DecalRenderingCommon.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Materials/Material.h"
#include "RenderUtils.h"
#include "MeshPassProcessor.h"
 
class FMaterial;
class FRHIBlendState;
class FRHIRasterizerState;
struct FMaterialShaderParameters;
struct FShaderCompilerEnvironment;
 
union FDecalBlendDesc
{
    uint32 Packed = 0;
 
    struct
    {
        uint32 BlendMode : 8;
        uint32 RenderStageMask : 8;
        uint32 bWriteBaseColor : 1;
        uint32 bWriteNormal : 1;
        uint32 bWriteRoughnessSpecularMetallic : 1;
        uint32 bWriteEmissive : 1;
        uint32 bWriteAmbientOcclusion : 1;
        uint32 bWriteDBufferMask : 1;
    };
};
 
enum class EDecalRenderStage : uint8
{
    None = 0,
 
    // DBuffer decal pass.
    BeforeBasePass = 1,
    // GBuffer decal pass.
    BeforeLighting = 2,
 
    // Mobile decal pass with limited functionality.
    Mobile = 3,
    // Mobile decal pass for mobile deferred platforms.
    MobileBeforeLighting = 4,
 
    // Emissive decal pass.
    // DBuffer decals with an emissive component will use this pass.
    Emissive = 5,
    // Ambient occlusion decal pass.
    // A decal can write regular attributes in another pass and then AO in this pass.
    AmbientOcclusion = 6,
 
    Num,
};
 
enum class EDecalRenderTargetMode : uint8
{
    None = 0,
 
    DBuffer = 1,
    SceneColorAndGBuffer = 2,
    // GBuffer with no normal is necessary for decals sampling the normal from the GBuffer.
    SceneColorAndGBufferNoNormal = 3,
    SceneColor = 4,
    AmbientOcclusion = 5,
 
    Num,
};
 
enum class EDecalRasterizerState : uint8
{
    Undefined,
    CCW,
    CW,
};
 
namespace DecalRendering
{
    FDecalBlendDesc ComputeDecalBlendDesc(EShaderPlatform Platform, const FMaterial& Material);
 
    FDecalBlendDesc ComputeDecalBlendDesc(EShaderPlatform Platform, FMaterialShaderParameters const& MaterialShaderParameters);
 
    bool IsCompatibleWithRenderStage(FDecalBlendDesc DecalBlendDesc, EDecalRenderStage DecalRenderStage);
 
    EDecalRenderStage GetRenderStage(EDecalRenderTargetMode RenderTargetMode, EShadingPath ShadingPath);
 
    EDecalRenderStage GetBaseRenderStage(FDecalBlendDesc DecalBlendDesc);
 
    EDecalRenderTargetMode GetRenderTargetMode(FDecalBlendDesc DecalBlendDesc, EDecalRenderStage DecalRenderStage);
 
    uint8 GetDecalRenderTargetModeMask(const FMaterial& Material, ERHIFeatureLevel::Type FeatureLevel);
 
    bool IsCompatibleWithRenderTargetMode(uint8 DecalRenderTargetModeMask, EDecalRenderTargetMode DecalRenderTargetMode);
 
    EMeshPass::Type GetMeshPassType(EDecalRenderTargetMode RenderTargetMode);
 
    uint32 GetRenderTargetCount(FDecalBlendDesc DecalBlendDesc, EDecalRenderTargetMode RenderTargetMode);
 
    uint32 GetRenderTargetWriteMask(FDecalBlendDesc DecalBlendDesc, EDecalRenderStage DecalRenderStage, EDecalRenderTargetMode RenderTargetMode);
 
    FRHIBlendState* GetDecalBlendState(FDecalBlendDesc DecalBlendDesc, EDecalRenderStage DecalRenderStage, EDecalRenderTargetMode RenderTargetMode);
 
    EDecalRasterizerState GetDecalRasterizerState(bool bInsideDecal, bool bIsInverted, bool ViewReverseCulling);
 
    FRHIRasterizerState* GetDecalRasterizerState(EDecalRasterizerState DecalRasterizerState);
 
    void ModifyCompilationEnvironment(EShaderPlatform Platform, FDecalBlendDesc DecalBlendDesc, EDecalRenderStage DecalRenderStage, FShaderCompilerEnvironment& OutEnvironment);
};