Blending Algorithm

/* Blending Algorithm */

function blend(a, b, mode = 0) {
    // 0 = Normal, 1 = Dissolve, 2 = Multiply,3 = Screen
    switch (mode) {
    case 0:
        return b;
        break;
    case 1:
        return (~~(Math.random() * 2) == 0) ? a : b;
        break;
    case 2:
        return a * b;
        break;
    case 3:
        return 1 - (1 - a) * (1 - b);
        break;
    }
}