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Implement the initial version of auto-thickness

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Evgenii Golubev 7 年前
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c249e283
共有 1 个文件被更改，包括 110 次插入 和 44 次删除
  1. 154
      ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/Lit.hlsl

154
ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/Lit.hlsl
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// Additional bits set in 'bsdfData.materialFeatures' to save registers and simplify feature tracking.
#define MATERIAL_FEATURE_FLAGS_SSS_OUTPUT_SPLIT_LIGHTING ((MATERIAL_FEATURE_MASK_FLAGS + 1) << 0)
#define MATERIAL_FEATURE_FLAGS_SSS_TEXTURING_MODE_OFFSET FastLog2((MATERIAL_FEATURE_MASK_FLAGS + 1) << 1) // 2 bits
#define MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN ((MATERIAL_FEATURE_MASK_FLAGS + 1) << 3)
#define MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_AUTO_THICKNESS ((MATERIAL_FEATURE_MASK_FLAGS + 1) << 3)
uint FeatureFlagsToTileVariant(uint featureFlags)
{

bsdfData.thickness = _ThicknessRemaps[diffusionProfile].x + _ThicknessRemaps[diffusionProfile].y * thickness;
#if SHADEROPTIONS_USE_DISNEY_SSS
bsdfData.transmittance = ComputeTransmittanceDisney( _ShapeParams[diffusionProfile].rgb,
_TransmissionTintsAndFresnel0[diffusionProfile].rgb,
bsdfData.thickness);
#else
bsdfData.transmittance = ComputeTransmittanceJimenez( _HalfRcpVariancesAndWeights[diffusionProfile][0].rgb,
_HalfRcpVariancesAndWeights[diffusionProfile][0].a,
_HalfRcpVariancesAndWeights[diffusionProfile][1].rgb,
_HalfRcpVariancesAndWeights[diffusionProfile][1].a,
_TransmissionTintsAndFresnel0[diffusionProfile].rgb,
bsdfData.thickness);
#endif
// The difference between the thin and the regular (a.k.a. auto-thickness) modes is the following:
// * in the thin object mode, we assume that the geometry is thin enough for us to safely share
// the shadowing information between the front and the back faces;
// * the thin mode uses baked (textured) thickness for all transmission calculations;
// * the thin mode uses wrapped diffuse lighting for the NdotL;
// * the auto-thickness mode uses the baked (textured) thickness to compute transmission from
// indirect lighting and non-shadow-casting lights; for shadowed lights, it calculates
// the thickness using the distance to the closest occluder sampled from the shadow map.
// If the distance is large, it may indicate that the closest occluder is not the back face of
// the current object. That's not a problem, since large thickness will result in low intensity.
bsdfData.materialFeatures |= useThinObjectMode ? MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN : 0;
if (useThinObjectMode)
{
// Apply no displacement.
bsdfData.thickness = 0;
}
else
{
// Compute the thickness in world units along the normal.
float thicknessInMeters = bsdfData.thickness * METERS_PER_MILLIMETER;
float thicknessInUnits = thicknessInMeters * _WorldScales[bsdfData.diffusionProfile].y;
bsdfData.materialFeatures |= useThinObjectMode ? 0 : MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_AUTO_THICKNESS;
bsdfData.thickness = thicknessInUnits;
}
// Compute transmittance using baked thickness here. It may be overridden for direct lighting
// in the auto-thickness mode (but is always be used for indirect lighting).
#if SHADEROPTIONS_USE_DISNEY_SSS
bsdfData.transmittance = ComputeTransmittanceDisney(_ShapeParams[diffusionProfile].rgb,
_TransmissionTintsAndFresnel0[diffusionProfile].rgb,
bsdfData.thickness);
#else
bsdfData.transmittance = ComputeTransmittanceJimenez(_HalfRcpVariancesAndWeights[diffusionProfile][0].rgb,
_HalfRcpVariancesAndWeights[diffusionProfile][0].a,
_HalfRcpVariancesAndWeights[diffusionProfile][1].rgb,
_HalfRcpVariancesAndWeights[diffusionProfile][1].a,
_TransmissionTintsAndFresnel0[diffusionProfile].rgb,
bsdfData.thickness);
#endif
}
// Assume bsdfData.normalWS is init

// - we integrate the diffuse reflectance profile w.r.t. the radius (while also accounting
// for the thickness) to compute the transmittance;
// - we multiply the transmitted radiance by the transmittance.
float3 EvaluateTransmission(BSDFData bsdfData, float NdotL, float NdotV, float attenuation)
float3 EvaluateTransmission(BSDFData bsdfData, float3 transmittance, float NdotL, float NdotV, float attenuation)
bool useThinObjectMode = HasFeatureFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN);
float backNdotL = useThinObjectMode ? wrappedNdotL : negatedNdotL;
bool autoThicknessMode = HasFeatureFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_AUTO_THICKNESS);
float backNdotL = autoThicknessMode ? negatedNdotL : wrappedNdotL;
// Apply BSDF-specific diffuse transmission to attenuation. See also: [SSS-NOTE-TRSM]
// We don't multiply by 'bsdfData.diffuseColor' here. It's done only once in PostEvaluateBSDF().

float intensity = max(0, attenuation * backNdotL); // Warning: attenuation can be greater than 1 due to the inverse square attenuation (when position is close to light)
return intensity * bsdfData.transmittance;
return intensity * transmittance;
}
//-----------------------------------------------------------------------------

float3 L = -lightData.forward; // Lights point backward in Unity
float NdotL = dot(N, L); // Note: Ideally this N here should be vertex normal - use for transmisison
if (HasFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_TRANSMISSION))
float3 transmittance = bsdfData.transmittance;
bool autoThicknessMode = HasFeatureFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_AUTO_THICKNESS);
UNITY_BRANCH
if (autoThicknessMode && NdotL < 0 && lightData.shadowIndex >= 0)
// Compute displacement for fake thickObject transmission
posInput.positionWS += ComputeThicknessDisplacement(bsdfData, L, NdotL);
// TODO: perform bilinear filtering of the shadow map.
// Recompute transmittance using the thickness value computed from the shadow map.
#if 0
// Does not work, I get a compiler crash...
float3 occluderPosWS = EvalShadow_GetClosestSample_Cascade(lightLoopContext.shadowContext, posInput.positionWS, bsdfData.normalWS, lightData.shadowIndex, float4(L, 0));
#else
#define SHADOW_DISPATCH_DIR_TEX 3 // Manually keep it in sync with Shadow.hlsl...
float3 occluderPosWS = EvalShadow_GetClosestSample_Cascade(lightLoopContext.shadowContext, lightLoopContext.shadowContext.tex2DArray[SHADOW_DISPATCH_DIR_TEX], posInput.positionWS, bsdfData.normalWS, lightData.shadowIndex, float4(L, 0));
#endif
float thicknessInUnits = distance(posInput.positionWS, occluderPosWS);
float thicknessInMeters = thicknessInUnits * _WorldScales[bsdfData.diffusionProfile].x;
float thicknessInMillimeters = thicknessInMeters * MILLIMETERS_PER_METER;
// TODO: optimize.
#if SHADEROPTIONS_USE_DISNEY_SSS
transmittance = ComputeTransmittanceDisney(_ShapeParams[bsdfData.diffusionProfile].rgb,
_TransmissionTintsAndFresnel0[bsdfData.diffusionProfile].rgb,
thicknessInMillimeters);
#else
transmittance = ComputeTransmittanceJimenez(_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][0].rgb,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][0].a,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][1].rgb,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][1].a,
_TransmissionTintsAndFresnel0[bsdfData.diffusionProfile].rgb,
thicknessInMillimeters);
#endif
// Make sure we do not sample the shadow map twice.
lightData.shadowIndex = -1;
// Note: we do not modify the distance to the light, or the light angle for the back face.
// This is a performance-saving optimization which makes sense as long as the thickness is small.
}
float3 color;

lighting.specular *= intensity * lightData.specularScale;
}
UNITY_BRANCH if (HasFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_TRANSMISSION))
// TODO: move this before BSDF() to save VGPRs.
if (HasFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_TRANSMISSION))
lighting.diffuse += EvaluateTransmission(bsdfData, NdotL, ClampNdotV(preLightData.NdotV), attenuation * lightData.diffuseScale);
lighting.diffuse += EvaluateTransmission(bsdfData, transmittance, NdotL, ClampNdotV(preLightData.NdotV), attenuation * lightData.diffuseScale);
}
// Save ALU by applying light and cookie colors only once.

float3 N = bsdfData.normalWS;
float NdotL = dot(N, L);
if (HasFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_TRANSMISSION))
float3 transmittance = bsdfData.transmittance;
bool autoThicknessMode = HasFeatureFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_AUTO_THICKNESS);
UNITY_BRANCH
if (autoThicknessMode && NdotL < 0 && lightData.shadowIndex >= 0)
// Compute displacement for fake thickObject transmission
// Warning: distances computed above are NOT modified!
// This is not correct, of course, but is done for performance reasons.
posInput.positionWS += ComputeThicknessDisplacement(bsdfData, L, NdotL);
// TODO: perform bilinear filtering of the shadow map.
// Recompute transmittance using the thickness value computed from the shadow map.
#if 0
// Does not work, I get a compiler crash...
float3 occluderPosWS = EvalShadow_GetClosestSample_Punctual(lightLoopContext.shadowContext, posInput.positionWS, lightData.shadowIndex, L);
#else
#define SHADOW_DISPATCH_PUNC_TEX 3 // Manually keep it in sync with Shadow.hlsl...
float3 occluderPosWS = EvalShadow_GetClosestSample_Punctual(lightLoopContext.shadowContext, lightLoopContext.shadowContext.tex2DArray[SHADOW_DISPATCH_PUNC_TEX], posInput.positionWS, lightData.shadowIndex, L);
#endif
float thicknessInUnits = distance(posInput.positionWS, occluderPosWS);
float thicknessInMeters = thicknessInUnits * _WorldScales[bsdfData.diffusionProfile].x;
float thicknessInMillimeters = thicknessInMeters * MILLIMETERS_PER_METER;
// TODO: optimize.
#if SHADEROPTIONS_USE_DISNEY_SSS
transmittance = ComputeTransmittanceDisney(_ShapeParams[bsdfData.diffusionProfile].rgb,
_TransmissionTintsAndFresnel0[bsdfData.diffusionProfile].rgb,
thicknessInMillimeters);
#else
transmittance = ComputeTransmittanceJimenez(_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][0].rgb,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][0].a,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][1].rgb,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][1].a,
_TransmissionTintsAndFresnel0[bsdfData.diffusionProfile].rgb,
thicknessInMillimeters);
#endif
// Make sure we do not sample the shadow map twice.
lightData.shadowIndex = -1;
// Note: we do not modify the distance to the light, or the light angle for the back face.
// This is a performance-saving optimization which makes sense as long as the thickness is small.
}
float3 color;

lighting.specular *= intensity * lightData.specularScale;
}
UNITY_BRANCH if (HasFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_TRANSMISSION))
// TODO: move this before BSDF() to save VGPRs.
if (HasFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_TRANSMISSION))
lighting.diffuse += EvaluateTransmission(bsdfData, NdotL, ClampNdotV(preLightData.NdotV), attenuation * lightData.diffuseScale);
lighting.diffuse += EvaluateTransmission(bsdfData, transmittance, NdotL, ClampNdotV(preLightData.NdotV), attenuation * lightData.diffuseScale);
}
// Save ALU by applying light and cookie colors only once.

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