Merge pull request #133 from Dogway/patch-1

Update white_point.slang

misc/white_point.slang

@@ -1,8 +1,13 @@
 #version 450
 
-// white point adjustment
-// by hunterk
-// based on blog post by Tanner Helland
+// 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
@@ -18,7 +23,7 @@ layout(push_constant) uniform Push
    float wp_blue;
 } params;
 
-#pragma parameter temperature "White Point" 6500.0 0.0 12000.0 100.0
+#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
@@ -45,51 +50,109 @@ layout(location = 0) in vec2 vTexCoord;
 layout(location = 0) out vec4 FragColor;
 layout(set = 0, binding = 2) uniform sampler2D Source;
 
-// white point adjustment
-// based on blog post by Tanner Helland
-// http://www.tannerhelland.com/4435/convert-temperature-rgb-algorithm-code/
+
+
 vec3 wp_adjust(vec3 color){
-   const float target_white_point = 9300.0;
-   const mat3 RGBtoYIQ = mat3(
-      0.2989, 0.5870, 0.1140,
-      0.5959, -0.2744, -0.3216,
-      0.2115, -0.5229, 0.3114);
 
-   const mat3 YIQtoRGB = mat3(
-      1.0, 0.956, 0.6210,
-      1.0, -0.2720, -0.6474,
-      1.0, -1.1060, 1.7046);
+    float temp = params.temperature / 100.;
+    float k = params.temperature / 10000.;
+    float lk = log(k);
 
-   float temp = params.temperature / 100.0;
-   
-   // all calculations assume a scale of 255. We'll normalize this at the end
-   vec3 wp = vec3(255.);
+    vec3 wp = vec3(1.);
 
     // calculate RED
-   wp.r = (temp <= 66.) ? 255. : 329.698727446 * pow((temp - 60.), -0.1332047592);
+    wp.r = (temp <= 65.) ? 1. : 0.32068362618584273 + (0.19668730877673762 * pow(k - 0.21298613432655075, - 1.5139012907556737)) + (- 0.013883432789258415 * lk);
 
     // calculate GREEN
-   wp.g = (temp <= 66.) ? 99.4708025861 * log(temp) - 161.1195681661 : 288.1221695283 * pow((temp - 60.), -0.0755148492);
+    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 >= 66.) ? 255. : (temp <= 19.) ? 0. : 138.5177312231 * log(temp - 10.) - 305.0447927307;
+    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 and normalize
-   wp.rgb = clamp(wp.rgb, vec3(0.), vec3(255.)) / vec3(255.);
+    // clamp
+    wp.rgb = clamp(wp.rgb, vec3(0.), vec3(1.));
 
-   // this is dumb, but various cores don't always show white as white. Use this to make white white...
+    // R/G/B independent manual White Point adjustment
     wp.rgb += vec3(params.wp_red, params.wp_green, params.wp_blue);
 
-   // apply transformation
-   vec3 adjusted = (color * wp);
-   vec3 base_luma = color * RGBtoYIQ;
-   vec3 adjusted_luma = adjusted * RGBtoYIQ;
-   adjusted = (params.luma_preserve > 0.5) ? adjusted_luma + (vec3(base_luma.r,0.,0.) - vec3(adjusted_luma.r,0.,0.)) : adjusted_luma;
-   
-   return adjusted * YIQtoRGB;
+    // 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()
 {
-   FragColor = vec4(wp_adjust(texture(Source, vTexCoord).rgb), 1.0);
+   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);
 }