slang-shaders/misc/white_point.slang

#version 450

// White Point Mapping
//          ported by Dogway
//
// From the first comment post (sRGB primaries and linear light compensated)
//      http://www.zombieprototypes.com/?p=210#comment-4695029660
// Based on the Neil Bartlett's blog update
//      http://www.zombieprototypes.com/?p=210
// Inspired itself by Tanner Helland's work
//      http://www.tannerhelland.com/4435/convert-temperature-rgb-algorithm-code/

layout(push_constant) uniform Push
{
    vec4 SourceSize;
    vec4 OriginalSize;
    vec4 OutputSize;
    uint FrameCount;
   float temperature;
   float luma_preserve;
   float wp_red;
   float wp_green;
   float wp_blue;
} params;

#pragma parameter temperature "White Point" 9311.0 1031.0 12047.0 72.0
#pragma parameter luma_preserve "Preserve Luminance" 1.0 0.0 1.0 1.0
#pragma parameter wp_red "Red Shift" 0.0 -1.0 1.0 0.01
#pragma parameter wp_green "Green Shift" 0.0 -1.0 1.0 0.01
#pragma parameter wp_blue "Blue Shift" 0.0 -1.0 1.0 0.01

layout(std140, set = 0, binding = 0) uniform UBO
{
    mat4 MVP;
} global;

#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;

void main()
{
   gl_Position = global.MVP * Position;
   vTexCoord = TexCoord;
}

#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;



vec3 wp_adjust(vec3 color){

    float temp = params.temperature / 100.;
    float k = params.temperature / 10000.;
    float lk = log(k);

    vec3 wp = vec3(1.);

    // calculate RED
    wp.r = (temp <= 65.) ? 1. : 0.32068362618584273 + (0.19668730877673762 * pow(k - 0.21298613432655075, - 1.5139012907556737)) + (- 0.013883432789258415 * lk);

    // calculate GREEN
    float mg = 1.226916242502167 + (- 1.3109482654223614 * pow(k - 0.44267061967913873, 3.) * exp(- 5.089297600846147 * (k - 0.44267061967913873))) + (0.6453936305542096 * lk);
    float pg = 0.4860175851734596 + (0.1802139719519286 * pow(k - 0.14573069517701578, - 1.397716496795082)) + (- 0.00803698899233844 * lk);
    wp.g = (temp <= 65.5) ? ((temp <= 8.) ? 0. : mg) : pg;

    // calculate BLUE
    wp.b = (temp <= 19.) ? 0. : (temp >= 66.) ? 1. : 1.677499032830161 + (- 0.02313594016938082 * pow(k - 1.1367244820333684, 3.) * exp(- 4.221279555918655 * (k - 1.1367244820333684))) + (1.6550275798913296 * lk);

    // clamp
    wp.rgb = clamp(wp.rgb, vec3(0.), vec3(1.));

    // R/G/B independent manual White Point adjustment
    wp.rgb += vec3(params.wp_red, params.wp_green, params.wp_blue);

    // Linear color input
    return color * wp;
}

vec3 sRGB_to_XYZ(vec3 RGB){

    const mat3x3 m = mat3x3(
    0.4124564,  0.3575761,  0.1804375,
    0.2126729,  0.7151522,  0.0721750,
    0.0193339,  0.1191920,  0.9503041);
    return RGB * m;
}


vec3 XYZtoYxy(vec3 XYZ){

    float XYZrgb = XYZ.r+XYZ.g+XYZ.b;
    float Yxyr = XYZ.g;
    float Yxyg = (XYZrgb <= 0.0) ? 0.3805 : XYZ.r / XYZrgb;
    float Yxyb = (XYZrgb <= 0.0) ? 0.3769 : XYZ.g / XYZrgb;
    return vec3(Yxyr,Yxyg,Yxyb);
}

vec3 XYZ_to_sRGB(vec3 XYZ){

    const mat3x3 m = mat3x3(
    3.2404542, -1.5371385, -0.4985314,
   -0.9692660,  1.8760108,  0.0415560,
    0.0556434, -0.2040259,  1.0572252);
    return XYZ * m;
}


vec3 YxytoXYZ(vec3 Yxy){

    float Xs = Yxy.r * (Yxy.g/Yxy.b);
    float Xsz = (Yxy.r <= 0.0) ? 0 : 1;
    vec3 XYZ = vec3(Xsz,Xsz,Xsz) * vec3(Xs, Yxy.r, (Xs/Yxy.g)-Xs-Yxy.r);
    return XYZ;
}


vec3 linear_to_sRGB(vec3 color, float gamma){

    color = clamp(color, 0.0, 1.0);
    color.r = (color.r <= 0.00313066844250063) ?
    color.r * 12.92 : 1.055 * pow(color.r, 1.0 / gamma) - 0.055;
    color.g = (color.g <= 0.00313066844250063) ?
    color.g * 12.92 : 1.055 * pow(color.g, 1.0 / gamma) - 0.055;
    color.b = (color.b <= 0.00313066844250063) ?
    color.b * 12.92 : 1.055 * pow(color.b, 1.0 / gamma) - 0.055;

    return color.rgb;
}


vec3 sRGB_to_linear(vec3 color, float gamma){

    color = clamp(color, 0.0, 1.0);
    color.r = (color.r <= 0.04045) ?
    color.r / 12.92 : pow((color.r + 0.055) / (1.055), gamma);
    color.g = (color.g <= 0.04045) ?
    color.g / 12.92 : pow((color.g + 0.055) / (1.055), gamma);
    color.b = (color.b <= 0.04045) ?
    color.b / 12.92 : pow((color.b + 0.055) / (1.055), gamma);

    return color.rgb;
}


void main()
{
   vec3 original = sRGB_to_linear(texture(Source, vTexCoord).rgb, 2.40);
   vec3 adjusted = wp_adjust(original);
   vec3 base_luma = XYZtoYxy(sRGB_to_XYZ(original));
   vec3 adjusted_luma = XYZtoYxy(sRGB_to_XYZ(adjusted));
   adjusted = (params.luma_preserve == 1.0) ? adjusted_luma + (vec3(base_luma.r,0.,0.) - vec3(adjusted_luma.r,0.,0.)) : adjusted_luma;
   FragColor = vec4(linear_to_sRGB(XYZ_to_sRGB(YxytoXYZ(adjusted)), 2.40), 1.0);
}