GPUFeedbackCompaction.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "GlobalShader.h"
#include "ShaderParameterStruct.h"
 
// Setups FBuildFeedbackHashTableCS arguments to run one lane per feedback element
class FBuildFeedbackHashTableIndirectArgsCS : public FGlobalShader
{
    DECLARE_GLOBAL_SHADER(FBuildFeedbackHashTableIndirectArgsCS);
    SHADER_USE_PARAMETER_STRUCT(FBuildFeedbackHashTableIndirectArgsCS, FGlobalShader);
 
    BEGIN_SHADER_PARAMETER_STRUCT(FParameters, )
        SHADER_PARAMETER_RDG_BUFFER_UAV(RWBuffer<uint>, RWBuildHashTableIndirectArgs)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, FeedbackBufferAllocator)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, FeedbackBuffer)
        SHADER_PARAMETER(uint32, FeedbackBufferSize)
    END_SHADER_PARAMETER_STRUCT()
 
    class FFeedbackBufferStride : SHADER_PERMUTATION_RANGE_INT("FEEDBACK_BUFFER_STRIDE", 1, 2);
    using FPermutationDomain = TShaderPermutationDomain<FFeedbackBufferStride>;
 
    static bool ShouldCompilePermutation(const FGlobalShaderPermutationParameters& Parameters);
    static void ModifyCompilationEnvironment(const FGlobalShaderPermutationParameters& Parameters, FShaderCompilerEnvironment& OutEnvironment);
};
 
// Takes a list of feedback elements and builds a hash table with element counts
class FBuildFeedbackHashTableCS : public FGlobalShader
{
    DECLARE_GLOBAL_SHADER(FBuildFeedbackHashTableCS)
    SHADER_USE_PARAMETER_STRUCT(FBuildFeedbackHashTableCS, FGlobalShader);
 
    BEGIN_SHADER_PARAMETER_STRUCT(FParameters, )
        RDG_BUFFER_ACCESS(BuildHashTableIndirectArgs, ERHIAccess::IndirectArgs)
        SHADER_PARAMETER_RDG_BUFFER_UAV(RWStructuredBuffer<uint>, RWHashTableKeys)
        SHADER_PARAMETER_RDG_BUFFER_UAV(RWStructuredBuffer<uint>, RWHashTableElementIndices)
        SHADER_PARAMETER_RDG_BUFFER_UAV(RWStructuredBuffer<uint>, RWHashTableElementCounts)
        SHADER_PARAMETER(uint32, HashTableSize)
        SHADER_PARAMETER(uint32, HashTableIndexWrapMask)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, FeedbackBufferAllocator)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, FeedbackBuffer)
        SHADER_PARAMETER(uint32, FeedbackBufferSize)
    END_SHADER_PARAMETER_STRUCT()
 
    class FFeedbackBufferStride : SHADER_PERMUTATION_RANGE_INT("FEEDBACK_BUFFER_STRIDE", 1, 2);
    using FPermutationDomain = TShaderPermutationDomain<FFeedbackBufferStride>;
 
    static uint32 GetGroupSize() { return 64; }
    static bool ShouldCompilePermutation(const FGlobalShaderPermutationParameters& Parameters);
    static void ModifyCompilationEnvironment(const FGlobalShaderPermutationParameters& Parameters, FShaderCompilerEnvironment& OutEnvironment);
};
 
// Compacts feedback element hash table into a unique and tightly packed array of feedback elements with counts
class FCompactFeedbackHashTableCS : public FGlobalShader
{
    DECLARE_GLOBAL_SHADER(FCompactFeedbackHashTableCS)
    SHADER_USE_PARAMETER_STRUCT(FCompactFeedbackHashTableCS, FGlobalShader);
 
    BEGIN_SHADER_PARAMETER_STRUCT(FParameters, )
        SHADER_PARAMETER_RDG_BUFFER_UAV(RWStructuredBuffer<uint2>, RWCompactedFeedbackBuffer)
        SHADER_PARAMETER(uint32, CompactedFeedbackBufferSize)
        SHADER_PARAMETER(uint32, CompactedFeedbackCountShiftBits)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, HashTableElementIndices)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, HashTableElementCounts)
        SHADER_PARAMETER(uint32, HashTableSize)
        SHADER_PARAMETER(uint32, HashTableIndexWrapMask)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, FeedbackBufferAllocator)
        SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<uint>, FeedbackBuffer)
        SHADER_PARAMETER(uint32, FeedbackBufferSize)
    END_SHADER_PARAMETER_STRUCT()
 
    class FFeedbackBufferStride : SHADER_PERMUTATION_RANGE_INT("FEEDBACK_BUFFER_STRIDE", 1, 2);
    using FPermutationDomain = TShaderPermutationDomain<FFeedbackBufferStride>;
 
    static uint32 GetGroupSize() { return 64; }
    static bool ShouldCompilePermutation(const FGlobalShaderPermutationParameters& Parameters);
    static void ModifyCompilationEnvironment(const FGlobalShaderPermutationParameters& Parameters, FShaderCompilerEnvironment& OutEnvironment);
};