D3D中公告板的使用示例

D3D中公告板的使用示例

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公告板(billboard)是一种允许在2D对象出现在3D中的很酷的技术。举例来说，一个复杂的对象，诸如一棵树，在一个建模程序中，可以从侧视图（side view）进行渲染，然后在一个矩阵的多边形上进行绘制。这个矩形的多边形通常朝向观察点，因此不论从多边形的哪个角度进行观察，树纹理都好像是从渲染一侧被观察到。

如下所示，不管从哪个位置或角度观察多边形，公告板技术保证了多边形始终朝向观察点。

公告板的原理就是通过使用世界矩阵，根据观察点来排列多边形，因为观察的角度已知（或能够获得一个观察变换矩阵），就只需要使用相反的观察角来构造矩阵。 不必改变多边形的位置，因为角度就已经足够了。

构造公告板世界矩阵（这个矩阵可以应用到一个网格或多边形上）的第一种方法就是使用已知观察角的相反值。

举例来说，假设已经设置好了带有顶点的顶点缓冲，观察点角度存储为x_rot，y_rot，z_rot，并且公告板对象的坐标是x_coord，y_coord，z_coord。下面的代码演示了如何设置矩阵，以便用于渲染公告板顶点缓冲：

    float  x_rot = D3DX_PI / 4, y_rot = D3DX_PI / 2, z_rot = D3DX_PI / 8;
     float  x_coord = 2.0f, y_coord = 3.0f, z_coord = 5.0f;

    D3DXMATRIX mat_billboard;
    D3DXMATRIX mat_x_rot, mat_y_rot, mat_z_rot;
    D3DXMATRIX mat_trans;

     // 构造公告板矩阵

    // 使用同观察点相反的角度进行定位，以便进行观察。
    D3DXMatrixRotationX(&mat_x_rot, -x_rot);
    D3DXMatrixRotationY(&mat_y_rot, -y_rot);
    D3DXMatrixRotationZ(&mat_z_rot, -z_rot);

     // 使用公告板对象坐标进行定位
    D3DXMatrixTranslation(&mat_trans, x_coord, y_coord, z_coord);

     // 合并矩阵
    D3DXMatrixIdentity(&mat_billboard);
    D3DXMatrixMultiply(&mat_billboard, &mat_billboard, &mat_trans);
    D3DXMatrixMultiply(&mat_billboard, &mat_billboard, &mat_z_rot);
    D3DXMatrixMultiply(&mat_billboard, &mat_billboard, &mat_y_rot);
    D3DXMatrixMultiply(&mat_billboard, &mat_billboard, &mat_x_rot);

     // 设置矩阵
    g_d3d_device->SetTransform(D3DTS_WORLD, &mat_billboard);

     // 继续绘制顶点缓冲，此顶点缓冲已经在合适的坐标上进行定位，以朝向观察点。

 

创建公告板世界矩阵的第二种方法是从Direct3D获取当前的观察矩阵并将此矩阵转置。这个转置矩阵会将所有的东西进行恰当的定位，以朝向观察点。接着就只需应用网格的平移矩阵，在世界中正确地确定网格的位置。

下面的代码演示了如何从观察矩阵构造出公告板矩阵，并使用这个矩阵来绘制公告板对象：

   float  x_coord = 2.0f, y_coord = 3.0f, z_coord = 5.0f;

    D3DXMATRIX mat_trans, mat_world, mat_transpose;

     // 得到当前的Direct3D观察矩阵
    g_d3d_device->GetTransform(D3DTS_VIEW, &mat_transpose);

     // 创建网格的平移矩阵
    D3DXMatrixTranslation(&mat_trans, x_coord, y_coord, z_coord);

     // 将前两个矩阵相乘得到世界变换矩阵
    D3DXMatrixMultiply(&mat_world, &mat_transpose, &mat_trans);

     // 设置世界变换矩阵
    g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);

     // 继续绘制顶点缓冲，此顶点缓冲已经在合适的坐标上进行定位，以朝向观察点。

 

公告板是一种强大的技术，它实际上也是其他一些特效的基础，比如粒子。

源码中的Setup_Mesh函数用来创建顶点缓冲和从文件取得纹理数据，其中用到了D3DXCreateTextureFromFileEx函数，来看看它的使用信息：

Creates a texture from a file. This is a more advanced function than D3DXCreateTextureFromFile.

HRESULT D3DXCreateTextureFromFileEx(
  LPDIRECT3DDEVICE9 pDevice,
  LPCTSTR pSrcFile,
  UINT Width,
  UINT Height,
  UINT MipLevels,
  DWORD Usage,
  D3DFORMAT Format,
  D3DPOOL Pool,
  DWORD Filter,
  DWORD MipFilter,
  D3DCOLOR ColorKey,
  D3DXIMAGE_INFO * pSrcInfo,
  PALETTEENTRY * pPalette,
  LPDIRECT3DTEXTURE9 * ppTexture
);

Parameters

pDevice

[in] Pointer to an IDirect3DDevice9 interface, representing the device to be associated with the texture.

pSrcFile

[in] Pointer to a string that specifies the filename. If the compiler settings require Unicode, the data type LPCTSTR resolves to LPCWSTR. Otherwise, the string data type resolves to LPCSTR. See Remarks.

Width

[in] Width in pixels. If this value is zero or D3DX_DEFAULT, the dimensions are taken from the file and rounded up to a power of two. If the device supports non-power of 2 textures and D3DX_DEFAULT_NONPOW2 is specified, the size will not be rounded.

Height

[in] Height, in pixels. If this value is zero or D3DX_DEFAULT, the dimensions are taken from the file and rounded up to a power of two. If the device supports non-power of 2 textures and D3DX_DEFAULT_NONPOW2 is sepcified, the size will not be rounded.

MipLevels

[in] Number of mip levels requested. If this value is zero or D3DX_DEFAULT, a complete mipmap chain is created. If D3DX_FROM_FILE, the size will be taken exactly as it is in the file, and the call will fail if this violates device capabilities.

Usage

[in] 0, D3DUSAGE_RENDERTARGET, or D3DUSAGE_DYNAMIC. Setting this flag to D3DUSAGE_RENDERTARGET indicates that the surface is to be used as a render target. The resource can then be passed to the pNewRenderTarget parameter of the IDirect3DDevice9::SetRenderTarget method. If either D3DUSAGE_RENDERTARGET or D3DUSAGE_DYNAMIC is specified, Pool must be set to D3DPOOL_DEFAULT, and the application should check that the device supports this operation by calling IDirect3D9::CheckDeviceFormat. D3DUSAGE_DYNAMIC indicates that the surface should be handled dynamically. See Using Dynamic Textures.

Format

[in] Member of the D3DFORMAT enumerated type, describing the requested pixel format for the texture. The returned texture might have a different format from that specified by Format. Applications should check the format of the returned texture. If D3DFMT_UNKNOWN, the format is taken from the file. If D3DFMT_FROM_FILE, the format is taken exactly as it is in the file, and the call will fail if this violates device capabilities.

Pool

[in] Member of the D3DPOOL enumerated type, describing the memory class into which the texture should be placed.

Filter

[in] A combination of one or more D3DX_FILTER constants controlling how the image is filtered. Specifying D3DX_DEFAULT for this parameter is the equivalent of specifying D3DX_FILTER_TRIANGLE | D3DX_FILTER_DITHER.

MipFilter

[in] A combination of one or more D3DX_FILTER constants controlling how the image is filtered. Specifying D3DX_DEFAULT for this parameter is the equivalent of specifying D3DX_FILTER_BOX. In addition, use bits 27-31 to specify the number of mip levels to be skipped (from the top of the mipmap chain) when a .dds texture is loaded into memory; this allows you to skip up to 32 levels.

ColorKey

[in] D3DCOLOR value to replace with transparent black, or 0 to disable the color key. This is always a 32-bit ARGB color, independent of the source image format. Alpha is significant and should usually be set to FF for opaque color keys. Thus, for opaque black, the value would be equal to 0xFF000000.

pSrcInfo

[in, out] Pointer to a D3DXIMAGE_INFO structure to be filled in with a description of the data in the source image file, or NULL.

pPalette

[out] Pointer to a PALETTEENTRY structure, representing a 256-color palette to fill in, or NULL.

ppTexture

[out] Address of a pointer to an IDirect3DTexture9 interface, representing the created texture object.

Return Values

If the function succeeds, the return value is D3D_OK. If the function fails, the return value can be one of the following: D3DERR_INVALIDCALL.

D3DERR_NOTAVAILABLED3DERR_OUTOFVIDEOMEMORYD3DXERR_INVALIDDATAE_OUTOFMEMORY

Remarks

The compiler setting also determines the function version. If Unicode is defined, the function call resolves to D3DXCreateTextureFromFileExW. Otherwise, the function call resolves to D3DXCreateTextureFromFileExA because ANSI strings are being used.

Use D3DXCheckTextureRequirements to determine if your device can support the texture given the current state.

This function supports the following file formats: .bmp, .dds, .dib, .hdr, .jpg, .pfm, .png, .ppm, and .tga. See D3DXIMAGE_FILEFORMAT.

Mipmapped textures automatically have each level filled with the loaded texture. When loading images into mipmapped textures, some devices are unable to go to a 1x1 image and this function will fail. If this happens, then the images need to be loaded manually.

For the best performance when using D3DXCreateTextureFromFileEx:

1. Doing image scaling and format conversion at load time can be slow. Store images in the format and resolution they will be used. If the target hardware requires power of 2 dimensions, then create and store images using power of 2 dimensions.
2. For mipmap image creation at load time, filter using D3DX_FILTER_BOX. A box filter is much faster than other filter types such as D3DX_FILTER_TRIANGLE.
3. Consider using DDS files. Since DDS files can be used to represent any Direct3D 9 texture format, they are very easy for D3DX to read. Also, they can store mipmaps, so any mipmap-generation algorithms can be used to author the images.

When skipping mipmap levels while loading a .dds file, use the D3DX_SKIP_DDS_MIP_LEVELS macro to generate the MipFilter value. This macro takes the number of levels to skip and the filter type and returns the filter value, which would then be passed into the MipFilter parameter.

我们来看看Do_Frame是如何进行公告板的绘制的，以下是关键代码：

     // build view matrix
    D3DXMatrixLookAtLH(&mat_view, &D3DXVECTOR3(cos(angle) * 200.0, 200.0, sin(angle) * 200.0),
        &D3DXVECTOR3(0.0, 0.0, 0.0), &D3DXVECTOR3(0.0, 1.0, 0.0));

     // set view matrix
    g_d3d_device->SetTransform(D3DTS_VIEW, &mat_view);

     // Begin scene
     if (SUCCEEDED(g_d3d_device->BeginScene()))
    {
         // 1) draw the floor
        
        // binds a vertex buffer to a device data stream
        g_d3d_device->SetStreamSource(0, g_floor_vb, 0,  sizeof (VERTEX));

         // set the current vertex stream declation
        g_d3d_device->SetFVF(VERTEX_FVF);

         // assigns a texture to a stage for a device
        g_d3d_device->SetTexture(0, g_floor_texture);

         // build world matrix, we only need identity matrix, because we do not need to change original floor position.
        D3DXMatrixIdentity(&mat_world);

         // set world matrix
        g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);        

         // renders a sequence of noindexed, geometric primitives of the specified type from the current set
        // of data input stream.
        g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);

         // 2) draw the billboards

        g_d3d_device->SetStreamSource(0, g_billboard_vb, 0,  sizeof (VERTEX));
        g_d3d_device->SetTexture(0, g_billboard_texture);

         // enable alpha test
        g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
         // get world matrix, just get it from view matrix's transpose.
        D3DXMatrixTranspose(&mat_world, &mat_view);
        
         // draw all billboard images
         for ( short  i = 0; i < 3; i++)
        {
             for ( short  j = 0; j < 3; j++)
            {
                mat_world._41 = i * 80.0 - 80.0;
                mat_world._42 = 0.0;
                mat_world._43 = j * 80.0 - 80.0;

                 // set world matrix
                g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
                 // draw polygon
                g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
            }
        }

         // disable alpha test
        g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);

         // release texture
        g_d3d_device->SetTexture(0, NULL);

         // end the scene
        g_d3d_device->EndScene();
    }

1） 地板的绘制：首先调用 D3DXMatrixLookAtLH取得视口矩阵，接着调用SetTransform设置视口矩阵。绘制地板时先调用SetStreamSource和SetFVF设置顶点信息，再调用SetTexture设置纹理，接着调用D3DXMatrixIdentity单位化世界矩阵并设置世界矩阵，因为我们不需要改变地板的位置，所以世界矩阵直接设置为单位矩阵就可以了；再接着调用DrawPrimitive绘制图形。

2）公告板的绘制：首先设置顶点数据格式，接着启用alpha测试，再接着将视口矩阵转置得到世界矩阵，使用两层for循环来平移世界矩阵并设置世界矩阵，最后绘制这些公告板。
 

       // draw all billboard images
         for( short i = 0; i < 3; i++)
        {
             for( short j = 0; j < 3; j++)
            {
                mat_world._41 = i * 80.0 - 80.0;
                mat_world._42 = 0.0;
                mat_world._43 = j * 80.0 - 80.0;

                 // set world matrix
                g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
                 // draw polygon
                g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
            }
        }

完整源码如下:
 

/***************************************************************************************
PURPOSE:
    Billboard Demo

Required libraries:
  WINMM.lib, D3D9.LIB, D3DX9.LIB.
 ***************************************************************************************/

#include <windows.h>
#include <stdio.h>
#include "d3d9.h"
#include "d3dx9.h"

#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "d3d9.lib")
#pragma comment(lib, "d3dx9.lib")

#pragma warning(disable : 4305 4244)

#define  WINDOW_WIDTH    400
#define  WINDOW_HEIGHT   400

#define  Safe_Release(p) if((p)) (p)->Release();

// window handles, class and caption text.
HWND g_hwnd;
HINSTANCE g_inst;
static   char  g_class_name[] = "BillboardClass";
static   char  g_caption[]    = "Billboard Demo";

// the Direct3D and device object
IDirect3D9* g_d3d = NULL;
IDirect3DDevice9* g_d3d_device = NULL;

// The 3D vertex format and descriptor
typedef  struct
{
     float  x, y, z;   // 3D coordinates    
     float  u, v;      // texture coordinates
} VERTEX;

#define  VERTEX_FVF   (D3DFVF_XYZ | D3DFVF_TEX1)

// the billboard vertex buffer and texture
IDirect3DVertexBuffer9* g_billboard_vb = NULL;
IDirect3DTexture9*      g_billboard_texture = NULL;

// the floor vertex buffer and texture
IDirect3DVertexBuffer9* g_floor_vb = NULL;
IDirect3DTexture9*      g_floor_texture = NULL;

//--------------------------------------------------------------------------------
// Window procedure.
//--------------------------------------------------------------------------------
long  WINAPI Window_Proc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
     switch (msg)
    {
     case  WM_DESTROY:
        PostQuitMessage(0);
         return  0;
    }

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

//--------------------------------------------------------------------------------
// Copy vertex data into vertex buffer, create texture from file.
//--------------------------------------------------------------------------------
BOOL Setup_Mesh()
{
    BYTE* vertex_ptr;

    VERTEX billboard_verts[] = {
        { -42.0f, 80.0f, 0.0f, 0.0f, 0.0f },
        {  40.0f, 80.0f, 0.0f, 1.0f, 0.0f },
        { -40.0f,  0.0f, 0.0f, 0.0f, 1.0f },
        {  40.0f,  0.0f, 0.0f, 1.0f, 1.0f }
    };

    VERTEX floor_verts[] = {
        { -100.0f, 0.0f,  100.0f, 0.0f, 0.0f },
        {  100.0f, 0.0f,  100.0f, 1.0f, 0.0f },
        { -100.0f, 0.0f, -100.0f, 0.0f, 1.0f },
        { 100.0f, 0.0f, -100.0f, 1.0f, 1.0f }
    };

     // create vertex buffers and stuff in data
    
    // for billboard
     if (FAILED(g_d3d_device->CreateVertexBuffer( sizeof (billboard_verts), 0, VERTEX_FVF, D3DPOOL_DEFAULT, 
                                               &g_billboard_vb, NULL)))   
         return  FALSE;   

     // locks a range of vertex data and obtains a pointer to the vertex buffer memory
     if (FAILED(g_billboard_vb->Lock(0, 0, ( void **)&vertex_ptr, 0)))
         return  FALSE;

    memcpy(vertex_ptr, billboard_verts,  sizeof (billboard_verts));

     // unlocks vertex data
    g_billboard_vb->Unlock();

     // for floor
     if (FAILED(g_d3d_device->CreateVertexBuffer( sizeof (floor_verts), 0, VERTEX_FVF, D3DPOOL_DEFAULT, &g_floor_vb, NULL)))    
         return  FALSE;    

     // locks a range of vertex data and obtains a pointer to the vertex buffer memory
     if (FAILED(g_floor_vb->Lock(0, 0, ( void **)&vertex_ptr, 0)))
         return  FALSE;

    memcpy(vertex_ptr, floor_verts,  sizeof (floor_verts));

     // unlocks vertex data
    g_floor_vb->Unlock();

     // get textures    
    D3DXCreateTextureFromFile(g_d3d_device, "Floor.bmp", &g_floor_texture);

     // Creates a texture from a file. 
    D3DXCreateTextureFromFileEx(g_d3d_device, "Billboard.bmp", D3DX_DEFAULT, D3DX_DEFAULT,
        D3DX_DEFAULT, 0, D3DFMT_A1R5G5B5, D3DPOOL_MANAGED, D3DX_FILTER_TRIANGLE, D3DX_FILTER_TRIANGLE,
        D3DCOLOR_RGBA(0,0,0,255), NULL, NULL, &g_billboard_texture);

     return  TRUE;
}

//--------------------------------------------------------------------------------
// Initialize d3d, d3d device, vertex buffer, texutre; set render state for d3d;
// set perspective matrix.
//--------------------------------------------------------------------------------
BOOL Do_Init()
{
    D3DPRESENT_PARAMETERS present_param;
    D3DDISPLAYMODE  display_mode;
    D3DXMATRIX mat_proj, mat_view;    

     // do a windowed mode initialization of Direct3D
     if ((g_d3d = Direct3DCreate9(D3D_SDK_VERSION)) == NULL)
         return  FALSE;

     // retrieves the current display mode of the adapter
     if (FAILED(g_d3d->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &display_mode)))
         return  FALSE;

    ZeroMemory(&present_param,  sizeof (present_param));

     // initialize d3d presentation parameter
    present_param.Windowed               = TRUE;
    present_param.SwapEffect             = D3DSWAPEFFECT_DISCARD;
    present_param.BackBufferFormat       = display_mode.Format;
    present_param.EnableAutoDepthStencil = TRUE;
    present_param.AutoDepthStencilFormat = D3DFMT_D16;

     // creates a device to represent the display adapter
     if (FAILED(g_d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, g_hwnd,
                                  D3DCREATE_SOFTWARE_VERTEXPROCESSING, &present_param, &g_d3d_device)))
         return  FALSE;     

     // set render state

    // disable d3d lighting
    g_d3d_device->SetRenderState(D3DRS_LIGHTING, FALSE);
     // enable z-buffer
    g_d3d_device->SetRenderState(D3DRS_ZENABLE, D3DZB_TRUE);
     // set alpha reference value and function
    g_d3d_device->SetRenderState(D3DRS_ALPHAREF, 0x01);
    g_d3d_device->SetRenderState(D3DRS_ALPHAFUNC, D3DCMP_GREATEREQUAL);

     // create and set the projection matrix

    // builds a left-handed perspective projection matrix based on a field of view
    D3DXMatrixPerspectiveFovLH(&mat_proj, D3DX_PI/4.0, 1.0, 1.0, 1000.0);

     // sets a single device transformation-related state
    g_d3d_device->SetTransform(D3DTS_PROJECTION, &mat_proj);

     // create the meshes
    Setup_Mesh();    

     return  TRUE;
}

//--------------------------------------------------------------------------------
// Release all d3d resource.
//--------------------------------------------------------------------------------
BOOL Do_Shutdown()
{
    Safe_Release(g_billboard_vb);
    Safe_Release(g_billboard_texture);
    Safe_Release(g_floor_vb);
    Safe_Release(g_floor_texture);
    Safe_Release(g_d3d_device);
    Safe_Release(g_d3d);

     return  TRUE;
}

//--------------------------------------------------------------------------------
// Render a frame.
//--------------------------------------------------------------------------------
BOOL Do_Frame()
{
    D3DXMATRIX mat_view, mat_world;

     // clear device back buffer
    g_d3d_device->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_RGBA(0, 64, 128, 255), 1.0f, 0);

     // update the view position
     float  angle = ( float ) timeGetTime() / 2000.0;

     // build view matrix
    D3DXMatrixLookAtLH(&mat_view, &D3DXVECTOR3(cos(angle) * 200.0, 200.0, sin(angle) * 200.0),
        &D3DXVECTOR3(0.0, 0.0, 0.0), &D3DXVECTOR3(0.0, 1.0, 0.0));

     // set view matrix
    g_d3d_device->SetTransform(D3DTS_VIEW, &mat_view);

     // Begin scene
     if (SUCCEEDED(g_d3d_device->BeginScene()))
    {
         // 1) draw the floor
        
        // binds a vertex buffer to a device data stream
        g_d3d_device->SetStreamSource(0, g_floor_vb, 0,  sizeof (VERTEX));

         // set the current vertex stream declation
        g_d3d_device->SetFVF(VERTEX_FVF);

         // assigns a texture to a stage for a device
        g_d3d_device->SetTexture(0, g_floor_texture);

         // build world matrix, we only need identity matrix, because we do not need to change original floor position.
        D3DXMatrixIdentity(&mat_world);

         // set world matrix
        g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);        

         // renders a sequence of noindexed, geometric primitives of the specified type from the current set
        // of data input stream.
        g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);

         // 2) draw the billboards

        g_d3d_device->SetStreamSource(0, g_billboard_vb, 0,  sizeof (VERTEX));
        g_d3d_device->SetTexture(0, g_billboard_texture);

         // enable alpha test
        g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
         // get world matrix, just get it from view matrix's transpose.
        D3DXMatrixTranspose(&mat_world, &mat_view);
        
         // draw all billboard images
         for ( short  i = 0; i < 3; i++)
        {
             for ( short  j = 0; j < 3; j++)
            {
                mat_world._41 = i * 80.0 - 80.0;
                mat_world._42 = 0.0;
                mat_world._43 = j * 80.0 - 80.0;

                 // set world matrix
                g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
                 // draw polygon
                g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
            }
        }

         // disable alpha test
        g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);

         // release texture
        g_d3d_device->SetTexture(0, NULL);

         // end the scene
        g_d3d_device->EndScene();
    }

     // present the contents of the next buffer in the sequence of back buffers owned by the device
    g_d3d_device->Present(NULL, NULL, NULL, NULL);

     return  TRUE;
}

//--------------------------------------------------------------------------------
// Main function, routine entry.
//--------------------------------------------------------------------------------
int  WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR cmd_line,  int  cmd_show)
{
    WNDCLASSEX  win_class;
    MSG         msg;

    g_inst = inst;

     // create window class and register it
    win_class.cbSize        =  sizeof (win_class);
    win_class.style         = CS_CLASSDC;
    win_class.lpfnWndProc   = Window_Proc;
    win_class.cbClsExtra    = 0;
    win_class.cbWndExtra    = 0;
    win_class.hInstance     = inst;
    win_class.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    win_class.hCursor       = LoadCursor(NULL, IDC_ARROW);
    win_class.hbrBackground = NULL;
    win_class.lpszMenuName  = NULL;
    win_class.lpszClassName = g_class_name;
    win_class.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

     if (! RegisterClassEx(&win_class))
         return  FALSE;

     // create the main window
    g_hwnd = CreateWindow(g_class_name, g_caption, WS_CAPTION | WS_SYSMENU, 0, 0,
                          WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, inst, NULL);

     if (g_hwnd == NULL)
         return  FALSE;

    ShowWindow(g_hwnd, SW_NORMAL);
    UpdateWindow(g_hwnd);

     // initialize game
     if (Do_Init() == FALSE)
         return  FALSE;

     // start message pump, waiting for signal to quit.
    ZeroMemory(&msg,  sizeof (MSG));

     while (msg.message != WM_QUIT)
    {
         if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        
         // draw a frame
         if (Do_Frame() == FALSE)
             break ;
    }

     // run shutdown function
    Do_Shutdown();

    UnregisterClass(g_class_name, inst);
    
     return  ( int ) msg.wParam;
}

效果图：