DirectX11

DirectX11

目录：

DirectX11-教程3（上）：

下面我们来看一下新的D3DClass头文件：

D3dclass.h

// Filename: d3dclass.h#ifndef _D3DCLASS_H_
#define _D3DCLASS_H_

在我们的头文件中首先要指定用于链接的、需要使用的类所在的库文件。这些库可以完成设置和绘制3D图形，还有专门与硬件通信得函数来获取显示刷新率、可用的显卡等信息。你可能已发现仍然使用了一些DirectX10的库文件，因为有些功能在DirectX11中和之前版本一样，就直接使用原来的库了。

/
// LINKING //
/
#pragma comment(lib, "dxgi.lib")
#pragma comment(lib, "d3d11.lib")
#pragma comment(lib, "d3dx11.lib")
#pragma comment(lib, "d3dx10.lib")

然后我们要包含这些lib库文件对应的头文件，也要包含DirectX类型定义的头文件。

//
// INCLUDES //
//
#include <dxgi.h>
#include <d3dcommon.h>
#include <d3d11.h>
#include <d3dx10math.h>

这里D3DClass的定义尽量保持简单。包含一个常有的构造函数、复制构造函数和析构函数。注意它有Initialize函数和Shutdown函数。这篇教程会重点讲它们。另外还有一些辅助函数和一些私有变量，当我们看D3DClass.cpp时会提到这些变量。现在只讲最关键的Initialize和Shutdown函数。

// Class name: D3DClassclass D3DClass
{
public:D3DClass();D3DClass(const D3DClass&);~D3DClass();bool Initialize(int, int, bool, HWND, bool, float, float);void Shutdown();void BeginScene(float, float, float, float);void EndScene();ID3D11Device* GetDevice();ID3D11DeviceContext* GetDeviceContext();void GetProjectionMatrix(D3DXMATRIX&);void GetWorldMatrix(D3DXMATRIX&);void GetOrthoMatrix(D3DXMATRIX&);void GetVideoCardInfo(char*, int&);private:bool m_vsync_enabled;int m_videoCardMemory;char m_videoCardDescription[128];IDXGISwapChain* m_swapChain;ID3D11Device* m_device;ID3D11DeviceContext* m_deviceContext;ID3D11RenderTargetView* m_renderTargetView;ID3D11Texture2D* m_depthStencilBuffer;ID3D11DepthStencilState* m_depthStencilState;ID3D11DepthStencilView* m_depthStencilView;ID3D11RasterizerState* m_rasterState;D3DXMATRIX m_projectionMatrix;D3DXMATRIX m_worldMatrix;D3DXMATRIX m_orthoMatrix;
};#endif

如果你已经了解过Direct3D，你可能注意到这里没有包含一个观察矩阵。因为我把它放到了camera类中，后面我们会提到。

D3dclass.cpp

// Filename: d3dclass.cpp#include "d3dclass.h"

像大部分类一样，我们在构造函数中首先将成员指针设置为空。所有在头文件中的成员指针都在这里。

D3DClass::D3DClass()
{m_swapChain = 0;m_device = 0;m_deviceContext = 0;m_renderTargetView = 0;m_depthStencilBuffer = 0;m_depthStencilState = 0;m_depthStencilView = 0;m_rasterState = 0;
}D3DClass::D3DClass(const D3DClass& other)
{
}D3DClass::~D3DClass()
{
}

Initialize函数负责DirectX11中的D3D所有的初始化。这里有必需的和以后会用到的代码。我可以简化，但最好还是能覆盖后续相关的例子。

函数中screenWidth和screenHeight两个参数是我们在SystemClass中创建的窗口的宽和高。Direct3D需要使用它们来创建相同尺寸的窗口。hwnd参数是一个窗口的句柄，Direct3D需要通过它来访问之前创建的窗口。fullscreen指定我们运行在窗口模式还是全屏模式，也用于创建窗口。screenDepth和screenNear用于设置渲染在窗口里的3D场景的景深。vsync参数用于表示我们是否希望Direct3D按照显示刷新率的速度渲染还是最快可能的渲染。

bool D3DClass::Initialize(int screenWidth, int screenHeight, bool vsync, HWND hwnd, bool fullscreen, float screenDepth, float screenNear)
{HRESULT result;IDXGIFactory* factory;IDXGIAdapter* adapter;IDXGIOutput* adapterOutput;unsigned int numModes, i, numerator, denominator, stringLength;DXGI_MODE_DESC* displayModeList;DXGI_ADAPTER_DESC adapterDesc;int error;DXGI_SWAP_CHAIN_DESC swapChainDesc;D3D_FEATURE_LEVEL featureLevel;ID3D11Texture2D* backBufferPtr;D3D11_TEXTURE2D_DESC depthBufferDesc;D3D11_DEPTH_STENCIL_DESC depthStencilDesc;D3D11_DEPTH_STENCIL_VIEW_DESC depthStencilViewDesc;D3D11_RASTERIZER_DESC rasterDesc;D3D11_VIEWPORT viewport;float fieldOfView, screenAspect;// Store the vsync setting.m_vsync_enabled = vsync;

初始化Direct3D之前，我们需要从显卡或显示器获得刷新率。每台电脑都有部分差别，所以我们需要再查询一下。我们先查询表示刷新率的分数的分子分母，DirectX会用它们计算出正确的刷新率。如果我们设置一个计算机不支持的值，那么显示的时候会采用复制像素的方式而不是交换缓冲区，这样会降低性能并在调试时输出很多错误。

	// Create a DirectX graphics sult = CreateDXGIFactory(__uuidof(IDXGIFactory), (void**)&factory);if(FAILED(result)){return false;}// Use the factory to create an adapter for the primary graphics interface (video card).result = factory->EnumAdapters(0, &adapter);if(FAILED(result)){return false;}// Enumerate the primary adapter output (monitor).result = adapter->EnumOutputs(0, &adapterOutput);if(FAILED(result)){return false;}// Get the number of modes that fit the DXGI_FORMAT_R8G8B8A8_UNORM display format for the adapter output (monitor).result = adapterOutput->GetDisplayModeList(DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_ENUM_MODES_INTERLACED, &numModes, NULL);if(FAILED(result)){return false;}// Create a list to hold all the possible display modes for this monitor/video card combination.displayModeList = new DXGI_MODE_DESC[numModes];if(!displayModeList){return false;}// Now fill the display mode sult = adapterOutput->GetDisplayModeList(DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_ENUM_MODES_INTERLACED, &numModes, displayModeList);if(FAILED(result)){return false;}// Now go through all the display modes and find the one that matches the screen width and height.// When a match is found store the numerator and denominator of the refresh rate for that monitor.for(i=0; i<numModes; i++){if(displayModeList[i].Width == (unsigned int)screenWidth){if(displayModeList[i].Height == (unsigned int)screenHeight){numerator = displayModeList[i].RefreshRate.Numerator;denominator = displayModeList[i].RefreshRate.Denominator;}}}

我们现在有了用于计算刷新率的分子分母，最后我们再获取显卡名称和显存大小

	// Get the adapter (video card) sult = adapter->GetDesc(&adapterDesc);if(FAILED(result)){return false;}// Store the dedicated video card memory in megabytes.m_videoCardMemory = (int)(adapterDesc.DedicatedVideoMemory / 1024 / 1024);// Convert the name of the video card to a character array and  = wcstombs_s(&stringLength, m_videoCardDescription, 128, adapterDesc.Description, 128);if(error != 0){return false;}

现在我们保存了足够的信息，可以释放用于查询这些信息的结构体和指针了

	// Release the display mode list.delete [] displayModeList;displayModeList = 0;// Release the adapter output.adapterOutput->Release();adapterOutput = 0;// Release the adapter.adapter->Release();adapter = 0;// Release the factory.factory->Release();factory = 0;

可以开始初始化了。首先设置交换链的描述体。交换链包含显卡绘制使用的前后缓冲区。通常使用一个后缓冲，在它上进行所有的绘制，然后与前缓存交换后在屏幕上显示出来。因此叫交换链。

	// Initialize the swap chain description.ZeroMemory(&swapChainDesc, sizeof(swapChainDesc));// Set to a single back buffer.swapChainDesc.BufferCount = 1;// Set the width and height of the back buffer.swapChainDesc.BufferDesc.Width = screenWidth;swapChainDesc.BufferDesc.Height = screenHeight;// Set regular 32-bit surface for the back buffer.swapChainDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;

接下来设置的是刷新率。刷新率是一秒钟将后缓冲交换到前缓冲多少次。如果设置graphicsclass.h中的vsync为真，则我们将刷新率锁定到系统的设置（例如60hz）。表示我们每秒只绘制60次画面（如果系统刷新率大于60，这里也会大于）。当然如果vsync为假，则会尽可能多的绘制，但可能会有些视觉问题。

	// Set the refresh rate of the back buffer.if(m_vsync_enabled){swapChainDesc.BufferDesc.RefreshRate.Numerator = numerator;swapChainDesc.BufferDesc.RefreshRate.Denominator = denominator;}else{swapChainDesc.BufferDesc.RefreshRate.Numerator = 0;swapChainDesc.BufferDesc.RefreshRate.Denominator = 1;}// Set the usage of the back buffer.swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;// Set the handle for the window to render to.swapChainDesc.OutputWindow = hwnd;// Turn multisampling off.swapChainDesc.SampleDesc.Count = 1;swapChainDesc.SampleDesc.Quality = 0;// Set to full screen or windowed mode.if(fullscreen){swapChainDesc.Windowed = false;}else{swapChainDesc.Windowed = true;}// Set the scan line ordering and scaling to unspecified.swapChainDesc.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;swapChainDesc.BufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;// Discard the back buffer contents after presenting.swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;// Don't set the advanced flags.swapChainDesc.Flags = 0;

设置完交换链的描述体，我们还需要设置一个叫特性级别的变量。这个变量告诉DirectX我们想用哪个版本的dx。这里设置的11.0表示DirectX11。如果希望支持多版本或在低端设备上运行，你也可以设置为10或9来用低版本的DirectX。

	// Set the feature level to DirectX 11.featureLevel = D3D_FEATURE_LEVEL_11_0;

交换链描述体和特性级别设置好后，我们就可以创建交换链、D3d设备、D3d设备上下文。D3d设备和D3d设备上下文很重要，它们是所有Direct3D函数的接口，因此几乎所有地方都需要使用它们。

如果你了解之前版本的DirectX，你肯定记得D3d设备，但对D3d设备上下文很模式。之前版本的D3d设备的功能被拆分成现在的两个类里面，所以你现在两个类都要用。

如果用户没有支持DirectX11的显卡，那么创建设备和设备上下文时会失败。如果你想测试DirectX11的功能却没有支持DirectX11的显卡，可以用D3D_DRIVER_TYPE_REFERENCE来替换D3D_DRIVER_TYPE_HARDWARE，这时DirectX会使用CPU来替代显卡完成绘制。注意这种模式速度只有使用显卡的千分之一，但对那些现在没有DirectX11显卡的人来说却足够了。

	// Create the swap chain, Direct3D device, and Direct3D sult = D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, 0, &featureLevel, 1, D3D11_SDK_VERSION, &swapChainDesc, &m_swapChain, &m_device, NULL, &m_deviceContext);if(FAILED(result)){return false;}

如果你的主显卡不支持DirectX11，创建设备的调用会失败。例如你用DirectX10显卡做主显卡，而用DirectX11显卡做从显卡。还有一些混合显卡优先使用低功耗的Intel显卡而将高功耗的Nvidia显卡用做替补。为了解决这个问题，你不能使用默认设备，而需要枚举所有的显卡然后让用户选择一个用于设备的创建。

现在我们有了一个交换链，还需要获得一个后缓存的指针并将它绑定到交换链。我们使用CreateRenderTargetView函数来绑定。

	// Get the pointer to the sult = m_swapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&backBufferPtr);if(FAILED(result)){return false;}// Create the render target view with the back sult = m_device->CreateRenderTargetView(backBufferPtr, NULL, &m_renderTargetView);if(FAILED(result)){return false;}// Release pointer to the back buffer as we no longer need it.backBufferPtr->Release();backBufferPtr = 0;

我们还需要一个深度缓存描述体。它用来创建深度缓存，然后我们的多边形才能够在三维空间正确显示。有时我们还同时指定模板缓存。模板缓存可以实现一些特效，例如：动态模糊、阴影体等。

	// Initialize the description of the depth buffer.ZeroMemory(&depthBufferDesc, sizeof(depthBufferDesc));// Set up the description of the depth buffer.depthBufferDesc.Width = screenWidth;depthBufferDesc.Height = screenHeight;depthBufferDesc.MipLevels = 1;depthBufferDesc.ArraySize = 1;depthBufferDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;depthBufferDesc.SampleDesc.Count = 1;depthBufferDesc.SampleDesc.Quality = 0;depthBufferDesc.Usage = D3D11_USAGE_DEFAULT;depthBufferDesc.BindFlags = D3D11_BIND_DEPTH_STENCIL;depthBufferDesc.CPUAccessFlags = 0;depthBufferDesc.MiscFlags = 0;

我们可以使用描述体创建深度模板缓存了。你可能注意到我们使用的是CreateTexture2D函数，因为深度模板缓存就是个2D的texture。当多边形经过拣选和光栅化后，最终的结果就是保存在2D缓存上不同颜色的像素。然后这些缓存的图像被显示到屏幕。

	// Create the texture for the depth buffer using the filled sult = m_device->CreateTexture2D(&depthBufferDesc, NULL, &m_depthStencilBuffer);if(FAILED(result)){return false;}

我们可以设置深度模板的描述体了。我们设置好深度检测的方式，然后Direct3D会对每个像素进行检查。

	// Initialize the description of the stencil state.ZeroMemory(&depthStencilDesc, sizeof(depthStencilDesc));// Set up the description of the stencil state.depthStencilDesc.DepthEnable = true;depthStencilDesc.DepthWriteMask = D3D11_DEPTH_WRITE_MASK_ALL;depthStencilDesc.DepthFunc = D3D11_COMPARISON_LESS;depthStencilDesc.StencilEnable = true;depthStencilDesc.StencilReadMask = 0xFF;depthStencilDesc.StencilWriteMask = 0xFF;// Stencil operations if pixel is front-facing.depthStencilDesc.FrontFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;depthStencilDesc.FrontFace.StencilDepthFailOp = D3D11_STENCIL_OP_INCR;depthStencilDesc.FrontFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;depthStencilDesc.FrontFace.StencilFunc = D3D11_COMPARISON_ALWAYS;// Stencil operations if pixel is back-facing.depthStencilDesc.BackFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;depthStencilDesc.BackFace.StencilDepthFailOp = D3D11_STENCIL_OP_DECR;depthStencilDesc.BackFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;depthStencilDesc.BackFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

用填充好的描述体可以创建深度模板状态

	// Create the depth sult = m_device->CreateDepthStencilState(&depthStencilDesc, &m_depthStencilState);if(FAILED(result)){return false;}

设置好深度模板状态，就起作用了。注意我们通过设备上下文来设置

	// Set the depth stencil state.m_deviceContext->OMSetDepthStencilState(m_depthStencilState, 1);

下面我们需要创建深度模板视图的描述体，它告知Direct3D将深度缓存当深度模板纹理。然后调用CreateDepthStencilView来创建它。

	// Initailze the depth stencil view.ZeroMemory(&depthStencilViewDesc, sizeof(depthStencilViewDesc));// Set up the depth stencil view description.depthStencilViewDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;depthStencilViewDesc.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;depthStencilViewDesc.Texture2D.MipSlice = 0;// Create the depth sult = m_device->CreateDepthStencilView(m_depthStencilBuffer, &depthStencilViewDesc, &m_depthStencilView);if(FAILED(result)){return false;}

然后就可以调用OMSetRenderTargets了，这个函数将渲染目标视图和深度模板缓存绑定到输出管线。然后显卡将最终图像渲染到我们此前创建的后缓存。渲染完毕将后缓存交换到前面显示到屏幕。

	// Bind the render target view and depth stencil buffer to the output render pipeline.m_deviceContext->OMSetRenderTargets(1, &m_renderTargetView, m_depthStencilView);

设置好渲染目标后，我们看一下其它后面会用到的函数。首先我们创建一个可以控制怎么渲染的光栅状态。我们可以选择线框模式渲染或显示多面体的前后面。DirectX有一个设置好的默认值，和我们下面设置的一样。但你只有自己设置的渲染状态才可以改变。

	// Setup the raster description which will determine how and what polygons will be drawn.rasterDesc.AntialiasedLineEnable = false;rasterDesc.CullMode = D3D11_CULL_BACK;rasterDesc.DepthBias = 0;rasterDesc.DepthBiasClamp = 0.0f;rasterDesc.DepthClipEnable = true;rasterDesc.FillMode = D3D11_FILL_SOLID;rasterDesc.FrontCounterClockwise = false;rasterDesc.MultisampleEnable = false;rasterDesc.ScissorEnable = false;rasterDesc.SlopeScaledDepthBias = 0.0f;// Create the rasterizer state from the description we just sult = m_device->CreateRasterizerState(&rasterDesc, &m_rasterState);if(FAILED(result)){return false;}// Now set the rasterizer state.m_deviceContext->RSSetState(m_rasterState);

为了将裁剪体空间正确映射到渲染目标空间，视口需要被正确设置。这里设置为窗口大小。

	// Setup the viewport for rendering.viewport.Width = (float)screenWidth;viewport.Height = (float)screenHeight;viewport.MinDepth = 0.0f;viewport.MaxDepth = 1.0f;viewport.TopLeftX = 0.0f;viewport.TopLeftY = 0.0f;// Create the viewport.m_deviceContext->RSSetViewports(1, &viewport);

可以创建投影矩阵了。投影矩阵用于将3D坐标转换到刚才创建的2D视口空间。还需要传递给shaders一个投影矩阵的拷贝来进行实际的渲染。

	// Setup the projection matrix.fieldOfView = (float)D3DX_PI / 4.0f;screenAspect = (float)screenWidth / (float)screenHeight;// Create the projection matrix for 3D rendering.D3DXMatrixPerspectiveFovLH(&m_projectionMatrix, fieldOfView, screenAspect, screenNear, screenDepth);

还需要创建另一个矩阵：世界矩阵，用来将顶点坐标由物体坐标系转换到世界坐标系。它可以实现物体的旋转、移动、缩放。现在我们只将它初始化为单位矩阵。在渲染时也需要将它的拷贝传递给shaders。

	// Initialize the world matrix to the identity matrix.D3DXMatrixIdentity(&m_worldMatrix);

还可以在这里创建视点矩阵，视点矩阵用于计算我们观察场景时所处的位置。你可以把它想象为一个照相机，通过这个照相机观察整个场景。因此从逻辑上它更应该放在cameraClass里面，后面的教程会讲到，这里就不提了。

Initialize函数最后创建一个正交矩阵，渲染用户界面等2D元素时会用到它。当后面我们讲到2D渲染和字符显示时还会提到它。

	// Create an orthographic projection matrix for 2D rendering.D3DXMatrixOrthoLH(&m_orthoMatrix, (float)screenWidth, (float)screenHeight, screenNear, screenDepth);return true;
}

Shutdown函数会释放并清除Initialize函数中使用的指针，很明了。但在清理之前我先强制将交换链切换到窗口模式，如果没这样做而在全屏模式释放交换链会抛出异常。所以在关闭Direct3D前我们还是强制为窗口模式以免报错。

void D3DClass::Shutdown()
{// Before shutting down set to windowed mode or when you release the swap chain it will throw an exception.if(m_swapChain){m_swapChain->SetFullscreenState(false, NULL);}if(m_rasterState){m_rasterState->Release();m_rasterState = 0;}if(m_depthStencilView){m_depthStencilView->Release();m_depthStencilView = 0;}if(m_depthStencilState){m_depthStencilState->Release();m_depthStencilState = 0;}if(m_depthStencilBuffer){m_depthStencilBuffer->Release();m_depthStencilBuffer = 0;}if(m_renderTargetView){m_renderTargetView->Release();m_renderTargetView = 0;}if(m_deviceContext){m_deviceContext->Release();m_deviceContext = 0;}if(m_device){m_device->Release();m_device = 0;}if(m_swapChain){m_swapChain->Release();m_swapChain = 0;}return;
}

在D3DClass里有一堆帮助函数。前两个是BeginScene和EndScene。BeginScene会在每一帧开始绘制3D场景前调用。它只清空后续要使用的缓存。EndScene则在所有绘制完成后告诉交换链显示最终结果

void D3DClass::BeginScene(float red, float green, float blue, float alpha)
{float color[4];// Setup the color to clear the lor[0] = red;color[1] = green;color[2] = blue;color[3] = alpha;// Clear the back buffer.m_deviceContext->ClearRenderTargetView(m_renderTargetView, color);// Clear the depth buffer.m_deviceContext->ClearDepthStencilView(m_depthStencilView, D3D11_CLEAR_DEPTH, 1.0f, 0);return;
}void D3DClass::EndScene()
{// Present the back buffer to the screen since rendering is complete.if(m_vsync_enabled){// Lock to screen refresh rate.m_swapChain->Present(1, 0);}else{// Present as fast as possible.m_swapChain->Present(0, 0);}return;
}

后面的函数只是简单的返回D3d设备和D3d设备上下文。在框架中会经常用到它们

ID3D11Device* D3DClass::GetDevice()
{return m_device;
}ID3D11DeviceContext* D3DClass::GetDeviceContext()
{return m_deviceContext;
}

紧接着三个帮助函数返回投影矩阵、视点矩阵、正交矩阵。因为大部分shaders需要这些矩阵，通过这些很方便的获得这些数据。我只是解释为什么需要他们，但今天不会用到它们

void D3DClass::GetProjectionMatrix(D3DXMATRIX& projectionMatrix)
{projectionMatrix = m_projectionMatrix;return;
}void D3DClass::GetWorldMatrix(D3DXMATRIX& worldMatrix)
{worldMatrix = m_worldMatrix;return;
}void D3DClass::GetOrthoMatrix(D3DXMATRIX& orthoMatrix)
{orthoMatrix = m_orthoMatrix;return;
}

最后一个帮助函数返回显卡名称和显存大小。在不同配置的电脑上知道这些会有助于调试

void D3DClass::GetVideoCardInfo(char* cardName, int& memory)
{strcpy_s(cardName, 128, m_videoCardDescription);memory = m_videoCardMemory;return;
}

小结

我们不但可以初始化和清理D3d还能显示一种颜色。编译并运行会显示和上一节一样的窗口，只是可以初始化D3d并显示了灰色。编译运行也能验证编译器是否配置好，是否能使用DirectX SDK里的头文件和库文件。