索引缓冲区

 在Direct3D中，实体模型中的一个点可能被多个三角形面所共用，如果每个三角形都构造三个顶点，对比较浪费资源的，为了节省资源，引入了索引缓冲区：把顶点的具体数据和代表图元格式的顶点顺序分开存储，顶点数据仍然放到顶点缓存区中，索引缓存区则按照图元格式，顺序存放顶点的索引。

下面是一个简单的使用例子，画出两个三角形：

1. /******************************************************
2. FileName: CTDUIMessage.h   - TDOnline/UISystem
3. Author: lsm   Version:        Date: 08/11/4
4. Description: 索引缓冲区的使用
5. History:
6.       
8. ******************************************************/
10. /*-------------Head------------*/
11. #include "assert.h"
12. #include "d3dx9.h"
13. #pragma warning(disable : 4996)
14. #include "strsafe.h"
15. #pragma warning(disable : 4996)
17. LPDIRECT3D9                g_pD3DObj   = NULL; //D3D 对象
18. LPDIRECT3DDEVICE9          g_pD3DDev   = NULL; //D3D 设备
19. LPDIRECT3DVERTEXBUFFER9    g_pVerBuf   = NULL; //顶点缓冲区
20. LPDIRECT3DINDEXBUFFER9     g_pInBuf    = NULL; //索引缓冲区
22. TCHAR g_AppName[] = TEXT("D3D");//类名
24. #define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)//灵活顶点格式
26. struct CUSTOMVERTEX 
27. {
28.     D3DXVECTOR3 position;
29.     float       rhw;
30.     D3DCOLOR    color;
31. };
32. /*---------------End------------*/
35. /*==========================================
36. Function name: InitD3D
37. Description: 初始化D3D对象
38. ==========================================*/
39. HRESULT InitD3D(HWND hWnd)
40. {
41.     if((g_pD3DObj = Direct3DCreate9(D3D_SDK_VERSION)) == NULL)//创建3D对象
42.     {
43.         assert(false);
44.         return E_FAIL;
45.     }
47.     D3DDISPLAYMODE devMode;
48.     if (FAILED(g_pD3DObj->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &devMode)))//获得显卡信息
49.     {
50.         assert(false);
51.         return E_FAIL;
52.     }
54.     D3DPRESENT_PARAMETERS d3dpp;
55.     ZeroMemory(&d3dpp, sizeof(d3dpp));
56.     d3dpp.Windowed               = true;
57.     d3dpp.SwapEffect             = D3DSWAPEFFECT_DISCARD;
58.     d3dpp.BackBufferFormat       = D3DFMT_UNKNOWN;
60.     if(FAILED(g_pD3DObj->CreateDevice(
61.                                       D3DADAPTER_DEFAULT,
62.                                       D3DDEVTYPE_HAL,
63.                                       hWnd,
64.                                       D3DCREATE_SOFTWARE_VERTEXPROCESSING,
65.                                       &d3dpp,
66.                                       &g_pD3DDev
67.                                       )))
68.     {
69.         assert(false);
70.         return E_FAIL;
71.     }
73.     return S_OK;
74. }
76. /*==========================================
77. Function name: InitVBuf
78. Description: 填充顶点缓冲区
79. ==========================================*/
80. HRESULT InitVBuf()
81. {
82.     if (FAILED(g_pD3DDev->CreateVertexBuffer(
83.                                              4*sizeof(CUSTOMVERTEX),
84.                                              0,
85.                                              D3DFVF_CUSTOMVERTEX,
86.                                              D3DPOOL_DEFAULT,
87.                                              &g_pVerBuf,
88.                                              NULL
89.                                              )))
90.     {
91.         return E_FAIL;
92.     }
94.     CUSTOMVERTEX *vertices;
96.     if (FAILED(g_pVerBuf->Lock(0, 0, (void**)&vertices, 0)))//锁住内存
97.     {
98.         return E_FAIL;
99.     }
101.     vertices[0].position = D3DXVECTOR3(150.0f,  50.0f, 1.0f);//四个点,注意三角形的构造顺序
102.     vertices[0].rhw      = 1.0f;
103.     vertices[0].color    = 0xffff0000;
104.     vertices[1].position = D3DXVECTOR3( 50.0f, 220.0f, 1.0f);
105.     vertices[1].rhw      = 1.0f;
106.     vertices[1].color    = 0xff0000ff;
107.     vertices[2].position = D3DXVECTOR3(150.0f, 250.0f, 1.0f);
108.     vertices[2].rhw      = 1.0f;
109.     vertices[2].color    = 0xffffffff;
110.     vertices[3].position = D3DXVECTOR3(250.0f, 250.0f, 0.0f);
111.     vertices[3].rhw      = 1.0f;
112.     vertices[3].color    = 0xff000fff;
114.     g_pVerBuf->Unlock();
117.     WORD indexBuf[] = {0, 3, 2, 0, 2, 1};//以下是索引缓冲区
118.     void *pIndex;
119.     g_pD3DDev->CreateIndexBuffer(sizeof(indexBuf), 0, D3DFMT_INDEX16, D3DPOOL_DEFAULT,&g_pInBuf, NULL);
120.     g_pInBuf->Lock(0, sizeof(indexBuf), (void **)&pIndex, 0);
121.     memcpy(pIndex, indexBuf, sizeof(indexBuf));
122.     g_pInBuf->Unlock();
124.     return S_OK;
125. }
128. /*==========================================
129. Function name: Cleanup
130. Description: 释放对象
131. ==========================================*/
132. VOID Cleanup()
133. {
134.     if (g_pVerBuf != NULL)
135.     {
136.         g_pVerBuf->Release();
137.     }
139.     if (g_pD3DDev != NULL)
140.     {
141.         g_pD3DDev->Release();
142.     }
144.     if (g_pD3DObj != NULL)
145.     {
146.         g_pD3DObj->Release();
147.     }
148. }
150. /*==========================================
151. Function name: Render
152. Description: 负责渲染
153. ==========================================*/
154. VOID Render()
155. {
156.     if (g_pD3DDev == NULL)
157.     {
158.         return ;
159.     }
161.     g_pD3DDev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 255), 1, 0);
163.     if (SUCCEEDED(g_pD3DDev->BeginScene()))
164.     {
165.         g_pD3DDev->SetStreamSource(0, g_pVerBuf, 0, sizeof(CUSTOMVERTEX));
166.         g_pD3DDev->SetFVF(D3DFVF_CUSTOMVERTEX);
167.         g_pD3DDev->SetIndices(g_pInBuf);
168.         g_pD3DDev->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, 0, 0, 4, 0, 2);
169.         //g_pD3DDev->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);
171.         g_pD3DDev->EndScene();
172.     }
174.     g_pD3DDev->Present(NULL, NULL, NULL, NULL);
175. }
176. /*==========================================
177. Function name: MsgProc
178. Description: 负责消息循环
179. ==========================================*/
180. LRESULT WINAPI MsgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
181. {
182.     switch(msg)
183.     {
184.     case WM_DESTROY:
185.         Cleanup();
186.         PostQuitMessage(0);
187.         return 0;
188.     }
190.     return DefWindowProc(hWnd, msg, wParam, lParam);
191. }
193. /*==========================================
194. Function name: WinMain
195. Description: 程序启动函数
196. ==========================================*/
197. INT WINAPI WinMain(HINSTANCE hInst, HINSTANCE, LPSTR, INT)
198. {
199.     WNDCLASSEX wc = {
200.                    sizeof(WNDCLASSEX), 
201.                    CS_CLASSDC, 
202.                    MsgProc, 
203.                    0L, 
204.                    0L, 
205.                    GetModuleHandle(NULL),
206.                    NULL,
207.                    NULL,
208.                    NULL,
209.                    NULL,
210.                    g_AppName,
211.                    NULL
212.                    };
213.     RegisterClassEx(&wc);
215.     HWND hWnd = CreateWindow(
216.                              g_AppName, 
217.                              TEXT("D3D Tutorial 1"), 
218.                              WS_OVERLAPPEDWINDOW, 
219.                              100, 
220.                              100, 
221.                              300, 
222.                              300,
223.                              NULL, 
224.                              NULL, 
225.                              wc.hInstance, 
226.                              NULL 
227.                              );
229.     if (hWnd == NULL)
230.     {
231.         return -1;
232.     }
234.     if(SUCCEEDED(InitD3D(hWnd)))
235.     {
236.         if(SUCCEEDED(InitVBuf()))
237.         {
238.             ShowWindow(hWnd, SW_SHOWDEFAULT);
239.             UpdateWindow(hWnd);
241.             MSG msg;
242.             ZeroMemory(&msg, sizeof(msg));
243.             while (msg.message != WM_QUIT)
244.             {
245.                 if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
246.                 {
247.                     TranslateMessage(&msg);
248.                     DispatchMessage(&msg);
249.                 }
250.                 else
251.                 {
252.                     Render();
253.                 }
254.             }
255.         }
256.     }
258.     UnregisterClass(g_AppName, wc.hInstance);
259.     return 0;
260. }