulelts
_moverManager.Clear();
//add a new bullet in the center of the screen
mover = (Mover)_moverManager.CreateTopBullet();
mover.pos = new Vector2(graphics.PreferredBackBufferWidth / 2f, graphics.PreferredBackBufferHeight / 2f);
mover.InitTopNode(_myPatterns[_CurrentPattern].RootNode);
}