protected override void Update(GameTime gameTime)
{
// Allows the default game to exit on Xbox 360 and Windows
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
core.Update(gameTime, Keyboard.GetState());
ball.Update(gameTime);
// TODO: Add your update logic here
base.Update(gameTime);
}