Direct3D 11 学习笔记（二）

Direct3D 11 学习笔记（二）

DXUT

　　DXUT 能够提供一个简单的接口来处理 window 的创建，D3D device 的创建。
　　在不使用 DXUT 框架的时候，我们需要自己调用 windows 的 API 来创建窗口：

    // 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( nullptr, IDC_ARROW );
    wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
    wcex.lpszMenuName = nullptr;
    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, 800, 600 };
    AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );
    g_hWnd = CreateWindow( L"TutorialWindowClass", L"Direct3D 11 Tutorial 7",
                           WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX,
                           CW_USEDEFAULT, CW_USEDEFAULT, rc.right - rc.left, 
                           rc.bottom - rc.top, nullptr, nullptr, hInstance,
                           nullptr );
    if( !g_hWnd )
        return E_FAIL;

    ShowWindow( g_hWnd, nCmdShow );

    return S_OK;

　　需要自己调用 D3D11CreateDeviceAndSwapChain 来创建 device 和 swap chain，代码如下：

    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 |= D3D11_CREATE_DEVICE_DEBUG;
#endif

    D3D_DRIVER_TYPE driverTypes[] =
    {
        D3D_DRIVER_TYPE_HARDWARE,
        D3D_DRIVER_TYPE_WARP,
        D3D_DRIVER_TYPE_REFERENCE,
    };
    UINT numDriverTypes = ARRAYSIZE( driverTypes );

    D3D_FEATURE_LEVEL featureLevels[] =
    {
        D3D_FEATURE_LEVEL_11_1,
        D3D_FEATURE_LEVEL_11_0,
        D3D_FEATURE_LEVEL_10_1,
        D3D_FEATURE_LEVEL_10_0,
    };
    UINT numFeatureLevels = ARRAYSIZE( featureLevels );

    for( UINT driverTypeIndex = 0; driverTypeIndex < numDriverTypes; driverTypeIndex++ )
    {
        g_driverType = driverTypes[driverTypeIndex];
        hr = D3D11CreateDevice( nullptr, g_driverType, nullptr, createDeviceFlags, 
                                featureLevels, numFeatureLevels, D3D11_SDK_VERSION, 
                                &g_pd3dDevice, &g_featureLevel, &g_pImmediateContext );

        if ( hr == E_INVALIDARG )
        {
            // DirectX 11.0 platforms will not recognize D3D_FEATURE_LEVEL_11_1 so we need to retry without it
            hr = D3D11CreateDevice( nullptr, g_driverType, nullptr, createDeviceFlags,
                                    &featureLevels[1], numFeatureLevels - 1, D3D11_SDK_VERSION,
                                    &g_pd3dDevice, &g_featureLevel, &g_pImmediateContext );
        }

        if( SUCCEEDED( hr ) )
            break;
    }
    if( FAILED( hr ) )
        return hr;

    // Obtain DXGI factory from device (since we used nullptr for pAdapter above)
    IDXGIFactory1* dxgiFactory = nullptr;
    {
        IDXGIDevice* dxgiDevice = nullptr;
        hr = g_pd3dDevice->QueryInterface( __uuidof(IDXGIDevice), 
                                           reinterpret_cast<void**>(&dxgiDevice) );
        if (SUCCEEDED(hr))
        {
            IDXGIAdapter* adapter = nullptr;
            hr = dxgiDevice->GetAdapter(&adapter);
            if (SUCCEEDED(hr))
            {
                hr = adapter->GetParent( __uuidof(IDXGIFactory1), 
                                         reinterpret_cast<void**>(&dxgiFactory) );
                adapter->Release();
            }
            dxgiDevice->Release();
        }
    }
    if (FAILED(hr))
        return hr;

    // Create swap chain
    IDXGIFactory2* dxgiFactory2 = nullptr;
    hr = dxgiFactory->QueryInterface( __uuidof(IDXGIFactory2), 
                                      reinterpret_cast<void**>(&dxgiFactory2) );
    if ( dxgiFactory2 )
    {
        // DirectX 11.1 or later
        hr = g_pd3dDevice->QueryInterface( __uuidof(ID3D11Device1), 
                                           reinterpret_cast<void**>(&g_pd3dDevice1) );
        if (SUCCEEDED(hr))
        {
            (void) g_pImmediateContext->QueryInterface( __uuidof(ID3D11DeviceContext1),
                                               reinterpret_cast<void**>(&g_pImmediateContext1) );
        }

        DXGI_SWAP_CHAIN_DESC1 sd;
        ZeroMemory(&sd, sizeof(sd));
        sd.Width = width;
        sd.Height = height;
        sd.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
        sd.SampleDesc.Count = 1;
        sd.SampleDesc.Quality = 0;
        sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
        sd.BufferCount = 1;

        hr = dxgiFactory2->CreateSwapChainForHwnd( g_pd3dDevice, g_hWnd, &sd, nullptr, 
                                                   nullptr, &g_pSwapChain1 );
        if (SUCCEEDED(hr))
        {
            hr = g_pSwapChain1->QueryInterface( __uuidof(IDXGISwapChain), 
                                                reinterpret_cast<void**>(&g_pSwapChain) );
        }

        dxgiFactory2->Release();
    }
    else
    {
        // DirectX 11.0 systems
        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;

        hr = dxgiFactory->CreateSwapChain( g_pd3dDevice, &sd, &g_pSwapChain );
    }

    // Note this tutorial doesn't handle full-screen swapchains so we block the ALT+ENTER shortcut
    dxgiFactory->MakeWindowAssociation( g_hWnd, DXGI_MWA_NO_ALT_ENTER );

    dxgiFactory->Release();

    if (FAILED(hr))
        return hr;

    // Create a render target view
    ID3D11Texture2D* pBackBuffer = nullptr;
    hr = g_pSwapChain->GetBuffer( 0, __uuidof( ID3D11Texture2D ), 
                                  reinterpret_cast<void**>( &pBackBuffer ) );
    if( FAILED( hr ) )
        return hr;

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

    // Create depth stencil texture
    D3D11_TEXTURE2D_DESC descDepth;
    ZeroMemory( &descDepth, sizeof(descDepth) );
    descDepth.Width = width;
    descDepth.Height = height;
    descDepth.MipLevels = 1;
    descDepth.ArraySize = 1;
    descDepth.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
    descDepth.SampleDesc.Count = 1;
    descDepth.SampleDesc.Quality = 0;
    descDepth.Usage = D3D11_USAGE_DEFAULT;
    descDepth.BindFlags = D3D11_BIND_DEPTH_STENCIL;
    descDepth.CPUAccessFlags = 0;
    descDepth.MiscFlags = 0;
    hr = g_pd3dDevice->CreateTexture2D( &descDepth, nullptr, &g_pDepthStencil );
    if( FAILED( hr ) )
        return hr;

    // Create the depth stencil view
    D3D11_DEPTH_STENCIL_VIEW_DESC descDSV;
    ZeroMemory( &descDSV, sizeof(descDSV) );
    descDSV.Format = descDepth.Format;
    descDSV.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;
    descDSV.Texture2D.MipSlice = 0;
    hr = g_pd3dDevice->CreateDepthStencilView( g_pDepthStencil, &descDSV, &g_pDepthStencilView );
    if( FAILED( hr ) )
        return hr;

    g_pImmediateContext->OMSetRenderTargets( 1, &g_pRenderTargetView, g_pDepthStencilView );

    // Setup the viewport
    D3D11_VIEWPORT vp;
    vp.Width = (FLOAT)width;
    vp.Height = (FLOAT)height;
    vp.MinDepth = 0.0f;
    vp.MaxDepth = 1.0f;
    vp.TopLeftX = 0;
    vp.TopLeftY = 0;
    g_pImmediateContext->RSSetViewports( 1, &vp );

　　我们使用 DXUT 框架之后，只需要使用如下代码就可以完成上述内容：

    // Parse the command line, show msgboxes on error, no extra command line params
    DXUTInit( true, true, nullptr ); 

    DXUTSetCursorSettings( true, true ); // Show the cursor and clip it when in full screen
    DXUTCreateWindow( L"Tutorial08" );

    // Only require 10-level hardware or later
    DXUTCreateDevice( D3D_FEATURE_LEVEL_10_0, true, 800, 600 );

　　
　　
　　在上述代码完成后，我们直接使用 DXUTMainLoop() 就可以进入 DXUT 的循环，通过 DXUT 提供的回调函数来控制我们的渲染过程，回调函数如下：

    // Set general DXUT callbacks
    DXUTSetCallbackFrameMove( OnFrameMove );
    DXUTSetCallbackKeyboard( OnKeyboard );
    DXUTSetCallbackMsgProc( MsgProc );
    DXUTSetCallbackDeviceChanging( ModifyDeviceSettings );
    DXUTSetCallbackDeviceRemoved( OnDeviceRemoved );

    // Set the D3D11 DXUT callbacks. Remove these sets if the app doesn't need to support D3D11
    DXUTSetCallbackD3D11DeviceAcceptable( IsD3D11DeviceAcceptable );
    DXUTSetCallbackD3D11DeviceCreated( OnD3D11CreateDevice );
    DXUTSetCallbackD3D11SwapChainResized( OnD3D11ResizedSwapChain );
    DXUTSetCallbackD3D11FrameRender( OnD3D11FrameRender );
    DXUTSetCallbackD3D11SwapChainReleasing( OnD3D11ReleasingSwapChain );
    DXUTSetCallbackD3D11DeviceDestroyed( OnD3D11DestroyDevice );

　　上述代码来源于微软 D3D11 官方教程源码。