win32 – Direct3D 11的demo创建

#include <d3d11.h>  
#include <chrono>

using namespace std::chrono;

#pragma comment(lib,"D3D11.lib")
//-----------------------------------------------------------------------------  
// 全局变量  
//-----------------------------------------------------------------------------  
HRESULT hr;
ID3D11Device* g_pd3dDevice = nullptr;
IDXGISwapChain* g_pSwapChain = nullptr;
ID3D11DeviceContext* g_pImmediateContext = nullptr;
ID3D11RenderTargetView* pTarget = nullptr;
std::chrono::steady_clock::time_point last;

//-----------------------------------------------------------------------------  
// Desc: 初始化Direct3D  
//-----------------------------------------------------------------------------  
HRESULT InitD3D(HWND hWnd)
{
    DXGI_SWAP_CHAIN_DESC sd;
    ZeroMemory(&sd, sizeof(sd));
    sd.BufferCount = 1;  // BufferCount: number of buffers  1: 设置一个后缓存，再加上一个自动设置的前缓存，就是双缓存
    sd.BufferDesc.Width = 0; //系统自动设置合适的值
    sd.BufferDesc.Height = 0;
    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
    sd.BufferDesc.RefreshRate.Numerator = 0;  //不处于全屏模式，所以不用管刷新率
    sd.BufferDesc.RefreshRate.Denominator = 0;
    sd.BufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;  //程序自己决定缩放比率
    sd.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED; //对于大多数显示器，不用设置扫描线顺序
    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;  // Use the surface or resource as an output render target.
    sd.OutputWindow = hWnd;
    sd.SampleDesc.Count = 1;   //不需要抗锯齿，一般默认该值
    sd.SampleDesc.Quality = 0;
    sd.Windowed = TRUE; //窗口化

    if (FAILED(hr = D3D11CreateDeviceAndSwapChain(
        NULL,
        D3D_DRIVER_TYPE_HARDWARE,
        NULL,
        0,
        NULL,
        0,
        D3D11_SDK_VERSION,
        &sd,
        &g_pSwapChain,
        &g_pd3dDevice,
        NULL,
        &g_pImmediateContext)))
    {
        return hr;
    }
    //gain access to texture subresource in swap chain (back buffer)
    ID3D11Resource* pBackBuffer = nullptr;
    g_pSwapChain->GetBuffer(0, _uuidof(ID3D11Resource), reinterpret_cast<void**>(&pBackBuffer)); // Get the back buffer  0: 后缓存的索引
    g_pd3dDevice->CreateRenderTargetView(
        pBackBuffer,
        nullptr,
        &pTarget  // pTarget is used to save RenderTarget view
    );
    pBackBuffer->Release(); 

}


//-----------------------------------------------------------------------------  
// Desc: 释放创建对象  
//-----------------------------------------------------------------------------  
VOID Cleanup()
{
    //释放Direct3D设备对象  
    if (g_pd3dDevice != NULL)
        g_pd3dDevice->Release();
    //释放Direct3D对象  
    if (g_pSwapChain != NULL)
        g_pSwapChain->Release();
    if (g_pImmediateContext != NULL)
        g_pImmediateContext->Release();
    if (pTarget != NULL)
        pTarget->Release();
}

//定时器
float Peek()
{
    return duration<float>(steady_clock::now() - last).count();
}

//-----------------------------------------------------------------------------  
// Desc: 渲染图形  
//-----------------------------------------------------------------------------  
void Render()
{
    // Just clear the backbuffer
    float r = sin(Peek()) / 2.0f + 0.5f;
    float ClearColor[4] = { r, r, 1.0f, 1.0f }; //red,green,blue,alpha
    g_pImmediateContext->ClearRenderTargetView(pTarget, ClearColor); // undertake all the drawing work
    g_pSwapChain->Present(0u, 0u);    //Presents a rendered image to the user.
}


//-----------------------------------------------------------------------------  
// Desc: 消息处理  
//-----------------------------------------------------------------------------  
LRESULT WINAPI MsgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
    case WM_DESTROY:
        Cleanup();
        PostQuitMessage(0);
        return 0;

    case WM_PAINT:
        Render();
        ValidateRect(hWnd, NULL);
        return 0;
    }

    return DefWindowProc(hWnd, msg, wParam, lParam);
}


//-----------------------------------------------------------------------------  
// Desc: 程序入口  
//-----------------------------------------------------------------------------  
INT WINAPI WinMain(HINSTANCE hInst, HINSTANCE, LPSTR, INT)
{
    //注册窗口类  
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,
                      GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
                      L"ClassName", NULL };
    RegisterClassEx(&wc);

    //创建窗口  
    HWND hWnd = CreateWindow(L"ClassName", L"A Direct3D appp",
        WS_OVERLAPPEDWINDOW, 200, 100, 600, 500,
        NULL, NULL, wc.hInstance, NULL);
    last = steady_clock::now(); //running timer
    //初始化Direct3D  
    if (SUCCEEDED(InitD3D(hWnd)))
    {
        //显示主窗口  
        ShowWindow(hWnd, SW_SHOWDEFAULT);
        UpdateWindow(hWnd);

        //进入消息循环  
        MSG msg;
        ZeroMemory(&msg, sizeof(msg));
        while (msg.message != WM_QUIT)
        {
            if (PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
            {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }
            else
            {
                Render();  //渲染图形  
            }
        }
    }

    UnregisterClass(L"ClassName", wc.hInstance);
    return 0;
}