oklab.glsl

oklab.glsl

float fixedpow(float a, float x)
{
    return pow(abs(a), x) * sign(a);
}

float cbrt(float a)
{
    return fixedpow(a, 0.3333333333);
}

vec3 lsrgb2oklab(vec3 c)
{
    float l = 0.4122214708 * c.r + 0.5363325363 * c.g + 0.0514459929 * c.b;
    float m = 0.2119034982 * c.r + 0.6806995451 * c.g + 0.1073969566 * c.b;
    float s = 0.0883024619 * c.r + 0.2817188376 * c.g + 0.6299787005 * c.b;

    float l_ = cbrt(l);
    float m_ = cbrt(m);
    float s_ = cbrt(s);

    return vec3(
        0.2104542553 * l_ + 0.7936177850 * m_ - 0.0040720468 * s_,
        1.9779984951 * l_ - 2.4285922050 * m_ + 0.4505937099 * s_,
        0.0259040371 * l_ + 0.7827717662 * m_ - 0.8086757660 * s_
    );
}

vec3 oklab2lsrgb(vec3 c)
{
    float l_ = c.r + 0.3963377774 * c.g + 0.2158037573 * c.b;
    float m_ = c.r - 0.1055613458 * c.g - 0.0638541728 * c.b;
    float s_ = c.r - 0.0894841775 * c.g - 1.2914855480 * c.b;

    float l = l_ * l_ * l_;
    float m = m_ * m_ * m_;
    float s = s_ * s_ * s_;

    return vec3(
        4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s,
        -1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s,
        -0.0041960863 * l - 0.7034186147 * m + 1.7076147010 * s
    );
}