More complex ACES

assets/shaders/post_process.glsl

@@ -15,15 +15,63 @@ void main() {
 
 #if FRAGMENT_SHADER
 
+// Translated from https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl
+// sRGB => XYZ => D65_2_D60 => AP1 => RRT_SAT
+const mat3 ACESInputMat = mat3(
+  vec3(0.59719, 0.07600, 0.02840),
+  vec3(0.35458, 0.90834, 0.01566),
+  vec3(0.04823, 0.13383, 0.83777)
+);
+
+// ODT_SAT => XYZ => D60_2_D65 => sRGB
+const mat3 ACESOutputMat = mat3(
+  vec3( 1.60475, -0.10208, -0.00327),
+  vec3(-0.53108,  1.10813, -0.00605),
+  vec3(-0.07367, -0.07276,  1.07602)
+);
+
+vec3 RRTAndODTFit(vec3 v) {
+    vec3 a = v * (v + 0.0245786f) - 0.000090537f;
+    vec3 b = v * (0.983729f * v + 0.4329510f) + 0.238081f;
+    return a / b;
+}
+
+vec3 ACESFitted(vec3 color)
+{
+    color = ACESInputMat * color;
+
+    // Apply RRT and ODT
+    color = RRTAndODTFit(color);
+
+    color = ACESOutputMat * color;
+
+    // Clamp to [0, 1]
+    color = clamp(color, 0, 1);
+
+    return color;
+}
+
 layout(binding = 0) uniform sampler2D screen_sampler;
 
 out vec4 FragColor;
 
-void main() {
-  float gamma = 2.2;
-  vec4 hdr_color = texture(screen_sampler, VertexOut.uv);
+vec3 linearToSRGB(vec3 color) {
+  vec3 x = color * 12.92f;
+  vec3 y = 1.055f * pow(clamp(color, 0, 1), vec3(1.0f / 2.4f)) - 0.055f;
 
-  FragColor.rgb = pow(hdr_color.rgb, vec3(1.0/gamma));
+  vec3 clr = color;
+  clr.r = color.r < 0.0031308f ? x.r : y.r;
+  clr.g = color.g < 0.0031308f ? x.g : y.g;
+  clr.b = color.b < 0.0031308f ? x.b : y.b;
+
+  return clr;
+}
+
+void main() {
+  vec3 hdr_color = texture(screen_sampler, VertexOut.uv).rgb;
+  hdr_color = ACESFitted(hdr_color);
+
+  FragColor.rgb = linearToSRGB(hdr_color);
   FragColor.a = 1;
 }