private Point fisica(float dt, float x, float y, int diametro) {
		x += vx;
		y += vy;
		if (vx < 0 && x <= 0 || vx > 0 && x + diametro >= getWidth())
			vx = -vx;
		if (vy < 0 && y < 0 || vy > 0 && y + diametro >= getHeight())
			vy = -vy;
		return new Point(Math.round(x), Math.round(y));
	}