89 lines
5.0 KiB
HLSL
89 lines
5.0 KiB
HLSL
// Copyright Epic Games, Inc. All Rights Reserved.
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#pragma once
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#define SharedAmbientInnerSampler View.SharedBilinearClampedSampler
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#define SharedAmbientOuterSampler View.SharedBilinearClampedSampler
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#define SharedDirectionalInnerSampler View.SharedBilinearClampedSampler
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#define SharedDirectionalOuterSampler View.SharedBilinearClampedSampler
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void ComputeVolumeUVs(float3 TranslatedWorldPosition, float3 LightingPositionOffset, out float3 InnerVolumeUVs, out float3 OuterVolumeUVs, out float FinalLerpFactor)
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{
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// Apply an offset to the world position used for lighting, which breaks up artifacts from using a low res volume texture
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InnerVolumeUVs = (TranslatedWorldPosition + LightingPositionOffset * View.TranslucencyLightingVolumeInvSize[0].w - View.TranslucencyLightingVolumeMin[0].xyz) * View.TranslucencyLightingVolumeInvSize[0].xyz;
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OuterVolumeUVs = (TranslatedWorldPosition + LightingPositionOffset * View.TranslucencyLightingVolumeInvSize[1].w - View.TranslucencyLightingVolumeMin[1].xyz) * View.TranslucencyLightingVolumeInvSize[1].xyz;
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// Controls how fast the lerp between the inner and outer cascades happens
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// Larger values result in a shorter transition distance
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float TransitionScale = 6;
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// Setup a 3d lerp factor going to 0 at the edge of the inner volume
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float3 LerpFactors = saturate((.5f - abs(InnerVolumeUVs - .5f)) * TransitionScale);
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FinalLerpFactor = LerpFactors.x * LerpFactors.y * LerpFactors.z;
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}
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float4 GetAmbientLightingVectorFromTranslucentLightingVolume(float3 InnerVolumeUVs, float3 OuterVolumeUVs, float FinalLerpFactor)
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{
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// Lookup the inner and outer cascade ambient lighting values
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float4 InnerLighting = Texture3DSampleLevel(TranslucencyLightingVolumeAmbientInner, SharedAmbientInnerSampler, InnerVolumeUVs, 0);
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float4 OuterLighting = Texture3DSampleLevel(TranslucencyLightingVolumeAmbientOuter, SharedAmbientOuterSampler, OuterVolumeUVs, 0);
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// Lerp between cascades
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return lerp(OuterLighting, InnerLighting, FinalLerpFactor);
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}
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float3 GetDirectionalLightingVectorFromTranslucentLightingVolume(float3 InnerVolumeUVs, float3 OuterVolumeUVs, float FinalLerpFactor)
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{
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// Fetch both the ambient and directional values for both cascades
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float3 InnerVector1 = Texture3DSampleLevel(TranslucencyLightingVolumeDirectionalInner, SharedDirectionalInnerSampler, InnerVolumeUVs, 0).rgb;
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float3 OuterVector1 = Texture3DSampleLevel(TranslucencyLightingVolumeDirectionalOuter, SharedDirectionalOuterSampler, OuterVolumeUVs, 0).rgb;
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// Lerp between cascades
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return lerp(OuterVector1, InnerVector1, FinalLerpFactor);
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}
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#include "SHCommon.ush"
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void GetVolumeLightingNonDirectional(float4 AmbientLightingVector, float3 DiffuseColor, inout float3 InterpolatedLighting, out float4 VolumeLighting)
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{
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// Normal is not taken into account with non directional lighting, and only the ambient term of the SH coefficients are needed
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FOneBandSHVectorRGB TranslucentLighting;
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TranslucentLighting.R.V.x = AmbientLightingVector.r;
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TranslucentLighting.G.V.x = AmbientLightingVector.g;
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TranslucentLighting.B.V.x = AmbientLightingVector.b;
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FOneBandSHVector DiffuseTransferSH = CalcDiffuseTransferSH1(1);
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VolumeLighting = float4(DotSH1(TranslucentLighting, DiffuseTransferSH), AmbientLightingVector.a);
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InterpolatedLighting = DiffuseColor * VolumeLighting.rgb;
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}
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void GetVolumeLightingDirectional(float4 AmbientLightingVector, float3 DirectionalLightingVector, float3 WorldNormal, float3 DiffuseColor, float DirectionalLightingIntensity, inout float3 InterpolatedLighting, out float4 VolumeLighting)
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{
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// Reconstruct the SH coefficients based on what was encoded
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FTwoBandSHVectorRGB TranslucentLighting;
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TranslucentLighting.R.V.x = AmbientLightingVector.r;
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TranslucentLighting.G.V.x = AmbientLightingVector.g;
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TranslucentLighting.B.V.x = AmbientLightingVector.b;
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float3 NormalizedAmbientColor = AmbientLightingVector.rgb / (Luminance(AmbientLightingVector.rgb) + 0.00001f);
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// Scale the monocrome directional coefficients with the normalzed ambient color as an approximation to the uncompressed values
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TranslucentLighting.R.V.yzw = DirectionalLightingVector.rgb * NormalizedAmbientColor.r;
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TranslucentLighting.G.V.yzw = DirectionalLightingVector.rgb * NormalizedAmbientColor.g;
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TranslucentLighting.B.V.yzw = DirectionalLightingVector.rgb * NormalizedAmbientColor.b;
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// Compute diffuse lighting which takes the normal into account
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FTwoBandSHVector DiffuseTransferSH = CalcDiffuseTransferSH(WorldNormal * DirectionalLightingIntensity, 1);
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VolumeLighting = float4(max(half3(0, 0, 0), DotSH(TranslucentLighting, DiffuseTransferSH)), AmbientLightingVector.a);
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InterpolatedLighting += DiffuseColor * VolumeLighting.rgb;
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}
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float4 GetVolumeLightingDirectional(float4 AmbientLightingVector, float3 DirectionalLightingVector, float3 WorldNormal, float DirectionalLightingIntensity)
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{
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float3 DiffuseColor = 1.0f;
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float3 InterpolatedLighting = 0.0f;
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float4 VolumeLighting = 0.0f;
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GetVolumeLightingDirectional(AmbientLightingVector, DirectionalLightingVector, WorldNormal, DiffuseColor, DirectionalLightingIntensity, InterpolatedLighting, VolumeLighting);
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return VolumeLighting;
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}
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