LocalFogVolumeRendering.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "EngineDefines.h"
#include "RenderGraph.h"
#include "RenderResource.h"
#include "RenderGraphResources.h"
#include "SceneView.h"
#include "Containers/Array.h"
 
class FScene;
class FViewInfo;
struct FMinimalSceneTextures;
 
 
 
/*=============================================================================
    Local height fog rendering GPU data
=============================================================================*/
 
BEGIN_SHADER_PARAMETER_STRUCT(FLocalFogVolumeCommonParameters, )
    SHADER_PARAMETER_RDG_BUFFER_SRV(Buffer<float4>, LocalFogVolumeInstances)
    SHADER_PARAMETER(FUintVector2, LocalFogVolumeTileDataTextureResolution)
    SHADER_PARAMETER(uint32, LocalFogVolumeInstanceCount)
    SHADER_PARAMETER(uint32, LocalFogVolumeTilePixelSize)
    SHADER_PARAMETER(float,  LocalFogVolumeMaxDensityIntoVolumetricFog)
    SHADER_PARAMETER(uint32, ShouldRenderLocalFogVolumeInVolumetricFog)
    SHADER_PARAMETER(float,  GlobalStartDistance)
    SHADER_PARAMETER(FVector4f, HalfResTextureSizeAndInvSize)
    SHADER_PARAMETER(FVector3f, DirectionalLightColor)
    SHADER_PARAMETER(FVector3f, DirectionalLightDirection)
END_SHADER_PARAMETER_STRUCT()
 
BEGIN_SHADER_PARAMETER_STRUCT(FLocalFogVolumeUniformParameters, )
    SHADER_PARAMETER_STRUCT_INCLUDE(FLocalFogVolumeCommonParameters, LocalFogVolumeCommon)
    SHADER_PARAMETER_RDG_TEXTURE_SRV(Texture2DArray<uint>, LocalFogVolumeTileDataTexture)
END_SHADER_PARAMETER_STRUCT()
 
/*=============================================================================
    Local height fog rendering common data
=============================================================================*/
 
class FLocalFogVolumeGPUInstanceData
{
public:
 
    uint32 Data0[4];
    uint32 Data1[4];
    uint32 Data2[4];
 
    float GetUniformScale() 
    {
        union { uint32 U; float F; } FU = { Data0[3] };
        return FU.F;
    }
};
 
class FLocalFogVolumeSortKey
{
public:
    union
    {
        uint64 PackedData;
 
        struct
        {
            uint64 Index : 16; // Index of the volume
            uint64 Distance : 32; // then by distance
            uint64 Priority : 16; // First order by priority
        } FogVolume;
    };
 
    FORCEINLINE bool operator!=(FLocalFogVolumeSortKey B) const
    {
        return PackedData != B.PackedData;
    }
 
    FORCEINLINE bool operator<(FLocalFogVolumeSortKey B) const
    {
        return PackedData > B.PackedData;
    }
};
 
// This can be generated once for a scene and then shared between all the views to generate the GPU buffer data needed for rendering while accounting for sorting.
struct FLocalFogVolumeSortingData
{
    uint32 LocalFogVolumeInstanceCount;
    uint32 LocalFogVolumeInstanceCountFinal;
    FLocalFogVolumeGPUInstanceData* LocalFogVolumeGPUInstanceData;
    FVector* LocalFogVolumeCenterPos;
    TArray<FLocalFogVolumeSortKey>  LocalFogVolumeSortKeys;
};
 
struct FLocalFogVolumeViewData
{
    uint32 GPUInstanceCount = 0;
    FRDGBufferRef GPUInstanceDataBuffer = nullptr;
    FRDGBufferSRVRef GPUInstanceDataBufferSRV = nullptr;
 
    FRDGBufferRef GPUInstanceCullingDataBuffer = nullptr;
    FRDGBufferSRVRef GPUInstanceCullingDataBufferSRV = nullptr;
 
    FRDGBufferRef    GPUTileDataBuffer = nullptr;
    FRDGBufferSRVRef GPUTileDataBufferSRV = nullptr;
    FRDGBufferUAVRef GPUTileDataBufferUAV = nullptr;
    FRDGBufferRef    GPUTileDrawIndirectBuffer = nullptr;
    FRDGBufferUAVRef GPUTileDrawIndirectBufferUAV = nullptr;
 
    TRDGUniformBufferRef<FLocalFogVolumeUniformParameters> UniformBuffer = nullptr;
 
    FLocalFogVolumeUniformParameters UniformParametersStruct;
 
    FRDGTextureRef      TileDataTextureArray = nullptr;     // First slice is the instance count, later slices are instance indices.
    FRDGTextureSRVRef   TileDataTextureArraySRV = nullptr;
    FRDGTextureUAVRef   TileDataTextureArrayUAV = nullptr;
 
    bool                bUseHalfResLocalFogVolume = false;  // Only for the mobile path for now
    FIntPoint           HalfResResolution;
    FRDGTextureRef      HalfResLocalFogVolumeView = nullptr;
    FRDGTextureSRVRef   HalfResLocalFogVolumeViewSRV = nullptr;
    FRDGTextureRef      HalfResLocalFogVolumeDepth = nullptr;
    FRDGTextureSRVRef   HalfResLocalFogVolumeDepthSRV = nullptr;
};
 
 
/*=============================================================================
    Local height fog rendering functions
=============================================================================*/
 
bool ProjectSupportsLocalFogVolumes();
bool ShouldRenderLocalFogVolume(const FScene* Scene, const FSceneViewFamily& SceneViewFamily);
bool ShouldRenderLocalFogVolumeDuringHeightFogPass(const FScene* Scene, const FSceneViewFamily& SceneViewFamily);
bool ShouldRenderLocalFogVolumeInVolumetricFog(const FScene* Scene, const FSceneViewFamily& SceneViewFamily, bool bShouldRenderVolumetricFog);
bool ShouldRenderLocalFogVolumeVisualizationPass(const FScene* Scene, const FSceneViewFamily& SceneViewFamily);
float GetLocalFogVolumeGlobalStartDistance();
bool IsLocalFogVolumeHalfResolution();
 
void GetLocalFogVolumeViewSortingData(const FScene* Scene, const FViewInfo& View, FRDGBuilder& GraphBuilder, FLocalFogVolumeSortingData& Out);
 
void SetDummyLocalFogVolumeForViews(FRDGBuilder& GraphBuilder, TArray<FViewInfo>& Views);
void SetDummyLocalFogVolumeForViews(FRDGBuilder& GraphBuilder, TArray<FViewInfo*>& Views);
void SetDummyLocalFogVolumeForView(FRDGBuilder& GraphBuilder, FViewInfo& View);
void SetDummyLocalFogVolumeUniformParametersStruct(FRDGBuilder& GraphBuilder, FLocalFogVolumeUniformParameters& UniformParametersStruct);
 
void InitLocalFogVolumesForViews(
    const FScene* Scene,
    TArray<FViewInfo>& Views,
    const FSceneViewFamily& SceneViewFamily,
    FRDGBuilder& GraphBuilder,
    bool bShouldRenderVolumetricFog,
    bool bUseHalfResLocalFogVolume);
 
void RenderLocalFogVolume(
    const FScene* Scene,
    TArray<FViewInfo>& Views,
    const FSceneViewFamily& SceneViewFamily,
    FRDGBuilder& GraphBuilder,
    const FMinimalSceneTextures& SceneTextures,
    FRDGTextureRef LightShaftOcclusionTexture,
    bool bVisualizationPass = false);
 
void RenderLocalFogVolumeMobile(
    FRHICommandList& RHICmdList, 
    const FViewInfo& View);
void RenderLocalFogVolumeHalfResMobile(
    FRDGBuilder& GraphBuilder,
    const FViewInfo& View);
 
void RenderLocalFogVolumeVisualization(
    const FScene* Scene,
    TArray<FViewInfo>& Views,
    const FSceneViewFamily& SceneViewFamily,
    FRDGBuilder& GraphBuilder,
    const FMinimalSceneTextures& SceneTextures);