} else {
        k = y > y3 ? 1 : y2 === y3 ? 0 : (y2 - y) / (y2 - y3);
        xa = x2 - (x2 - x3) * k;
        car = c2r - (c2r - c3r) * k;
        cag = c2g - (c2g - c3g) * k;