GPUFastFourierTransform.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
GPUFastFourierTransform.h: Interface for Fast Fourier Transform (FFT) on GPU.
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "Math/NumericLimits.h"
#include "GlobalShader.h"
#include "RendererInterface.h"
#include "RHI.h"
#include "RHIStaticStates.h"
#include "Shader.h"
#include "ShaderParameterUtils.h"
 
namespace GPUFFT
{
 
    enum class FFT_XFORM_TYPE : int
    {
        FORWARD_HORIZONTAL = 0,
        FORWARD_VERTICAL   = 1,
        
        INVERSE_HORIZONTAL = 2,
        INVERSE_VERTICAL = 3
    };
 
    static FFT_XFORM_TYPE GetInverseOfXForm(const FFT_XFORM_TYPE& XForm) 
    {
        return  static_cast<FFT_XFORM_TYPE> ((static_cast<int> (XForm) + 2) % 4);
    }
 
    bool IsHorizontal(const FFT_XFORM_TYPE& XFormType);
    
    bool IsForward(const FFT_XFORM_TYPE& XFormType);
 
    class FFTDescription
    {
    public:
        FFTDescription(const FFT_XFORM_TYPE& XForm, const FIntPoint& XFormExtent);
        FFTDescription() {};
 
        // The Transform extent used to construct the description 
        FIntPoint TransformExtent() const;
        bool IsHorizontal() const;
        bool IsForward() const;
        const TCHAR* FFT_TypeName() const;
        
        // member data public
        FFT_XFORM_TYPE  XFormType = FFT_XFORM_TYPE::FORWARD_HORIZONTAL;
        uint32 SignalLength = 0;
        uint32 NumScanLines = 0;
        ERDGPassFlags ComputePassFlags = ERDGPassFlags::Compute;
    };
 
    uint32 MaxScanLineLength();// { return 4096; }
 
    static EPixelFormat PixelFormat() { return PF_A32B32G32R32F; }
 
    typedef FVector3f  FPreFilter;
    static bool IsActive(const FPreFilter& Filter) { return (Filter.X < Filter.Y); }
 
 
    struct ComplexFFTImage1D
    {
        static void MultiPass(
            FRDGBuilder& GraphBuilder,
            const FGlobalShaderMap* ShaderMap,
            const FFTDescription& FFTDesc,
            FRDGTextureSRVRef SrcTexture, const FIntRect& SrcWindow,
            FRDGTextureRef DstTexture,
            FRDGBufferRef PostFilterParameters = nullptr,
            const bool bScrubNaNs = false);
 
    };
    
    
 
    struct TwoForOneRealFFTImage1D
    {
        static void MultiPass(
            FRDGBuilder& GraphBuilder,
            const FGlobalShaderMap* ShaderMap,
            const FFTDescription& FFTDesc,
            FRDGTextureSRVRef SrcTexture, const FIntRect& SrcWindow,
            FRDGTextureRef DstTexture, const FIntRect& DstWindow,
            const FPreFilter& PreFilter = FPreFilter(TNumericLimits<float>::Max(), TNumericLimits<float>::Lowest(), 0.f),
            FRDGBufferRef PostFilterParameters = nullptr);
 
    };
 
    struct ConvolutionWithTextureImage1D
    {
        static void MultiPass(
            FRDGBuilder& GraphBuilder,
            const FGlobalShaderMap* ShaderMap,
            const FFTDescription& FFTDesc,
            FRDGTextureSRVRef SrcTexture, const FIntRect& SrcWindow,
            FRDGTextureRef TransformedKernel,
            FRDGTextureRef DstTexture);
    };
 
 
    void FFTImage2D(
        FRDGBuilder& GraphBuilder,
        const FGlobalShaderMap* ShaderMap,
        const FIntPoint& FrequencySize, bool bHorizontalFirst,
        FRDGTextureSRVRef SrcTexture, const FIntRect& ROIRect,
        FRDGTextureRef ResultTexture);
 
 
 
    
 
    void ConvolutionWithTextureImage2D(
        FRDGBuilder& GraphBuilder,
        ERDGPassFlags ComputePassFlags,
        const FGlobalShaderMap* ShaderMap,
        const FIntPoint& FrequencySize,
        bool bHorizontalFirst,
        FRDGTextureRef TransformedKernel,
        FRDGTextureSRVRef SrcTexture, const FIntRect& ROIRect,
        FRDGTextureRef DstTexture, const FIntRect& DstRect,
        const FPreFilter& PreFilter,
        FRDGBufferRef PostFilterParameters,
        ETextureCreateFlags AdditionalTextureCreateFlags);
 
    FIntPoint Convolution2DBufferSize(const FIntPoint& FrequencySize, const bool bHorizontalFirst, const FIntPoint& SrcExtent);
 
    void CopyImage2D(
        FRDGBuilder& GraphBuilder,
        ERDGPassFlags ComputePassFlags,
        const FGlobalShaderMap* ShaderMap,
        FRDGTextureSRVRef SrcTexture, const FIntRect& SrcWindow,
        FRDGTextureRef DstTexture, const FIntRect& DstWindow,
        const FPreFilter& PreFilter = FPreFilter(TNumericLimits<float>::Max(), TNumericLimits<float>::Lowest(), 0.f));
};