59 lines
1.9 KiB
HLSL
59 lines
1.9 KiB
HLSL
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// Copyright Epic Games, Inc. All Rights Reserved.
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half3 LinearTo709Branchless(half3 lin)
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{
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lin = max(6.10352e-5, lin); // minimum positive non-denormal (fixes black problem on DX11 AMD and NV)
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return min(lin * 4.5, pow(max(lin, 0.018), 0.45) * 1.099 - 0.099);
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}
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half3 LinearToSrgbBranchless(half3 lin)
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{
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lin = max(6.10352e-5, lin); // minimum positive non-denormal (fixes black problem on DX11 AMD and NV)
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return min(lin * 12.92, pow(max(lin, 0.00313067), 1.0/2.4) * 1.055 - 0.055);
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// Possible that mobile GPUs might have native pow() function?
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//return min(lin * 12.92, exp2(log2(max(lin, 0.00313067)) * (1.0/2.4) + log2(1.055)) - 0.055);
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}
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half LinearToSrgbBranchingChannel(half lin)
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{
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if(lin < 0.00313067) return lin * 12.92;
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return pow(lin, (1.0/2.4)) * 1.055 - 0.055;
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}
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half3 LinearToSrgbBranching(half3 lin)
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{
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return half3(
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LinearToSrgbBranchingChannel(lin.r),
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LinearToSrgbBranchingChannel(lin.g),
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LinearToSrgbBranchingChannel(lin.b));
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}
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half3 sRGBToLinear( half3 Color )
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{
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Color = max(6.10352e-5, Color); // minimum positive non-denormal (fixes black problem on DX11 AMD and NV)
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return Color > 0.04045 ? pow( Color * (1.0 / 1.055) + 0.0521327, 2.4 ) : Color * (1.0 / 12.92);
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}
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/**
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* @param GammaCurveRatio The curve ratio compared to a 2.2 standard gamma, e.g. 2.2 / DisplayGamma. So normally the value is 1.
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*/
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half3 ApplyGammaCorrection(float3 LinearColor, float GammaCurveRatio)
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{
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// Apply "gamma" curve adjustment.
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float3 CorrectedColor = pow(LinearColor, GammaCurveRatio);
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#if MAC
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// Note, MacOSX native output is raw gamma 2.2 not sRGB!
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CorrectedColor = pow(CorrectedColor, 1.0/2.2);
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#else
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#if USE_709
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// Didn't profile yet if the branching version would be faster (different linear segment).
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CorrectedColor = LinearTo709Branchless(CorrectedColor);
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#else
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CorrectedColor = LinearToSrgbBranching(CorrectedColor);
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#endif
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#endif
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return CorrectedColor;
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}
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