OpenGL绘制简单的时钟（首发测试）

编辑器 vs2012
  1 #include <windows.h>
  2 #include <GL/glut.h>//本来OpenGL程序一般还要包含<GL/gl.h>和<GL/glu.h>，
  3                     //但GLUT的头文件中已经自动将这两个文件包含了，不必再次包含。
  4 #include <math.h>
  5 #include<time.h>
  6 
  7 const GLfloat Pi = 3.1415926536;
  8 const GLfloat R=0.8f;
  9 const int n=200;
 10 static GLfloat angle=2*Pi;
 11 
 12 float Mysecond(struct tm *ptr)
 13 {
 14     return ((Pi/2)-(((float)ptr->tm_sec)/60)*2*Pi);
 15     
 16 }
 17 
 18 float Mymin(struct tm *ptr)
 19 {
 20     //return (Pi/2)-(((ptr->tm_min+(((float)ptr->tm_sec)/60))/60)*2*Pi);
 21     return ((Pi/2)-((ptr->tm_min+(Mysecond(ptr)/60))/60)*2*Pi);
 22 };
 23 
 24 float Myhour(struct tm *ptr)
 25 {
 26     if(0<ptr->tm_hour&&ptr->tm_hour<12)
 27     {
 28         return ((Pi/2)-((float)ptr->tm_hour+Mymin(ptr)/60.0)/12.0*2*Pi);
 29     }else{
 30         return ((Pi/2)-((ptr->tm_hour-12.0+Mymin(ptr)/60.0)/12)*2*Pi);
 31     }
 32 };
 33 void myDisplay(void)
 34 
 35 {
 36     //glShadeModel(GL_SMOOTH);
 37     //获取系统时间
 38     struct tm *ptr;
 39     time_t it;
 40     it=time(NULL);
 41     ptr=localtime(&it);
 42     
 43      glClear(GL_COLOR_BUFFER_BIT);//清除，GL_COLOR_BUFFER_BIT表示清除颜色
 44      glEnable(GL_POINT_SMOOTH);
 45     glEnable(GL_LINE_SMOOTH);
 46     glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); // Make round points, not square points
 47     glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);  // Antialias the lines
 48     glEnable(GL_BLEND);
 49     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 50      //钟盘
 51      glColor3f(0.5,0.5,0.5);
 52      glBegin(GL_POLYGON);
 53      for(int i=0;i<n;i++){
 54          glVertex2f(R*cos(2*Pi/n*i), R*sin(2*Pi/n*i));
 55      }
 56      glEnd();
 57 
 58      //刻度
 59      glColor3f(1.0,1.0,1.0);
 60      glBegin(GL_POINTS);
 61      glPointSize(5.0f);
 62      for(int j=0;j<12;j++)
 63      {
 64          glVertex2f(0.75*cos(2*Pi/12*j),0.75*sin(2*Pi/12*j));
 65          //for(int k=
 66      }
 67      
 68      glEnd();
 69      //中心点
 70      glPointSize(5.0f);
 71      glColor3f(0.0,0.0,0.0);
 72      glBegin(GL_POINTS);
 73      glVertex2f(0.0,0.0);
 74      glEnd();
 75 
 76      //时针
 77      glLineWidth(5.0f);
 78      glColor3f(0.0,0.0,0.0);//红色
 79      //glRotatef((angle/3600.0),0.0,0.0,1.0);
 80      
 81      glBegin(GL_LINES);
 82      glRotatef((angle/3600.0),0.0,0.0,1.0);
 83      glVertex2f(0.0,0.0);
 84      glVertex2f(cos(Myhour(ptr))*R*0.55,sin(Myhour(ptr))*R*0.55);
 85      glEnd();
 86      
 87      //分针
 88      glLineWidth(5.0f);
 89      glColor3f(0.0,0.0,0.0);//绿色
 90      //glRotatef((angle/60.0),0.0,0.0,1.0);
 91      
 92      glBegin(GL_LINES);
 93      glRotatef((angle/60.0),0.0,0.0,1.0);
 94      glVertex2f(0.0,0.0);
 95      glVertex2f(cos(Mymin(ptr))*R*0.65,sin(Mymin(ptr))*R*0.65);
 96      glEnd();
 97 
 98      //秒针
 99      glLineWidth(3.0f);
100      glColor3f(0.0,0.0,0.0);//蓝色
101      //glRotatef(angle,0.0,0.0,1.0);
102      
103      glBegin(GL_LINES);
104      glRotatef(angle,0.0,0.0,1.0);
105      glVertex2f(0.0,0.0);
106      glVertex2f(cos(Mysecond(ptr))*R*0.85,sin(Mysecond(ptr))*R*0.85);
107      glEnd();
108      glFlush();//glFlush，保证前面的OpenGL命令立即执行（而不是让它们在缓冲区中等待）。
109 
110 }
111 
112 void myIdle(void)
113 {
114     angle-=((2*Pi)/60);
115     Sleep(1000);
116     if(angle<0.0f){
117         angle=2*Pi;
118     }
119     myDisplay();
120 }
121 
122 int main(int argc, char *argv[])
123 
124 {
125 
126      glutInit(&argc, argv);//glutInit，对GLUT进行初始化，这个函数必须在其它的GLUT使用之前调用一次。其格式比较死板，一般照抄这句glutInit(&argc, argv)就可以了。
127 
128      glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);//设置显示方式,其中GLUT_RGB表示使用RGB颜色,与之对应的GLUT_INDEX表示使用索引颜色。GLUT_SINGLE表示使用单缓冲，与之对应的还有GLUT_DOUBLE（使用双缓冲）
129 
130      glutInitWindowPosition(300,100);//设置窗口在屏幕中的位置.
131 
132      glutInitWindowSize(400, 400);//设置窗口的大小
133 
134      glutCreateWindow("时钟");//根据前面设置的信息创建窗口。参数将被作为窗口的标题。注意：窗口被创建后，并不立即显示到屏幕上。需要调用glutMainLoop才能看到窗口。
135 
136      glutDisplayFunc(&myDisplay);//调用画图函数
137      glutIdleFunc(&myIdle);
138 
139      glutMainLoop();//进行一个消息循环。这个函数可以显示窗口，并且等待窗口关闭后才会返回
140 
141      return 0;
142 
143 }

效果