VirtualTextureTranscodeCache.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "VirtualTextureUploadCache.h"
#include "PixelFormat.h"
#include "Misc/MemoryReadStream.h"
#include "Containers/HashTable.h"
 
class FUploadingVirtualTexture;
class FVirtualTextureCodec;
struct FVirtualTextureBuiltData;
 
struct FVTTranscodeParams
{
    IMemoryReadStreamRef Data;
    const FVirtualTextureCodec* Codec;
    const FVirtualTextureBuiltData* VTData;
    FName Name;
    uint32 ChunkIndex;
    uint32 vAddress;
    uint8 vLevel;
    uint8 LayerMask;
};
 
union FVTTranscodeTileHandle
{
    explicit FVTTranscodeTileHandle(uint64 InPacked = 0u) : PackedData(InPacked) {}
    FVTTranscodeTileHandle(uint32 InIndex, uint32 InMagic) : Index(InIndex), Magic(InMagic) {}
 
    inline bool IsValid() const { return PackedData != 0u; }
 
    uint64 PackedData;
    struct
    {
        uint32 Index;
        uint32 Magic;
    };
};
static_assert(sizeof(FVTTranscodeTileHandle) == sizeof(uint64), "");
 
struct FVTTranscodeKey
{
    union
    {
        uint64 Key;
        struct
        {
            uint32 ProducerID;
            uint32 vAddress : 24;
            uint32 vLevel : 4;
            uint32 LayerMask : 4;
        };
    };
    uint16 Hash;
};
 
struct FVTTranscodeTileHandleAndStatus
{
    FVTTranscodeTileHandleAndStatus() : IsComplete(false) {}
    FVTTranscodeTileHandleAndStatus(const FVTTranscodeTileHandle& InHandle, bool InComplete) : Handle(InHandle), IsComplete(InComplete) {}
 
    FVTTranscodeTileHandle Handle;
    bool IsComplete;
};
 
class FVirtualTextureTranscodeCache
{
public:
    FVirtualTextureTranscodeCache();
 
    static FVTTranscodeKey GetKey(const FVirtualTextureProducerHandle& ProducerHandle, uint8 LayerMask, uint8 vLevel, uint32 vAddress);
 
    FVTTranscodeTileHandleAndStatus FindTask(const FVTTranscodeKey& InKey) const;
 
    FVTTranscodeTileHandle SubmitTask(
        FRHICommandListBase& RHICmdList,
        FVirtualTextureUploadCache& InUploadCache,
        const FVTTranscodeKey& InKey,
        const FVirtualTextureProducerHandle& InProducerHandle,
        const FVTTranscodeParams& InParams,
        const FGraphEventArray* InPrerequisites = NULL);
 
    bool IsTaskFinished(FVTTranscodeTileHandle InHandle) const;
    void WaitTaskFinished(FVTTranscodeTileHandle InHandle) const;
    const FVTUploadTileHandle* AcquireTaskResult(FVTTranscodeTileHandle InHandle);
    
    FGraphEventRef GetTaskEvent(FVTTranscodeTileHandle InHandle) const;
    void GatherProducePageDataTasks(FVirtualTextureProducerHandle const& ProducerHandle, FGraphEventArray& InOutTasks) const;
 
    void RetireOldTasks(FRHICommandListBase& RHICmdList, FVirtualTextureUploadCache& InUploadCache);
 
private:
    enum ListType
    {
        LIST_FREE,
        LIST_PENDING,
 
        LIST_COUNT,
    };
 
    struct FTaskEntry
    {
        uint64 Key;
        FGraphEventRef GraphEvent;
        FVTUploadTileHandle StageTileHandle[VIRTUALTEXTURE_SPACE_MAXLAYERS];
        uint32 PackedProducerHandle;
        uint32 FrameSubmitted;
        uint16 Magic;
        uint16 Hash;
        int16 NextIndex;
        int16 PrevIndex;
    };
 
    void RemoveFromList(int32 Index)
    {
        FTaskEntry& Entry = Tasks[Index];
        check(Index >= LIST_COUNT); // if we're trying to remove a list head, something is corrupt
        Tasks[Entry.PrevIndex].NextIndex = Entry.NextIndex;
        Tasks[Entry.NextIndex].PrevIndex = Entry.PrevIndex;
        Entry.NextIndex = Entry.PrevIndex = Index;
    }
 
    void AddToList(int32 HeadIndex, int32 Index)
    {
        FTaskEntry& Head = Tasks[HeadIndex];
        FTaskEntry& Entry = Tasks[Index];
        check(Index >= LIST_COUNT); // if we're trying to add a list head, something is corrupt
        check(Index <= 0xffff);
 
        // make sure we're not currently in any list
        check(Entry.NextIndex == Index);
        check(Entry.PrevIndex == Index);
 
        Entry.NextIndex = HeadIndex;
        Entry.PrevIndex = Head.PrevIndex;
        Tasks[Head.PrevIndex].NextIndex = Index;
        Head.PrevIndex = Index;
    }
 
    TArray<FTaskEntry> Tasks;
    FHashTable TileIDToTaskIndex;
    FHashTable ProducerToTaskIndex;
};