(Directx11学习)开天辟地第一式

我们首先创建一个窗口，该窗口带有消息处理：

最基本的win32中创建窗口程序：

//--------------------------------------------------------------------------------------
//author:tongli
//--------------------------------------------------------------------------------------
#include <windows.h>
#include "resource.h"


HINSTANCE   g_hInst = NULL;
HWND        g_hWnd = NULL;


HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow );
LRESULT CALLBACK    WndProc( HWND, UINT, WPARAM, LPARAM );


/*入口函数*/
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance,
			 LPWSTR lpCmdLine, int nCmdShow )
{
    if( FAILED( InitWindow( hInstance, nCmdShow ) ) )
        return 0;

    // Main message loop
    MSG msg = {0};

    /*消息循环*/
    while( GetMessage( &msg, NULL, 0, 0 ) )
    {
        TranslateMessage( &msg );
        DispatchMessage( &msg );
    }

    return ( int )msg.wParam;
}


HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow )
{
    // Register class
    WNDCLASSEX wcex;
    wcex.cbSize = sizeof( WNDCLASSEX );
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon( hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
    wcex.hCursor = LoadCursor( NULL, IDC_ARROW );
    wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = L"TutorialWindowClass";
    wcex.hIconSm = LoadIcon( wcex.hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
    if( !RegisterClassEx( &wcex ) )//注册窗口类
        return E_FAIL;

    // Create window
    g_hInst = hInstance;
    RECT rc = { 0, 0, 640, 480 };
    AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );//根据rc计算窗口的大小
    g_hWnd = CreateWindow( L"TutorialWindowClass", L"Direct3D 10 Tutorial 0: Setting Up Window", WS_OVERLAPPEDWINDOW,
                           CW_USEDEFAULT, CW_USEDEFAULT, rc.right - rc.left, rc.bottom - rc.top, NULL, NULL, hInstance,
                           NULL );
    if( !g_hWnd )
        return E_FAIL;

    ShowWindow( g_hWnd, nCmdShow );

    return S_OK;
}

/*消息处理*/
LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam )
{
    PAINTSTRUCT ps;
    HDC hdc;

    switch( message )
    {
        case WM_PAINT:
            hdc = BeginPaint( hWnd, &ps );
            EndPaint( hWnd, &ps );
            break;

        case WM_DESTROY:
            PostQuitMessage( 0 );
            break;

        default:
            return DefWindowProc( hWnd, message, wParam, lParam );
    }

    return 0;
}

上面的是创建窗口，有了窗口，接下来的就是渲染：

渲染图像需要两个对象：设备对象和交换链。

设备对象被应用程序用来在缓存上进行绘制，同时该设备也有创建资源的方法。

交换链的作用就是将设备渲染的缓存呈现到屏幕上。交换链包含2个或者2个以上的缓存区，一般是用2个，分别是前景缓存区和后台缓存区，缓存区里存的是设备将要渲染的纹理。前景缓存区存储的是现在正在窗口显示的，该缓存的内存是不可更改的。后台缓存区保存着窗口接下来将要显示的内容，一旦后台缓存区的内容渲染完毕，交换链就交换两个缓存区的内容，后台缓存区就变成前景缓存区。一次类推。

为了创建一个交换链，必须实现DXGI_SWAP_CHAIN_DESC结构，该结构是对即将创建的交换链的描述：

需要注意的是：BackBufferUsage是一个描述应用程序使用后台缓存方式的标示符。在例子中要渲染后台缓存，所以设置为：

BackBufferUsage为DXGI_USAGE_RENDER_TARGET_OUTPUT

DXGI_SWAP_CHAIN_DESC sd;
ZeroMemory( &sd, sizeof(sd) );//为sd分配内存
sd.BufferCount = 1;
sd.BufferDesc.Width = 640;
sd.BufferDesc.Height = 480;
sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
sd.BufferDesc.RefreshRate.Numerator = 60;
sd.BufferDesc.RefreshRate.Denominator = 1;
sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;//渲染后台缓存
sd.OutputWindow = g_hWnd;//交换链要将图像显示的窗口
sd.SampleDesc.Count = 1;//是否开启多重采样。
sd.SampleDesc.Quality = 0;
sd.Windowed = TRUE;

接下来就是调用D3D10CreateDeviceAndSwapchain函数创建设备和交换链。

if( FAILED( D3D10CreateDeviceAndSwapChain( NULL, D3D10_DRIVER_TYPE_REFERENCE, NULL,
                     0, D3D10_SDK_VERSION, &sd, &g_pSwapChain, &g_pd3dDevice ) ) )
    {
        return FALSE;
    }

在这里说明一点，第四个参数在某些系统下必须设置为0，具体的原因还没弄清楚。

接下来是创建一个目标渲染视图，该视图是D3D10资源视图的一种，该资源视图允许将资源以一种特定的状态绑定在视图流水线上。可以把该资源视图比作C语言中的类型。C语言中的一块内存可以转换为int,或者float或者结构类型等等。一块内存如果我们不知道他的类型对于我们来讲意义不大。D3D 10资源类型和这个类似。例如：一个2D的纹理,就好比那一块内存，一旦我们得到这块内存，我们可以以不通的资源视图(类型)来绑定这块内存，比如作为一个渲染目标来渲染，作为一个深度模板缓存，或者是一个纹理资源等。

创建一个目标渲染视图，是因为我们想将后台缓存作为缓存目标，这样D3D10才可以在上面渲染。首先调用GetBuffer()来得到后台缓存对象。作为可选项，我们可以创建一个D3D10_RENDERTARGETVIEW_DESC对象来描述目标渲染视图，该描述是CreateRenderTargetView的第二个参数，在这里使用默认的NULL。创建了目标渲染视图，然后用OmSetRenderTarget()来绑定流水线，这样流水线输出的结构将进入了后台缓存中。代码如下：

// Create a render target view
    ID3D10Texture2D *pBackBuffer;
    if( FAILED( g_pSwapChain->GetBuffer( 0, __uuidof( ID3D10Texture2D ), (LPVOID*)&pBackBuffer ) ) )//获取后台缓存对象
        return FALSE;
    hr = g_pd3dDevice->CreateRenderTargetView( pBackBuffer, NULL, &g_pRenderTargetView );//创建渲染目标对象
    pBackBuffer->Release();
    if( FAILED( hr ) )
        return FALSE;
    g_pd3dDevice->OMSetRenderTargets( 1, &g_pRenderTargetView, NULL );

最后一步：

在D3D进行渲染前初始化视口(ViewPort)。视口映射剪辑空间坐标，目的是使显示协调。X和Y的范围是-1到1，Z的范围是0到1，这个渲染目标空间，也叫做像素。在D3D 9 中，如果没有设置视口，会有一个默认的，但是D3D10中没有默认的了，也就是必须自己设置。因为我们绝大多数时候是以整个范围作为渲染目标，所以，将左上角设置为(0, 0)，而宽和高设置为何渲染目标一致。、

D3D10_VIEWPORT vp;
    vp.Width = 640;
    vp.Height = 480;
    vp.MinDepth = 0.0f;
    vp.MaxDepth = 1.0f;
    vp.TopLeftX = 0;
    vp.TopLeftY = 0;
    g_pd3dDevice->RSSetViewports( 1, &vp );

修改事件循环：

建立完窗口和D3D设备，然后去渲染窗口。有一个问题是，如果我们使用GetMessage()来获取消息，如果消息队列中没有消息，则将处于阻塞状态，可以用PeekMessage()来替换，当消息队列中没有消息的时候，可以立即返回而不会阻塞。

更改后的消息循环代码：

 MSG msg = {0};
    while( WM_QUIT != msg.message )
    {
        if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) )
        {
            TranslateMessage( &msg );
            DispatchMessage( &msg );
        }
        else
        {
            Render();  // Do some rendering
        }
    }

渲染：

这里写个简单的渲染的例子，用单一的颜色来填充整个屏幕，D3D10中最简单的方法来填充整个屏幕就是：ClearTargetView()。定义一个D3D10_COLOR结构来描述颜色，然后作为该函数的参数。然后在调用Present()函数来呈现。Present()函数的主要作用是显示后台缓存的内容来给用户看。

 void Render()
    {
        //
        // Clear the backbuffer
        //
        float ClearColor[4] = { 0.0f, 0.125f, 0.6f, 1.0f }; // RGBA
        g_pd3dDevice->ClearRenderTargetView( g_pRenderTargetView, ClearColor );
    
        g_pSwapChain->Present( 0, 0 );
    }

下面贴出源码：

/*
*author tongli
*/
#include <windows.h>
#include <d3d10.h>
#include <d3dx10.h>
#include "resource.h"

HINSTANCE               g_hInst = NULL;
HWND                    g_hWnd = NULL;
D3D10_DRIVER_TYPE       g_driverType = D3D10_DRIVER_TYPE_NULL;
ID3D10Device*           g_pd3dDevice = NULL;
IDXGISwapChain*         g_pSwapChain = NULL;
ID3D10RenderTargetView* g_pRenderTargetView = NULL;

HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow );
HRESULT InitDevice();
void CleanupDevice();
LRESULT CALLBACK    WndProc( HWND, UINT, WPARAM, LPARAM );
void Render();

int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow )
{
    if( FAILED( InitWindow( hInstance, nCmdShow ) ) )
        return 0;

    if( FAILED( InitDevice() ) )
    {
        CleanupDevice();
        return 0;
    }

    // Main message loop
    MSG msg = {0};
    while( WM_QUIT != msg.message )
    {
        if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) )
        {
            TranslateMessage( &msg );
            DispatchMessage( &msg );
        }
        else
        {
            Render();
        }
    }

    CleanupDevice();

    return ( int )msg.wParam;
}
//--------------------------------------------------------------------------------------
// Register class and create window
//--------------------------------------------------------------------------------------
HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow )
{
    // Register class
    WNDCLASSEX wcex;
    wcex.cbSize = sizeof( WNDCLASSEX );
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon( hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
    wcex.hCursor = LoadCursor( NULL, IDC_ARROW );
    wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = L"TutorialWindowClass";
    wcex.hIconSm = LoadIcon( wcex.hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
    if( !RegisterClassEx( &wcex ) )
        return E_FAIL;

    // Create window
    g_hInst = hInstance;
    RECT rc = { 0, 0, 640, 480 };
    AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );
    g_hWnd = CreateWindow( L"TutorialWindowClass", L"Direct3D 10 Tutorial 1: Direct3D 10 Basics", WS_OVERLAPPEDWINDOW,
                           CW_USEDEFAULT, CW_USEDEFAULT, rc.right - rc.left, rc.bottom - rc.top, NULL, NULL, hInstance,
                           NULL );
    if( !g_hWnd )
        return E_FAIL;

    ShowWindow( g_hWnd, nCmdShow );

    return S_OK;
}


//--------------------------------------------------------------------------------------
// Called every time the application receives a message
//--------------------------------------------------------------------------------------
LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam )
{
    PAINTSTRUCT ps;
    HDC hdc;

    switch( message )
    {
        case WM_PAINT:
            hdc = BeginPaint( hWnd, &ps );
            EndPaint( hWnd, &ps );
            break;

        case WM_DESTROY:
            PostQuitMessage( 0 );
            break;

        default:
            return DefWindowProc( hWnd, message, wParam, lParam );
    }

    return 0;
}


//--------------------------------------------------------------------------------------
// Create Direct3D device and swap chain
//--------------------------------------------------------------------------------------
HRESULT InitDevice()
{
    HRESULT hr = S_OK;;

    RECT rc;
    GetClientRect( g_hWnd, &rc );
    UINT width = rc.right - rc.left;
    UINT height = rc.bottom - rc.top;

    UINT createDeviceFlags = 0;
//#ifdef _DEBUG
//    createDeviceFlags |= D3D10_CREATE_DEVICE_DEBUG;
//#endif

    D3D10_DRIVER_TYPE driverTypes[] =
    {
        D3D10_DRIVER_TYPE_HARDWARE,
        D3D10_DRIVER_TYPE_REFERENCE,
    };
    UINT numDriverTypes = sizeof( driverTypes ) / sizeof( driverTypes[0] );

    DXGI_SWAP_CHAIN_DESC sd;
    ZeroMemory( &sd, sizeof( sd ) );
    sd.BufferCount = 1;
    sd.BufferDesc.Width = width;
    sd.BufferDesc.Height = height;
    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
    sd.BufferDesc.RefreshRate.Numerator = 60;
    sd.BufferDesc.RefreshRate.Denominator = 1;
    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
    sd.OutputWindow = g_hWnd;
    sd.SampleDesc.Count = 1;
    sd.SampleDesc.Quality = 0;
    sd.Windowed = TRUE;

    for( UINT driverTypeIndex = 0; driverTypeIndex < numDriverTypes; driverTypeIndex++ )
    {
        g_driverType = driverTypes[driverTypeIndex];
		hr = D3D10CreateDeviceAndSwapChain( NULL, g_driverType, NULL, createDeviceFlags,
		D3D10_SDK_VERSION, &sd, &g_pSwapChain, &g_pd3dDevice );
		
        if( SUCCEEDED( hr ) )
            break;
    }
    if( FAILED( hr ) )
        return hr;

    // Create a render target view
    ID3D10Texture2D* pBackBuffer;
    hr = g_pSwapChain->GetBuffer( 0, __uuidof( ID3D10Texture2D ), ( LPVOID* )&pBackBuffer );
    if( FAILED( hr ) )
        return hr;

    hr = g_pd3dDevice->CreateRenderTargetView( pBackBuffer, NULL, &g_pRenderTargetView );
    pBackBuffer->Release();
    if( FAILED( hr ) )
        return hr;

    g_pd3dDevice->OMSetRenderTargets( 1, &g_pRenderTargetView, NULL );

    // Setup the viewport
    D3D10_VIEWPORT vp;
    vp.Width = width;
    vp.Height = height;
    vp.MinDepth = 0.0f;
    vp.MaxDepth = 1.0f;
    vp.TopLeftX = 0;
    vp.TopLeftY = 0;
    g_pd3dDevice->RSSetViewports( 1, &vp );

    return S_OK;
}


//--------------------------------------------------------------------------------------
// Render the frame
//--------------------------------------------------------------------------------------
void Render()
{
    // Just clear the backbuffer
    float ClearColor[4] = { 0.0f, 0.125f, 0.3f, 1.0f }; //red,green,blue,alpha
    g_pd3dDevice->ClearRenderTargetView( g_pRenderTargetView, ClearColor );
    g_pSwapChain->Present( 0, 0 );
}


//--------------------------------------------------------------------------------------
// Clean up the objects we've created
//--------------------------------------------------------------------------------------
void CleanupDevice()
{
    if( g_pd3dDevice ) g_pd3dDevice->ClearState();

    if( g_pRenderTargetView ) g_pRenderTargetView->Release();
    if( g_pSwapChain ) g_pSwapChain->Release();
    if( g_pd3dDevice ) g_pd3dDevice->Release();
}