Add color fade

ShaderSrc/DrawQuadPaletteP.hlsl

@@ -1,5 +1,6 @@
 #include "DrawQuad.h"
 #include "DrawQuadPixelConstants.h"
+#include "Functions.h"
 
 SamplerState nearestNeighborSampler : register(s0);
 Texture2D<uint> surfaceTexture : register(t0);
@@ -20,7 +21,10 @@ SDrawQuadPixelOutput PSMain(SDrawQuadPixelInput input)
 {
 	SDrawQuadPixelOutput result;
 	int2 pixelCoordinate = int2(floor(input.texCoord.xy));
-	result.color = ApplyFlicker(pixelCoordinate, float4(SamplePixel(int2(floor(input.texCoord.xy))), 1.0) * constants_Modulation);
+	result.color = float4(SamplePixel(int2(floor(input.texCoord.xy))), 1.0);
+	result.color *= constants_Modulation;
+	result.color = ApplyFlicker(pixelCoordinate, constants_FlickerStartThreshold, constants_FlickerEndThreshold, result.color * constants_Modulation);
+	result.color = ApplyDesaturation(constants_Desaturation, result.color);
 	
 	if (result.color.a <= 0.0)
 		discard;

ShaderSrc/DrawQuadPixelConstants.h

@@ -5,15 +5,7 @@ cbuffer SDrawQuadPixelConstants : register(b0)
 	int2 constants_FlickerAxis;
 	int constants_FlickerStartThreshold;
 	int constants_FlickerEndThreshold;
+	
+	float constants_Desaturation;
+	float3 constants_Unused;
 };
-
-float4 ApplyFlicker(int2 coordinate, float4 color)
-{
-	int flickerTotal = dot(constants_FlickerAxis, coordinate);
-	if (flickerTotal < constants_FlickerStartThreshold)
-		return float4(0, 0, 0, 0);
-	else if (flickerTotal >= constants_FlickerEndThreshold)
-		return color;
-	else
-		return float4(1, 1, 1, 1);
-}

ShaderSrc/Functions.h

@@ -0,0 +1,59 @@
+float SRGBToLinear(float v)
+{
+	if (v <= 0.04045)
+		return v * (1.0 / 12.92);
+	else
+		return pow(((v + 0.055) * (1.0 / 1.055)), 2.4);
+}
+
+float2 SRGBToLinear(float2 v)
+{
+	return float2(SRGBToLinear(v.x), SRGBToLinear(v.y));
+}
+
+float3 SRGBToLinear(float3 v)
+{
+	return float3(SRGBToLinear(v.x), SRGBToLinear(v.y), SRGBToLinear(v.z));
+}
+
+float LinearToSRGB(float v)
+{
+	if (v <= 0.0031308)
+		return 12.92 * v;
+	else
+		return 1.055 * pow(v, 1.0 / 2.4) - 0.055;
+}
+
+float2 LinearToSRGB(float2 v)
+{
+	return float2(LinearToSRGB(v.x), LinearToSRGB(v.y));
+}
+
+float3 LinearToSRGB(float3 v)
+{
+	return float3(LinearToSRGB(v.x), LinearToSRGB(v.y), LinearToSRGB(v.z));
+}
+
+float4 ApplyFlicker(int2 coordinate, int startThreshold, int endThreshold, float4 color)
+{
+	int flickerTotal = dot(constants_FlickerAxis, coordinate);
+	if (flickerTotal < startThreshold)
+		return float4(0, 0, 0, 0);
+	else if (flickerTotal >= endThreshold)
+		return color;
+
+	return float4(1, 1, 1, 1);
+}
+
+float4 ApplyDesaturation(float desaturation, float4 color)
+{
+	if (desaturation == 0.0)
+		return color;
+	
+	float3 srgbColor = LinearToSRGB(color.rgb);
+	float grayLevel = dot(srgbColor, float3(3.0, 6.0, 1.0) / 10.0);
+
+	srgbColor = srgbColor * (1.0 - desaturation) + float3(grayLevel, grayLevel, grayLevel) * desaturation;
+	
+	return float4(SRGBToLinear(srgbColor), color.a);
+}