LandscapeEditReadback.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "TextureResource.h"
 
class FLandscapeEditLayerReadback
{
public:
    FLandscapeEditLayerReadback();
    ~FLandscapeEditLayerReadback();
 
    bool SetHash(uint64 InHash);
    uint64 GetHash() const { return Hash; }
 
    using FPerChannelLayerNames = TStaticArray<FName, 4>;
 
    struct FComponentReadbackContext
    {
        FIntPoint ComponentKey;
        int32 UpdateModes = 0;
        FPerChannelLayerNames PerChannelLayerNames;
    };
    using FReadbackContext = TArray<FComponentReadbackContext>;
 
    void Enqueue(UTexture2D const* InSourceTexture, FReadbackContext&& InReadbackContext);
 
    /* Tick the read back tasks. */
    void Tick();
    /* Flush all read back tasks to completion. This may stall waiting for the render thread. */
    void Flush();
 
    int32 GetCompletedResultNum() const;
 
    TArray< TArray<FColor> > const& GetResult(int32 InResultIndex) const;
    FReadbackContext const& GetResultContext(int32 InResultIndex) const;
 
    /* Release results. Pass in a value which is no more than the value returned by GetCompletedResultNum(). */
    void ReleaseCompletedResults(int32 InResultNum);
 
    static bool HasWork();
 
    static void GarbageCollectTasks();
 
    static void FlushAllReadbackTasks();
 
private:
    uint64 Hash = 0;
    TArray<int32> TaskHandles;
};