AdaptiveVirtualTexture.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Containers/BinaryHeap.h"
#include "Containers/HashTable.h"
#include "VirtualTexturing.h"
 
class FAllocatedVirtualTexture;
class FRDGBuilder;
class FRDGExternalAccessQueue;
class FRHICommandListImmediate;
class FVirtualTextureSystem;
class FRHICommandListBase;
 
class FAdaptiveVirtualTexture final : public IAdaptiveVirtualTexture
{
public:
    FAdaptiveVirtualTexture(FAdaptiveVTDescription const& InAdaptiveDesc, FAllocatedVTDescription const& InAllocatedDesc);
 
    void Init(FRHICommandListBase& RHICmdList, FVirtualTextureSystem* InSystem);
 
    uint32 GetPackedAllocationRequest(uint32 vAddress, uint32 vLevelPlusOne, uint32 Frame) const;
    void QueuePackedAllocationRequests(TConstArrayView<uint32> InRequests, uint32 InFrame);
    static void QueuePackedAllocationRequests(FVirtualTextureSystem* InSystem, TConstArrayView<uint32> InRequests, uint32 InFrame);
    void UpdateAllocations(FVirtualTextureSystem* InSystem, FRHICommandListImmediate& RHICmdList, uint32 InFrame);
    void ApplyPageTableUpdates(FVirtualTextureSystem* InSystem, FRDGBuilder& GraphBuilder, FRDGExternalAccessQueue& ExternalAccessQueue);
 
    //~ Begin IAdaptiveVirtualTexture Interface.
    virtual IAllocatedVirtualTexture* GetAllocatedVirtualTexture() override;
    virtual int32 GetSpaceID() const override;
    //~ End IAdaptiveVirtualTexture Interface.
 
    struct FProducerInfo
    {
        FVirtualTextureProducerHandle ProducerHandle;
        FIntRect RemappedTextureRegion;
        uint32 RemappedMaxLevel;
    };
    void GetProducers(FIntRect const& InTextureRegion, uint32 InMaxLevel, TArray<FProducerInfo>& OutProducerInfos) const;
 
    struct FAllocatedInfo
    {
        IAllocatedVirtualTexture* AllocatedVirtualTexture;
        FBox2D RemappedUV;
        uint32 RemappedLevel;
    };
    void GetAllocatedVirtualTextures(FBox2D const& InUVRegion, uint32 InLevel, TArray<FAllocatedInfo>& OutInfos, TArray<uint32>& OutAllocationRequests);
 
protected:
    //~ Begin IAdaptiveVirtualTexture Interface.
    virtual void Destroy(class FVirtualTextureSystem* InSystem) override;
    //~ End IAdaptiveVirtualTexture Interface.
 
private:
    uint32 GetAllocationIndex(uint32 GridIndex) const;
    uint32 GetAllocationIndex(FAllocatedVirtualTexture* InAllocatedVT) const;
 
    void Allocate(FRHICommandListBase& RHICmdList, FVirtualTextureSystem* InSystem, uint32 InRequest, uint32 InFrame);
    void Allocate(FRHICommandListBase& RHICmdList, FVirtualTextureSystem* InSystem, uint32 InGridIndex, uint32 InAllocationIndex, uint32 InNewLevel, uint32 InFrame);
    void Free(FVirtualTextureSystem* InSystem, uint32 InAllocationIndex, uint32 InFrame);
    bool FreeLRU(FRHICommandListBase& RHICmdList, FVirtualTextureSystem* InSystem, uint32 InFrame, uint32 InFrameUnusedThreshold);
 
    static IAllocatedVirtualTexture* AllocateVirtualTexture(
        FRHICommandListBase& RHICmdList,
        FVirtualTextureSystem* InSystem,
        FAllocatedVTDescription const& InAllocatedDesc,
        FIntPoint InGridSize,
        uint8 InForcedSpaceID,
        int32 InWidthInTiles,
        int32 InHeightInTiles,
        FIntPoint InAddressOffset,
        int32 InLevelOffset);
 
    static void DestroyVirtualTexture(FVirtualTextureSystem* InSystem, IAllocatedVirtualTexture* InAllocatedVT, TArray<FVirtualTextureProducerHandle>& OutProducersToRelease);
    static void RemapVirtualTexturePages(FVirtualTextureSystem* InSystem, FAllocatedVirtualTexture* OldAllocatedVT, FAllocatedVirtualTexture* NewAllocatedVT, uint32 InFrame);
 
private:
    FAdaptiveVTDescription AdaptiveDesc;
    FAllocatedVTDescription AllocatedDesc;
    int32 MaxLevel;
    FIntPoint GridSize;
 
    FAllocatedVirtualTexture* AllocatedVirtualTextureLowMips;
 
    struct FAllocation
    {
        FAllocation(int32 InGridIndex, FAllocatedVirtualTexture* InAllocatedVT)
            : GridIndex(InGridIndex)
            , AllocatedVT(InAllocatedVT)
        {}
 
        uint32 GridIndex;
        FAllocatedVirtualTexture* AllocatedVT;
    };
 
    int32 NumAllocated;
    TArray<FAllocation> AllocationSlots;
    TArray<int32> FreeSlots;
    FHashTable GridIndexMap;
    FHashTable AllocatedVTMap;
    TArray<int32> SlotsPendingRootPageMap;
    FBinaryHeap<uint32, uint32> LRUHeap;
 
    TArray<uint32> RequestsToMap;
 
    struct FIndirectionTextureUpdate
    {
        uint32 X;
        uint32 Y;
        uint32 Value;
    };
 
    TArray<FIndirectionTextureUpdate> TextureUpdates;
 
    TArray<FVirtualTextureProducerHandle> ProducersToRelease;
};