UploadingVirtualTexture.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "VirtualTextureBuiltData.h"
#include "GenericPlatform/GenericPlatformFile.h"
#include "Misc/MemoryReadStream.h"
#include "Containers/BitArray.h"
#include "Containers/List.h"
#include "Templates/UniquePtr.h"
#include "Async/TaskGraphInterfaces.h"
#include "VirtualTexturing.h"
 
#include <atomic>
 
class FUploadingVirtualTexture;
class IFileCacheHandle;
 
class FVirtualTextureCodec : public TIntrusiveLinkedList<FVirtualTextureCodec>
{
    friend struct FTranscodeTask;
public:
    static void RetireOldCodecs();
 
    ~FVirtualTextureCodec();
    void Init(IMemoryReadStreamRef& HeaderData);
 
    // Tracks completion of FCreateCodecTask.
    inline bool IsCreationComplete() const { return !CompletedEvent || CompletedEvent->IsComplete(); }
 
    inline bool IsIdle() const { return IsCreationComplete() && AllTranscodeTasksComplete(); }
 
    void LinkGlobalHead();
    void LinkGlobalTail();
 
    static FVirtualTextureCodec* ListHead;
    static FVirtualTextureCodec ListTail;
    static uint32 NumCodecs;
 
    FGraphEventRef CompletedEvent;
 
    class FUploadingVirtualTexture* Owner;
    void* Contexts[VIRTUALTEXTURE_DATA_MAXLAYERS] = { nullptr };
    uint32 ChunkIndex = 0u;
    uint32 LastFrameUsed = 0u;
 
protected:
 
    // This codec may be used by transcode tasks (see FTranscodeTask),
    // which must be all complete before the codec is released by RetireOldTasks().
    inline bool AllTranscodeTasksComplete() const { return TaskRefs.load() == 0; }
    inline void BeginTranscodeTask() const { TaskRefs.fetch_add(1); }
    inline void EndTranscodeTask() const { TaskRefs.fetch_sub(1); }
 
    mutable std::atomic<uint32> TaskRefs {};
};
 
struct FVTCodecAndStatus
{
    FVTCodecAndStatus(EVTRequestPageStatus InStatus, const FVirtualTextureCodec* InCodec = nullptr) : Codec(InCodec), Status(InStatus) {}
    const FVirtualTextureCodec* Codec;
    EVTRequestPageStatus Status;
};
 
struct FVTDataAndStatus
{
    FVTDataAndStatus(EVTRequestPageStatus InStatus, const IMemoryReadStreamRef& InData = nullptr) : Data(InData), Status(InStatus) {}
    IMemoryReadStreamRef Data;
    EVTRequestPageStatus Status;
};
 
// IVirtualTexture implementation that is uploading from CPU to GPU and gets its data from a FChunkProvider
class FUploadingVirtualTexture : public IVirtualTexture
{
public:
    FUploadingVirtualTexture(const FName& InName, FVirtualTextureBuiltData* InData, int32 FirstMipToUse);
    virtual ~FUploadingVirtualTexture();
 
    // IVirtualTexture interface
    virtual uint32 GetLocalMipBias(uint8 vLevel, uint32 vAddress) const override;
    virtual bool IsPageStreamed(uint8 vLevel, uint32 vAddress) const override { return true; }
    virtual FVTRequestPageResult RequestPageData(FRHICommandListBase& RHICmdList, const FVirtualTextureProducerHandle& ProducerHandle, uint8 LayerMask, uint8 vLevel, uint64 vAddress, EVTRequestPagePriority Priority) override;
    virtual IVirtualTextureFinalizer* ProducePageData(FRHICommandListBase& RHICmdList,
        ERHIFeatureLevel::Type FeatureLevel,
        EVTProducePageFlags Flags,
        const FVirtualTextureProducerHandle& ProducerHandle, uint8 LayerMask, uint8 vLevel, uint64 vAddress,
        uint64 RequestHandle,
        const FVTProduceTargetLayer* TargetLayers) override;
    virtual void GatherProducePageDataTasks(FVirtualTextureProducerHandle const& ProducerHandle, FGraphEventArray& InOutTasks) const override;
    virtual void GatherProducePageDataTasks(uint64 RequestHandle, FGraphEventArray& InOutTasks) const override;
    virtual void DumpToConsole(bool verbose) override;
    // End IVirtualTexture interface
 
    inline const FName& GetName() const { return Name; }
    inline const FVirtualTextureBuiltData* GetVTData() const { return Data; }
 
    // gets the codec for the given chunk, data is not valid until returned OutCompletionEvents are complete
    FVTCodecAndStatus GetCodecForChunk(FGraphEventArray& OutCompletionEvents, uint32 ChunkIndex, EVTRequestPagePriority Priority);
 
    // read a portion of a chunk
    FVTDataAndStatus ReadData(FGraphEventArray& OutCompletionEvents, uint32 ChunkIndex, size_t Offset, size_t Size, EVTRequestPagePriority Priority);
 
private:
    friend class FVirtualTextureCodec;
 
    FName Name;
    FVirtualTextureBuiltData* Data;
    TArray< TUniquePtr<IFileCacheHandle> > HandlePerChunk;
    TArray< TUniquePtr<FVirtualTextureCodec> > CodecPerChunk;
    TBitArray<> InvalidChunks; // marks chunks that failed to load
    int32 FirstMipOffset;
 
    struct FVirtualTextureChunkStreamingManager* StreamingManager;
};