CustomRenderPass.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    CustomRenderPass.h: Custom render pass implementation.
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "RenderGraphFwd.h"
#include "Engine/EngineTypes.h"
 
// ----------------------------------------------------------------------------------
class ICustomRenderPass
{
public:
    virtual ~ICustomRenderPass() {}
 
    virtual const FName& GetTypeName() const PURE_VIRTUAL(ICustomRenderPass::GetTypeName, static FName Name; return Name;);
};
 
#define IMPLEMENT_CUSTOM_RENDER_PASS(TypeName) const FName& GetTypeName() const override { return GetTypeNameStatic(); } \
    static const FName& GetTypeNameStatic() { static FName Name(TEXT(#TypeName)); return Name; }
 
 
// ----------------------------------------------------------------------------------
class ICustomRenderPassUserData
{
public:
    virtual ~ICustomRenderPassUserData() {}
    virtual const FName& GetTypeName() const PURE_VIRTUAL(ICustomRenderPassUserData::GetTypeName, static FName Name; return Name;);
};
 
#define IMPLEMENT_CUSTOM_RENDER_PASS_USER_DATA(TypeName) const FName& GetTypeName() const override { return GetTypeNameStatic(); } \
    static const FName& GetTypeNameStatic() { static FName Name(TEXT(#TypeName)); return Name; }
 
 
// ----------------------------------------------------------------------------------
class FCustomRenderPassBase : public ICustomRenderPass
{
public:
    friend class FSceneRenderer;
    friend class FDeferredShadingSceneRenderer;
 
    enum class ERenderMode : uint8
    {
        DepthPass,
        DepthAndBasePass
    };
 
    enum class ERenderOutput : uint8
    {
        SceneDepth,
        DeviceDepth,
        SceneColorAndDepth,
        SceneColorAndAlpha, // The alpha is inverted opacity (throughput).
        SceneColorNoAlpha,
        BaseColor,
        Normal,
        MAX
    };
 
    enum class ERenderCaptureType
    {
        NoCapture, 
        Capture,
        BeginCapture,
        EndCapture,
    };
 
    FCustomRenderPassBase() = delete;
    ENGINE_API FCustomRenderPassBase(const FString& InDebugName, ERenderMode InRenderMode, ERenderOutput InRenderOutput, const FIntPoint& InRenderTargetSize);
 
    virtual ~FCustomRenderPassBase() {}
    
    ENGINE_API void BeginPass(FRDGBuilder& GraphBuilder);
    ENGINE_API void PreRender(FRDGBuilder& GraphBuilder);
    ENGINE_API void PostRender(FRDGBuilder& GraphBuilder);
    ENGINE_API void EndPass(FRDGBuilder& GraphBuilder);
 
    ENGINE_API ESceneCaptureSource GetSceneCaptureSource() const;
 
    ENGINE_API void PerformRenderCapture(ERenderCaptureType InRenderCaptureType, const FString& InFileName = FString());
 
    const FString& GetDebugName() const { return DebugName; }
    ERenderMode GetRenderMode() const { return RenderMode; }
    ERenderOutput GetRenderOutput() const { return RenderOutput; }
    FRDGTextureRef GetRenderTargetTexture() const { return RenderTargetTexture; }
    const FIntPoint& GetRenderTargetSize() const { return RenderTargetSize; }
 
    bool IsTranslucentIncluded() const
    {
        return bSceneColorWithTranslucent &&
            (RenderOutput == FCustomRenderPassBase::ERenderOutput::SceneColorAndAlpha ||
             RenderOutput == FCustomRenderPassBase::ERenderOutput::SceneColorNoAlpha ||
             RenderOutput == FCustomRenderPassBase::ERenderOutput::SceneColorAndDepth ||
             bSceneColorIsUserSceneTexture);
    }
 
    ENGINE_API void SetUserData(TUniquePtr<ICustomRenderPassUserData>&& InUserData);
    ENGINE_API ICustomRenderPassUserData* GetUserData(const FName& InTypeName) const;
 
    template <typename UserDataType>
    typename TEnableIf<TPointerIsConvertibleFromTo<UserDataType, ICustomRenderPassUserData>::Value, UserDataType>::Type* GetUserDataTyped() const
    {
        if (ICustomRenderPassUserData* UserData = GetUserData(UserDataType::GetTypeNameStatic()))
        {
            return reinterpret_cast<UserDataType*>(UserData);
        }
        return nullptr;
    }
 
protected:
    virtual void OnBeginPass(FRDGBuilder& GraphBuilder) {}
    virtual void OnPreRender(FRDGBuilder& GraphBuilder) {}
    virtual void OnPostRender(FRDGBuilder& GraphBuilder) {}
    virtual void OnEndPass(FRDGBuilder& GraphBuilder) {}
 
    void OverrideRenderOutput(ERenderOutput InRenderOutput)
    {
        RenderOutput = InRenderOutput;
    }
 
protected:
    FString DebugName;
    ERenderMode RenderMode = ERenderMode::DepthPass;
    ERenderOutput RenderOutput = ERenderOutput::SceneDepth;
    bool bSceneColorWithTranslucent = false;
 
    // If the SceneColor generated by this Custom Render Pass is referenced as a UserSceneTexture, translucency should render if enabled,
    // even if RenderOutput is not SceneColor.  Otherwise, translucency is disabled with the assumption it's wasteful to render translucency
    // to a SceneColor buffer that's not used.  See IsTranslucentIncluded() function above.
    bool bSceneColorIsUserSceneTexture = false;
 
    FRDGTextureRef RenderTargetTexture = nullptr;
    FIntPoint RenderTargetSize = FIntPoint(ForceInit);
 
    TArray<class FViewInfo*> Views;
 
    TMap<FName, TUniquePtr<ICustomRenderPassUserData>> UserDatas;
 
private:
    ERenderCaptureType RenderCaptureType = ERenderCaptureType::NoCapture;
    FString RenderCaptureFileName;
};