HierarchicalStaticMeshSceneProxy.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "PrimitiveSceneProxy.h"
#include "PrimitiveViewRelevance.h"
#include "Engine/InstancedStaticMesh.h"
#include "Components/InstancedStaticMeshComponent.h"
#include "StaticMeshResources.h"
#include "Components/HierarchicalInstancedStaticMeshComponent.h"
#include "Async/Mutex.h"
 
struct FClusterNode;
struct FFoliageElementParams;
struct FFoliageRenderInstanceParams;
struct FFoliageCullInstanceParams;
 
struct FFoliageOcclusionResults
{
    TArray<bool> Results; // we keep a copy from the View as the view will get destroyed too often
    int32 ResultsStart;
    int32 NumResults;
    uint32 FrameNumberRenderThread;
 
    FFoliageOcclusionResults(TArray<bool>* InResults, int32 InResultsStart, int32 InNumResults)
    : Results(*InResults)
    , ResultsStart(InResultsStart)
    , NumResults(InNumResults)
    , FrameNumberRenderThread(GFrameNumberRenderThread)
    {
    }
};
 
class FHierarchicalStaticMeshSceneProxy final : public FInstancedStaticMeshSceneProxy
{
    TSharedRef<TArray<FClusterNode>, ESPMode::ThreadSafe> ClusterTreePtr;
    const TArray<FClusterNode>& ClusterTree;
 
    TArray<FBox> UnbuiltBounds;
    int32 FirstUnbuiltIndex;
    int32 InstanceCountToRender;
 
    int32 FirstOcclusionNode;
    int32 LastOcclusionNode;
    TArray<FBoxSphereBounds> OcclusionBounds;
    TMap<uint32, FFoliageOcclusionResults> OcclusionResults;
    UE::FMutex OcclusionResultsMutex;
    EHISMViewRelevanceType ViewRelevance;
    bool bDitheredLODTransitions;
    uint32 SceneProxyCreatedFrameNumberRenderThread;
 
#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
    mutable TArray<uint32> SingleDebugRuns[MAX_STATIC_MESH_LODS];
    mutable int32 SingleDebugTotalInstances[MAX_STATIC_MESH_LODS];
    mutable TArray<uint32> MultipleDebugRuns[MAX_STATIC_MESH_LODS];
    mutable int32 MultipleDebugTotalInstances[MAX_STATIC_MESH_LODS];
    mutable int32 CaptureTag;
#endif
 
public:
    ENGINE_API SIZE_T GetTypeHash() const override;
 
    FHierarchicalStaticMeshSceneProxy(UHierarchicalInstancedStaticMeshComponent* InComponent, ERHIFeatureLevel::Type InFeatureLevel);
 
    ENGINE_API void SetupOcclusion(UHierarchicalInstancedStaticMeshComponent* InComponent);
 
    // FPrimitiveSceneProxy interface.
    
    ENGINE_API virtual void CreateRenderThreadResources(FRHICommandListBase& RHICmdList) override;
    
    ENGINE_API virtual FPrimitiveViewRelevance GetViewRelevance(const FSceneView* View) const override;
 
    ENGINE_API virtual void GetDynamicMeshElements(const TArray<const FSceneView*>& Views, const FSceneViewFamily& ViewFamily, uint32 VisibilityMap, FMeshElementCollector& Collector) const override;
 
    ENGINE_API virtual const TArray<FBoxSphereBounds>* GetOcclusionQueries(const FSceneView* View) const override;
    
    ENGINE_API virtual void AcceptOcclusionResults(const FSceneView* View, TArray<bool>* Results, int32 ResultsStart, int32 NumResults) override;
 
    virtual bool AllowInstanceCullingOcclusionQueries() const override { return false; }
 
    virtual bool HasSubprimitiveOcclusionQueries() const override
    {
        return FirstOcclusionNode > 0;
    }
 
    virtual bool GetInstanceDrawDistanceMinMax(FVector2f& OutDistanceMinMax) const override;
 
    ENGINE_API virtual void DrawStaticElements(FStaticPrimitiveDrawInterface* PDI) override;
 
    ENGINE_API virtual void ApplyWorldOffset(FRHICommandListBase& RHICmdList, FVector InOffset) override;
 
    ENGINE_API void FillDynamicMeshElements(const FSceneView* View, FMeshElementCollector& Collector, const FFoliageElementParams& ElementParams, const FFoliageRenderInstanceParams& Instances) const;
 
    template<bool TUseVector, bool THasWPODisplacement>
    void Traverse(const FFoliageCullInstanceParams& Params, int32 Index, int32 MinLOD, int32 MaxLOD, bool bFullyContained = false) const;
};