OPenGL 画球代码

#include <GL/glut.h>
#include<cstdio>
#include<cmath>

#define PI 3.14159265358979323846
#define PI2 6.28318530717958647692
#define r 80

GLsizei width = 600,height = 600;

int uStepsNum = 25;


void Init()
{
      glClearColor(1,1,1,1);
      glClearDepth(1);
      glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
      glOrtho(100.0, -100.0 ,100.0, -100.0, 100.0, -100.0);


      glRotated(30,1,0,0);
      glRotated(60,0,1,0);
      glRotated(0,0,0,1);

}

void displayFunc()
{

    double i,j;
    double w = 1/(double)uStepsNum;    
    glColor3f(1.0,0.0,0.0);
    for(i=0;i<=1;i+=w)
    {
        glBegin(GL_LINE_LOOP);
        for(j=0;j<=1;j+=w)
        {     
           double x=r*sin(PI*i)*cos(PI2*j);
           double y=r*sin(PI*i)*sin(PI2*j);
           double z=r*cos(PI*i);
           glVertex3d(x,y,z);   
        }
        glEnd();
    }
    glColor3f(0.0,1.0,0.0);
    glBegin(GL_LINE_LOOP);
   for(i=0;i<=1+w;i+=w)
    {
        
        for(j=0;j<=1+w;j+=w)
        {     
           double x=r*sin(PI*j)*cos(PI2*i);
           double y=r*sin(PI*j)*sin(PI2*i);
           double z=r*cos(PI*j);
           glVertex3d(x,y,z);   
        }
        
    }
    glEnd();

    glutSwapBuffers();
}


int main(int argc,char* argv[])
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(width,height);
    glutCreateWindow("球体");
    Init();
    glutDisplayFunc(displayFunc);
    glutMainLoop();
}