UnrealEngineUWP/Engine/Source/Runtime/Renderer/Private/PostProcess/RenderTargetPool.cpp

// Copyright 1998-2014 Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	RenderTargetPool.cpp: Scene render target pool manager.
=============================================================================*/

#include "RendererPrivate.h"
#include "ScenePrivate.h"
#include "RenderTargetPool.h"

/** The global render targets pool. */
TGlobalResource<FRenderTargetPool> GRenderTargetPool;

DEFINE_LOG_CATEGORY_STATIC(LogRenderTargetPool, Warning, All);

static void DumpRenderTargetPoolMemory(FOutputDevice& OutputDevice)
{
	GRenderTargetPool.DumpMemoryUsage(OutputDevice);
}
static FAutoConsoleCommandWithOutputDevice GDumpRenderTargetPoolMemoryCmd(
	TEXT("r.DumpRenderTargetPoolMemory"),
	TEXT("Dump allocation information for the render target pool."),
	FConsoleCommandWithOutputDeviceDelegate::CreateStatic(DumpRenderTargetPoolMemory)
	);

static void DumpRenderTargetPoolEvents(const TArray<FString>& Args)
{
	uint32 SizeInKBThreshold = -1;
	if(Args.Num() && Args[0].IsNumeric())
	{
		SizeInKBThreshold = FCString::Atof(*Args[0]);
	}

	if(SizeInKBThreshold != -1)
	{
		UE_LOG(LogRenderTargetPool, Display, TEXT("r.DumpRenderTargetPoolEvents is now enabled, use r.DumpRenderTargetPoolEvents ? for help"));

		GRenderTargetPool.EnableEventRecording(SizeInKBThreshold);
	}
	else
	{
		GRenderTargetPool.DisableEventDisplay();

		UE_LOG(LogRenderTargetPool, Display, TEXT("r.DumpRenderTargetPoolEvents is now disabled, use r.DumpRenderTargetPoolEvents <SizeInKB> to enable or r.DumpRenderTargetPoolEvents ? for help"));
	}
}
static FAutoConsoleCommand GDumpRenderTargetPoolEventsCmd(
	TEXT("r.DumpRenderTargetPoolEvents"),
	TEXT("Dump for the render target pool events. Optional parameter defines threshold in KB (default is 1024 for 1MB)."),
	FConsoleCommandWithArgsDelegate::CreateStatic(DumpRenderTargetPoolEvents)
	);

bool FRenderTargetPool::IsEventRecordingEnabled() const
{
#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
	return bEventRecording; 
#else
	return false;
#endif
}

IPooledRenderTarget* FRenderTargetPoolEvent::GetValidatedPointer() const
{
	int32 Index = GRenderTargetPool.FindIndex(Pointer);

	if(Index >= 0)
	{
		return Pointer;
	}

	return 0;
}

bool FRenderTargetPoolEvent::NeedsDeallocEvent()
{
	if(GetEventType() == ERTPE_Alloc)
	{
		if(Pointer)
		{
			IPooledRenderTarget* ValidPointer = GetValidatedPointer();
			if(ValidPointer->IsFree())
			{
				Pointer = 0;
				return true;
			}
		}
	}

	return false;
}


static uint32 ComputeSizeInKB(FPooledRenderTarget& Element)
{
	return (Element.ComputeMemorySize() + 1023) / 1024;
}

FRenderTargetPool::FRenderTargetPool()
	: AllocationLevelInKB(0)
	, bCurrentlyOverBudget(false)
	, bEventRecording(false)
	, bEventRecordingTrigger(false)
	, SizeInKBThreshold(0)
	, CurrentTimeStep(0)
{
}

bool FRenderTargetPool::FindFreeElement(const FPooledRenderTargetDesc& Desc, TRefCountPtr<IPooledRenderTarget> &Out, const TCHAR* InDebugName)
{
	check(IsInRenderingThread());

	if(!Desc.IsValid())
	{
		// no need to do anything
		return true;
	}

	// if we can keep the current one, do that
	if(Out)
	{
		FPooledRenderTarget* Current = (FPooledRenderTarget*)Out.GetReference();

		if(Out->GetDesc() == Desc)
		{
			// we can reuse the same, but the debug name might have changed
			Current->Desc.DebugName = InDebugName;
			RHIBindDebugLabelName(Current->GetRenderTargetItem().TargetableTexture, InDebugName);
			check(!Out->IsFree());
			return true;
		}
		else
		{
			// release old reference, it might free a RT we can use
			Out = 0;

			if(Current->IsFree())
			{
				int32 Index = FindIndex(Current);

				check(Index >= 0);

				// we don't use Remove() to not shuffle around the elements for better transparency on RenderTargetPoolEvents
				PooledRenderTargets[Index] = 0;
			}
		}
	}

	FPooledRenderTarget* Found = 0;
	uint32 FoundIndex = -1;

	// try to find a suitable element in the pool
	for(uint32 i = 0; i < (uint32)PooledRenderTargets.Num(); ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(Element && Element->IsFree() && Element->GetDesc() == Desc)
		{
			Found = Element;
			FoundIndex = i;
			break;
		}
	}

	if(!Found)
	{
		UE_LOG(LogRenderTargetPool, Display, TEXT("%d MB, NewRT %s %s"), (AllocationLevelInKB + 1023) / 1024, *Desc.GenerateInfoString(), InDebugName);

		// not found in the pool, create a new element
		Found = new FPooledRenderTarget(Desc);

		PooledRenderTargets.Add(Found);

		if(Desc.TargetableFlags & (TexCreate_RenderTargetable | TexCreate_DepthStencilTargetable | TexCreate_UAV))
		{
			if(Desc.Is2DTexture())
			{
				RHICreateTargetableShaderResource2D(
					Desc.Extent.X,
					Desc.Extent.Y,
					Desc.Format,
					Desc.NumMips,
					Desc.Flags,
					Desc.TargetableFlags,
					Desc.bForceSeparateTargetAndShaderResource,
					(FTexture2DRHIRef&)Found->RenderTargetItem.TargetableTexture,
					(FTexture2DRHIRef&)Found->RenderTargetItem.ShaderResourceTexture,
					Desc.NumSamples
					);
			}
			else if(Desc.Is3DTexture())
			{
				Found->RenderTargetItem.ShaderResourceTexture = RHICreateTexture3D(
					Desc.Extent.X,
					Desc.Extent.Y,
					Desc.Depth,
					Desc.Format,
					Desc.NumMips,
					Desc.TargetableFlags,
					NULL);

				// similar to RHICreateTargetableShaderResource2D
				Found->RenderTargetItem.TargetableTexture = Found->RenderTargetItem.ShaderResourceTexture;
			}
			else
			{
				check(Desc.IsCubemap());
				if(Desc.IsArray())
				{
					RHICreateTargetableShaderResourceCubeArray(
						Desc.Extent.X,
						Desc.ArraySize,
						Desc.Format,
						Desc.NumMips,
						Desc.Flags,
						Desc.TargetableFlags,
						false,
						(FTextureCubeRHIRef&)Found->RenderTargetItem.TargetableTexture,
						(FTextureCubeRHIRef&)Found->RenderTargetItem.ShaderResourceTexture
						);
				}
				else
				{
					RHICreateTargetableShaderResourceCube(
						Desc.Extent.X,
						Desc.Format,
						Desc.NumMips,
						Desc.Flags,
						Desc.TargetableFlags,
						false,
						(FTextureCubeRHIRef&)Found->RenderTargetItem.TargetableTexture,
						(FTextureCubeRHIRef&)Found->RenderTargetItem.ShaderResourceTexture
						);
				}

			}

			RHIBindDebugLabelName(Found->RenderTargetItem.TargetableTexture, InDebugName);
		}
		else
		{
			if(Desc.Is2DTexture())
			{
				// this is useful to get a CPU lockable texture through the same interface
				Found->RenderTargetItem.ShaderResourceTexture = RHICreateTexture2D(
					Desc.Extent.X,
					Desc.Extent.Y,
					Desc.Format,
					Desc.NumMips,
					Desc.NumSamples,
					Desc.Flags,
					NULL);
			}
			else if(Desc.Is3DTexture())
			{
				Found->RenderTargetItem.ShaderResourceTexture = RHICreateTexture3D(
					Desc.Extent.X,
					Desc.Extent.Y,
					Desc.Depth,
					Desc.Format,
					Desc.NumMips,
					Desc.Flags,
					NULL);
			}
			else 
			{
				check(Desc.IsCubemap());
				if(Desc.IsArray())
				{
					FTextureCubeRHIRef CubeTexture = RHICreateTextureCubeArray(Desc.Extent.X,Desc.ArraySize,Desc.Format,Desc.NumMips,Desc.Flags | Desc.TargetableFlags | TexCreate_ShaderResource,NULL);
					Found->RenderTargetItem.TargetableTexture = Found->RenderTargetItem.ShaderResourceTexture = CubeTexture;
				}
				else
				{
					FTextureCubeRHIRef CubeTexture = RHICreateTextureCube(Desc.Extent.X,Desc.Format,Desc.NumMips,Desc.Flags | Desc.TargetableFlags | TexCreate_ShaderResource,NULL);
					Found->RenderTargetItem.TargetableTexture = Found->RenderTargetItem.ShaderResourceTexture = CubeTexture;
				}
			}

			RHIBindDebugLabelName(Found->RenderTargetItem.ShaderResourceTexture, InDebugName);
		}

		if(Desc.TargetableFlags & TexCreate_UAV)
		{
			// The render target desc is invalid if a UAV is requested with an RHI that doesn't support the high-end feature level.
			check(GRHIFeatureLevel == ERHIFeatureLevel::SM5);
			Found->RenderTargetItem.UAV = RHICreateUnorderedAccessView(Found->RenderTargetItem.TargetableTexture);
		}

		AllocationLevelInKB += ComputeSizeInKB(*Found);
		VerifyAllocationLevel();

		FoundIndex = PooledRenderTargets.Num() - 1;
	}

#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
	{
		static const auto ICVar = IConsoleManager::Get().FindTConsoleVariableDataInt(TEXT("r.RenderTargetPoolTest"));
		
		if(ICVar->GetValueOnRenderThread())
		{
			if(Found->GetDesc().TargetableFlags & TexCreate_RenderTargetable)
			{
				RHISetRenderTarget(Found->RenderTargetItem.TargetableTexture, FTextureRHIRef());	
				RHIClear(true, FLinearColor(1000, 1000, 1000, 1000), false, 1.0f, false, 0, FIntRect());
			}
			else if(Found->GetDesc().TargetableFlags & TexCreate_UAV)
			{
				const uint32 ZeroClearValue[4] = { 1000, 1000, 1000, 1000 };
				RHIClearUAV(Found->RenderTargetItem.UAV, ZeroClearValue);
			}

			if(Desc.TargetableFlags & TexCreate_DepthStencilTargetable)
			{
				RHISetRenderTarget(FTextureRHIRef(), Found->RenderTargetItem.TargetableTexture);
				RHIClear(false, FLinearColor(0, 0, 0, 0), true, 0.0f, false, 0, FIntRect());
			}
		}
	}
#endif

	check(Found->IsFree());

	Found->Desc.DebugName = InDebugName;
	Found->UnusedForNFrames = 0;

	AddAllocEvent(FoundIndex, Found);

	// assign to the reference counted variable
	Out = Found;

	check(!Found->IsFree());

	return false;
}

void FRenderTargetPool::CreateUntrackedElement(const FPooledRenderTargetDesc& Desc, TRefCountPtr<IPooledRenderTarget> &Out, const FSceneRenderTargetItem& Item)
{
	check(IsInRenderingThread());

	Out = 0;

	// not found in the pool, create a new element
	FPooledRenderTarget* Found = new FPooledRenderTarget(Desc);

	Found->RenderTargetItem = Item;

	// assign to the reference counted variable
	Out = Found;
}

void FRenderTargetPool::GetStats(uint32& OutWholeCount, uint32& OutWholePoolInKB, uint32& OutUsedInKB) const
{
	OutWholeCount = (uint32)PooledRenderTargets.Num();
	OutUsedInKB = 0;
	OutWholePoolInKB = 0;
		
	for(uint32 i = 0; i < (uint32)PooledRenderTargets.Num(); ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(Element)
		{
			uint32 SizeInKB = ComputeSizeInKB(*Element);

			OutWholePoolInKB += SizeInKB;

			if(!Element->IsFree())
			{
				OutUsedInKB += SizeInKB;
			}
		}
	}

	check(AllocationLevelInKB == OutWholePoolInKB);
}

void FRenderTargetPool::AddPhaseEvent(const TCHAR *InPhaseName)
{
	if(IsEventRecordingEnabled())
	{
		AddDeallocEvents();

		const FString* LastName = GetLastEventPhaseName();

		if(!LastName || *LastName != InPhaseName)
		{
			if(CurrentTimeStep)
			{
				// put a break to former data
				++CurrentTimeStep;
			}

			FRenderTargetPoolEvent NewEvent(InPhaseName, CurrentTimeStep);

			RenderTargetPoolEvents.Add(NewEvent);
		}
	}
}

// helper class to get a consistent layout in multiple functions
// MaxX and Y are the output value that can be requested during or after iteration
// Examples usages:
//    FRenderTargetPoolEventIterator It(RenderTargetPoolEvents, OptionalStartIndex);
//    while(FRenderTargetPoolEvent* Event = It.Iterate()) {}
struct FRenderTargetPoolEventIterator
{
	int32 Index;
	TArray<FRenderTargetPoolEvent>& RenderTargetPoolEvents;
	bool bLineContent;
	uint32 TotalWidth;
	int32 Y;

	// constructor
	FRenderTargetPoolEventIterator(TArray<FRenderTargetPoolEvent>& InRenderTargetPoolEvents, int32 InIndex = 0)
		: Index(InIndex)
		, RenderTargetPoolEvents(InRenderTargetPoolEvents)
		, bLineContent(false)
		, TotalWidth(1)
		, Y(0)
	{
		Touch();
	}

	FRenderTargetPoolEvent* operator*()
	{
		if(Index < RenderTargetPoolEvents.Num())
		{
			return &RenderTargetPoolEvents[Index];
		}

		return 0;
	}

	// @return 0 if end was reached
	FRenderTargetPoolEventIterator& operator++()
	{
		if(Index < RenderTargetPoolEvents.Num())
		{
			++Index;
		}

		Touch();

		return *this;
	}
	
	int32 FindClosingEventY() const
	{
		FRenderTargetPoolEventIterator It = *this;

		const ERenderTargetPoolEventType StartType = (*It)->GetEventType();

		if(StartType == ERTPE_Alloc)
		{
			int32 PoolEntryId = RenderTargetPoolEvents[Index].GetPoolEntryId();

			++It;

			// search for next Dealloc of the same PoolEntryId
			for(; *It; ++It)
			{
				FRenderTargetPoolEvent* Event = *It;

				if(Event->GetEventType() == ERTPE_Dealloc && Event->GetPoolEntryId() == PoolEntryId)
				{
					break;
				}
			}
		}
		else if(StartType == ERTPE_Phase)
		{
			++It;

			// search for next Phase
			for(; *It; ++It)
			{
				FRenderTargetPoolEvent* Event = *It;

				if(Event->GetEventType() == ERTPE_Phase)
				{
					break;
				}
			}
		}
		else
		{
			check(0);
		}

		return It.Y;
	}

private:

	void Touch()
	{
		if(Index < RenderTargetPoolEvents.Num())
		{
			const FRenderTargetPoolEvent& Event = RenderTargetPoolEvents[Index];

			const ERenderTargetPoolEventType Type = Event.GetEventType();

			if(Type == ERTPE_Alloc)
			{
				// for now they are all equal width
				TotalWidth = FMath::Max(TotalWidth, Event.GetColumnX() + Event.GetColumnSize());
			}
			Y = Event.GetTimeStep();
		}
	}
};

FIntPoint FRenderTargetPool::ComputeEventDisplayExtent()
{
	FRenderTargetPoolEventIterator It(RenderTargetPoolEvents);

	for(; *It; ++It)
	{
	}

	return FIntPoint(It.TotalWidth, It.Y + 1);
}

const FString* FRenderTargetPool::GetLastEventPhaseName()
{
	// could be optimized but this is a debug view

	// start from the end for better performance
	for(int32 i = RenderTargetPoolEvents.Num() - 1; i >= 0; --i)
	{
		const FRenderTargetPoolEvent* Event = &RenderTargetPoolEvents[i];

		if(Event->GetEventType() == ERTPE_Phase)
		{
			return &Event->GetPhaseName();
		}
	}

	return 0;
}

FRenderTargetPool::SMemoryStats FRenderTargetPool::ComputeView()
{
	SMemoryStats MemoryStats;

#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
	{
		struct FRTPColumn
		{
			// index into the column, -1 if this is no valid column
			uint32 PoolEntryId;
			// for sorting
			uint64 SizeInBytes;
			// for sorting
			bool bVRam;

			// default constructor
			FRTPColumn()
				: PoolEntryId(-1)
				, SizeInBytes(0)
			{
			}

			// constructor
			FRTPColumn(const FRenderTargetPoolEvent& Event)
				: PoolEntryId(Event.GetPoolEntryId())
				, SizeInBytes(Event.GetSizeInBytes())
				, bVRam((Event.GetDesc().Flags & TexCreate_FastVRAM) != 0)
			{
			}

			// sort criteria
			bool operator <(const FRTPColumn& rhs) const
			{
				// sort VRam first (only matters on XboxOne but nice to alwasy see it)
				if(bVRam != rhs.bVRam) return bVRam > rhs.bVRam;

				// we want the large ones first
				return SizeInBytes > rhs.SizeInBytes;
			}
		};

		TArray<FRTPColumn> Colums;

		// generate Colums
		for(int32 i = 0, Num = RenderTargetPoolEvents.Num(); i < Num; i++)
		{
			FRenderTargetPoolEvent* Event = &RenderTargetPoolEvents[i];

			if(Event->GetEventType() == ERTPE_Alloc)
			{
				uint32 PoolEntryId = Event->GetPoolEntryId();

				if(PoolEntryId >= (uint32)Colums.Num())
				{
					Colums.SetNum(PoolEntryId + 1);
				}

				Colums[PoolEntryId] = FRTPColumn(*Event);
			}
		}

		Colums.Sort();

		{
			uint32 ColumnX = 0;

			for(int32 ColumnIndex = 0, Num = Colums.Num(); ColumnIndex < Num; ++ColumnIndex)
			{
				const FRTPColumn& RTPColumn = Colums[ColumnIndex];

				uint32 ColumnSize = RTPColumn.SizeInBytes;

				// hide columns that are too small to make a difference (e.g. <1 MB)
				if(RTPColumn.SizeInBytes <= SizeInKBThreshold * 1024)
				{
					ColumnSize = 0;
				}
				else
				{
					MemoryStats.DisplayedUsageInBytes += RTPColumn.SizeInBytes;

					// give an entry some size to be more UI friendly (if we get mouse UI for zooming in we might not want that any more)
					ColumnSize = FMath::Max((uint32)(1024 * 1024), ColumnSize);
				}

				MemoryStats.TotalUsageInBytes += RTPColumn.SizeInBytes;
				
				for(int32 EventIndex = 0, Num = RenderTargetPoolEvents.Num(); EventIndex < Num; EventIndex++)
				{
					FRenderTargetPoolEvent* Event = &RenderTargetPoolEvents[EventIndex];

					if(Event->GetEventType() != ERTPE_Phase)
					{
						uint32 PoolEntryId = Event->GetPoolEntryId();

						if(RTPColumn.PoolEntryId == PoolEntryId)
						{
							Event->SetColumn(ColumnIndex, ColumnX, ColumnSize);
						}
					}
				}
				ColumnX += ColumnSize;
			}
		}
	}
#endif

	return MemoryStats;
}

inline void DrawBorder(FCanvas& Canvas, const FIntRect Rect, FLinearColor Color)
{
	// top
	Canvas.DrawTile(Rect.Min.X, Rect.Min.Y, Rect.Max.X - Rect.Min.X, 1, 0, 0, 1, 1, Color);
	// bottom
	Canvas.DrawTile(Rect.Min.X, Rect.Max.Y - 1, Rect.Max.X - Rect.Min.X, 1, 0, 0, 1, 1, Color);
	// left
	Canvas.DrawTile(Rect.Min.X, Rect.Min.Y + 1, 1, Rect.Max.Y - Rect.Min.Y - 2, 0, 0, 1, 1, Color);
	// right
	Canvas.DrawTile(Rect.Max.X - 1, Rect.Min.Y + 1, 1, Rect.Max.Y - Rect.Min.Y - 2, 0, 0, 1, 1, Color);
}

void FRenderTargetPool::PresentContent(const FSceneView& View)
{
	if(RenderTargetPoolEvents.Num())
	{
		FIntPoint TotalExtent = ComputeEventDisplayExtent();
		FIntPoint DisplayLeftTop(20, 50);
		// on the right we leave more space to make the mouse tooltip readable
		FIntPoint DisplayExtent(View.ViewRect.Width() - DisplayLeftTop.X * 2 - 140, View.ViewRect.Height() - DisplayLeftTop.Y * 2);

		// if the area is not too small
		if(DisplayExtent.X > 50 && DisplayExtent.Y > 50)
		{
			SMemoryStats MemoryStats = ComputeView();

			RHISetRenderTarget(View.Family->RenderTarget->GetRenderTargetTexture(),FTextureRHIRef());
			RHISetViewport(0, 0, 0.0f, GSceneRenderTargets.GetBufferSizeXY().X, GSceneRenderTargets.GetBufferSizeXY().Y, 1.0f );

			RHISetBlendState(TStaticBlendState<>::GetRHI());
			RHISetRasterizerState(TStaticRasterizerState<>::GetRHI());
			RHISetDepthStencilState(TStaticDepthStencilState<false,CF_Always>::GetRHI());

			// this is a helper class for FCanvas to be able to get screen size
			class FRenderTargetTemp : public FRenderTarget
			{
			public:
				const FSceneView& View;

				FRenderTargetTemp(const FSceneView& InView) : View(InView)
				{
				}
				virtual FIntPoint GetSizeXY() const
				{
					return View.UnscaledViewRect.Size();
				};
				virtual const FTexture2DRHIRef& GetRenderTargetTexture() const
				{
					return View.Family->RenderTarget->GetRenderTargetTexture();
				}
			} TempRenderTarget(View);

			FCanvas Canvas(&TempRenderTarget, NULL, View.Family->CurrentRealTime, View.Family->CurrentWorldTime, View.Family->DeltaWorldTime);

			// TinyFont property
			const int32 FontHeight = 12;

			FIntPoint MousePos = View.CursorPos;
			//		FVector2D MousePos = FSlateApplication::Get().GetCursorPos();
			//		FVector2D MousePos = SceneViewport ? SceneViewport->GetSoftwareCursorPosition() : FVector2D(-1, -1);

			FLinearColor BackgroundColor = FLinearColor(0.0f, 0.0f, 0.0f, 0.7f);
			FLinearColor PhaseColor = FLinearColor(0.2f, 0.1f, 0.05f, 0.8f);
			FLinearColor ElementColor = FLinearColor(0.3f, 0.3f, 0.3f, 0.9f);
			FLinearColor ElementColorVRam = FLinearColor(0.4f, 0.25f, 0.25f, 0.9f);

			UTexture2D* GradientTexture = UCanvas::StaticClass()->GetDefaultObject<UCanvas>()->GradientTexture0;

			// background rectangle
			Canvas.DrawTile(DisplayLeftTop.X, DisplayLeftTop.Y - 1 * FontHeight - 1, DisplayExtent.X, DisplayExtent.Y + FontHeight, 0, 0, 1, 1, BackgroundColor);

			{
				uint32 MB = 1024 * 1024;
				uint32 MBm1 = MB - 1;

				FString Headline = *FString::Printf(TEXT("RenderTargetPool elements(x) over time(y) >= %dKB, Displayed/Total:%d/%dMB"), 
					SizeInKBThreshold, 
					(uint32)((MemoryStats.DisplayedUsageInBytes + MBm1) / MB),
					(uint32)((MemoryStats.TotalUsageInBytes + MBm1) / MB));
				Canvas.DrawShadowedString(DisplayLeftTop.X, DisplayLeftTop.Y - 1 * FontHeight - 1, *Headline, GEngine->GetTinyFont(), FLinearColor(1, 1, 1));
			}

			float ScaleX = DisplayExtent.X / (float)TotalExtent.X;
			float ScaleY = DisplayExtent.Y / (float)TotalExtent.Y;

			// 0 if none
			FRenderTargetPoolEvent* HighlightedEvent = 0;
			FIntRect HighlightedRect;

			// Phase events
			for(FRenderTargetPoolEventIterator It(RenderTargetPoolEvents); *It; ++It)
			{
				FRenderTargetPoolEvent* Event = *It;

				if(Event->GetEventType() == ERTPE_Phase)
				{
					int32 Y0 = It.Y;
					int32 Y1 = It.FindClosingEventY();

					FIntPoint PixelLeftTop((int32)(DisplayLeftTop.X), (int32)(DisplayLeftTop.Y + ScaleY * Y0));
					FIntPoint PixelRightBottom((int32)(DisplayLeftTop.X + DisplayExtent.X), (int32)(DisplayLeftTop.Y + ScaleY * Y1));

					bool bHighlight = MousePos.X >= PixelLeftTop.X && MousePos.X < PixelRightBottom.X && MousePos.Y >= PixelLeftTop.Y && MousePos.Y <= PixelRightBottom.Y;

					if(bHighlight)
					{
						HighlightedEvent = Event;
						HighlightedRect = FIntRect(PixelLeftTop, PixelRightBottom);
					}

					// UMax is 0.9f to avoid getting some wrap texture leaking in at the bottom
					Canvas.DrawTile(PixelLeftTop.X, PixelLeftTop.Y, PixelRightBottom.X - PixelLeftTop.X, PixelRightBottom.Y - PixelLeftTop.Y, 0, 0, 1, 0.9f, PhaseColor, GradientTexture->Resource);
				}
			}

			// Alloc / Dealloc events
			for(FRenderTargetPoolEventIterator It(RenderTargetPoolEvents); *It; ++It)
			{
				FRenderTargetPoolEvent* Event = *It;

				if(Event->GetEventType() == ERTPE_Alloc && Event->GetColumnSize())
				{
					int32 Y0 = It.Y;
					int32 Y1 = It.FindClosingEventY();

					int32 X0 = Event->GetColumnX();
					// for now they are all equal width
					int32 X1 = X0 + Event->GetColumnSize();

					FIntPoint PixelLeftTop((int32)(DisplayLeftTop.X + ScaleX * X0), (int32)(DisplayLeftTop.Y + ScaleY * Y0));
					FIntPoint PixelRightBottom((int32)(DisplayLeftTop.X + ScaleX * X1), (int32)(DisplayLeftTop.Y + ScaleY * Y1));

					bool bHighlight = MousePos.X >= PixelLeftTop.X && MousePos.X < PixelRightBottom.X && MousePos.Y >= PixelLeftTop.Y && MousePos.Y <= PixelRightBottom.Y;

					if(bHighlight)
					{
						HighlightedEvent = Event;
						HighlightedRect = FIntRect(PixelLeftTop, PixelRightBottom);
					}

					FLinearColor Color = ElementColor;

					// Highlight EDRAM/FastVRAM usage
					if(Event->GetDesc().Flags & TexCreate_FastVRAM)
					{
						Color = ElementColorVRam;
					}

					Canvas.DrawTile(
						PixelLeftTop.X, PixelLeftTop.Y,
						PixelRightBottom.X - PixelLeftTop.X - 1, PixelRightBottom.Y - PixelLeftTop.Y - 1,
						0, 0, 1, 1, Color);
				}
			}

			if(HighlightedEvent)
			{
				DrawBorder(Canvas, HighlightedRect, FLinearColor(0.8f, 0 , 0, 0.5f));

				// Offset to not intersect with crosshair (in editor) or arrow (in game).
				FIntPoint Pos = MousePos + FIntPoint(12, 4);

				if(HighlightedEvent->GetEventType() == ERTPE_Phase)
				{
					Canvas.DrawShadowedString(Pos.X, Pos.Y + 0 * FontHeight, *HighlightedEvent->GetPhaseName(), GEngine->GetTinyFont(), FLinearColor(0.5f, 0.5f, 1));
				}
				else
				{
					FString SizeString = FString::Printf(TEXT("%d KB"), (HighlightedEvent->GetSizeInBytes() + 1024) / 1024);

					Canvas.DrawShadowedString(Pos.X, Pos.Y + 0 * FontHeight, HighlightedEvent->GetDesc().DebugName, GEngine->GetTinyFont(), FLinearColor(1, 1, 0));
					Canvas.DrawShadowedString(Pos.X, Pos.Y + 1 * FontHeight, *HighlightedEvent->GetDesc().GenerateInfoString(), GEngine->GetTinyFont(), FLinearColor(1, 1, 0));
					Canvas.DrawShadowedString(Pos.X, Pos.Y + 2 * FontHeight, *SizeString, GEngine->GetTinyFont(), FLinearColor(1, 1, 0));
				}
			}

			Canvas.Flush();
		}
	}

	VisualizeTexture.PresentContent(View);
}

void FRenderTargetPool::AddDeallocEvents()
{
	check(IsInRenderingThread());

	bool bWorkWasDone = false;

	for(uint32 i = 0, Num = (uint32)RenderTargetPoolEvents.Num(); i < Num; ++i)
	{
		FRenderTargetPoolEvent& Event = RenderTargetPoolEvents[i];

		if(Event.NeedsDeallocEvent())
		{
			FRenderTargetPoolEvent NewEvent(Event.GetPoolEntryId(), CurrentTimeStep);

			// for convenience - is actually redundant
			NewEvent.SetDesc(Event.GetDesc());

			RenderTargetPoolEvents.Add(NewEvent);
			bWorkWasDone = true;
		}
	}

	if(bWorkWasDone)
	{
		++CurrentTimeStep;
	}
}

void FRenderTargetPool::AddAllocEvent(uint32 InPoolEntryId, FPooledRenderTarget* In)
{
	check(In);

	if(IsEventRecordingEnabled())
	{
		AddDeallocEvents();

		check(IsInRenderingThread());

		FRenderTargetPoolEvent NewEvent(InPoolEntryId, CurrentTimeStep++, In);

		RenderTargetPoolEvents.Add(NewEvent);
	}
}


void FRenderTargetPool::AddAllocEventsFromCurrentState()
{
	if(!IsEventRecordingEnabled())
	{
		return;
	}

	check(IsInRenderingThread());

	bool bWorkWasDone = false;

	for(uint32 i = 0; i < (uint32)PooledRenderTargets.Num(); ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(Element && !Element->IsFree())
		{
			FRenderTargetPoolEvent NewEvent(i, CurrentTimeStep, Element);

			RenderTargetPoolEvents.Add(NewEvent);
			bWorkWasDone = true;
		}
	}

	if(bWorkWasDone)
	{
		++CurrentTimeStep;
	}
}

void FRenderTargetPool::TickPoolElements()
{
	check(IsInRenderingThread());

	bEventRecording = false;

	if(bEventRecordingTrigger)
	{
		bEventRecordingTrigger = false;
		bEventRecording = true;
		CurrentTimeStep = 0;
		RenderTargetPoolEvents.Empty();
	}

	uint32 MinimumPoolSizeInKB;
	{
		static const auto CVar = IConsoleManager::Get().FindTConsoleVariableDataInt(TEXT("r.RenderTargetPoolMin"));

		MinimumPoolSizeInKB = FMath::Clamp(CVar->GetValueOnRenderThread(), 0, 2000) * 1024;
	}

	for(uint32 i = 0; i < (uint32)PooledRenderTargets.Num(); ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(Element)
		{
			Element->OnFrameStart();
		}
	}

	// we need to release something, take the oldest ones first
	while(AllocationLevelInKB > MinimumPoolSizeInKB)
	{
		// -1: not set
		int32 OldestElementIndex = -1;

		// find oldest element we can remove
		for(uint32 i = 0, Num = (uint32)PooledRenderTargets.Num(); i < Num; ++i)
		{
			FPooledRenderTarget* Element = PooledRenderTargets[i];

			if(Element && Element->UnusedForNFrames > 2)
			{
				if(OldestElementIndex != -1)
				{
					if(PooledRenderTargets[OldestElementIndex]->UnusedForNFrames < Element->UnusedForNFrames)
					{
						OldestElementIndex = i;
					}
				}
				else
				{
					OldestElementIndex = i;
				}
			}
		}

		if(OldestElementIndex != -1)
		{
			AllocationLevelInKB -= ComputeSizeInKB(*PooledRenderTargets[OldestElementIndex]);

			// we assume because of reference counting the resource gets released when not needed any more
			// we don't use Remove() to not shuffle around the elements for better transparency on RenderTargetPoolEvents
			PooledRenderTargets[OldestElementIndex] = 0;

			VerifyAllocationLevel();
		}
		else
		{
			// There is no element we can remove but we are over budget, better we log that.
			// Options:
			//   * Increase the pool
			//   * Reduce rendering features or resolution
			//   * Investigate allocations, order or reusing other render targets can help
			//   * Ignore (editor case, might start using slow memory which can be ok)
			if(!bCurrentlyOverBudget)
			{
				UE_LOG(LogRenderTargetPool, Warning, TEXT("r.RenderTargetPoolMin exceeded %d/%d MB (ok in editor, bad on fixed memory platform)"), (AllocationLevelInKB + 1023) / 1024, MinimumPoolSizeInKB / 1024);
				bCurrentlyOverBudget = true;
			}
			// at this point we need to give up
			break;
		}

/*	
	// confused more than it helps (often a name is used on two elements in the pool and some pool elements are not rendered to this frame)
	else
	{
		// initial state of a render target (e.g. Velocity@0)
		GRenderTargetPool.VisualizeTexture.SetCheckPoint(Element);
*/	}

	if(AllocationLevelInKB <= MinimumPoolSizeInKB)
	{
		if(bCurrentlyOverBudget)
		{
			UE_LOG(LogRenderTargetPool, Display, TEXT("r.RenderTargetPoolMin resolved %d/%d MB"), (AllocationLevelInKB + 1023) / 1024, MinimumPoolSizeInKB / 1024);
			bCurrentlyOverBudget = false;
		}
	}

//	CompactEventArray();

	AddPhaseEvent(TEXT("FromLastFrame"));
	AddAllocEventsFromCurrentState();
	AddPhaseEvent(TEXT("Rendering"));
}


int32 FRenderTargetPool::FindIndex(IPooledRenderTarget* In) const
{
	check(IsInRenderingThread());

	if(In)
	{
		for(uint32 i = 0, Num = (uint32)PooledRenderTargets.Num(); i < Num; ++i)
		{
			const FPooledRenderTarget* Element = PooledRenderTargets[i];

			if(Element == In)
			{
				return i;
			}
		}
	}

	// not found
	return -1;
}

void FRenderTargetPool::FreeUnusedResource(TRefCountPtr<IPooledRenderTarget>& In)
{
	check(IsInRenderingThread());
	
	int32 Index = FindIndex(In);

	if(Index != -1)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[Index];

		if(Element)
		{
			AllocationLevelInKB -= ComputeSizeInKB(*Element);
			// we assume because of reference counting the resource gets released when not needed any more
			// we don't use Remove() to not shuffle around the elements for better transparency on RenderTargetPoolEvents
			PooledRenderTargets[Index] = 0;

			In.SafeRelease();

			VerifyAllocationLevel();
		}
	}
}

void FRenderTargetPool::FreeUnusedResources()
{
	check(IsInRenderingThread());

	for(uint32 i = 0, Num = (uint32)PooledRenderTargets.Num(); i < Num; ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(Element && Element->IsFree())
		{
			AllocationLevelInKB -= ComputeSizeInKB(*Element);
			// we assume because of reference counting the resource gets released when not needed any more
			// we don't use Remove() to not shuffle around the elements for better transparency on RenderTargetPoolEvents
			PooledRenderTargets[i] = 0;
		}
	}

	VerifyAllocationLevel();
}


void FRenderTargetPool::DumpMemoryUsage(FOutputDevice& OutputDevice)
{
	OutputDevice.Logf(TEXT("Pooled Render Targets:"));
	for(int32 i = 0; i < PooledRenderTargets.Num(); ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(Element)
		{
			OutputDevice.Logf(
				TEXT("  %6.3fMB %4dx%4d%s%s %2dmip(s) %s (%s)"),
				ComputeSizeInKB(*Element) / 1024.0f,
				Element->Desc.Extent.X,
				Element->Desc.IsCubemap() ? Element->Desc.Extent.X : Element->Desc.Extent.Y,
				Element->Desc.Depth > 1 ? *FString::Printf(TEXT("x%3d"), Element->Desc.Depth) : (Element->Desc.IsCubemap() ? TEXT("cube") : TEXT("    ")),
				Element->Desc.bIsArray ? *FString::Printf(TEXT("[%3d]"), Element->Desc.ArraySize) : TEXT("     "),
				Element->Desc.NumMips,
				Element->Desc.DebugName,
				GPixelFormats[Element->Desc.Format].Name
				);
		}
	}
	uint32 NumTargets=0;
	uint32 UsedKB=0;
	uint32 PoolKB=0;
	GetStats(NumTargets,PoolKB,UsedKB);
	OutputDevice.Logf(TEXT("%.3fMB total, %.3fMB used, %d render targets"), PoolKB / 1024.f, UsedKB / 1024.f, NumTargets);
}

uint32 FPooledRenderTarget::AddRef() const
{
	return uint32(++NumRefs);
}

uint32 FPooledRenderTarget::Release() const
{
	uint32 Refs = uint32(--NumRefs);
	if(Refs == 0)
	{
		// better we remove const from Release()
		FSceneRenderTargetItem& NonConstItem = (FSceneRenderTargetItem&)RenderTargetItem;

		NonConstItem.SafeRelease();
		delete this;
	}
	return Refs;
}

uint32 FPooledRenderTarget::GetRefCount() const
{
	return uint32(NumRefs);
}

void FPooledRenderTarget::SetDebugName(const TCHAR *InName)
{
	check(InName);

	Desc.DebugName = InName;
}

const FPooledRenderTargetDesc& FPooledRenderTarget::GetDesc() const
{
	return Desc;
}

void FRenderTargetPool::ReleaseDynamicRHI()
{
	check(IsInRenderingThread());
	PooledRenderTargets.Empty();
}

// for debugging purpose
FPooledRenderTarget* FRenderTargetPool::GetElementById(uint32 Id) const
{
	// is used in game and render thread

	if(Id >= (uint32)PooledRenderTargets.Num())
	{
		return 0;
	}

	return PooledRenderTargets[Id];
}

void FRenderTargetPool::VerifyAllocationLevel() const
{
/*
	// to verify internal consistency
	uint32 OutWholeCount;
	uint32 OutWholePoolInKB;
	uint32 OutUsedInKB;

	GetStats(OutWholeCount, OutWholePoolInKB, OutUsedInKB);
*/
}

void FRenderTargetPool::CompactPool()
{
	for(uint32 i = 0, Num = (uint32)PooledRenderTargets.Num(); i < Num; ++i)
	{
		FPooledRenderTarget* Element = PooledRenderTargets[i];

		if(!Element)
		{
			PooledRenderTargets.RemoveAtSwap(i);
			--Num;
		}
	}
}

bool FPooledRenderTarget::OnFrameStart()
{
	check(IsInRenderingThread());

	// If there are any references to the pooled render target other than the pool itself, then it may not be freed.
	if(!IsFree())
	{
		check(!UnusedForNFrames);
		return false;
	}

	++UnusedForNFrames;

	// this logic can be improved
	if(UnusedForNFrames > 10)
	{
		// release
		return true;
	}

	return false;
}

uint32 FPooledRenderTarget::ComputeMemorySize() const
{
	uint32 Size = 0;

	if(Desc.Is2DTexture())
	{
		Size += RHIComputeMemorySize((const FTexture2DRHIRef&)RenderTargetItem.TargetableTexture);
		if(RenderTargetItem.ShaderResourceTexture != RenderTargetItem.TargetableTexture)
		{
			Size += RHIComputeMemorySize((const FTexture2DRHIRef&)RenderTargetItem.ShaderResourceTexture);
		}
	}
	else if(Desc.Is3DTexture())
	{
		Size += RHIComputeMemorySize((const FTexture3DRHIRef&)RenderTargetItem.TargetableTexture);
		if(RenderTargetItem.ShaderResourceTexture != RenderTargetItem.TargetableTexture)
		{
			Size += RHIComputeMemorySize((const FTexture3DRHIRef&)RenderTargetItem.ShaderResourceTexture);
		}
	}
	else
	{
		Size += RHIComputeMemorySize((const FTextureCubeRHIRef&)RenderTargetItem.TargetableTexture);
		if(RenderTargetItem.ShaderResourceTexture != RenderTargetItem.TargetableTexture)
		{
			Size += RHIComputeMemorySize((const FTextureCubeRHIRef&)RenderTargetItem.ShaderResourceTexture);
		}
	}

	return Size;
}

bool FPooledRenderTarget::IsFree() const
{
	check(GetRefCount() >= 1);
	// If the only reference to the pooled render target is from the pool, then it's unused.
	return GetRefCount() == 1;
}