1 #include <windows.h>
  2 #include <gl/gl.h>
  3 #include <stdio.h>
  4
  5 #define PI acos(-1.0)
  6
  7 //存储n边形的n个点坐标
  8 float px[1000] = {0};
  9 float py[1000] = {0};
 10 int n;  //n边形
 11
 12 void GetAllPoint(int n)   //得到n边形n个点的坐标
 13 {
 14     float x,y;
 15     float r = 0.8;      //半径
 16     float si = 2*PI/n;  //360°/n
 17     float angle = si/2; //开始度数
 18     int pnum = 0;
 19     while(angle<=2*PI){
 20         x = r*cos(angle);
 21         y = r*sin(angle);
 22         px[pnum] = x;
 23         py[pnum++] = y;
 24         angle = angle+si;
 25     }
 26 }
 27
 28 void ShowPic1(int n)    //画出n边形的外边框
 29 {
 30     int i;
 31     float x,y;
 32     for(i=0;i<n;i++){
 33         x = px[i];
 34         y = py[i];
 35         glVertex2f(x,y);
 36     }
 37 }
 38
 39 void ShowPic2(int n)    //画出n边形的中间连线
 40 {
 41     int i,j;
 42     float x0,y0,x,y;
 43     for(i=0;i<n;i++){
 44         x0 = px[i];
 45         y0 = py[i];
 46         for(j=0;j<n;j++){
 47             if(i==j)
 48                 continue;
 49             glVertex2f(x0,y0);
 50             x = px[j];
 51             y = py[j];
 52             glVertex2f(x,y);
 53         }
 54     }
 55 }
 56
 57 LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM);
 58 void EnableOpenGL(HWND hwnd, HDC*, HGLRC*);
 59 void DisableOpenGL(HWND, HDC, HGLRC);
 60
 61 int WINAPI WinMain(HINSTANCE hInstance,
 62                    HINSTANCE hPrevInstance,
 63                    LPSTR lpCmdLine,
 64                    int nCmdShow)
 65 {
 66     WNDCLASSEX wcex;
 67     HWND hwnd;
 68     HDC hDC;
 69     HGLRC hRC;
 70     MSG msg;
 71     BOOL bQuit = FALSE;
 72     float theta = 0.0f;
 73
 74     printf("请输入n (n边形)：\n");
 75     scanf("%d",&n);
 76
 77     GetAllPoint(n); //获取多边形全部的点
 78
 79     /* register window class */
 80     wcex.cbSize = sizeof(WNDCLASSEX);
 81     wcex.style = CS_OWNDC;
 82     wcex.lpfnWndProc = WindowProc;
 83     wcex.cbClsExtra = 0;
 84     wcex.cbWndExtra = 0;
 85     wcex.hInstance = hInstance;
 86     wcex.hIcon = LoadIcon(NULL, IDI_APPLICATION);
 87     wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
 88     wcex.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
 89     wcex.lpszMenuName = NULL;
 90     wcex.lpszClassName = "GLSample";
 91     wcex.hIconSm = LoadIcon(NULL, IDI_APPLICATION);;
 92
 93
 94     if (!RegisterClassEx(&wcex))
 95         return 0;
 96
 97     /* create main window */
 98     hwnd = CreateWindowEx(0,
 99                           "GLSample",
100                           "钻石图案",
101                           WS_OVERLAPPEDWINDOW,
102                           CW_USEDEFAULT,
103                           CW_USEDEFAULT,
104                           700,
105                           700,
106                           NULL,
107                           NULL,
108                           hInstance,
109                           NULL);
110
111     ShowWindow(hwnd, nCmdShow);
112
113     /* enable OpenGL for the window */
114     EnableOpenGL(hwnd, &hDC, &hRC);
115
116     /* program main loop */
117     while (!bQuit)
118     {
119         /* check for messages */
120         if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
121         {
122             /* handle or dispatch messages */
123             if (msg.message == WM_QUIT)
124             {
125                 bQuit = TRUE;
126             }
127             else
128             {
129                 TranslateMessage(&msg);
130                 DispatchMessage(&msg);
131             }
132         }
133         else
134         {
135             /* OpenGL animation code goes here */
136
137             glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
138             glClear(GL_COLOR_BUFFER_BIT);
139
140             //glPushMatrix();
141             //glRotatef(theta, 0.0f, 0.0f, 1.0f);
142
143             glBegin(GL_LINE_STRIP);
144                 glColor3f(1.0f, 0.0f, 0.0f);    //设置画笔颜色
145                 ShowPic1(n);    //输出n边形的外边框
146             glEnd();
147
148             //printf("%d\n",pnum);
149
150             glBegin(GL_LINES);
151                 ShowPic2(n);    //画出n边形的中间连线
152             glEnd();
153
154             glPopMatrix();
155
156             SwapBuffers(hDC);
157
158             theta += 1.0f;
159             Sleep (1);
160         }
161     }
162
163     /* shutdown OpenGL */
164     DisableOpenGL(hwnd, hDC, hRC);
165
166     /* destroy the window explicitly */
167     DestroyWindow(hwnd);
168
169     return msg.wParam;
170 }
171
172 LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
173 {
174     switch (uMsg)
175     {
176         case WM_CLOSE:
177             PostQuitMessage(0);
178         break;
179
180         case WM_DESTROY:
181             return 0;
182
183         case WM_KEYDOWN:
184         {
185             switch (wParam)
186             {
187                 case VK_ESCAPE:
188                     PostQuitMessage(0);
189                 break;
190             }
191         }
192         break;
193
194         default:
195             return DefWindowProc(hwnd, uMsg, wParam, lParam);
196     }
197
198     return 0;
199 }
200
201 void EnableOpenGL(HWND hwnd, HDC* hDC, HGLRC* hRC)
202 {
203     PIXELFORMATDESCRIPTOR pfd;
204
205     int iFormat;
206
207     /* get the device context (DC) */
208     *hDC = GetDC(hwnd);
209
210     /* set the pixel format for the DC */
211     ZeroMemory(&pfd, sizeof(pfd));
212
213     pfd.nSize = sizeof(pfd);
214     pfd.nVersion = 1;
215     pfd.dwFlags = PFD_DRAW_TO_WINDOW |
216                   PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
217     pfd.iPixelType = PFD_TYPE_RGBA;
218     pfd.cColorBits = 24;
219     pfd.cDepthBits = 16;
220     pfd.iLayerType = PFD_MAIN_PLANE;
221
222     iFormat = ChoosePixelFormat(*hDC, &pfd);
223
224     SetPixelFormat(*hDC, iFormat, &pfd);
225
226     /* create and enable the render context (RC) */
227     *hRC = wglCreateContext(*hDC);
228
229     wglMakeCurrent(*hDC, *hRC);
230 }
231
232 void DisableOpenGL (HWND hwnd, HDC hDC, HGLRC hRC)
233 {
234     wglMakeCurrent(NULL, NULL);
235     wglDeleteContext(hRC);
236     ReleaseDC(hwnd, hDC);
237 }