//*通过3个顶点来渲染一个2D的三角形，介绍顶点缓冲器的概念，缓冲器是Direct3D用来存储并渲染顶点的一个
对象，需要特定的一个结构体来定义这个顶点，和相应的a custom FVF (flexible vertex format)
然后还得为顶点缓冲区里的数据定义格式，这样：
自定义顶点结构体：
struct CUSTOMVERTEX
{
    FLOAT x, y, z, rhw; // The transformed position for the vertex.
    DWORD color;        // The vertex color.
};
根据我们自定义顶点结构定义FVF，以保证以上的顶点能定义能够创建
FVF(Flexible Vertex Format) 是Direct3d中的可变顶点格式，通过它可以定义三角形的顶点格式，
然后通过创建顶点缓冲区并设置渲染源来显示基本的图形。

D3DFVF_XYZ和D3DFVF_XYZRHW的区别是：

1.D3DXYZ默认的坐标系统用户区中心是 (0,0) 而rhw的左上角是 (0,0)
2.D3DXYZ默认的非光照的，而RHW默认就是高洛夫的光照模式。

在 RHW下需要设置
#define FVF_XYZ (D3DFVF_XYZ | D3DFVF_DIFFUSE)
g_pd3dDevice->SetRenderState(D3DRS_LIGHTING,FALSE)
  
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)
  D3DFVF_D3DFVF_XYZRHW            : 表示顶点坐标
  D3DFVF_DIFFUSE         : 表示顶点有颜色
  告诉渲染器这个自定义的点由一个转化的点伴随着一个颜色组成。
   they are already in 2D window coordinates.
  This means that the point (0,0) is at the top left corner and the positive x-axis
  is right and the positive y-axis is down. These vertices are also lit,
  meaning that they are not using Direct3D lighting but are supplying their own color.
*/
#include <d3d9.h>

#pragma comment(lib,"d3d9.lib")

LPDIRECT3D9               g_pD3D       = NULL;//创建D3D设备
LPDIRECT3DDEVICE9         g_pd3dDevice = NULL;//我们的渲染设备
LPDIRECT3DVERTEXBUFFER9   g_pVB       = NULL; //存放顶点的容器


struct CUSTOMVERTEX
{
    FLOAT  x,y,z,rhw;
    DWORD color;
};

#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)


HRESULT InitD3D(HWND hWnd)
{
    if(NULL==(g_pD3D=Direct3DCreate9(D3D_SDK_VERSION)))
    {
        return E_FAIL;
    }
    D3DPRESENT_PARAMETERS d3ddp ;
    /*
    D3DPRESENT_PARAMETERS结构体：
    BackBufferWidth：全屏幕式后备缓冲的宽度
    BackBufferHeight ：全屏幕式后备缓冲的高度  
    BackBufferFormat： 后备缓冲的格式
    BackBufferCount： 后备缓冲数目
    MultiSampleType： 全屏抗锯齿类型
    MultiSampleQuality： 全屏抗锯齿质量等级
    SwapEffect： 交换缓冲类型
    hDeviceWindow： 设备窗口句柄
    Windowed： 全屏或窗口
    EnableAutoDepthStencil： 激活深度缓冲
    AutoDepthStencilFormat： 深度缓冲格式
    FullScreen_RefreshRateInHz： 显示器刷新率
    PresentationInterval： 图像最大刷新速度 */

    ZeroMemory(&d3ddp,sizeof(d3ddp));// 给d3ddp分配一段内存
    d3ddp.Windowed =TRUE ;//TRUE if the application runs windowed; FALSE if the application runs full-screen.
    d3ddp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3ddp.BackBufferFormat = D3DFMT_UNKNOWN;D3DFMT_UNKNOWN;//可以指定为BackBufferFormat而在窗口模式。这告诉运行时使用当前的显示模式格式，无需调用


    if (FAILED(g_pD3D->CreateDevice(D3DADAPTER_DEFAULT,
        D3DDEVTYPE_HAL,
        hWnd,
        D3DCREATE_SOFTWARE_VERTEXPROCESSING,
        &d3ddp,
        &g_pd3dDevice)))
    {
        return E_FAIL;
    }/*IDirect3D9::CreateDevice(UINT Adapter, D3DDEVTYPE DeviceType,
    HWND hFocusWindow, DWORD BehaviorFlags,
        D3DPRESENT_PARAMETERS *pPresentationParameters,
        IDirect3DDevice9 **ppReturnedDeviceInterface)*/
    return S_OK;
}
HRESULT InitGeometry()
{
    CUSTOMVERTEX Vertices[]=
    {
        { 150.0f,  50.0f, 0.5f, 1.0f, 0xffff0000, }, // x, y, z, rhw, color
        { 250.0f, 250.0f, 0.5f, 1.0f, 0xff00ff00, },
        {  50.0f, 250.0f, 0.5f, 1.0f, 0xff00ffff, },
    };

    if( FAILED( g_pd3dDevice->CreateVertexBuffer(4*sizeof(CUSTOMVERTEX),
        0 , D3DFVF_CUSTOMVERTEX, D3DPOOL_DEFAULT,&g_pVB, NULL )) )
        return E_FAIL;

    VOID *pVertices;
    if (FAILED(g_pVB->Lock(0,sizeof(Vertices),(void**)&pVertices,0)))
    {
        return E_FAIL;
    }
    memcpy(pVertices,Vertices,sizeof(Vertices));
    g_pVB ->Unlock();

}
VOID Cleanup()
{
    if (g_pVB !=NULL)
    {
        g_pVB->Release();
    }
    if (g_pd3dDevice !=NULL)
    {
        g_pd3dDevice->Release();
    }
    if (g_pD3D!=NULL)
    {
        g_pD3D ->Release();
    }
}
VOID Render()
{
    g_pd3dDevice->Clear(0,NULL,D3DCLEAR_TARGET,D3DCOLOR_XRGB(0,0,255),1.0f,0L);//
    if(SUCCEEDED(g_pd3dDevice->BeginScene()))
    {
        //g_pd3dDevice->SetStreamSource(0,g_pVB,0,sizeof(CUSTOMVERTEX));
        g_pd3dDevice->SetStreamSource(0,g_pVB,0,sizeof( CUSTOMVERTEX ) );

        g_pd3dDevice->SetFVF(D3DFVF_CUSTOMVERTEX);
        g_pd3dDevice->DrawPrimitive(D3DPT_TRIANGLELIST,0,1);
        g_pd3dDevice->EndScene();
    }
    g_pd3dDevice->Present(NULL,NULL,NULL,NULL);
}
LRESULT WINAPI MsgProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
    switch (msg)
    {
    case WM_DESTROY:
        Cleanup();
        PostQuitMessage(0);
        return 0;

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

}
INT WINAPI WinMain( HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nShowCmd )
{
    WNDCLASSEX wcex;
    wcex.cbSize =sizeof(WNDCLASSEX);
    wcex.cbClsExtra = 0L;
    wcex.cbWndExtra = 0L;
    wcex.hbrBackground = NULL;
    wcex.hCursor = NULL;
    wcex.hIcon =NULL;
    wcex.hIconSm =NULL;
    wcex.lpfnWndProc =MsgProc;
    wcex.lpszClassName =L"D3D";
    wcex.lpszMenuName = NULL;
    wcex.style =CS_CLASSDC;
    wcex.hInstance = hInstance;//( NULL );
    RegisterClassEx(&wcex);
    HWND hWnd;
    hWnd = CreateWindow(L"D3D",L"HHAH",WS_OVERLAPPEDWINDOW,100,100,300,300,
        NULL,NULL,wcex.hInstance,NULL);
    if (SUCCEEDED(InitD3D(hWnd)))
    {
        if (SUCCEEDED(InitGeometry()))
        ShowWindow(hWnd,SW_SHOWDEFAULT);
        UpdateWindow(hWnd);
        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();
        }
    }
    UnregisterClass(L"D3D",wcex.hInstance);
    return 0;
}