VelocityRendering.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "RHI.h"
#include "HitProxies.h"
#include "RendererInterface.h"
#include "DepthRendering.h"
 
class FPrimitiveSceneInfo;
class FPrimitiveSceneProxy;
class FScene;
class FStaticMeshBatch;
class FViewInfo;
 
struct FPrimitiveViewRelevance;
 
enum class EVelocityPass : uint32
{
    // Renders a separate velocity pass for opaques.
    Opaque = 0,
 
    // Renders a separate velocity / depth pass for translucency AFTER the translucent pass.
    Translucent,
 
    // Renders a secondary translucent velocity / depth pass for pixels that are clipped by opacity mask clip value (e.g., write has pixel animation mask).
    TranslucentClippedDepth,
 
    Count
};
 
EMeshPass::Type GetMeshPassFromVelocityPass(EVelocityPass VelocityPass);
 
// Group Velocity Rendering accessors, types, etc.
struct FVelocityRendering
{
    static EPixelFormat GetFormat(EShaderPlatform ShaderPlatform);
 
    static ETextureCreateFlags GetCreateFlags(EShaderPlatform ShaderPlatform);
    
    static FRDGTextureDesc GetRenderTargetDesc(EShaderPlatform ShaderPlatform, FIntPoint Extent, const bool bRequireMultiView = false);
 
    static bool IsVelocityPassSupported(EShaderPlatform ShaderPlatform);
 
    static bool DepthPassCanOutputVelocity(ERHIFeatureLevel::Type FeatureLevel);
 
    static bool BasePassCanOutputVelocity(EShaderPlatform ShaderPlatform);
 
    static bool IsParallelVelocity(EShaderPlatform ShaderPlatform);
};
 
class FVelocityMeshProcessor : public FMeshPassProcessor
{
public:
    FVelocityMeshProcessor(
        EMeshPass::Type MeshPassType,
        const FScene* Scene,
        ERHIFeatureLevel::Type FeatureLevel,
        const FSceneView* InViewIfDynamicMeshCommand,
        const FMeshPassProcessorRenderState& InPassDrawRenderState,
        FMeshPassDrawListContext* InDrawListContext);
 
    FMeshPassProcessorRenderState PassDrawRenderState;
 
    /* Checks whether the primitive should emit velocity for the current view by comparing screen space size against a threshold. */
    static bool PrimitiveHasVelocityForView(const FViewInfo& View, const FPrimitiveSceneProxy* PrimitiveSceneProxy);
 
protected:
    bool Process(
        const FMeshBatch& MeshBatch,
        uint64 BatchElementMask,
        int32 StaticMeshId,
        const FPrimitiveSceneProxy* RESTRICT PrimitiveSceneProxy,
        const FMaterialRenderProxy& RESTRICT MaterialRenderProxy,
        const FMaterial& RESTRICT MaterialResource,
        ERasterizerFillMode MeshFillMode,
        ERasterizerCullMode MeshCullMode);
 
    bool CollectPSOInitializersInternal(
        const FSceneTexturesConfig& SceneTexturesConfig,
        const FPSOPrecacheVertexFactoryData& VertexFactoryData,
        const FMaterial& RESTRICT MaterialResource,
        ERasterizerFillMode MeshFillMode,
        ERasterizerCullMode MeshCullMode,
        TArray<FPSOPrecacheData>& PSOInitializers);
 
protected:
    EDepthDrawingMode EarlyZPassMode = DDM_None;
    EMeshPass::Type MeshPassType = EMeshPass::Type::Num;
};
 
class FOpaqueVelocityMeshProcessor : public FSceneRenderingAllocatorObject<FOpaqueVelocityMeshProcessor>, public FVelocityMeshProcessor
{
public:
    FOpaqueVelocityMeshProcessor(
        const FScene* Scene,
        ERHIFeatureLevel::Type FeatureLevel,
        const FSceneView* InViewIfDynamicMeshCommand,
        const FMeshPassProcessorRenderState& InPassDrawRenderState,
        FMeshPassDrawListContext* InDrawListContext,
        EDepthDrawingMode InEarlyZPassMode);
 
    static bool PrimitiveCanHaveVelocity(EShaderPlatform ShaderPlatform, const FPrimitiveSceneProxy* PrimitiveSceneProxy);
    static bool PrimitiveCanHaveVelocity(EShaderPlatform ShaderPlatform, bool bDrawVelocity, bool bHasStaticLighting);
 
    static bool PrimitiveHasVelocityForFrame(EShaderPlatform ShaderPlatform, const FPrimitiveSceneProxy* PrimitiveSceneProxy);
 
private:
    bool TryAddMeshBatch(
        const FMeshBatch& RESTRICT MeshBatch,
        uint64 BatchElementMask,
        const FPrimitiveSceneProxy* RESTRICT PrimitiveSceneProxy,
        int32 StaticMeshId,
        const FMaterialRenderProxy* MaterialRenderProxy,
        const FMaterial* Material);
 
    virtual void AddMeshBatch(
        const FMeshBatch& RESTRICT MeshBatch,
        uint64 BatchElementMask,
        const FPrimitiveSceneProxy* RESTRICT PrimitiveSceneProxy,
        int32 StaticMeshId = -1) override final;
 
    virtual void CollectPSOInitializers(
        const FSceneTexturesConfig& SceneTexturesConfig,
        const FMaterial& Material,
        const FPSOPrecacheVertexFactoryData& VertexFactoryData,
        const FPSOPrecacheParams& PreCacheParams,
        TArray<FPSOPrecacheData>& PSOInitializers) override final;
};
 
class FTranslucentVelocityMeshProcessor : public FSceneRenderingAllocatorObject<FTranslucentVelocityMeshProcessor>, public FVelocityMeshProcessor
{
public:
    FTranslucentVelocityMeshProcessor(
        const FScene* Scene,
        ERHIFeatureLevel::Type FeatureLevel,
        const FSceneView* InViewIfDynamicMeshCommand,
        const FMeshPassProcessorRenderState& InPassDrawRenderState,
        FMeshPassDrawListContext* InDrawListContext,
        EMeshPass::Type Meshpass);
 
    static bool PrimitiveCanHaveVelocity(EShaderPlatform ShaderPlatform, const FPrimitiveSceneProxy* PrimitiveSceneProxy);
 
    static bool PrimitiveHasVelocityForFrame(const FPrimitiveSceneProxy* PrimitiveSceneProxy);
 
private:
    bool TryAddMeshBatch(
        const FMeshBatch& RESTRICT MeshBatch,
        uint64 BatchElementMask,
        const FPrimitiveSceneProxy* RESTRICT PrimitiveSceneProxy,
        int32 StaticMeshId,
        const FMaterialRenderProxy* MaterialRenderProxy,
        const FMaterial* Material);
 
    virtual void AddMeshBatch(
        const FMeshBatch& RESTRICT MeshBatch,
        uint64 BatchElementMask,
        const FPrimitiveSceneProxy* RESTRICT PrimitiveSceneProxy,
        int32 StaticMeshId = -1) override final;
 
    virtual void CollectPSOInitializers(
        const FSceneTexturesConfig& SceneTexturesConfig,
        const FMaterial& Material, 
        const FPSOPrecacheVertexFactoryData& VertexFactoryData,
        const FPSOPrecacheParams& PreCacheParams,
        TArray<FPSOPrecacheData>& PSOInitializers) override final;
};