private static Animacion crearAnimacionPelota() {
        Animacion anim = new Animacion();
        for (int i = 0; i <= 20; i++) {
            anim.sumaCuadro (Toolkit.getDefaultToolkit ().getImage (Pelota.class.getResource ("Images/ball/basketball" + i + ".png")), 60);
        }
        return anim;
    }