opengl绘制钟表

- -应付下实验吧

#include<cstdio>

#include<time.h>
#include<math.h>
#include <GL/glut.h>
//sleep ,gluttimefunc
struct tm* localTime;
int hour, minute, second;
double pi=3.1415926;

void gettime(){//读取时间到全局变量
time_t curTime;
time(&curTime);
localTime = localtime(&curTime);
hour=localTime->tm_hour;
minute=localTime->tm_min;
second=localTime->tm_sec;
}

void display_watch()//绘制钟表
{

   //可见到的坐标系为x,y轴线[-1,1]的正方形区域

   glClear(GL_COLOR_BUFFER_BIT);
   glEnable(GL_LINE_SMOOTH);

   double r=0.8,r2=0.7,rat=0,ww=7,tim=360;
   double rr1=0.4,rr2=0.64,rr3=0.75,w1=10,w2=8,w3=4;

   glColor3f(0.0,1.0,0.4);
   glBegin(GL_POLYGON);//绘制钟外层圆形
   for(int q=1;q<=tim;q++){
       glVertex3f(r*cos(rat),r*sin(rat),0);
       rat+=pi/tim*2;
   }
   glEnd();

   glColor3f(0.0,0.8,0.7);
   glBegin(GL_POLYGON);//绘制钟内层圆形
   for(int q=1;q<=tim;q++){
       glVertex3f(r2*cos(rat),r2*sin(rat),0);
       rat+=pi/tim*2;
   }
   glEnd();

   glLineWidth(ww);//修改线宽，绘制刻度
   glColor3f(0.0,0.1,0.1);
   glBegin(GL_LINES);
   for(int q=1;q<=12;q++){
       glVertex3f((r2-0.1)*cos(rat),(r2-0.1)*sin(rat),0);
       glVertex3f(r*cos(rat),r*sin(rat),0);
       rat+=pi/6;
   }
   glEnd();

   rat=pi/2-pi*2/12*(hour+minute/60.0);//改变线宽，绘制时针
   glLineWidth(w1);
   glColor3f(1.0,1.0,1.0);
   glBegin(GL_LINES);
       glVertex3f(0,0,0);
       glVertex3f(rr1*cos(rat),rr1*sin(rat),0);
   glEnd();

   rat=pi/2-pi*2*(minute/60.0+second/60.0/60);//改变线宽，绘制分针
   glLineWidth(w2);
   glColor3f(1.0,1.0,1.0);
   glBegin(GL_LINES);
       glVertex3f(0,0,0);
       glVertex3f(rr2*cos(rat),rr2*sin(rat),0);
   glEnd();

   rat=pi/2-pi*2*(second/60.0);//改变线宽，绘制秒针
   glLineWidth(w3);
   glColor3f(1.0,1.0,1.0);
   glBegin(GL_LINES);
       glVertex3f(0,0,0);
       glVertex3f(rr3*cos(rat),rr3*sin(rat),0);
   glEnd();

   //printf("%d %d %d\n",hour,minute,second);
   glutSwapBuffers();

}

void idle(void)//读取时间到全局变量，重绘钟表
{

   gettime();
   glutPostRedisplay();
}

int main(int argc, char* argv[])
{

    glutInit(&argc, argv);

   glutInitDisplayMode(GLUT_DOUBLE| GLUT_RGB);
    glutInitWindowSize(666, 666);
   glutInitWindowPosition(0, 0);
   glutCreateWindow("watch");

   glutDisplayFunc(display_watch);

   //利用idle操作更新时钟
    glutIdleFunc(idle);

   glutMainLoop();


   return 0;
}

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