// Called when the mouse wheel is rotated
  public void onMouseWheelMoved(MouseWheelEvent e) {
    // If the wheel rotation is negative it means that it is moved forward.
    // Set move direction = forward, if wheel is moved forward.
    // Otherwise, set move direction = backward
    moveDirection = (e.getWheelRotation() < 0) ? 1 : -1;

    // Set the amount to move = absolute wheel rotation amount * 5 (speed)
    // Here 5 means 5 pixels per wheel rotation step. The higher value, the
    // more speed
    moveAmount += Math.abs(e.getWheelRotation()) * 5;
  }