Tutorial 1: Direct3D 11 Basics

#include <windows.h>
#include <d3d11.h>
#include <d3dx11.h>
#include "resource.h"

#pragma comment(lib, "dxguid.lib")
#pragma comment(lib, "d3d11.lib")
#pragma comment(lib, "d3dx11.lib")
#pragma comment(lib, "winmm.lib")

//--------------------------------------------------------------------------------------
// Global Variables
//--------------------------------------------------------------------------------------
HINSTANCE               g_hInst = NULL;
HWND                    g_hWnd = NULL;

D3D_DRIVER_TYPE         g_driverType = D3D_DRIVER_TYPE_NULL;
D3D_FEATURE_LEVEL       g_featureLevel = D3D_FEATURE_LEVEL_11_0;///Targets features supported by Direct3D 11.0 including shader shader model 5.

ID3D11Device*           g_pd3dDevice = NULL;///D3D11设备接口
ID3D11DeviceContext*    g_pImmediateContext = NULL;///DC
IDXGISwapChain*         g_pSwapChain = NULL;///交换链接口
ID3D11RenderTargetView* g_pRenderTargetView = NULL;///渲染目标视图


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


//--------------------------------------------------------------------------------------
// Entry point to the program. Initializes everything and goes into a message processing 
// loop. Idle time is used to render the scene.
//--------------------------------------------------------------------------------------
int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow )
{
    UNREFERENCED_PARAMETER( hPrevInstance );
    UNREFERENCED_PARAMETER( lpCmdLine );

    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(0, IDI_APPLICATION);
    wcex.hCursor = LoadCursor(0, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = L"TutorialWindowClass";
    wcex.hIconSm =  LoadIcon(0, IDI_APPLICATION);
    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 11 Tutorial 1: Direct3D 11 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;

		case WM_KEYDOWN:
			{
				if( wParam == VK_ESCAPE )
					::DestroyWindow(hWnd);
					
			}
			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 |= 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_0,///Targets features supported by Direct3D 11.0 including shader shader model 5.
        D3D_FEATURE_LEVEL_10_1,///Targets features supported by Direct3D 10.1 including shader shader model 4.
        D3D_FEATURE_LEVEL_10_0,
    };
	UINT numFeatureLevels = ARRAYSIZE( featureLevels );

	/// create the swap chain
    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; /// we want to render to the back buffer
    sd.OutputWindow = g_hWnd; ///represents the window that the swap chain will use to present images on the screen
    sd.SampleDesc.Count = 1;///SampleDesc is used to enable multi-sampling.Here disable multi-sampling
    sd.SampleDesc.Quality = 0;
    sd.Windowed = TRUE;

    for( UINT driverTypeIndex = 0; driverTypeIndex < numDriverTypes; driverTypeIndex++ )
    {
        g_driverType = driverTypes[driverTypeIndex];
		///创建device和swap chain
        hr = D3D11CreateDeviceAndSwapChain( NULL, g_driverType, NULL, createDeviceFlags, featureLevels, numFeatureLevels,
                                            D3D11_SDK_VERSION, &sd, 
											&g_pSwapChain, ///a swap chain interface
											&g_pd3dDevice, ///a device interface
											&g_featureLevel, ///a pointer to the feature level 
											&g_pImmediateContext ); ///an immediate context interface
        if( SUCCEEDED( hr ) )
            break;
    }
    if( FAILED( hr ) )
        return hr;

    // Create and set a render target view 创建并设置渲染目标视图
    ID3D11Texture2D* pBackBuffer = NULL;
    hr = g_pSwapChain->GetBuffer( 0, __uuidof( ID3D11Texture2D ), ( LPVOID* )&pBackBuffer );///get the back buffer object
    if( FAILED( hr ) )
        return hr;

    hr = g_pd3dDevice->CreateRenderTargetView( pBackBuffer, NULL, &g_pRenderTargetView );///create a default render target view 
    pBackBuffer->Release();
    if( FAILED( hr ) )
        return hr;

	///bind the render target view to the pipeline 将渲染目标视图绑定到渲染管线
    g_pImmediateContext->OMSetRenderTargets( 1, &g_pRenderTargetView, NULL );

    // Setup the viewport 设置视口大小，D3D11默认不会设置视口，此步骤必须手动设置
    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 );

    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_pImmediateContext->ClearRenderTargetView( g_pRenderTargetView, ClearColor );
    g_pSwapChain->Present( 0, 0 );///将交换链的后缓存内容显示到屏幕上
}


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

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

In Direct3D 11, a device is separated into

(1)a device object for creating resources: contains methods to create resources

(2)and a device-context object which performs rendering: is used by the application to perform rendering onto a buffer

Set up the Direct3D 11 device

(1)The first thing to do is to create three objects: a device, an immediate context, and a swap chain.(The immediate context is a new object in Direct3D 11.)

(2)The next thing we need to do is to create a render target view.

(3)The last thing we need to set up before Direct3D 11 can render is initialize the viewport.

We need to create a render target view because we would like to bind the back buffer of our swap chain as a render target. This enables Direct3D 11 to render onto it.