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refactor(color): clarify gamma conversion functions #1996

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Merged
alandtse merged 1 commit into from
Mar 21, 2026
Merged

refactor(color): clarify gamma conversion functions #1996

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54 changes: 16 additions & 38 deletions package/Shaders/Common/Color.hlsli
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Original file line number Diff line number Diff line change
Expand Up @@ -85,32 +85,32 @@ namespace Color
return color;
}

float GammaToLinear(float color)
float SkyrimGammaToLinear(float color)
{
return pow(abs(color), 1.6);
}

float LinearToGamma(float color)
float LinearToSkyrimGamma(float color)
{
return pow(abs(color), 1.0 / 1.6);
}

float3 GammaToLinear(float3 color)
float3 SkyrimGammaToLinear(float3 color)
{
return pow(abs(color), 1.6);
}

float3 LinearToGamma(float3 color)
float3 LinearToSkyrimGamma(float3 color)
{
return pow(abs(color), 1.0 / 1.6);
}

float3 GammaToTrueLinear(float3 color)
float3 SrgbToLinear(float3 color)
{
return pow(abs(color), 2.2);
}

float3 TrueLinearToGamma(float3 color)
float3 LinearToSrgb(float3 color)
{
return pow(abs(color), 1.0 / 2.2);
}
Expand All @@ -124,43 +124,21 @@ namespace Color

const static float PBRLightingCompensation = ENABLE_LL ? 1.0 : Math::PI;

float3 GammaToLinearLuminancePreserving(float3 color)
{
if (!ENABLE_LL) {
return color;
}
float originalLuminance = max(RGBToLuminance(color), 1e-5);
float3 linearColorRaw = GammaToLinear(color / originalLuminance);
float scale = GammaToLinear(originalLuminance).x;
return linearColorRaw * scale;
}

float3 GammaToLinearLuminancePreservingLight(float3 color)
{
if (!ENABLE_LL) {
return color;
}
float originalLuminance = max(RGBToLuminance(color), 1e-5);
float3 linearColorRaw = pow(abs(color / originalLuminance), SharedData::linearLightingSettings.lightGamma);
float scale = originalLuminance;
return linearColorRaw * scale;
}

// Linear Lighting Functions
float3 LLGammaToLinear(float3 color)
{
return ENABLE_LL ? GammaToLinear(color) : color;
return ENABLE_LL ? SkyrimGammaToLinear(color) : color;
}

float3 LLLinearToGamma(float3 color)
{
return ENABLE_LL ? LinearToGamma(color) : color;
return ENABLE_LL ? LinearToSkyrimGamma(color) : color;
}

float3 Diffuse(float3 color)
{
# if defined(TRUE_PBR)
return ENABLE_LL ? color : TrueLinearToGamma(color);
return ENABLE_LL ? color : LinearToSrgb(color);
# else
return ENABLE_LL ? pow(abs(color), SharedData::linearLightingSettings.colorGamma) * SharedData::linearLightingSettings.vanillaDiffuseColorMult : color;
# endif
Expand Down Expand Up @@ -195,7 +173,7 @@ namespace Color
float3 Glowmap(float3 color)
{
# if defined(TRUE_PBR)
return ENABLE_LL ? color * SharedData::linearLightingSettings.glowmapMult : TrueLinearToGamma(color);
return ENABLE_LL ? color * SharedData::linearLightingSettings.glowmapMult : LinearToSrgb(color);
# else
return ENABLE_LL ? pow(abs(color), SharedData::linearLightingSettings.glowmapGamma) * SharedData::linearLightingSettings.glowmapMult : color;
# endif
Expand Down Expand Up @@ -271,27 +249,27 @@ namespace Color

float3 RadianceToLinear(float3 color)
{
return ENABLE_LL ? color : GammaToLinear(color);
return ENABLE_LL ? color : SkyrimGammaToLinear(color);
}

float IrradianceToLinear(float color)
{
return ENABLE_LL ? color : GammaToLinear(color);
return ENABLE_LL ? color : SkyrimGammaToLinear(color);
}

float IrradianceToGamma(float color)
{
return ENABLE_LL ? color : LinearToGamma(color);
return ENABLE_LL ? color : LinearToSkyrimGamma(color);
}

float3 IrradianceToLinear(float3 color)
{
return ENABLE_LL ? color : GammaToLinear(color);
return ENABLE_LL ? color : SkyrimGammaToLinear(color);
}

float3 IrradianceToGamma(float3 color)
{
return ENABLE_LL ? color : LinearToGamma(color);
return ENABLE_LL ? color : LinearToSkyrimGamma(color);
}

float VanillaNormalization()
Expand All @@ -311,7 +289,7 @@ namespace Color
float3 Diffuse(float3 color)
{
# if defined(TRUE_PBR)
return TrueLinearToGamma(color);
return LinearToSrgb(color);
# else
return color;
# endif
Expand Down
2 changes: 1 addition & 1 deletion package/Shaders/Effect.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -943,7 +943,7 @@ PS_OUTPUT main(PS_INPUT input)
# endif

if (!(Permutation::ExtraShaderDescriptor & Permutation::ExtraFlags::InWorld) && SharedData::linearLightingSettings.enableLinearLighting) {
psout.Diffuse.xyz = Color::TrueLinearToGamma(psout.Diffuse.xyz);
psout.Diffuse.xyz = Color::LinearToSrgb(psout.Diffuse.xyz);
}
return psout;
}
Expand Down
2 changes: 1 addition & 1 deletion package/Shaders/ISCompositeLensFlareVolumetricLighting.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ PS_OUTPUT main(PS_INPUT input)
# if defined(LENS_FLARE)
float3 lensFlareColor = LFSourceTex.Sample(LFSourceSampler, input.TexCoord).xyz;
if (SharedData::linearLightingSettings.enableLinearLighting) {
color += Color::GammaToLinear(lensFlareColor);
color += Color::SkyrimGammaToLinear(lensFlareColor);
} else {
color += lensFlareColor;
}
Expand Down
2 changes: 1 addition & 1 deletion package/Shaders/ISHDR.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ PS_OUTPUT main(PS_INPUT input)
# endif

if (SharedData::linearLightingSettings.enableLinearLighting && SharedData::linearLightingSettings.enableGammaCorrection) {
srgbColor = Color::TrueLinearToGamma(srgbColor);
srgbColor = Color::LinearToSrgb(srgbColor);
}
srgbColor = FrameBuffer::ToSRGBColor(srgbColor);

Expand Down
24 changes: 12 additions & 12 deletions package/Shaders/Lighting.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -1312,7 +1312,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# if defined(TRUE_PBR)
[branch] if ((PBRFlags & PBR::TerrainFlags::LandTile0PBR) == 0)
{
landColorRGB1 = Color::GammaToTrueLinear(landColorRGB1 / Color::PBRLightingScale);
landColorRGB1 = Color::SrgbToLinear(landColorRGB1 / Color::PBRLightingScale);
}
# endif
float landAlpha1 = landColor1.a;
Expand Down Expand Up @@ -1393,7 +1393,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# if defined(TRUE_PBR)
[branch] if ((PBRFlags & PBR::TerrainFlags::LandTile1PBR) == 0)
{
landColorRGB2 = Color::GammaToTrueLinear(landColorRGB2 / Color::PBRLightingScale);
landColorRGB2 = Color::SrgbToLinear(landColorRGB2 / Color::PBRLightingScale);
}
# endif
float landAlpha2 = landColor2.a;
Expand Down Expand Up @@ -1473,7 +1473,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# if defined(TRUE_PBR)
[branch] if ((PBRFlags & PBR::TerrainFlags::LandTile2PBR) == 0)
{
landColorRGB3 = Color::GammaToTrueLinear(landColorRGB3 / Color::PBRLightingScale);
landColorRGB3 = Color::SrgbToLinear(landColorRGB3 / Color::PBRLightingScale);
}
# endif
float landAlpha3 = landColor3.a;
Expand Down Expand Up @@ -1553,7 +1553,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# if defined(TRUE_PBR)
[branch] if ((PBRFlags & PBR::TerrainFlags::LandTile3PBR) == 0)
{
landColorRGB4 = Color::GammaToTrueLinear(landColorRGB4 / Color::PBRLightingScale);
landColorRGB4 = Color::SrgbToLinear(landColorRGB4 / Color::PBRLightingScale);
}
# endif
float landAlpha4 = landColor4.a;
Expand Down Expand Up @@ -1633,7 +1633,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# if defined(TRUE_PBR)
[branch] if ((PBRFlags & PBR::TerrainFlags::LandTile4PBR) == 0)
{
landColorRGB5 = Color::GammaToTrueLinear(landColorRGB5 / Color::PBRLightingScale);
landColorRGB5 = Color::SrgbToLinear(landColorRGB5 / Color::PBRLightingScale);
}
# endif
float landAlpha5 = landColor5.a;
Expand Down Expand Up @@ -1714,7 +1714,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# if defined(TRUE_PBR)
[branch] if ((PBRFlags & PBR::TerrainFlags::LandTile5PBR) == 0)
{
landColorRGB6 = Color::GammaToTrueLinear(landColorRGB6 / Color::PBRLightingScale);
landColorRGB6 = Color::SrgbToLinear(landColorRGB6 / Color::PBRLightingScale);
}
# endif
float landAlpha6 = landColor6.a;
Expand Down Expand Up @@ -1864,13 +1864,13 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
if (!SharedData::linearLightingSettings.enableLinearLighting) {
baseColor.xyz = GetFacegenBaseColor(baseColor.xyz, uv);
} else {
baseColor.xyz = Color::GammaToLinear(GetFacegenBaseColor(Color::LinearToGamma(baseColor.xyz), uv));
baseColor.xyz = Color::SkyrimGammaToLinear(GetFacegenBaseColor(Color::LinearToSkyrimGamma(baseColor.xyz), uv));
}
# elif defined(FACEGEN_RGB_TINT)
if (!SharedData::linearLightingSettings.enableLinearLighting) {
baseColor.xyz = GetFacegenRGBTintBaseColor(baseColor.xyz, uv);
} else {
baseColor.xyz = Color::GammaToLinear(GetFacegenRGBTintBaseColor(Color::LinearToGamma(baseColor.xyz), uv));
baseColor.xyz = Color::SkyrimGammaToLinear(GetFacegenRGBTintBaseColor(Color::LinearToSkyrimGamma(baseColor.xyz), uv));
}
# endif // FACEGEN

Expand Down Expand Up @@ -2100,7 +2100,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
material.AO = rawRMAOS.z;

if (!SharedData::linearLightingSettings.enableLinearLighting) {
material.F0 = lerp(rawRMAOS.w, Color::GammaToTrueLinear(baseColor.xyz), material.Metallic);
material.F0 = lerp(rawRMAOS.w, Color::SrgbToLinear(baseColor.xyz), material.Metallic);
} else {
material.F0 = lerp(rawRMAOS.w, baseColor.xyz, material.Metallic);
}
Expand Down Expand Up @@ -2252,7 +2252,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
float4 envColorBase = TexEnvSampler.SampleLevel(SampEnvSampler, float3(1.0, 0.0, 0.0), 15);

if (envColorBase.a < 1.0) {
material.F0 = Color::GammaToLinear(envColorBase.rgb);
material.F0 = Color::SkyrimGammaToLinear(envColorBase.rgb);
material.Roughness = envColorBase.a;
} else {
material.F0 = 1.0;
Expand All @@ -2276,7 +2276,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# endif

if (!dynamicCubemap) {
float3 envColorBase = Color::GammaToLinear(TexEnvSampler.Sample(SampEnvSampler, envSamplingPoint).xyz);
float3 envColorBase = Color::SkyrimGammaToLinear(TexEnvSampler.Sample(SampEnvSampler, envSamplingPoint).xyz);
envColor = envColorBase.xyz * envMask;
}
}
Expand Down Expand Up @@ -3190,7 +3190,7 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
# endif

if ((!inWorld && !inReflection) && SharedData::linearLightingSettings.enableLinearLighting && !(Permutation::PixelShaderDescriptor & Permutation::LightingFlags::DefShadow)) {
psout.Diffuse.xyz = Color::TrueLinearToGamma(psout.Diffuse.xyz);
psout.Diffuse.xyz = Color::LinearToSrgb(psout.Diffuse.xyz);
}

return psout;
Expand Down
8 changes: 4 additions & 4 deletions package/Shaders/Tests/TestColor.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -101,16 +101,16 @@
float3 original = testColors[i];

// Test Gamma -> Linear -> Gamma
float3 linearColor = Color::GammaToLinear(original);
float3 backToGamma = Color::LinearToGamma(linearColor);
float3 linearColor = Color::SkyrimGammaToLinear(original);
float3 backToGamma = Color::LinearToSkyrimGamma(linearColor);

ASSERT(IsTrue, abs(backToGamma.r - original.r) < 0.01f);
ASSERT(IsTrue, abs(backToGamma.g - original.g) < 0.01f);
ASSERT(IsTrue, abs(backToGamma.b - original.b) < 0.01f);

// Test TrueLinear roundtrip
float3 trueLinearColor = Color::GammaToTrueLinear(original);
float3 backToGamma2 = Color::TrueLinearToGamma(trueLinearColor);
float3 trueLinearColor = Color::SrgbToLinear(original);
float3 backToGamma2 = Color::LinearToSrgb(trueLinearColor);

ASSERT(IsTrue, abs(backToGamma2.r - original.r) < 0.01f);
ASSERT(IsTrue, abs(backToGamma2.g - original.g) < 0.01f);
Expand Down
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