Froxel.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "ShaderParameterMacros.h"
#include "FroxelDefinitions.h"
 
class FRDGBuilder;
class FViewInfo;
 
namespace Froxel
{
 
BEGIN_SHADER_PARAMETER_STRUCT(FSharedParameters, )
    SHADER_PARAMETER(FVector4f, FroxelToViewScaleBias)
    SHADER_PARAMETER(FVector4f, FroxelToClipScaleBias)
    SHADER_PARAMETER(FVector2f, FroxelClipToViewScale)
    SHADER_PARAMETER(float, FroxelRecLog2DepthScale1)
    SHADER_PARAMETER(float, FroxelRecNearScale)
    SHADER_PARAMETER(float, FroxelDepthScale1)
    SHADER_PARAMETER(float, FroxelNear)
    SHADER_PARAMETER(float, FroxelViewToClipTransformScale)
    SHADER_PARAMETER(float, FroxelClipToViewTransformScale)
    SHADER_PARAMETER(float, FroxelClipToViewTransformBias)
    SHADER_PARAMETER(float, FroxelRadius)
    SHADER_PARAMETER(float, FroxelInvRadius)
    SHADER_PARAMETER(uint32, bFroxelIsOrtho)
    SHADER_PARAMETER(uint32, FroxelArgsOffset)
    SHADER_PARAMETER(uint32, FroxelArgsStride)
END_SHADER_PARAMETER_STRUCT()
 
BEGIN_SHADER_PARAMETER_STRUCT(FBuilderParameters, )
    SHADER_PARAMETER_STRUCT_INCLUDE(FSharedParameters, FroxelParameters)
    SHADER_PARAMETER_RDG_BUFFER_UAV(RWStructuredBuffer< FPackedFroxel >, OutFroxels)
    SHADER_PARAMETER_RDG_BUFFER_UAV(RWBuffer< uint >, OutFroxelArgs)
END_SHADER_PARAMETER_STRUCT()
 
BEGIN_SHADER_PARAMETER_STRUCT(FParameters, )
    SHADER_PARAMETER_STRUCT_INCLUDE(FSharedParameters, FroxelParameters)
    SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer< FPackedFroxel >, Froxels)
    SHADER_PARAMETER_RDG_BUFFER_SRV(Buffer< uint >, FroxelArgs)
END_SHADER_PARAMETER_STRUCT()
 
 
FSharedParameters MakeSharedParameters(const FViewInfo &View);
 
// per view froxel data.
struct FViewData
{
    class FRenderer *FroxelData = nullptr;
    FRDGBuffer* FroxelsRDG = nullptr;
    // Represents an argument to use with an indirect dispacth to perform some processing on the froxels. 
    FRDGBuffer* FroxelArgsRDG = nullptr;
    FSharedParameters SharedParameters;
    int32 ArgsOffset = 0;
 
    FBuilderParameters GetBuilderParameters(FRDGBuilder& GraphBuilder) const;
 
    FParameters GetShaderParameters(FRDGBuilder& GraphBuilder) const;
 
};
 
class FRenderer
{
public:
    // Stride in the indirect argument buffer, the 4th slot is used to store the atomic counter of individual froxels (rather than the group).
    static constexpr int32 ArgsStride = 4;
    // Work group size that should be used on an indirect dispatch using the argument produced
    static constexpr int32 IndirectWorkGroupSize = FROXEL_INDIRECT_ARG_WORKGROUP_SIZE;
    static constexpr int32 TileSize = FROXEL_TILE_SIZE; // 8x8 tiles
 
    FRenderer() {}
    FRenderer(bool bIsEnabled, FRDGBuilder& GraphBuilder, const TArray<FViewInfo>& Views);
 
    const FViewData *GetView(int32 ViewIndex) const { return Views.IsValidIndex(ViewIndex) ? &Views[ViewIndex] : nullptr; }
 
    bool IsEnabled() const { return !Views.IsEmpty(); }
 
private:
    TArray<FViewData> Views;
};
 
} // namespace froxel