TextureStreamIn.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
FTextureStreamIn.h: Implement a generic texture stream in strategy.
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "RenderAssetUpdate.h"
#include "TextureMipAllocator.h"
#include "Streaming/TextureMipDataProvider.h"
 
class UTexture;
 
class FTextureStreamIn : public TRenderAssetUpdate<FTextureUpdateContext>
{
public:
 
    FTextureStreamIn(const UTexture* InTexture, FTextureMipAllocator* InMipAllocator, FTextureMipDataProvider* InCustomMipDataProvider, FTextureMipDataProvider* InDefaultMipDataProvider);
    ~FTextureStreamIn();
 
    // Route FTextureMipDataProvider::Init()
    void InitMipDataProviders(const FContext& Context);
    
    // Route FTextureMipAllocator::AllocateMips()
    void AllocateNewMips(const FContext& Context);
    
    // Route FTextureMipDataProvider::GetMips()
    void GetMipData(const FContext& Context);
 
    // Route FTextureMipDataProvider::PollMips()
    void PollMipData(const FContext& Context);
 
    // Route FTextureMipAllocator::UploadMips()
    void UploadNewMips(const FContext& Context);
 
    // Route FTextureMipDataProvider::PostprocessGPUMipData
    void PostprocessGPUMipData(const FContext& Context);
 
    // Update the texture resource with the new RHI texture. Update is completed after this step and can not be canceled afterward.
    void FinalizeNewMips(const FContext& Context);
 
    // Route FTextureMipDataProvider::CleanUp()
    void CleanUpMipDataProviders(const FContext& Context);
 
    // Execute the cancellation for both MipAllocator and MipDataProviders.
    void Cancel(const FContext& Context);
 
    // Start an async task to cancel pending IO requests.
    void Abort() final override;
 
protected:
 
    // The first mip to be processed for DoGetMipData(). Starts at PendingFirstLODIdx and goes up to CurrentFirstLODIdx.
    int32 StartingMipIndex = INDEX_NONE;
 
    TUniquePtr<FTextureMipAllocator> MipAllocator;
    FTextureMipDataProviderArray MipDataProviders;
 
    FTextureUpdateSyncOptions SyncOptions;
    FTextureMipInfoArray MipInfos;
 
    // The actual implementation of the update steps which redirect to FTextureMipAllocator and FTextureMipDataProvider.
    void DoInitMipDataProviders(const FContext& Context);
    bool DoAllocateNewMips(const FContext& Context);
    void DoGetMipData(const FContext& Context);
    bool DoPollMipData(const FContext& Context);
    bool DoUploadNewMips(const FContext& Context);
    bool DoPostprocessGPUMipData(const FContext& Context);
    bool DoFinalizeNewMips(const FContext& Context);
    void DoCleanUpMipDataProviders(const FContext& Context);
 
    EThreadType GetMipDataProviderThread(FTextureMipDataProvider::ETickState TickState) const; 
    EThreadType GetMipAllocatorThread(FTextureMipAllocator::ETickState TickState) const;
 
    EThreadType GetCancelThread() const;
 
private:
 
    // An async task that will call FTextureMipDataProvider::AbortPollMips() on each mip data provider upon cancellation.
    class FAbortPollMipsTask : public FNonAbandonableTask
    {
    public:
        FAbortPollMipsTask(FTextureStreamIn* InPendingUpdate, bool bInIsPollingMipData, bool bInIsPostprocessingGPUMipData) 
            : PendingUpdate(InPendingUpdate)
            , bIsPollingMipData(bInIsPollingMipData)
            , bIsPostprocessingGPUMipData(bInIsPostprocessingGPUMipData)
        {
        }
        void DoWork();
        FORCEINLINE TStatId GetStatId() const
        {
            RETURN_QUICK_DECLARE_CYCLE_STAT(FAbortPollMipsTask, STATGROUP_ThreadPoolAsyncTasks);
        }
    protected:
        TRefCountPtr<FTextureStreamIn> PendingUpdate;
        bool bIsPollingMipData;
        bool bIsPostprocessingGPUMipData;
    };
 
    bool bIsPollingMipData = false; // Used to prevent indirecting any pointer in the abort task.
    bool bIsPostprocessingGPUMipData = false; // Used to prevent indirecting any pointer in the abort task.
    typedef FAutoDeleteAsyncTask<FAbortPollMipsTask> FAsyncAbortPollMipsTask;
    friend class FAbortPollMipsTask;
 
    // Whether FTextureMipAllocator::ETickThread is the same thread as EThreadType (as int32).
    FORCEINLINE static bool IsSameThread(FTextureMipAllocator::ETickThread TickThread, int32 TaskThread);
 
    // Whether FTextureMipDataProvider::ETickThread is the same thread as EThreadType (as int32).
    FORCEINLINE static bool IsSameThread(FTextureMipDataProvider::ETickThread TickThread, int32 TaskThread);
};