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Fix Legacy SSS profile having incorrect roughness.

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[FYI] sebastien.hillaire

[CL 35419325 by charles derousiers in ue5-main branch]
This commit is contained in:
charles derousiers
2024-08-09 08:30:56 -04:00
parent 279a0f6d3a
commit 8384249022
4 changed files with 44 additions and 4 deletions
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16
Engine/Shaders/Private/PostProcessGBufferHints.usf
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@@ -120,6 +120,8 @@ void MainPS(noperspective float4 UVAndScreenPos : TEXCOORD0, float4 SvPosition :
#include "ShaderPrint.ush"
#include "SceneTextureParameters.ush"
#include "DeferredShadingCommon.ush"
#include "ShadingModels.ush"
#include "SubsurfaceProfileCommon.ush"
void PrintShadingMode(inout FShaderPrintContext Ctx, uint In)
{
@@ -225,7 +227,19 @@ void MainCS(uint3 DispatchThreadId : SV_DispatchThreadID)
}
else if (Data.ShadingModelID == SHADINGMODELID_SUBSURFACE_PROFILE)
{
Print(Ctx, TEXT("SSS Profil ID : "), FontWhite); Print(Ctx, ExtractSubsurfaceProfileInt(Data.CustomData.x)); Newline(Ctx, RectMax);
const uint SSSProfileID = ExtractSubsurfaceProfileInt(Data.CustomData.x);
const half Opacity = Data.CustomData.a;
float LobeMix = 0;
float Lobe0Roughness = 0;
float Lobe1Roughness = 0;
GetProfileDualSpecular(SSSProfileID, Data.Roughness, Opacity, Lobe0Roughness, Lobe1Roughness, LobeMix);
Print(Ctx, TEXT("SSS Profil ID : "), FontWhite); Print(Ctx, SSSProfileID); Newline(Ctx, RectMax);
Print(Ctx, TEXT("SSS Lobe Mix : "), FontWhite); Print(Ctx, LobeMix); Newline(Ctx, RectMax);
Print(Ctx, TEXT("SSS Roughness0 : "), FontWhite); Print(Ctx, Lobe0Roughness); Newline(Ctx, RectMax);
Print(Ctx, TEXT("SSS Roughness1 : "), FontWhite); Print(Ctx, Lobe1Roughness); Newline(Ctx, RectMax);
Print(Ctx, TEXT("SSS SpecColor : "), FontWhite); Print(Ctx, Data.SpecularColor); Newline(Ctx, RectMax);
}
PrintBackgroundRect(Ctx, RectMin, RectMax);
Newline(Ctx);

12
Engine/Shaders/Private/Substrate/Substrate.ush
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@@ -4175,15 +4175,23 @@ FSubstrateBSDF UnpackSubstrateBSDFIn(FSubstrateMaterialContainer SubstrateBuffer
const uint PackedDiffuse20Bits = Data1 & 0x000FFFFF;
const uint PackedF020Bits = Data2 & 0x000FFFFF;
const float Roughness = UnpackR8(Data0 >> 24);
float Roughness = UnpackR8(Data0 >> 24);
const float SSSProfileRadiusScale = UnpackR8(Data1 >> 24);
const float SSSProfileId = UnpackR8(Data2 >> 24);
FHaziness Haziness = InitialiseHaziness();
// Average roughness for dual specular.
// When storing data as SINGLE_OPTLEGACYMODE_SSSPROFILE, the dual roughness is not translated/stored as haziness in order to save storage space.
// Thus we need to (re)compute them directly from the SSS profile data.
const uint SubsurfaceProfileUInt = SubstrateSubsurfaceProfileIdTo8bits(SSSProfileId);
GetSubsurfaceProfileDualSpecular(SubsurfaceProfileUInt, Roughness, SSSProfileRadiusScale, Roughness, Haziness.Roughness, Haziness.Weight);
SLAB_DIFFUSEALBEDO(OutBSDF) = UnpackR7G7B6Gamma2(PackedDiffuse20Bits);
SLAB_F0(OutBSDF) = UnpackR7G7B6Gamma2(PackedF020Bits);
SLAB_ROUGHNESS(OutBSDF) = Roughness;
SLAB_SSSPROFILEID(OutBSDF) = SSSProfileId;
SLAB_SSSPROFILERADIUSSCALE(OutBSDF) = SSSProfileRadiusScale;
SLAB_HAZINESS(OutBSDF) = PackHaziness(Haziness);
// When loading Substrate BSDF which have SSS enable, BaseColor and (optionally) Specular value can be overriden
// based on the SSS method used (screen space SSS / checherboarded screen space SSS / ...)
@@ -4209,7 +4217,7 @@ FSubstrateBSDF UnpackSubstrateBSDFIn(FSubstrateMaterialContainer SubstrateBuffer
BSDF_SETISTOPLAYER(OutBSDF, 1);
BSDF_SETSSSTYPE(OutBSDF, SSS_TYPE_DIFFUSION_PROFILE);
BSDF_SETHASMFP(OutBSDF, 1);
BSDF_SETHASHAZINESS(OutBSDF, 0);
BSDF_SETHASHAZINESS(OutBSDF, 1);
BSDF_SETISTHIN(OutBSDF, 0);
BSDF_SETHASFUZZ(OutBSDF, 0);
BSDF_SETHASTRANSABOVE(OutBSDF, 0);

9
Engine/Shaders/Private/Substrate/SubstrateExport.ush
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@@ -629,8 +629,15 @@ void PackSubstrateOut(
const uint PackedDiffuse20Bits = PackR7G7B6Gamma2( SLAB_DIFFUSEALBEDO(BSDF) , Dither);
const uint PackedF020Bits = PackR7G7B6Gamma2( SLAB_F0(BSDF) , Dither);
// When creating a slab with GetSubstrateSlabBSDF(), the SSS profile's dual roughness is expanded into haziness.
// But when storing data with SINGLE_OPTLEGACYMODE_SSSPROFILE we need to store the original roughness.
// The dual roughnesses will be recomputed based on the SSS profile data at load time. To retrieve the
// original roughness, we need to invert the computation done into GetSubstrateSlabBSDF()
const uint SubsurfaceProfileUInt = SubstrateSubsurfaceProfileIdTo8bits(SLAB_SSSPROFILEID(BSDF));
const float OriginalRoughness = GetSubsurfaceProfileOriginalRoughness(SubsurfaceProfileUInt, SLAB_ROUGHNESS(BSDF), SLAB_SSSPROFILERADIUSSCALE(BSDF));
// MRT0
SUBSTRATE_STORE_UINT1(Out | (PackR8(SLAB_ROUGHNESS(BSDF)) << 24));
SUBSTRATE_STORE_UINT1(Out | (PackR8(OriginalRoughness) << 24));
// MRT1 20 PackedDiffuse and Profile radius scale
SUBSTRATE_STORE_UINT1(PackedDiffuse20Bits | (PackR8(SLAB_SSSPROFILERADIUSSCALE(BSDF)) << 24));
// MRT2 24 PackedF0 and Profile ID

11
Engine/Shaders/Private/SubsurfaceProfileCommon.ush
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@@ -79,6 +79,17 @@ half4 GetSubsurfaceProfileTexture(Texture2D InSSProfilesTexture, SamplerState In
#endif
}
float GetSubsurfaceProfileOriginalRoughness(uint SubsurfaceProfileInt, half ModifiedLobeRoughness0, half Opacity)
{
const half4 Data = GetSubsurfaceProfileTexture(SSSS_DUAL_SPECULAR_OFFSET, SubsurfaceProfileInt);
// Smooth blend out dual specular when opacity is low, we have the extra SSSS_OPACITY_THRESHOLD_EPS so that we fade out by the time we
// get to 0.01, as opposed to 0.0.
half MaterialRoughnessToLobeRoughness0 = lerp(1.0f, Data.x * SSSS_MAX_DUAL_SPECULAR_ROUGHNESS, saturate((Opacity - SSSS_OPACITY_THRESHOLD_EPS) * 10.0f));
return ModifiedLobeRoughness0 / max(MaterialRoughnessToLobeRoughness0, 0.02f);
}
void GetSubsurfaceProfileDualSpecular(uint SubsurfaceProfileInt, half Roughness, half Opacity, out half LobeRoughness0, out half LobeRoughness1, out half LobeMix)
{
const half4 Data = GetSubsurfaceProfileTexture(SSSS_DUAL_SPECULAR_OFFSET, SubsurfaceProfileInt);