202 lines
12 KiB
Markdown
202 lines
12 KiB
Markdown
---
|
||
title: Untitled
|
||
date: 2024-02-04 12:57:56
|
||
excerpt:
|
||
tags:
|
||
rating: ⭐
|
||
---
|
||
# 前言
|
||
原文地址：https://www.cnblogs.com/timlly/p/15156626.html
|
||
|
||
# 概念
|
||
- FRenderResource：是渲染线程的渲染资源基础父类，实际的数据和逻辑由子类实现。可以认为是渲染线程中承载**CPU相关相关渲染的载体**。
|
||
- 比如输入的顶点数据、顶点Index数据、贴图数据等。
|
||
- FRHIResource：抽象了GPU侧的资源，也是众多RHI资源类型的父类。可以认为是承载**显卡API相关资源的载体**。
|
||
- 比如TextureSampler、TextureObject等。
|
||
- FRHICommand：其父类为**FRHICommandBase**结构体。其含有**FRHICommandBase* Next**用来保存下一个Command的指针，所以存储他的结构为**链表**。
|
||
- 含有接口：void void ExecuteAndDestruct(FRHICommandListBase& CmdList, FRHICommandListDebugContext& DebugContext)。执行完就销毁。
|
||
- UE使用**FRHICOMMAND_MACRO**宏来快速定义各种RHICommand。主要功能包含：
|
||
- 数据和资源的设置、更新、清理、转换、拷贝、回读。
|
||
- 图元绘制。
|
||
- Pass、SubPass、场景、ViewPort等的开始和结束事件。
|
||
- 栅栏、等待、广播接口。
|
||
- 光线追踪。
|
||
- Slate、调试相关的命令。
|
||
- FRHICommandList：是**RHI的指令队列**，用来管理、执行一组FRHICommand的对象。
|
||
- 其子类有**FRHICommandListImmediate**（立即执行队列）、FRHIComputeCommandList_RecursiveHazardous与TRHIComputeCommandList_RecursiveHazardous（命令列表的递归使用）
|
||
- IRHICommandContext：是RHI的命令上下文接口类，定义了一组图形API相关的操作。在可以并行处理命令列表的平台上，它是一个单独的对象类。
|
||
- 主要的接口函数有：
|
||
- 派发ComputeShader
|
||
- 渲染查询（可见性？）
|
||
- 相关开始/结束函数。
|
||
- 设置数据（Viewport、GraphicsPipelineState等）
|
||
- 设置ShadserParameter
|
||
- 绘制图元
|
||
- 纹理拷贝/更新
|
||
- Raytracing
|
||
- IRHICommandContext的接口和FRHICommandList的接口高度相似且重叠。IRHICommandContext还有许多子类：
|
||
- IRHICommandContextPSOFallback：不支持真正的图形管道的RHI命令上下文。
|
||
- FNullDynamicRHI：空实现的动态绑定RHI。
|
||
- FOpenGLDynamicRHI：OpenGL的动态RHI。
|
||
- FD3D11DynamicRHI：D3D11的动态RHI。
|
||
- FMetalRHICommandContext：Metal平台的命令上下文。
|
||
- FD3D12CommandContextBase：D3D12的命令上下文。
|
||
- FVulkanCommandListContext：Vulkan平台的命令队列上下文。
|
||
- FEmptyDynamicRHI：动态绑定的RHI实现的接口。
|
||
- FValidationContext：校验上下文。
|
||
- IRHICommandContextContainer：IRHICommandContextContainer就是包含了IRHICommandContext对象的类型。相当于存储了一个或一组命令上下文的容器，以支持并行化地提交命令队列，只在D3D12、Metal、Vulkan等现代图形API中有实现。
|
||
- D3D12存储了FD3D12Adapter* Adapter、FD3D12CommandContext* CmdContext、 FD3D12CommandContextRedirector* CmdContextRedirector。
|
||
- FDynamicRHI：FDynamicRHI是由动态绑定的RHI实现的接口，它定义的接口和CommandList、CommandContext比较相似。
|
||
- 代码详见[[#FDynamicRHI]]
|
||
- FRHICommandListExecutor
|
||
|
||
## FDynamicRHI
|
||
```c++
|
||
class RHI_API FDynamicRHI
|
||
{
|
||
public:
|
||
virtual ~FDynamicRHI() {}
|
||
|
||
virtual void Init() = 0;
|
||
virtual void PostInit() {}
|
||
virtual void Shutdown() = 0;
|
||
|
||
void InitPixelFormatInfo(const TArray<uint32>& PixelFormatBlockBytesIn);
|
||
|
||
// ---- RHI接口 ----
|
||
|
||
// 下列接口要求FlushType: Thread safe
|
||
virtual FSamplerStateRHIRef RHICreateSamplerState(const FSamplerStateInitializerRHI& Initializer) = 0;
|
||
virtual FRasterizerStateRHIRef RHICreateRasterizerState(const FRasterizerStateInitializerRHI& Initializer) = 0;
|
||
virtual FDepthStencilStateRHIRef RHICreateDepthStencilState(const FDepthStencilStateInitializerRHI& Initializer) = 0;
|
||
virtual FBlendStateRHIRef RHICreateBlendState(const FBlendStateInitializerRHI& Initializer) = 0;
|
||
|
||
// 下列接口要求FlushType: Wait RHI Thread
|
||
virtual FVertexDeclarationRHIRef RHICreateVertexDeclaration(const FVertexDeclarationElementList& Elements) = 0;
|
||
virtual FPixelShaderRHIRef RHICreatePixelShader(TArrayView<const uint8> Code, const FSHAHash& Hash) = 0;
|
||
virtual FVertexShaderRHIRef RHICreateVertexShader(TArrayView<const uint8> Code, const FSHAHash& Hash) = 0;
|
||
virtual FHullShaderRHIRef RHICreateHullShader(TArrayView<const uint8> Code, const FSHAHash& Hash) = 0;
|
||
virtual FDomainShaderRHIRef RHICreateDomainShader(TArrayView<const uint8> Code, const FSHAHash& Hash) = 0;
|
||
virtual FGeometryShaderRHIRef RHICreateGeometryShader(TArrayView<const uint8> Code, const FSHAHash& Hash) = 0;
|
||
virtual FComputeShaderRHIRef RHICreateComputeShader(TArrayView<const uint8> Code, const FSHAHash& Hash) = 0;
|
||
|
||
// FlushType: Must be Thread-Safe.
|
||
virtual FRenderQueryPoolRHIRef RHICreateRenderQueryPool(ERenderQueryType QueryType, uint32 NumQueries = UINT32_MAX);
|
||
inline FComputeFenceRHIRef RHICreateComputeFence(const FName& Name);
|
||
|
||
virtual FGPUFenceRHIRef RHICreateGPUFence(const FName &Name);
|
||
virtual void RHICreateTransition(FRHITransition* Transition, ERHIPipeline SrcPipelines, ERHIPipeline DstPipelines, ERHICreateTransitionFlags CreateFlags, TArrayView<const FRHITransitionInfo> Infos);
|
||
virtual void RHIReleaseTransition(FRHITransition* Transition);
|
||
|
||
// FlushType: Thread safe.
|
||
virtual FStagingBufferRHIRef RHICreateStagingBuffer();
|
||
virtual void* RHILockStagingBuffer(FRHIStagingBuffer* StagingBuffer, FRHIGPUFence* Fence, uint32 Offset, uint32 SizeRHI);
|
||
virtual void RHIUnlockStagingBuffer(FRHIStagingBuffer* StagingBuffer);
|
||
|
||
// FlushType: Thread safe, but varies depending on the RHI
|
||
virtual FBoundShaderStateRHIRef RHICreateBoundShaderState(FRHIVertexDeclaration* VertexDeclaration, FRHIVertexShader* VertexShader, FRHIHullShader* HullShader, FRHIDomainShader* DomainShader, FRHIPixelShader* PixelShader, FRHIGeometryShader* GeometryShader) = 0;
|
||
// FlushType: Thread safe
|
||
virtual FGraphicsPipelineStateRHIRef RHICreateGraphicsPipelineState(const FGraphicsPipelineStateInitializer& Initializer);
|
||
|
||
// FlushType: Thread safe, but varies depending on the RHI
|
||
virtual FUniformBufferRHIRef RHICreateUniformBuffer(const void* Contents, const FRHIUniformBufferLayout& Layout, EUniformBufferUsage Usage, EUniformBufferValidation Validation) = 0;
|
||
virtual void RHIUpdateUniformBuffer(FRHIUniformBuffer* UniformBufferRHI, const void* Contents) = 0;
|
||
|
||
// FlushType: Wait RHI Thread
|
||
virtual FIndexBufferRHIRef RHICreateIndexBuffer(uint32 Stride, uint32 Size, uint32 InUsage, ERHIAccess InResourceState, FRHIResourceCreateInfo& CreateInfo) = 0;
|
||
virtual void* RHILockIndexBuffer(FRHICommandListImmediate& RHICmdList, FRHIIndexBuffer* IndexBuffer, uint32 Offset, uint32 Size, EResourceLockMode LockMode);
|
||
virtual void RHIUnlockIndexBuffer(FRHICommandListImmediate& RHICmdList, FRHIIndexBuffer* IndexBuffer);
|
||
virtual void RHITransferIndexBufferUnderlyingResource(FRHIIndexBuffer* DestIndexBuffer, FRHIIndexBuffer* SrcIndexBuffer);
|
||
|
||
// FlushType: Wait RHI Thread
|
||
virtual FVertexBufferRHIRef RHICreateVertexBuffer(uint32 Size, uint32 InUsage, ERHIAccess InResourceState, FRHIResourceCreateInfo& CreateInfo) = 0;
|
||
// FlushType: Flush RHI Thread
|
||
virtual void* RHILockVertexBuffer(FRHICommandListImmediate& RHICmdList, FRHIVertexBuffer* VertexBuffer, uint32 Offset, uint32 SizeRHI, EResourceLockMode LockMode);
|
||
virtual void RHIUnlockVertexBuffer(FRHICommandListImmediate& RHICmdList, FRHIVertexBuffer* VertexBuffer);
|
||
// FlushType: Flush Immediate (seems dangerous)
|
||
virtual void RHICopyVertexBuffer(FRHIVertexBuffer* SourceBuffer, FRHIVertexBuffer* DestBuffer) = 0;
|
||
virtual void RHITransferVertexBufferUnderlyingResource(FRHIVertexBuffer* DestVertexBuffer, FRHIVertexBuffer* SrcVertexBuffer);
|
||
|
||
// FlushType: Wait RHI Thread
|
||
virtual FStructuredBufferRHIRef RHICreateStructuredBuffer(uint32 Stride, uint32 Size, uint32 InUsage, ERHIAccess InResourceState, FRHIResourceCreateInfo& CreateInfo) = 0;
|
||
// FlushType: Flush RHI Thread
|
||
virtual void* RHILockStructuredBuffer(FRHICommandListImmediate& RHICmdList, FRHIStructuredBuffer* StructuredBuffer, uint32 Offset, uint32 SizeRHI, EResourceLockMode LockMode);
|
||
virtual void RHIUnlockStructuredBuffer(FRHICommandListImmediate& RHICmdList, FRHIStructuredBuffer* StructuredBuffer);
|
||
|
||
// FlushType: Wait RHI Thread
|
||
virtual FUnorderedAccessViewRHIRef RHICreateUnorderedAccessView(FRHIStructuredBuffer* StructuredBuffer, bool bUseUAVCounter, bool bAppendBuffer) = 0;
|
||
// FlushType: Wait RHI Thread
|
||
virtual FUnorderedAccessViewRHIRef RHICreateUnorderedAccessView(FRHITexture* Texture, uint32 MipLevel) = 0;
|
||
// FlushType: Wait RHI Thread
|
||
virtual FUnorderedAccessViewRHIRef RHICreateUnorderedAccessView(FRHITexture* Texture, uint32 MipLevel, uint8 Format);
|
||
|
||
(......)
|
||
|
||
// RHI帧更新，须从主线程调用，FlushType: Thread safe
|
||
virtual void RHITick(float DeltaTime) = 0;
|
||
// 阻塞CPU直到GPU执行完成变成空闲. FlushType: Flush Immediate (seems wrong)
|
||
virtual void RHIBlockUntilGPUIdle() = 0;
|
||
// 开始当前帧，并确保GPU正在积极地工作 FlushType: Flush Immediate (copied from RHIBlockUntilGPUIdle)
|
||
virtual void RHISubmitCommandsAndFlushGPU() {};
|
||
|
||
// 通知RHI准备暂停它.
|
||
virtual void RHIBeginSuspendRendering() {};
|
||
// 暂停RHI渲染并将控制权交给系统的操作, FlushType: Thread safe
|
||
virtual void RHISuspendRendering() {};
|
||
// 继续RHI渲染, FlushType: Thread safe
|
||
virtual void RHIResumeRendering() {};
|
||
// FlushType: Flush Immediate
|
||
virtual bool RHIIsRenderingSuspended() { return false; };
|
||
|
||
// FlushType: called from render thread when RHI thread is flushed
|
||
// 仅在FRHIResource::FlushPendingDeletes内的延迟删除之前每帧调用.
|
||
virtual void RHIPerFrameRHIFlushComplete();
|
||
|
||
// 执行命令队列, FlushType: Wait RHI Thread
|
||
virtual void RHIExecuteCommandList(FRHICommandList* CmdList) = 0;
|
||
|
||
// FlushType: Flush RHI Thread
|
||
virtual void* RHIGetNativeDevice() = 0;
|
||
// FlushType: Flush RHI Thread
|
||
virtual void* RHIGetNativeInstance() = 0;
|
||
|
||
// 获取命令上下文. FlushType: Thread safe
|
||
virtual IRHICommandContext* RHIGetDefaultContext() = 0;
|
||
// 获取计算上下文. FlushType: Thread safe
|
||
virtual IRHIComputeContext* RHIGetDefaultAsyncComputeContext();
|
||
|
||
// FlushType: Thread safe
|
||
virtual class IRHICommandContextContainer* RHIGetCommandContextContainer(int32 Index, int32 Num) = 0;
|
||
|
||
// 直接由渲染线程调用的接口, 以优化RHI调用.
|
||
virtual FVertexBufferRHIRef CreateAndLockVertexBuffer_RenderThread(class FRHICommandListImmediate& RHICmdList, uint32 Size, uint32 InUsage, ERHIAccess InResourceState, FRHIResourceCreateInfo& CreateInfo, void*& OutDataBuffer);
|
||
virtual FIndexBufferRHIRef CreateAndLockIndexBuffer_RenderThread(class FRHICommandListImmediate& RHICmdList, uint32 Stride, uint32 Size, uint32 InUsage, ERHIAccess InResourceState, FRHIResourceCreateInfo& CreateInfo, void*& OutDataBuffer);
|
||
|
||
(......)
|
||
|
||
// Buffer Lock/Unlock
|
||
virtual void* LockVertexBuffer_BottomOfPipe(class FRHICommandListImmediate& RHICmdList, ...);
|
||
virtual void* LockIndexBuffer_BottomOfPipe(class FRHICommandListImmediate& RHICmdList, ...);
|
||
|
||
(......)
|
||
};
|
||
```
|
||
|
||
以上只显示了部分接口，其中部分接口要求从渲染线程调用，部分须从游戏线程调用。大多数接口在被调用前需刷新指定类型的命令，比如：
|
||
```c++
|
||
class RHI_API FDynamicRHI
|
||
{
|
||
// FlushType: Wait RHI Thread
|
||
void RHIExecuteCommandList(FRHICommandList* CmdList);
|
||
|
||
// FlushType: Flush Immediate
|
||
void RHIBlockUntilGPUIdle();
|
||
|
||
// FlushType: Thread safe
|
||
void RHITick(float DeltaTime);
|
||
};
|
||
```
|
||
可以在**FRHICommandListImmediate**的**ExecuteCommandList()**、**BlockUntilGPUIdle()**、**Tick()** 看到调用。
|
||
|
||
>需要注意的是，传统图形API（D3D11、OpenGL）除了继承FDynamicRHI，还需要继承**IRHICommandContextPSOFallback**，因为需要借助后者的接口处理PSO的数据和行为，以保证传统和现代API对PSO的一致处理行为。也正因为此，现代图形API（D3D12、Vulkan、Metal）不需要继承**IRHICommandContext**的任何继承体系的类型，单单直接继承**FDynamicRHI**就可以处理RHI层的所有数据和操作。
|
||
既然现代图形API（D3D12、Vulkan、Metal）的**DynamicRHI**没有继承**IRHICommandContext**的任何继承体系的类型，那么它们是如何实现FDynamicRHI::RHIGetDefaultContext的接口？下面以FD3D12DynamicRHI为例： |