（原）Unreal渲染相关的缓冲区及其自定义代码几种抓取

@authot: 白袍小道

转载说明那啥即可。
(图片和本文无关，嘿嘿，坑一下）
以下为Unreal4.18版本中对GPUBuffer部分的分析结果
（插入：比之够着，知至目的）
Memo of GBuffer (UE4.18)
- GBufferA : Normal(rgb), PerObjectGBufferData(a)
- GBufferB : Metallic(r), Specular(g), Roughness(b), ShadingModelID(a&0xF),
- SelectiveOutputMask(a&0xF0)
- GBufferC : BaseColor(rgb), IndirectIrradiance(a)
- GBufferD : CustomData(rgba)
- GBufferE : PrecomputedShadowFactors(rgba)
- SceneDepth
- CustomNativeDepth : depth®
- CustomStencilTexture
- GBufferVelocity : rgba
  
  补充说明：注意源码中对这一块的对齐处理，线程，访问方式的处理
Dbuffer
- DBufferA : PreMultColor(rgb), ColorOpacity(a)
- DBufferB : PreMulWorldNormal(rgb), NormalOpacity(a)
- DBufferC : PreMulRoughness(r ), RoughnessOpacity(g)
（一）、DeferredShadingRender中对Buffer的处理

从调式和RenderDoc可以详细看到过程，这里就不做详细说明

结果：

(二），代码抓取

结局：

https://twitter.com/i/status/1096091562642001920

这里主要用两种方式去获取，一种是通过Fmemory,一种直接用Unreal提供CopyShareMip

具体如下：

以下为全部代码：

DynamicAccessGBufferRenderTarget.h：

//////////////////这里就没有按照Buff处理做分装了，直接怼的（嘿嘿）

#pragma once

#include <memory>

#include "Engine/Texture2D.h"

#include "Object.h"

#include "DynamicAccessGBufferRenderTarget.generated.h"

UENUM(BlueprintType)                //"BlueprintType" is essential to include

enum class EDZShowGbuffer : uint8

{

VE_GDZSHOWBUFFERA         UMETA(DisplayName = "ShowGBuffA"),

VE_GDZSHOWBUFFERB         UMETA(DisplayName = "ShowGBuffB"),

VE_GDZSHOWBUFFERC        UMETA(DisplayName = "ShowGBuffC"),

VE_GDZSHOWBUFFERD        UMETA(DisplayName = "ShowGBuffD"),

VE_GDZSHOWBUFFERE        UMETA(DisplayName = "ShowGBuffE"),

};

UENUM(BlueprintType)                //"BlueprintType" is essential to include

enum class EDZCOPYGbufferType : uint8

{

VE_GDZSHOWGBUFFER_COPYMIP         UMETA(DisplayName = "COPY_Mip"),

VE_GDZSHOWBUFFERR_COPYMEMO         UMETA(DisplayName = "COPY_Memory"),

VE_GDZSHOWBUFFERC_CPUARRAY        UMETA(DisplayName = "COPY_MemoryForWhile"),

};

USTRUCT()

struct FCommitRenderData

{

GENERATED_BODY()

public:

EDZCOPYGbufferType ECOPYBuffType;

EDZShowGbuffer EShowBuff;

UTextureRenderTarget2D* mTextureTarget;

EPixelFormat format;

int32 canvasWidth = 512;

int32 canvasHeight = 512;

bool isGetGBufferData = false;

};

UCLASS(Blueprintable, BlueprintType)

class DZRENDERSTUDIOPLUGIN_API UDynamicAccessGBufferRenderTarget : public UObject

{

GENERATED_BODY()

public:

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = DynamicAccessGBufferRenderTarget)

EDZCOPYGbufferType ECOPYBuffType;

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = DynamicAccessGBufferRenderTarget)

EDZShowGbuffer EShowBuff;

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = DynamicAccessGBufferRenderTarget)

UTextureRenderTarget2D* mTextureTarget;

UFUNCTION(BlueprintCallable, Category = DynamicAccessGBufferRenderTarget)

void InitializeTexture(UTextureRenderTarget2D* pTextureTarget,EDZShowGbuffer pEShowBuff, EDZCOPYGbufferType pECOPYBuffType);

UFUNCTION(BlueprintCallable, Category = DynamicAccessGBufferRenderTarget)

void CaputerGBuffer();

UFUNCTION(BlueprintCallable, Category = DynamicAccessGBufferRenderTarget)

void ClearTexture();

UDynamicAccessGBufferRenderTarget();

~UDynamicAccessGBufferRenderTarget();

static void CaputerGBufer_Rebuild_RenderThread(FCommitRenderData* pRenderData);

static void CaputerGBuffer_RenderThread(FCommitRenderData* pRenderData);

static void Copy_TextureRHI(FRHICommandListImmediate& RHICmdList, FRHITexture2D* pDesc, FRHITexture2D* pSrc);

static void Copy_MemoryRHI(FRHICommandListImmediate& RHICmdList, FRHITexture2D* pDesc, FRHITexture2D* pSrc);

static void Copy_CPUArrayRHI();

private:

EPixelFormat format;

UPROPERTY()

FCommitRenderData CatchRenderData;

UPROPERTY()

bool isRebulidRenderTargetSuccess = false;

};

DynamicAccessGBufferRenderTarget.cpp

/**

* 1、这里步骤基本为先得到当前Buffer的大小，刷新RT目标的数据。并在基础属性变化时* 候再次刷新

* 2、抓取数据（由于BUFF在Render管线处理时候有获取和释放的处理也是为了能及时释* 放，所以手动加1，

* 当然成对的写法在DepthRender, Slate等都可以看到，这非常好。

* 3、CopyShare或者利用FMemory::Memcpy(但拷贝前需要加锁，完成后还需要解锁,所* * 以你懂的

**/

#include "DynamicAccessGBufferRenderTarget.h"

#include "private/PostProcess/SceneRenderTargets.h"

#include "Engine.h"

#include "RHICommandList.h"

UDynamicAccessGBufferRenderTarget::UDynamicAccessGBufferRenderTarget()

{

}

UDynamicAccessGBufferRenderTarget::~UDynamicAccessGBufferRenderTarget()

{

}

void UDynamicAccessGBufferRenderTarget::InitializeTexture(UTextureRenderTarget2D* pTextureTarget

, EDZShowGbuffer pEShowBuff, EDZCOPYGbufferType pECOPYBuffType)

{

if (mTextureTarget != pTextureTarget || EShowBuff != pEShowBuff || ECOPYBuffType != pECOPYBuffType)

{

mTextureTarget = pTextureTarget;

EShowBuff = pEShowBuff;

ECOPYBuffType = pECOPYBuffType;

isRebulidRenderTargetSuccess = false;

}

}

void UDynamicAccessGBufferRenderTarget::ClearTexture()

{

}

void UDynamicAccessGBufferRenderTarget::CaputerGBuffer()

{

if (!CatchRenderData.isGetGBufferData)

{

isRebulidRenderTargetSuccess = false;

CatchRenderData.EShowBuff = EShowBuff;

CatchRenderData.ECOPYBuffType = ECOPYBuffType;

CatchRenderData.mTextureTarget = mTextureTarget;

ENQUEUE_UNIQUE_RENDER_COMMAND_ONEPARAMETER(

DZRenderSutioBP_AccessGBufferRenderTarget_init,

FCommitRenderData*, RenderData, &CatchRenderData,

{

UDynamicAccessGBufferRenderTarget::CaputerGBufer_Rebuild_RenderThread(RenderData);

}

);

}

else

{

if (!isRebulidRenderTargetSuccess)

{

if (IsInGameThread())

{

mTextureTarget->InitCustomFormat(CatchRenderData.canvasWidth, CatchRenderData.canvasHeight, CatchRenderData.format, false);

mTextureTarget->ForceRebuildPlatformData();

}

isRebulidRenderTargetSuccess = true;

}

else

{

CatchRenderData.EShowBuff = EShowBuff;

CatchRenderData.ECOPYBuffType = ECOPYBuffType;

CatchRenderData.mTextureTarget = mTextureTarget;

ENQUEUE_UNIQUE_RENDER_COMMAND_ONEPARAMETER(

DZRenderSutioBP_InterceptSceneGBufferToRenderTarget,

FCommitRenderData*, RenderData, &CatchRenderData,

{

UDynamicAccessGBufferRenderTarget::CaputerGBuffer_RenderThread(RenderData);

}

);

}

}

}

void UDynamicAccessGBufferRenderTarget::CaputerGBufer_Rebuild_RenderThread(FCommitRenderData* pRenderData)

{

FRHICommandListImmediate& RHICmdList = GRHICommandList.GetImmediateCommandList();

//计数加一避免Render完成后直接清空了GBuffer,但会慢一帧，你猜

FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, 1);

FSceneRenderTargets& SceneContext = FSceneRenderTargets::Get(RHICmdList);

if (SceneContext.GBufferA)

{

FTexture2DRHIRef vTextTarget;

switch (pRenderData->EShowBuff)

{

case EDZShowGbuffer::VE_GDZSHOWBUFFERA:

vTextTarget = SceneContext.GetGBufferATexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERB:

vTextTarget = SceneContext.GetGBufferBTexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERC:

vTextTarget = SceneContext.GetGBufferCTexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERD:

vTextTarget = SceneContext.GetGBufferDTexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERE:

vTextTarget = SceneContext.GetGBufferETexture();

break;

default:

vTextTarget = SceneContext.GetGBufferATexture();

break;

}

pRenderData->format = vTextTarget->GetFormat();

pRenderData->canvasWidth = vTextTarget->GetSizeX();

pRenderData->canvasHeight = vTextTarget->GetSizeY();

pRenderData->isGetGBufferData = true;

}

FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, -1);

}

void UDynamicAccessGBufferRenderTarget::CaputerGBuffer_RenderThread(FCommitRenderData* pRenderData)

{

FRHICommandListImmediate& RHICmdList = GRHICommandList.GetImmediateCommandList();

//计数加一避免Render完成后直接清空了GBuffer,但会慢一帧，你猜

FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, 1);

FSceneRenderTargets& SceneContext = FSceneRenderTargets::Get(RHICmdList);

if (SceneContext.GBufferA && pRenderData->mTextureTarget != nullptr)

{

FTexture2DRHIRef vTextTarget;

switch (pRenderData->EShowBuff)

{

case EDZShowGbuffer::VE_GDZSHOWBUFFERA:

vTextTarget = SceneContext.GetGBufferATexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERB:

vTextTarget = SceneContext.GetGBufferBTexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERC:

vTextTarget = SceneContext.GetGBufferCTexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERD:

vTextTarget = SceneContext.GetGBufferDTexture();

break;

case EDZShowGbuffer::VE_GDZSHOWBUFFERE:

vTextTarget = SceneContext.GetGBufferETexture();

break;

break;

default:

vTextTarget = SceneContext.GetGBufferATexture();

break;

}

pRenderData->format = vTextTarget->GetFormat();

if (pRenderData->canvasWidth != vTextTarget->GetSizeX())

{

pRenderData->isGetGBufferData = false;

return;

}

FTextureReferenceRHIRef vTexRHIRef = pRenderData->mTextureTarget->TextureReference.TextureReferenceRHI;

FRHITexture* vRTTexture = vTexRHIRef->GetTextureReference()->GetReferencedTexture();

FRHITexture2D* vtex = (FRHITexture2D*)vRTTexture;

if (vtex == nullptr)

{

return;

}

switch (pRenderData->ECOPYBuffType)

{

case EDZCOPYGbufferType::VE_GDZSHOWGBUFFER_COPYMIP:

UDynamicAccessGBufferRenderTarget::Copy_TextureRHI(RHICmdList,vtex, vTextTarget);

break;

case EDZCOPYGbufferType::VE_GDZSHOWBUFFERR_COPYMEMO:

UDynamicAccessGBufferRenderTarget::Copy_MemoryRHI(RHICmdList, vtex, vTextTarget);

break;

case EDZCOPYGbufferType::VE_GDZSHOWBUFFERC_CPUARRAY:

UDynamicAccessGBufferRenderTarget::Copy_CPUArrayRHI();

break;

default:

break;

}

RHICmdList.CopySharedMips(vtex, vTextTarget);

}

//移除

FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, -1);

}

//利用SharedMip的共享方式在这里会快一些

//扩展方式

void UDynamicAccessGBufferRenderTarget::Copy_TextureRHI(FRHICommandListImmediate& RHICmdList,FRHITexture2D* pDesc,FRHITexture2D* pSrc)

{

RHICmdList.CopySharedMips(pDesc, pSrc);

}

//内存CPY，但需要锁住，这样就会让另外的渲染不能访问，会造成掉帧率。

void UDynamicAccessGBufferRenderTarget::Copy_MemoryRHI(FRHICommandListImmediate& RHICmdList, FRHITexture2D* pDesc, FRHITexture2D* pSrc)

{

uint32 Lolstrid = 0;

void * UAVRenderTargetData = RHILockTexture2D(pDesc, 0, RLM_WriteOnly, Lolstrid, true);

void * UAVCSData = RHILockTexture2D(pSrc, 0, RLM_ReadOnly, Lolstrid, true);

FMemory::Memcpy(UAVRenderTargetData, UAVCSData, GPixelFormats[pSrc->GetFormat()].BlockBytes * pSrc->GetSizeX() * pSrc->GetSizeY());

RHICmdList.UnlockTexture2D(pDesc, 0, false);

RHICmdList.UnlockTexture2D(pSrc, 0, false);

}

void UDynamicAccessGBufferRenderTarget::Copy_CPUArrayRHI()

{

}

蓝图和资源部分

1、RT （1个对应一个结果）

2、一个UI材质（用于做一些额外效果）

3、一个UI蓝图（就是调用代码和绑定资源，用C++也可以，偷懒下）

RT赋予

BP部分

UI_ShowCapResul_Child：

除了一些我们自己做的方式和LitMode中调试方式

还以通过像素检查器进行分析和查看

题外：

1、Create Custom GBUFFER ：http://www.catalinzima.com/xna/tutorials/deferred-rendering-in-xna/creating-the-g-buffer/

2、Buffer,RT ,Pipeline

https://medium.com/@lordned/unreal-engine-4-rendering-part-4-the-deferred-shading-pipeline-389fc0175789

3、https://en.wikipedia.org/wiki/Deferred_shading

4、高效的GPU GBUFFER管理：http://www.klayge.org/2015/05/25/%E9%AB%98%E6%95%88gpu-buffer%E7%AE%A1%E7%90%86%E4%B9%8Btransient-buffer/

巴特西

（原）Unreal渲染相关的缓冲区及其自定义代码几种抓取

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巴特西

（原）Unreal渲染相关的缓冲区 及其 自定义代码几种抓取

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（原）Unreal渲染相关的缓冲区及其自定义代码几种抓取