(khronos pbr) natural tonemap

Author: malytomas

data/cage/shader/effects/tonemap.glsl

@@ -1,4 +1,3 @@
-
 $include vertex.glsl
 
 $define shader fragment
@@ -7,37 +6,38 @@ layout(binding = 0) uniform sampler2D texColor;
 
 layout(std140, binding = 2) uniform Tonemap
 {
-	vec4 tonemapFirst; // shoulderStrength, linearStrength, linearAngle, toeStrength
-	vec4 tonemapSecond; // toeNumerator, toeDenominator, white, tonemapEnabled
-	vec4 gammaParams; // gamma
+	vec4 params; // gamma, tonemapEnabled
 };
 
 out vec3 outColor;
 
-vec3 uncharted2Tonemap(vec3 x)
+// https://github.com/KhronosGroup/ToneMapping/blob/main/PBR_Neutral/pbrNeutral.glsl
+vec3 neutralToneMapping(vec3 color)
 {
-	float shoulderStrength = tonemapFirst[0];
-	float linearStrength = tonemapFirst[1];
-	float linearAngle = tonemapFirst[2];
-	float toeStrength = tonemapFirst[3];
-	float toeNumerator = tonemapSecond[0];
-	float toeDenominator = tonemapSecond[1];
-	return ((x * (shoulderStrength * x + linearAngle * linearStrength) + toeStrength * toeNumerator) / (x * (shoulderStrength * x + linearStrength) + toeStrength * toeDenominator)) - toeNumerator / toeDenominator;
+	const float startCompression = 0.8 - 0.04;
+	const float desaturation = 0.15;
+	float x = min(color.r, min(color.g, color.b));
+	float offset = x < 0.08 ? x - 6.25 * x * x : 0.04;
+	color -= offset;
+	float peak = max(color.r, max(color.g, color.b));
+	if (peak < startCompression) return color;
+	const float d = 1. - startCompression;
+	float newPeak = 1. - d * d / (peak + d - startCompression);
+	color *= newPeak / peak;
+	float g = 1. - 1. / (desaturation * (peak - newPeak) + 1.);
+	return mix(color, newPeak * vec3(1, 1, 1), g);
 }
 
 void main()
 {
 	vec3 color = texelFetch(texColor, ivec2(gl_FragCoord.xy), 0).xyz;
 
 	// tone mapping
-	if (tonemapSecond[3] > 0.5)
-	{
-		const float exposureBias = 2;
-		color = uncharted2Tonemap(color * exposureBias) / uncharted2Tonemap(vec3(tonemapSecond[2]));
-	}
+	if (params[1] > 0.5)
+		color = neutralToneMapping(color);
 
 	// gamma correction
-	color = pow(color, vec3(gammaParams[0]));
+	color = pow(color, vec3(params[0]));
 
 	outColor = color;
 }

sources/include/cage-engine/sceneScreenSpaceEffects.h

@@ -23,7 +23,6 @@ namespace cage
 		ScreenSpaceAmbientOcclusion ssao;
 		ScreenSpaceBloom bloom;
 		ScreenSpaceEyeAdaptation eyeAdaptation;
-		ScreenSpaceTonemap tonemap;
 		ScreenSpaceDepthOfField depthOfField;
 		Real gamma = 2.2;
 		ScreenSpaceEffectsFlags effects = ScreenSpaceEffectsFlags::Default;

sources/include/cage-engine/screenSpaceEffects.h

@@ -48,7 +48,7 @@ namespace cage
 		TextureHandle outColor;
 	};
 
-	struct CAGE_ENGINE_API ScreenSpaceTonemapConfig : public ScreenSpaceCommonConfig, public ScreenSpaceTonemap
+	struct CAGE_ENGINE_API ScreenSpaceTonemapConfig : public ScreenSpaceCommonConfig
 	{
 		TextureHandle inColor;
 		TextureHandle outColor;

sources/include/cage-engine/screenSpaceEffectsProperties.h

@@ -45,17 +45,6 @@ namespace cage
 		uint32 blurPasses = 5;
 		Real threshold = 1;
 	};
-
-	struct CAGE_ENGINE_API ScreenSpaceTonemap
-	{
-		Real shoulderStrength = 0.15;
-		Real linearStrength = 0.5;
-		Real linearAngle = 0.1;
-		Real toeStrength = 0.2;
-		Real toeNumerator = 0.02;
-		Real toeDenominator = 0.3;
-		Real white = 11.2;
-	};
 }
 
 #endif // guard_screenSpaceEffectsProperties_h_0156sdrf4treth1

sources/libengine/graphics/renderPipeline.cpp

@@ -1186,11 +1186,10 @@ namespace cage
 					{
 						ScreenSpaceTonemapConfig cfg;
 						(ScreenSpaceCommonConfig &)cfg = commonConfig;
-						(ScreenSpaceTonemap &)cfg = data.effects.tonemap;
 						cfg.inColor = texSource;
 						cfg.outColor = texTarget;
-						cfg.tonemapEnabled = any(data.effects.effects & ScreenSpaceEffectsFlags::ToneMapping);
 						cfg.gamma = any(data.effects.effects & ScreenSpaceEffectsFlags::GammaCorrection) ? data.effects.gamma : 1;
+						cfg.tonemapEnabled = any(data.effects.effects & ScreenSpaceEffectsFlags::ToneMapping);
 						screenSpaceTonemap(cfg);
 						std::swap(texSource, texTarget);
 					}

sources/libengine/graphics/screenSpaceEffects.cpp

@@ -340,13 +340,10 @@ namespace cage
 
 		struct Shader
 		{
-			ScreenSpaceTonemap tonemap; // 7 reals
-			Real tonemapEnabled;
-			Vec4 gamma;
+			Vec4 params; // gamma, tonemapEnabled
 		} s;
-		s.tonemap = config;
-		s.tonemapEnabled = config.tonemapEnabled;
-		s.gamma = Vec4(1.0 / config.gamma, 0, 0, 0);
+		s.params[0] = 1.0 / config.gamma;
+		s.params[1] = config.tonemapEnabled;
 		q->universalUniformStruct(s, 2);
 
 		q->colorTexture(fb, 0, config.outColor);