public void update(GameContainer container, StateBasedGame game, int delta) {
float mouseX = container.getInput().getMouseX();
float mouseY = container.getInput().getMouseY();
float xDistance = mouseX - position.x;
float yDistance = mouseY - position.y;
double angle = Math.toDegrees(Math.atan2(yDistance, xDistance));
gun.setRotation((float) angle);
}