Moon in Opengl

#include<GL/glut.h>

int x=0,y=0,z=0;
float radius=7.0;
float u=0.0;

void display()
{

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
// glColor3f(1.0,0.0,1.0);

glutSolidSphere(1.0,30,30);
GLfloat direction[]={1.0,1.0,1.0,0.0};
glLightfv(GL_LIGHT0,GL_POSITION,direction);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
x=radius* cos(u);
y=0;
z=radius* sin(u);

gluLookAt(x,y,z,0,0,0,0,1,0);




   glFlush();
   glutSwapBuffers();
}
/*

void display() {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  GLfloat direction[] = {-1.0, -1.0, -1.0, 0.0};
  glLightfv(GL_LIGHT0, GL_POSITION, direction);
  glutSolidSphere(1.0, 25, 25);
  glMatrixMode(GL_MODELVIEW);
//  glPushMatrix();
  glLoadIdentity();

   x = radius * cos(u);
    y = 0;
    z = radius * sin(u);
  gluLookAt(x, y, z, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

  //glPopMatrix();
  glFlush();
  glutSwapBuffers();
}

*/
void init(void)
{

 GLfloat yellow[]={1.0,1.0,0.0};  
 glMatrixMode(GL_PROJECTION);
 glLoadIdentity();
 //gluOrtho2D(0.0,640.0,0.0,480.0);
 glLightfv(GL_LIGHT0,GL_DIFFUSE,yellow);
 glEnable(GL_LIGHT0);
 glEnable(GL_LIGHTING);
 glEnable(GL_DEPTH_TEST);

}




void timer(int v)
{
 u=u+0.1;
 glutPostRedisplay();
 glutTimerFunc(1000/60,timer,v);

}



void reshape(GLint w,GLint h)
{
glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(40,((GLfloat)w/(GLfloat)(h)),1,10.0);
   
}




int main(int argc,char **argv)
{
    glutInit(&argc,argv);
    glutInitWindowSize(640,480);
    glutInitWindowPosition(100,150);
    glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH);
    glutCreateWindow("Going for a SMILEY :-)");
 
 glutDisplayFunc(display);
 glutReshapeFunc(reshape);
   glutTimerFunc(100,timer,0);
    init();
    glutMainLoop();
}