程序代码：

#include <GL/glut.h>
#include <stdio.h>
#include <stdlib.h>

int Round(float a)  //对小数进行四舍五入
{
    int i=(int)a;
    float j=a-i;
    if(j<0.5)
        return i;
    if(j>0.5)
        return i+1;
    if(j==0.5)
    {
        if(i%2==0)
            return i;
        else
            return i+1;
    }
    return -1;
}

void display()  //边计算边画点
{
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0.0,250.0,0.0,550.0);  //对象显示区域
    glColor3f(1.0,0.0,0.0);  //对象设置为红色

    int _x=200,_y=500,i;
    int x=0,y=0;
    int p=2*_x-_y;

    glBegin(GL_POINTS);  //画第一点
    glVertex2i(0,0);
    glEnd();

    for(i=0;i<_y;i++) //找一点画一点
    {
      if(p<0)  //判断下一点
      {
         y=y+1;
         p=p+2*_x;
      }
      else  //判断下一点
      {
          x=x+1;
          y=y+1;
          p=p+2*_x-2*_y;
      }

      glBegin(GL_POINTS);  //画点
          glVertex2i(x,y);
      glEnd();
    }
   
    glFlush();  //刷新
   
}

void main(int argc,char **argv)
{
    glutInit(&argc,argv);  //glut初始化
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
    glutInitWindowPosition(100,100);  //窗体位置
    glutInitWindowSize(300,600);  //窗体大小
    glutCreateWindow("0810050225");  //窗体名字

    glClearColor(0.0,0.0,0.0,0.0);  //黑色背景
    glClear(GL_COLOR_BUFFER_BIT);

    glutDisplayFunc(display);  //执行

    glutMainLoop();  //程序等待
   
    system("pause");
}