MeshDrawCommands.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
MeshDrawCommands.h: Mesh draw commands.
=============================================================================*/
 
#pragma once
 
#include "MeshPassProcessor.h"
#include "TranslucentPassResource.h"
#include "InstanceCulling/InstanceCullingContext.h"
#include "InstanceCulling/InstanceCullingManager.h"
#include "ScenePrivateBase.h"
 
struct FMeshBatchAndRelevance;
class FStaticMeshBatch;
class FParallelCommandListSet;
class FInstanceCullingManager;
 
struct FPrimitiveIdVertexBufferPoolEntry
{
    int32 BufferSize = 0;
    uint32 LastDiscardId = 0;
    FBufferRHIRef BufferRHI;
};
 
class FPrimitiveIdVertexBufferPool : public FRenderResource
{
public:
    FPrimitiveIdVertexBufferPool();
    ~FPrimitiveIdVertexBufferPool();
 
    FPrimitiveIdVertexBufferPoolEntry Allocate(FRHICommandList& RHICmdList, int32 BufferSize);
    void ReturnToFreeList(FPrimitiveIdVertexBufferPoolEntry Entry);
    RENDERER_API void DiscardAll();
 
    virtual void ReleaseRHI() override;
 
private:
    uint32 DiscardId;
    TArray<FPrimitiveIdVertexBufferPoolEntry> Entries;
    FCriticalSection AllocationCS;
};
 
extern RENDERER_API TGlobalResource<FPrimitiveIdVertexBufferPool> GPrimitiveIdVertexBufferPool;
 
class FMeshDrawCommandPassSetupTaskContext
{
public:
    FMeshDrawCommandPassSetupTaskContext();
 
    const FViewInfo* View;
    const FScene* Scene;
    EShadingPath ShadingPath;
    EShaderPlatform ShaderPlatform;
    EMeshPass::Type PassType;
    bool bUseGPUScene;
    bool bDynamicInstancing;
    bool bReverseCulling;
    bool bRenderSceneTwoSided;
    FExclusiveDepthStencil::Type BasePassDepthStencilAccess;
    FExclusiveDepthStencil::Type DefaultBasePassDepthStencilAccess;
 
    // Mesh pass processor.
    FMeshPassProcessor* MeshPassProcessor;
    FMeshPassProcessor* MobileBasePassCSMMeshPassProcessor;
    const TArray<FMeshBatchAndRelevance, SceneRenderingAllocator>* DynamicMeshElements;
    const TArray<FMeshPassMask, SceneRenderingAllocator>* DynamicMeshElementsPassRelevance;
 
    // Commands.
    int32 InstanceFactor;
    int32 NumDynamicMeshElements;
    int32 NumDynamicMeshCommandBuildRequestElements;
    FMeshCommandOneFrameArray MeshDrawCommands;
    FMeshCommandOneFrameArray MobileBasePassCSMMeshDrawCommands;
    TArray<const FStaticMeshBatch*, SceneRenderingAllocator> DynamicMeshCommandBuildRequests;
    TArray<EMeshDrawCommandCullingPayloadFlags, SceneRenderingAllocator> DynamicMeshCommandBuildFlags;
    TArray<const FStaticMeshBatch*, SceneRenderingAllocator> MobileBasePassCSMDynamicMeshCommandBuildRequests;
    FDynamicMeshDrawCommandStorage MeshDrawCommandStorage;
    FGraphicsMinimalPipelineStateSet MinimalPipelineStatePassSet;
    bool NeedsShaderInitialisation;
 
    // Resources preallocated on rendering thread.
    FMeshCommandOneFrameArray TempVisibleMeshDrawCommands;
 
    // For UpdateTranslucentMeshSortKeys.
    ETranslucencyPass::Type TranslucencyPass;
    ETranslucentSortPolicy::Type TranslucentSortPolicy;
    FVector TranslucentSortAxis;
    FVector ViewOrigin;
    FMatrix ViewMatrix;
    const TScenePrimitiveArray<struct FPrimitiveBounds>* PrimitiveBounds;
 
    // For logging instancing stats.
    int32 VisibleMeshDrawCommandsNum;
    int32 NewPassVisibleMeshDrawCommandsNum;
    int32 MaxInstances;
 
    FInstanceCullingContext InstanceCullingContext;
};
 
class FParallelMeshDrawCommandPass
{
public:
    FParallelMeshDrawCommandPass()
        : bHasInstanceCullingDrawParameters(false)
        , MaxNumDraws(0)
    {
    }
 
    ~FParallelMeshDrawCommandPass();
 
    void DispatchPassSetup(
        FScene* Scene,
        const FViewInfo& View, 
        FInstanceCullingContext &&InstanceCullingContext,
        EMeshPass::Type PassType, 
        FExclusiveDepthStencil::Type BasePassDepthStencilAccess,
        FMeshPassProcessor* MeshPassProcessor,
        const TArray<FMeshBatchAndRelevance, SceneRenderingAllocator>& DynamicMeshElements,
        const TArray<FMeshPassMask, SceneRenderingAllocator>* DynamicMeshElementsPassRelevance,
        int32 NumDynamicMeshElements,
        TArray<const FStaticMeshBatch*, SceneRenderingAllocator>& InOutDynamicMeshCommandBuildRequests,
        TArray<EMeshDrawCommandCullingPayloadFlags, SceneRenderingAllocator> InOutDynamicMeshCommandBuildFlags,
        int32 NumDynamicMeshCommandBuildRequestElements,
        FMeshCommandOneFrameArray& InOutMeshDrawCommands,
        FMeshPassProcessor* MobileBasePassCSMMeshPassProcessor = nullptr, // Required only for the mobile base pass.
        FMeshCommandOneFrameArray* InOutMobileBasePassCSMMeshDrawCommands = nullptr // Required only for the mobile base pass.
    );
 
    void BuildRenderingCommands(
        FRDGBuilder& GraphBuilder,
        const FGPUScene& GPUScene,
        FInstanceCullingDrawParams& OutInstanceCullingDrawParams);
 
    void WaitForSetupTask();
 
    void Draw(FRHICommandList& RHICmdList, const FInstanceCullingDrawParams* InstanceCullingDrawParams = nullptr) const;
    void Dispatch(FRDGDispatchPassBuilder& DispatchPassBuilder, const FInstanceCullingDrawParams* InstanceCullingDrawParams = nullptr, float ViewportScale = 1.0f) const;
    void Dispatch(FRDGDispatchPassBuilder& DispatchPassBuilder, const FInstanceCullingDrawParams* InstanceCullingDrawParams, TFunctionRef<void(FRHICommandList&)> SetupCommandListFunction) const;
 
PRAGMA_DISABLE_DEPRECATION_WARNINGS
    UE_DEPRECATED(5.5, "Use Draw / Dispatch instead.")
    void DispatchDraw(FParallelCommandListSet* ParallelCommandListSet, FRHICommandList& RHICmdList, const FInstanceCullingDrawParams* InstanceCullingDrawParams = nullptr) const;
PRAGMA_ENABLE_DEPRECATION_WARNINGS
 
    void Cleanup();
    void SetDumpInstancingStats(const FString& InPassName);
    bool HasAnyDraw() const { return MaxNumDraws > 0; }
 
    static bool IsOnDemandShaderCreationEnabled();
 
    FInstanceCullingContext* GetInstanceCullingContext() { return &TaskContext.InstanceCullingContext; }
    const FGraphEventRef& GetTaskEvent() const { return TaskEventRef; }
 
    FGraphEventRef&& AcquireTaskEvent() { return MoveTemp(TaskEventRef); }
 
    // NOTE: It is only safe to access mesh draw commands after the setup task is complete (use WaitForSetupTask). 
    // Only access the data late in the frame to allow as much time as possible for async tasks to complete.
    const FMeshCommandOneFrameArray& GetMeshDrawCommands() const
    {
        return TaskContext.MeshDrawCommands;
    }
 
private:
    FMeshDrawCommandPassSetupTaskContext TaskContext;
    FGraphEventRef TaskEventRef;
    FString PassNameForStats;
 
    bool bHasInstanceCullingDrawParameters;
 
    // Maximum number of draws for this pass. Used to prealocate resources on rendering thread. 
    // Has a guarantee that if there won't be any draws, then MaxNumDraws = 0;
    int32 MaxNumDraws;
 
    void DumpInstancingStats() const;
};
 
inline bool HasAnyDraw(const FParallelMeshDrawCommandPass* Pass)
{
    return Pass && Pass->HasAnyDraw();
}
 
RENDERER_API extern void SortAndMergeDynamicPassMeshDrawCommands(
    const FSceneView& SceneView,
    FRHICommandList& RHICmdList,
    FMeshCommandOneFrameArray& VisibleMeshDrawCommands,
    FDynamicMeshDrawCommandStorage& MeshDrawCommandStorage,
    FRHIBuffer*& OutPrimitiveIdVertexBuffer,
    uint32 InstanceFactor,
    const FGPUScenePrimitiveCollector* DynamicPrimitiveCollector);