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240 行
11 KiB
240 行
11 KiB
#include "CoreRP/ShaderLibrary/Packing.hlsl"
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#include "../DiffusionProfile/DiffusionProfileSettings.cs.hlsl"
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#include "../DiffusionProfile/DiffusionProfile.hlsl"
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// ----------------------------------------------------------------------------
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// constant buffer declaration
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// ----------------------------------------------------------------------------
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CBUFFER_START(UnitySSSAndTransmissionParameters)
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// Warning: Unity is not able to losslessly transfer integers larger than 2^24 to the shader system.
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// Therefore, we bitcast uint to float in C#, and bitcast back to uint in the shader.
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uint _EnableSubsurfaceScattering; // Globally toggles subsurface and transmission scattering on/off
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float _TexturingModeFlags; // 1 bit/profile; 0 = PreAndPostScatter, 1 = PostScatter
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float _TransmissionFlags; // 1 bit/profile; 0 = regular, 1 = thin
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// Old SSS Model >>>
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float4 _HalfRcpVariancesAndWeights[DIFFUSION_PROFILE_COUNT][2]; // 2x Gaussians in RGB, A is interpolation weights
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// <<< Old SSS Model
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// Use float4 to avoid any packing issue between compute and pixel shaders
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float4 _ThicknessRemaps[DIFFUSION_PROFILE_COUNT]; // R: start, G = end - start, BA unused
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float4 _ShapeParams[DIFFUSION_PROFILE_COUNT]; // RGB = S = 1 / D, A = filter radius
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float4 _TransmissionTintsAndFresnel0[DIFFUSION_PROFILE_COUNT]; // RGB = 1/4 * color, A = fresnel0
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float4 _WorldScales[DIFFUSION_PROFILE_COUNT]; // X = meters per world unit; Y = world units per meter
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CBUFFER_END
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// ----------------------------------------------------------------------------
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// helper functions
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// ----------------------------------------------------------------------------
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// 0: [ albedo = albedo ]
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// 1: [ albedo = 1 ]
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// 2: [ albedo = sqrt(albedo) ]
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uint GetSubsurfaceScatteringTexturingMode(int diffusionProfile)
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{
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uint texturingMode = 0;
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#if defined(SHADERPASS) && (SHADERPASS == SHADERPASS_SUBSURFACE_SCATTERING)
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// If the SSS pass is executed, we know we have SSS enabled.
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bool enableSss = true;
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#else
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bool enableSss = _EnableSubsurfaceScattering != 0;
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#endif
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if (enableSss)
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{
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bool performPostScatterTexturing = IsBitSet(asuint(_TexturingModeFlags), diffusionProfile);
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if (performPostScatterTexturing)
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{
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// Post-scatter texturing mode: the albedo is only applied during the SSS pass.
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#if defined(SHADERPASS) && (SHADERPASS != SHADERPASS_SUBSURFACE_SCATTERING)
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texturingMode = 1;
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#endif
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}
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else
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{
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// Pre- and post- scatter texturing mode.
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texturingMode = 2;
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}
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}
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return texturingMode;
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}
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// Returns the modified albedo (diffuse color) for materials with subsurface scattering.
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// See GetSubsurfaceScatteringTexturingMode() above for more details.
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// Ref: Advanced Techniques for Realistic Real-Time Skin Rendering.
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float3 ApplySubsurfaceScatteringTexturingMode(uint texturingMode, float3 color)
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{
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switch (texturingMode)
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{
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case 2: color = sqrt(color); break;
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case 1: color = 1; break;
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default: color = color; break;
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}
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return color;
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}
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// ----------------------------------------------------------------------------
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// Encoding/decoding SSS buffer functions
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// ----------------------------------------------------------------------------
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struct SSSData
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{
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float3 diffuseColor;
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float subsurfaceMask;
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uint diffusionProfile;
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};
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#define SSSBufferType0 float4 // Must match GBufferType0 in deferred
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// SSSBuffer texture declaration
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TEXTURE2D(_SSSBufferTexture0);
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// Note: The SSS buffer used here is sRGB
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void EncodeIntoSSSBuffer(SSSData sssData, uint2 positionSS, out SSSBufferType0 outSSSBuffer0)
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{
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outSSSBuffer0 = float4(sssData.diffuseColor, PackFloatInt8bit(sssData.subsurfaceMask, sssData.diffusionProfile, 16));
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}
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// Note: The SSS buffer used here is sRGB
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void DecodeFromSSSBuffer(float4 sssBuffer, uint2 positionSS, out SSSData sssData)
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{
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sssData.diffuseColor = sssBuffer.rgb;
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UnpackFloatInt8bit(sssBuffer.a, 16, sssData.subsurfaceMask, sssData.diffusionProfile);
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}
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void DecodeFromSSSBuffer(uint2 positionSS, out SSSData sssData)
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{
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float4 sssBuffer = LOAD_TEXTURE2D(_SSSBufferTexture0, positionSS);
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DecodeFromSSSBuffer(sssBuffer, positionSS, sssData);
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}
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// OUTPUT_SSSBUFFER start from SV_Target2 as SV_Target0 and SV_Target1 are used for lighting buffer
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#define OUTPUT_SSSBUFFER(NAME) out SSSBufferType0 MERGE_NAME(NAME, 0) : SV_Target2
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#define ENCODE_INTO_SSSBUFFER(SURFACE_DATA, UNPOSITIONSS, NAME) EncodeIntoSSSBuffer(ConvertSurfaceDataToSSSData(SURFACE_DATA), UNPOSITIONSS, MERGE_NAME(NAME, 0))
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#define DECODE_FROM_SSSBUFFER(UNPOSITIONSS, SSS_DATA) DecodeFromSSSBuffer(UNPOSITIONSS, SSS_DATA)
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// In order to support subsurface scattering, we need to know which pixels have an SSS material.
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// It can be accomplished by reading the stencil buffer.
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// A faster solution (which avoids an extra texture fetch) is to simply make sure that
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// all pixels which belong to an SSS material are not black (those that don't always are).
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// We choose the blue color channel since it's perceptually the least noticeable.
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float3 TagLightingForSSS(float3 subsurfaceLighting)
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{
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subsurfaceLighting.b = max(subsurfaceLighting.b, HALF_MIN);
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return subsurfaceLighting;
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}
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// See TagLightingForSSS() for details.
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bool TestLightingForSSS(float3 subsurfaceLighting)
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{
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return subsurfaceLighting.b > 0;
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}
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// ----------------------------------------------------------------------------
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// Helper functions to use SSS/Transmission with a material
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// ----------------------------------------------------------------------------
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// Following function allow to easily setup SSS and transmission inside a material.
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// User can request either SSS functions, or Transmission functions, or both, by defining MATERIAL_INCLUDE_SUBSURFACESCATTERING and/or MATERIAL_INCLUDE_TRANSMISSION
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// before including this file.
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// + It require that the material follow naming convention for properties inside BSDFData
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// struct BSDFData
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// {
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// (...)
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// // Share for SSS and Transmission
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// uint materialFeatures;
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// uint diffusionProfile;
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// // For SSS
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// float3 diffuseColor;
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// float3 fresnel0;
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// float subsurfaceMask;
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// // For transmission
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// float thickness;
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// bool useThickObjectMode;
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// float3 transmittance;
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// perceptualRoughness; // Only if user chose to support DisneyDiffuse
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// (...)
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// }
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// Note: Transmission functions for light evaluation are included in LightEvaluation.hlsl file also based on the MATERIAL_INCLUDE_TRANSMISSION
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// For LightEvaluation.hlsl file it is required to define a BRDF for the transmission. Defining USE_DIFFUSE_LAMBERT_BRDF use Lambert, otherwise it use Disneydiffuse
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#define MATERIAL_FEATURE_SSS_TRANSMISSION_START (1 << 16) // It should be safe to start these flags
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#define MATERIAL_FEATURE_FLAGS_SSS_OUTPUT_SPLIT_LIGHTING ((MATERIAL_FEATURE_SSS_TRANSMISSION_START) << 0)
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#define MATERIAL_FEATURE_FLAGS_SSS_TEXTURING_MODE_OFFSET FastLog2((MATERIAL_FEATURE_SSS_TRANSMISSION_START) << 1) // Note: The texture mode is 2bit, thus go from '<< 1' to '<< 3'
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#define MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_MIXED_THICKNESS ((MATERIAL_FEATURE_SSS_TRANSMISSION_START) << 3)
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// Flags used as a shortcut to know if we have thin mode transmission
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#define MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN_THICKNESS ((MATERIAL_FEATURE_SSS_TRANSMISSION_START) << 4)
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#ifdef MATERIAL_INCLUDE_SUBSURFACESCATTERING
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void FillMaterialSSS(uint diffusionProfile, float subsurfaceMask, inout BSDFData bsdfData)
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{
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bsdfData.diffusionProfile = diffusionProfile;
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bsdfData.fresnel0 = _TransmissionTintsAndFresnel0[diffusionProfile].a;
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bsdfData.subsurfaceMask = subsurfaceMask;
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bsdfData.materialFeatures |= MATERIAL_FEATURE_FLAGS_SSS_OUTPUT_SPLIT_LIGHTING;
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bsdfData.materialFeatures |= GetSubsurfaceScatteringTexturingMode(diffusionProfile) << MATERIAL_FEATURE_FLAGS_SSS_TEXTURING_MODE_OFFSET;
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}
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bool ShouldOutputSplitLighting(BSDFData bsdfData)
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{
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return HasFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_SSS_OUTPUT_SPLIT_LIGHTING);
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}
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float3 GetModifiedDiffuseColorForSSS(BSDFData bsdfData)
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{
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// Subsurface scattering mode
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uint texturingMode = (bsdfData.materialFeatures >> MATERIAL_FEATURE_FLAGS_SSS_TEXTURING_MODE_OFFSET) & 3;
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return ApplySubsurfaceScatteringTexturingMode(texturingMode, bsdfData.diffuseColor);
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}
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#endif
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#ifdef MATERIAL_INCLUDE_TRANSMISSION
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// Assume that bsdfData.diffusionProfile is init
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void FillMaterialTransmission(uint diffusionProfile, float thickness, inout BSDFData bsdfData)
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{
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bsdfData.diffusionProfile = diffusionProfile;
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bsdfData.fresnel0 = _TransmissionTintsAndFresnel0[diffusionProfile].a;
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bsdfData.thickness = _ThicknessRemaps[diffusionProfile].x + _ThicknessRemaps[diffusionProfile].y * thickness;
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// The difference between the thin and the regular (a.k.a. auto-thickness) modes is the following:
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// * in the thin object mode, we assume that the geometry is thin enough for us to safely share
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// the shadowing information between the front and the back faces;
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// * the thin mode uses baked (textured) thickness for all transmission calculations;
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// * the thin mode uses wrapped diffuse lighting for the NdotL;
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// * the auto-thickness mode uses the baked (textured) thickness to compute transmission from
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// indirect lighting and non-shadow-casting lights; for shadowed lights, it calculates
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// the thickness using the distance to the closest occluder sampled from the shadow map.
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// If the distance is large, it may indicate that the closest occluder is not the back face of
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// the current object. That's not a problem, since large thickness will result in low intensity.
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bool useThinObjectMode = IsBitSet(asuint(_TransmissionFlags), diffusionProfile);
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bsdfData.materialFeatures |= useThinObjectMode ? MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN_THICKNESS : MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_MIXED_THICKNESS;
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// Compute transmittance using baked thickness here. It may be overridden for direct lighting
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// in the auto-thickness mode (but is always used for indirect lighting).
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#if SHADEROPTIONS_USE_DISNEY_SSS
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bsdfData.transmittance = ComputeTransmittanceDisney(_ShapeParams[diffusionProfile].rgb,
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_TransmissionTintsAndFresnel0[diffusionProfile].rgb,
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bsdfData.thickness);
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#else
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bsdfData.transmittance = ComputeTransmittanceJimenez( _HalfRcpVariancesAndWeights[diffusionProfile][0].rgb,
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_HalfRcpVariancesAndWeights[diffusionProfile][0].a,
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_HalfRcpVariancesAndWeights[diffusionProfile][1].rgb,
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_HalfRcpVariancesAndWeights[diffusionProfile][1].a,
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_TransmissionTintsAndFresnel0[diffusionProfile].rgb,
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bsdfData.thickness);
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#endif
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}
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#endif
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