VolumetricCloudRendering.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    VolumetricCloudRendering.h
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "EngineDefines.h"
#include "RendererInterface.h"
#include "RenderResource.h"
#include "VolumeLighting.h"
 
 
class FScene;
class FViewInfo;
class FLightSceneInfo;
class UVolumetricCloudComponent;
class FVolumetricCloudSceneProxy;
class FLightSceneProxy;
 
struct FEngineShowFlags;
 
 
 
BEGIN_SHADER_PARAMETER_STRUCT(FVolumetricCloudCommonShaderParameters, )
    SHADER_PARAMETER(FLinearColor, GroundAlbedo)
    SHADER_PARAMETER(FVector3f, CloudLayerCenterKm)
    SHADER_PARAMETER(float, PlanetRadiusKm)
    SHADER_PARAMETER(float, BottomRadiusKm)
    SHADER_PARAMETER(float, TopRadiusKm)
    SHADER_PARAMETER(float, TracingStartDistanceFromCamera)
    SHADER_PARAMETER(float, TracingStartMaxDistance)
    SHADER_PARAMETER(int32, TracingMaxDistanceMode)
    SHADER_PARAMETER(float, TracingMaxDistance)
    SHADER_PARAMETER(uint32, SampleCountClamp)
    SHADER_PARAMETER(int32, SampleCountMin)
    SHADER_PARAMETER(int32, SampleCountMax)
    SHADER_PARAMETER(float, InvDistanceToSampleCountMax)
    SHADER_PARAMETER(int32, ShadowSampleCountMax)
    SHADER_PARAMETER(float, ShadowTracingMaxDistance)
    SHADER_PARAMETER(float, StopTracingTransmittanceThreshold)
    SHADER_PARAMETER(float, SkyLightCloudBottomVisibility)
    SHADER_PARAMETER_ARRAY(FLinearColor, AtmosphericLightCloudScatteredLuminanceScale, [2])
    SHADER_PARAMETER_ARRAY(FVector4f,   CloudShadowmapFarDepthKm, [2]) // SHADER_PARAMETER_ARRAY of float is always a vector behind the scene and we must comply with SPIRV-Cross alignment requirement so using an array Float4 for now for easy indexing from code.
    SHADER_PARAMETER_ARRAY(FVector4f,   CloudShadowmapStrength, [2])
    SHADER_PARAMETER_ARRAY(FVector4f,   CloudShadowmapDepthBias, [2])
    SHADER_PARAMETER_ARRAY(FVector4f,   CloudShadowmapSampleCount, [2])
    SHADER_PARAMETER_ARRAY(FVector4f,CloudShadowmapSizeInvSize, [2])
    SHADER_PARAMETER_ARRAY(FVector4f,CloudShadowmapTracingSizeInvSize, [2])
    SHADER_PARAMETER_ARRAY(FMatrix44f,  CloudShadowmapTranslatedWorldToLightClipMatrix, [2])
    SHADER_PARAMETER_ARRAY(FMatrix44f,  CloudShadowmapTranslatedWorldToLightClipMatrixInv, [2])
    SHADER_PARAMETER_ARRAY(FVector4f, CloudShadowmapTracingPixelScaleOffset, [2])
    SHADER_PARAMETER_ARRAY(FVector4f, CloudShadowmapLightDir, [2])
    SHADER_PARAMETER_ARRAY(FVector4f, CloudShadowmapLightPos, [2])
    SHADER_PARAMETER_ARRAY(FVector4f, CloudShadowmapLightAnchorPos, [2])    // Snapped position on the planet the shadow map rotate around 
    SHADER_PARAMETER(float,     CloudSkyAOFarDepthKm)
    SHADER_PARAMETER(float,     CloudSkyAOStrength)
    SHADER_PARAMETER(float,     CloudSkyAOSampleCount)
    SHADER_PARAMETER(FVector4f, CloudSkyAOSizeInvSize)
    SHADER_PARAMETER(FMatrix44f,    CloudSkyAOTranslatedWorldToLightClipMatrix)
    SHADER_PARAMETER(FMatrix44f,    CloudSkyAOTranslatedWorldToLightClipMatrixInv)
    SHADER_PARAMETER(FVector3f, CloudSkyAOTraceDir)
END_SHADER_PARAMETER_STRUCT()
 
BEGIN_GLOBAL_SHADER_PARAMETER_STRUCT(FVolumetricCloudCommonGlobalShaderParameters, )
    SHADER_PARAMETER_STRUCT_INCLUDE(FVolumetricCloudCommonShaderParameters, VolumetricCloudCommonParams)
END_GLOBAL_SHADER_PARAMETER_STRUCT()
 
BEGIN_SHADER_PARAMETER_STRUCT(FLightCloudTransmittanceParameters, )
    SHADER_PARAMETER(FMatrix44f, CloudShadowmapTranslatedWorldToLightClipMatrix)
    SHADER_PARAMETER(float, CloudShadowmapFarDepthKm)
    SHADER_PARAMETER_RDG_TEXTURE(Texture2D<float3>, CloudShadowmapTexture)
    SHADER_PARAMETER_SAMPLER(SamplerState, CloudShadowmapSampler)
    SHADER_PARAMETER(float, CloudShadowmapStrength)
END_SHADER_PARAMETER_STRUCT()
 
bool SetupLightCloudTransmittanceParameters(FRDGBuilder& GraphBuilder, const FScene* Scene, const FViewInfo& View, const FLightSceneInfo* LightSceneInfo, FLightCloudTransmittanceParameters& OutParameters);
 
bool LightMayCastCloudShadow(const FScene* Scene, const FViewInfo& View, const FLightSceneInfo* LightSceneInfo);
 
class FVolumetricCloudRenderSceneInfo
{
public:
 
    explicit FVolumetricCloudRenderSceneInfo(FVolumetricCloudSceneProxy& VolumetricCloudSceneProxy);
    ~FVolumetricCloudRenderSceneInfo();
 
    FVolumetricCloudSceneProxy& GetVolumetricCloudSceneProxy() const { return VolumetricCloudSceneProxy; }
 
    FVolumetricCloudCommonShaderParameters& GetVolumetricCloudCommonShaderParameters() { return VolumetricCloudCommonShaderParameters; }
    const FVolumetricCloudCommonShaderParameters& GetVolumetricCloudCommonShaderParameters() const { return VolumetricCloudCommonShaderParameters; }
 
    TUniformBufferRef<FVolumetricCloudCommonGlobalShaderParameters>& GetVolumetricCloudCommonShaderParametersUB() { return VolumetricCloudCommonShaderParametersUB; }
    const TUniformBufferRef<FVolumetricCloudCommonGlobalShaderParameters>& GetVolumetricCloudCommonShaderParametersUB() const { return VolumetricCloudCommonShaderParametersUB; }
 
private:
 
    FVolumetricCloudSceneProxy& VolumetricCloudSceneProxy;
 
    FVolumetricCloudCommonShaderParameters VolumetricCloudCommonShaderParameters;
    TUniformBufferRef<FVolumetricCloudCommonGlobalShaderParameters> VolumetricCloudCommonShaderParametersUB;
};
 
 
bool ShouldRenderVolumetricCloud(const FScene* Scene, const FEngineShowFlags& EngineShowFlags);
bool ShouldRenderVolumetricCloudWithBlueNoise_GameThread(const FScene* Scene, const FSceneView& View);
 
bool ShouldViewVisualizeVolumetricCloudConservativeDensity(const FViewInfo& ViewInfo, const FEngineShowFlags& EngineShowFlags);
bool VolumetricCloudWantsToSampleLocalLights(const FScene* Scene, const FEngineShowFlags& EngineShowFlags);
uint32 GetVolumetricCloudDebugViewMode(const FEngineShowFlags& ShowFlags);
bool ShouldVolumetricCloudTraceWithMinMaxDepth(const FViewInfo& ViewInfo);
bool ShouldVolumetricCloudTraceWithMinMaxDepth(const TArray<FViewInfo>& Views);
bool VolumetricCloudWantsSeparatedAtmosphereMieRayLeigh(const FScene* Scene);
 
bool ShouldVolumetricCloudsApplyFogDuringReconstruction(const FViewInfo& ViewInfo);
 
// Structure with data necessary to specify a cloud render.
struct FCloudRenderContext
{
    // Per scene parameters
 
    FVolumetricCloudRenderSceneInfo* CloudInfo;
    FMaterialRenderProxy* CloudVolumeMaterialProxy;
 
    FRDGTextureRef SceneDepthZ = nullptr;
    FRDGTextureRef SceneDepthMinAndMax = nullptr;
 
    // Per view parameters
 
    FViewInfo* MainView;
    TUniformBufferRef<FViewUniformShaderParameters> ViewUniformBuffer;
    FRenderTargetBindingSlots RenderTargets;
 
    FRDGTextureRef SecondaryCloudTracingDataTexture = nullptr;
    FRDGTextureRef CloudAlphaHoldoutTexture = nullptr;
 
    bool bDisableCloudBlending;
    bool bShouldViewRenderVolumetricRenderTarget;
    bool bSkipAerialPerspective;
    bool bSkipHeightFog;
    bool bIsReflectionRendering;                // Reflection capture and real time sky capture
    bool bIsSkyRealTimeReflectionRendering;     // Real time sky capture only
    bool bSkipAtmosphericLightShadowmap;
    bool bSecondAtmosphereLightEnabled;
 
    bool bAsyncCompute;
    bool bCloudDebugViewModeEnabled;
    bool bAccumulateAlphaHoldOut;
 
    FUintVector4 TracingCoordToZbufferCoordScaleBias;
    FUintVector4 TracingCoordToFullResPixelCoordScaleBias;
    uint32 NoiseFrameIndexModPattern;
 
    FVolumeShadowingShaderParametersGlobal0 LightShadowShaderParams0;
    FRDGTextureRef VolumetricCloudShadowTexture[2];
 
    int VirtualShadowMapId0 = INDEX_NONE;
 
    FRDGTextureRef DefaultCloudColorCubeTexture = nullptr;
    FRDGTextureRef DefaultCloudColor02DTexture = nullptr;
    FRDGTextureRef DefaultCloudColor12DTexture = nullptr;
    FRDGTextureRef DefaultCloudDepthTexture = nullptr;
    FRDGTextureRef DefaultCloudAlphaHoldout = nullptr;
    FRDGTextureUAVRef DefaultCloudColorCubeTextureUAV = nullptr;
    FRDGTextureUAVRef DefaultCloudColor02DTextureUAV = nullptr;
    FRDGTextureUAVRef DefaultCloudColor12DTextureUAV = nullptr;
    FRDGTextureUAVRef DefaultCloudDepthTextureUAV = nullptr;
    FRDGTextureUAVRef DefaultCloudAlphaHoldoutUAV = nullptr;
 
    FRDGTextureUAVRef ComputeOverlapCloudColorCubeTextureUAVWithoutBarrier = nullptr;
 
    FCloudRenderContext();
 
    void CreateDefaultTexturesIfNeeded(FRDGBuilder& GraphBuilder);
 
private:
};
 
BEGIN_SHADER_PARAMETER_STRUCT(FVolumetricCloudShadowAOParameters, )
    SHADER_PARAMETER_RDG_TEXTURE(Texture2D, ShadowMap0)
    SHADER_PARAMETER_RDG_TEXTURE(Texture2D, ShadowMap1)
    SHADER_PARAMETER_RDG_TEXTURE(Texture2D, SkyAO)
END_SHADER_PARAMETER_STRUCT()
 
FVolumetricCloudShadowAOParameters GetCloudShadowAOParameters(FRDGBuilder& GraphBuilder, const FViewInfo& View, const FVolumetricCloudRenderSceneInfo* CloudInfo);
 
struct FCloudShadowAOData
{
    bool bShouldSampleCloudShadow;
    bool bShouldSampleCloudSkyAO;
    FRDGTextureRef VolumetricCloudShadowMap[2];
    FRDGTextureRef VolumetricCloudSkyAO;
};
 
void GetCloudShadowAOData(const FVolumetricCloudRenderSceneInfo* CloudInfo, const FViewInfo& View, FRDGBuilder& GraphBuilder, FCloudShadowAOData& OutData);