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8e389aec73
Now header is only uint and extra data is only read if needed. #rb none #preflight https://horde.devtools.epicgames.com/job/62821984046b81bf9393b136 #fyi charles.derousiers [CL 20221584 by Sebastien Hillaire in ue5-main branch]
72 lines
2.7 KiB
Plaintext
72 lines
2.7 KiB
Plaintext
// Copyright Epic Games, Inc. All Rights Reserved.
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/*=============================================================================
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VirtualShadowMaps/VirtualShadowMapTransmissionCommon.ush:
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=============================================================================*/
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#pragma once
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#include "../Common.ush"
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#include "../SceneTexturesCommon.ush"
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#include "../DeferredShadingCommon.ush"
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#include "VirtualShadowMapProjectionCommon.ush"
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half GetSubsurfaceOpacityFromGbuffer(uint2 PixelPos)
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{
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half Opacity = 1.0;
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#if STRATA_ENABLED
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Opacity = StrataGetOpacityFromSubSurface(StrataLoadSubsurfaceHeader(Strata.SSSTexture, PixelPos));
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#else // STRATA_ENABLED
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FGBufferData GBufferData = GetGBufferDataUint(PixelPos);
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// TODO: SUBSURFACE_PROFILE with fancy transmission
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if (GBufferData.ShadingModelID == SHADINGMODELID_SUBSURFACE ||
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GBufferData.ShadingModelID == SHADINGMODELID_PREINTEGRATED_SKIN ||
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GBufferData.ShadingModelID == SHADINGMODELID_TWOSIDED_FOLIAGE)
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{
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// This clamp aligns with SubsurfaceDensityFromOpacity
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// Various engine paths treat these subsurface materials differently
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// even when they have Opacity = 1 in the material shader, so this is
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// important to avoid things like backface transmission being shadowed by
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// contact shadows and so on.
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Opacity = min(GBufferData.CustomData.a, 0.99f);
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}
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#endif // STRATA_ENABLED
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return Opacity;
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}
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/**
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* Sample VSM to determine approximate thickness and compute simple subsurface transmission matching the
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* PCF path.
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*/
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half ComputeSimpleSubsurfaceTransmissionFromVirtualShadowMap(
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int VirtualShadowMapId,
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float3 TranslatedWorldPosition,
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half SubsurfaceOpacity)
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{
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// If the receiver is a subsurface material, we do a very simple transmission approximation
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// This matches the logic in the PCF kernel (ShadowFilteringCommon.ush) and the contact
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// shadows trace (DeferredLightingCommon.ush). Ideally these should all be unified in a single location.
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// Could optimize this in the case where we are doing single-sample VSM lookup anyways, but we would need
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// exclude contact shadows overwriting the occluder distance. Single sample direct shadows are not currently
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// a common case.
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// Do a separate unfiltered lookup to get approximate occluder distance
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FVirtualShadowMapSampleResult SSSResult = SampleVirtualShadowMapTranslatedWorld(
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VirtualShadowMapId,
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TranslatedWorldPosition,
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0.0f // RayStartDistance
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);
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if ( SSSResult.bValid && SSSResult.ShadowFactor < 1.0f )
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{
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float Density = SubsurfaceDensityFromOpacity( SubsurfaceOpacity );
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float Occlusion = 1.0f - saturate( exp( -Density * SSSResult.OccluderDistance ) );
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// NOTE: This square is arbitrary, but we have to be consistent with the PCF path
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return Square( 1.0f - Occlusion * ( 1.0f - SSSResult.ShadowFactor ) );
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}
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return 1.0f;
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}
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