ScreenSpaceDenoise.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "RenderGraph.h"
#include "IndirectLightRendering.h"
 
 
class FViewInfo;
struct FPreviousViewInfo;
class FLightSceneInfo;
class FSceneTextureParameters;
 
 
// TODO(Denoiser): namespace.
 
static const int32 kMaxDenoiserBufferProcessingCount = 4;
 
 
namespace Denoiser
{
 
BEGIN_SHADER_PARAMETER_STRUCT(FCommonShaderParameters, )
    SHADER_PARAMETER(FVector4f, DenoiserBufferSizeAndInvSize)
    SHADER_PARAMETER(FVector4f, DenoiserBufferBilinearUVMinMax)
    SHADER_PARAMETER(FVector4f, SceneBufferUVToScreenPosition) // TODO: move to view uniform buffer
END_SHADER_PARAMETER_STRUCT()
 
void SetupCommonShaderParameters(
    const FViewInfo& View,
    const FSceneTextureParameters& SceneTextures,
    const FIntRect DenoiserFullResViewport,
    float DenoisingResolutionFraction,
    FCommonShaderParameters* OutPublicCommonParameters);
 
} // namespace Denoiser
 
 
BEGIN_SHADER_PARAMETER_STRUCT(FSSDSignalTextures, )
    SHADER_PARAMETER_RDG_TEXTURE_ARRAY(Texture2D, Textures, [kMaxDenoiserBufferProcessingCount])
END_SHADER_PARAMETER_STRUCT()
 
 
class IScreenSpaceDenoiser
{
public:
    static const int32 kMaxBatchSize = 4;
 
    // Number of screen space harmonic to be feed when denoising multiple lights.
    static constexpr int32 kMultiPolychromaticPenumbraHarmonics = 4;
 
    // Number of border between screen space harmonics are used to denoise harmonical signal.
    static constexpr int32 kHarmonicBordersCount = kMultiPolychromaticPenumbraHarmonics + 1;
 
    // Number of texture to store spherical harmonics.
    static constexpr int32 kSphericalHarmonicTextureCount = 2;
 
 
    enum class EMode
    {
        // Denoising is disabled.
        Disabled,
 
        // Using default denoiser of the renderer.
        DefaultDenoiser,
 
        // Using a denoiser from a third party.
        ThirdPartyDenoiser,
    };
 
 
    BEGIN_SHADER_PARAMETER_STRUCT(FShadowVisibilityInputs, )
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Mask)
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, ClosestOccluder)
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FShadowVisibilityOutputs, )
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Mask)
    END_SHADER_PARAMETER_STRUCT()
        
    BEGIN_SHADER_PARAMETER_STRUCT(FHarmonicTextures, )
        SHADER_PARAMETER_RDG_TEXTURE_ARRAY(Texture2D, Harmonics, [kHarmonicBordersCount])
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FHarmonicUAVs, )
        SHADER_PARAMETER_RDG_TEXTURE_UAV_ARRAY(Texture2D, Harmonics, [kHarmonicBordersCount])
    END_SHADER_PARAMETER_STRUCT()
        
    BEGIN_SHADER_PARAMETER_STRUCT(FPolychromaticPenumbraHarmonics, )
        SHADER_PARAMETER_STRUCT(FHarmonicTextures, Diffuse)
        SHADER_PARAMETER_STRUCT(FHarmonicTextures, Specular)
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FPolychromaticPenumbraOutputs, )
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Diffuse)
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Specular)
    END_SHADER_PARAMETER_STRUCT()
        
    BEGIN_SHADER_PARAMETER_STRUCT(FReflectionsInputs, )
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Color)
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, RayHitDistance)
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, RayImaginaryDepth)
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FReflectionsOutputs, )
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Color)
    END_SHADER_PARAMETER_STRUCT()
        
    BEGIN_SHADER_PARAMETER_STRUCT(FAmbientOcclusionInputs, )
        // TODO: Merge this back to MaskAndRayHitDistance into RG texture for performance improvement of denoiser's reconstruction pass. May also support RayDistanceOnly for 1spp AO ray tracing.
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Mask)
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, RayHitDistance)
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FAmbientOcclusionOutputs, )
        // Ambient occlusion mask stored in the red channel as [0; 1].
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, AmbientOcclusionMask)
    END_SHADER_PARAMETER_STRUCT()
        
    BEGIN_SHADER_PARAMETER_STRUCT(FDiffuseIndirectInputs, )
        // Irradiance in RGB, AO mask in alpha.
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Color)
 
        // Ambient occlusion mask stored in the red channel as [0; 1].
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, AmbientOcclusionMask)
 
        // Hit distance in world space.
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, RayHitDistance)
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FDiffuseIndirectOutputs, )
        // Irradiance in RGB, AO mask in alpha.
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, Color)
        
        // Ambient occlusion mask stored in the red channel as [0; 1].
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, AmbientOcclusionMask)
    END_SHADER_PARAMETER_STRUCT()
        
    BEGIN_SHADER_PARAMETER_STRUCT(FDiffuseIndirectHarmonic, )
        SHADER_PARAMETER_RDG_TEXTURE_ARRAY(Texture2D, SphericalHarmonic, [kSphericalHarmonicTextureCount])
    END_SHADER_PARAMETER_STRUCT()
 
    BEGIN_SHADER_PARAMETER_STRUCT(FDiffuseIndirectHarmonicUAVs, )
        SHADER_PARAMETER_RDG_TEXTURE_UAV_ARRAY(RWTexture2D, SphericalHarmonic, [kSphericalHarmonicTextureCount])
    END_SHADER_PARAMETER_STRUCT()
 
        
    enum class EShadowRequirements
    {
        // Denoiser is unable to denoise that configuration.
        Bailout,
 
        // Denoiser only need ray hit distance and the diffuse mask of the penumbra.
        // FShadowPenumbraInputs::Penumbra: average diffuse penumbra mask in [0; 1]
        // FShadowPenumbraInputs::ClosestOccluder:
        //   -1: invalid sample
        //   >0: average hit distance of occluding geometry
        PenumbraAndAvgOccluder,
 
        PenumbraAndClosestOccluder,
    };
 
    struct FShadowRayTracingConfig
    {
        // Number of rays per pixels.
        int32 RayCountPerPixel = 1;
    };
 
    struct FShadowVisibilityParameters
    {
        const FLightSceneInfo* LightSceneInfo = nullptr;
        FShadowRayTracingConfig RayTracingConfig;
        FShadowVisibilityInputs InputTextures;
    };
 
    struct FReflectionsRayTracingConfig
    {
        // Resolution fraction the ray tracing is being traced at.
        float ResolutionFraction = 1.0f;
        
        // Number of rays per pixels.
        int32 RayCountPerPixel = 1;
    };
    
    struct FAmbientOcclusionRayTracingConfig
    {
        // Resolution fraction the ray tracing is being traced at.
        float ResolutionFraction = 1.0f;
 
        // Number of rays per pixels.
        float RayCountPerPixel = 1.0f;
    };
    
 
    static RENDERER_API FHarmonicTextures CreateHarmonicTextures(FRDGBuilder& GraphBuilder, FIntPoint Extent, const TCHAR* DebugName);
    static RENDERER_API FHarmonicUAVs CreateUAVs(FRDGBuilder& GraphBuilder, const FHarmonicTextures& Textures);
    static RENDERER_API FDiffuseIndirectHarmonicUAVs CreateUAVs(FRDGBuilder& GraphBuilder, const FDiffuseIndirectHarmonic& Textures);
 
 
 
    virtual ~IScreenSpaceDenoiser() {};
 
    virtual const TCHAR* GetDebugName() const = 0;
 
    virtual EShadowRequirements GetShadowRequirements(
        const FViewInfo& View,
        const FLightSceneInfo& LightSceneInfo,
        const FShadowRayTracingConfig& RayTracingConfig) const = 0;
 
    // TODO(Denoiser): Denoise specular occlusion. But requires refactor of direct lighting code.
    virtual void DenoiseShadowVisibilityMasks(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const TStaticArray<FShadowVisibilityParameters, IScreenSpaceDenoiser::kMaxBatchSize>& InputParameters,
        const int32 InputParameterCount,
        TStaticArray<FShadowVisibilityOutputs, IScreenSpaceDenoiser::kMaxBatchSize>& Outputs) const = 0;
 
    virtual FPolychromaticPenumbraOutputs DenoisePolychromaticPenumbraHarmonics(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FPolychromaticPenumbraHarmonics& Inputs) const = 0;
 
    virtual FReflectionsOutputs DenoiseReflections(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FReflectionsInputs& ReflectionInputs,
        const FReflectionsRayTracingConfig RayTracingConfig) const = 0;
 
    virtual FReflectionsOutputs DenoiseWaterReflections(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FReflectionsInputs& ReflectionInputs,
        const FReflectionsRayTracingConfig RayTracingConfig) const = 0;
    
    virtual FAmbientOcclusionOutputs DenoiseAmbientOcclusion(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FAmbientOcclusionInputs& ReflectionInputs,
        const FAmbientOcclusionRayTracingConfig RayTracingConfig) const = 0;
 
    virtual FSSDSignalTextures DenoiseDiffuseIndirect(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FDiffuseIndirectInputs& Inputs,
        const FAmbientOcclusionRayTracingConfig Config) const = 0;
 
    virtual FDiffuseIndirectOutputs DenoiseSkyLight(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FDiffuseIndirectInputs& Inputs,
        const FAmbientOcclusionRayTracingConfig Config) const = 0;
 
    virtual FSSDSignalTextures DenoiseDiffuseIndirectHarmonic(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FDiffuseIndirectHarmonic& Inputs,
        const HybridIndirectLighting::FCommonParameters& CommonDiffuseParameters) const = 0;
 
    virtual bool SupportsScreenSpaceDiffuseIndirectDenoiser(EShaderPlatform Platform) const = 0;
    virtual FSSDSignalTextures DenoiseScreenSpaceDiffuseIndirect(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FDiffuseIndirectInputs& Inputs,
        const FAmbientOcclusionRayTracingConfig Config) const = 0;
 
    static RENDERER_API FSSDSignalTextures DenoiseIndirectProbeHierarchy(
        FRDGBuilder& GraphBuilder,
        const FViewInfo& View,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FSSDSignalTextures& InputSignal,
        FRDGTextureRef CompressedDepthTexture,
        FRDGTextureRef CompressedShadingModelTexture);
 
    static RENDERER_API const IScreenSpaceDenoiser* GetDefaultDenoiser();
 
    static RENDERER_API EMode GetDenoiserMode(const TAutoConsoleVariable<int32>& CVar);
 
    static RENDERER_API FDiffuseIndirectOutputs DenoiseSkyLight(
        FRDGBuilder& GraphBuilder,
        TConstArrayView<FViewInfo> Views,
        FPreviousViewInfo* PreviousViewInfos,
        const FSceneTextureParameters& SceneTextures,
        const FDiffuseIndirectInputs& Inputs,
        const FAmbientOcclusionRayTracingConfig Config);
 
}; // class IScreenSpaceDenoiser
 
 
// The interface for the renderer to denoise what it needs, Plugins can come and point this to custom interface.
extern RENDERER_API const IScreenSpaceDenoiser* GScreenSpaceDenoiser;
 
extern int GetReflectionsDenoiserMode();