MotionDelayBuffer.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreMinimal.h"
#include "Templates/SharedPointer.h"
#include "LateUpdateManager.h"
#include "UObject/WeakObjectPtr.h"
 
#include "SceneViewExtension.h"
 
class USceneComponent;
class FSceneInterface;
class FMotionDelayBuffer;
class FSceneViewFamily;
class FMotionDelayTarget;
class FMotionDelayClient;
 
 
/* FMotionDelayService
 *****************************************************************************/
 
class FMotionDelayService
{
public:
    static HEADMOUNTEDDISPLAY_API void SetEnabled(bool bEnable);
    static HEADMOUNTEDDISPLAY_API bool RegisterDelayTarget(USceneComponent* MotionControlledComponent, const int32 PlayerIndex, const FName SourceId);
    static HEADMOUNTEDDISPLAY_API void RegisterDelayClient(TSharedRef<FMotionDelayClient, ESPMode::ThreadSafe> DelayClient);
};
 
/* FMotionDelayClient
 *****************************************************************************/
 
class FMotionDelayClient : public FSceneViewExtensionBase
{
public:
    HEADMOUNTEDDISPLAY_API FMotionDelayClient(const FAutoRegister& AutoRegister);
 
    virtual uint32 GetDesiredDelay() const = 0;
    virtual void GetExemptTargets(TArray<USceneComponent*>& ExemptTargets) const {}
 
    HEADMOUNTEDDISPLAY_API void Apply_RenderThread(FSceneInterface* Scene);
    HEADMOUNTEDDISPLAY_API void Restore_RenderThread(FSceneInterface* Scene);
 
public:
    HEADMOUNTEDDISPLAY_API virtual void BeginRenderViewFamily(FSceneViewFamily& InViewFamily) override;
    HEADMOUNTEDDISPLAY_API virtual void PostRenderViewFamily_RenderThread(FRDGBuilder& GraphBuilder, FSceneViewFamily& InViewFamily) override;
    HEADMOUNTEDDISPLAY_API virtual int32 GetPriority() const override;
    HEADMOUNTEDDISPLAY_API virtual bool IsActiveThisFrame_Internal(const FSceneViewExtensionContext& Context) const override;
 
protected:
    HEADMOUNTEDDISPLAY_API bool FindDelayTransform(USceneComponent* Target, uint32 Delay, FTransform& TransformOut);
 
private:
    struct FTargetTransform
    {
        TSharedPtr<FMotionDelayTarget, ESPMode::ThreadSafe> DelayTarget;
        FTransform DelayTransform;
        FTransform RestoreTransform;
    };
    TArray<FTargetTransform> TargetTransforms_RenderThread;
};
 
 
/* TCircularHistoryBuffer
 *****************************************************************************/
 
template<typename ElementType> class TCircularHistoryBuffer
{
public:
    TCircularHistoryBuffer(uint32 InitialCapacity = 0);
 
    ElementType& Add(const ElementType& Element);
    void Resize(uint32 NewCapacity);
 
    ElementType& operator[](uint32 Index);
    const ElementType& operator[](uint32 Index) const;
 
    void InsertAt(uint32 Index, const ElementType& Element);
 
    uint32 Capacity() const;
    int32  Num() const;
 
    void Empty();
 
    bool IsEmpty() const;
    bool IsFull() const;
    
private:
    void RangeCheck(const uint32 Index, bool bCheckIfUnderfilled = false) const;
    uint32 AsInternalIndex(uint32 Index) const;
    uint32 GetNextIndex(uint32 CurrentIndex) const;
 
    void ResizeGrow(uint32 AddedSlack);
    void Realign();
    void ResizeShrink(uint32 ShrinkAmount);
 
private:
    TArray<ElementType> Elements;
    uint32 Head;
    bool bIsFull;
};
 
// Templatized implementation
#include "MotionDelayBuffer.inl" // IWYU pragma: export