#!/usr/bin/perl -w
use strict;
use warnings;
use OpenGL qw/ :all /;
use OpenGL::Config;   

#!/usr/bin/perl -w
use strict;
use warnings;
use OpenGL qw/ :all /;
use OpenGL::Config;   


my $a=rand(1);
my $b=rand(1);
my $c=rand(1);
my $look=0.1;
my $lookx=0.1;
my $looky=0.1;

glutInit();
glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);
glutInitWindowPosition(100,100);
glutInitWindowSize(400,400);
glutCreateWindow("my  OpenGL program");
glClearColor(0,255);
glClear(GL_COLOR_BUFFER_BIT);  
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-2,2,-2,2);
gluLookAt($look,$look,0.0,0.0); 
glMatrixMode(GL_MODELVIEW);
glutDisplayFunc(\&mydis);
glutMouseFunc(\&mymouse);
glutMainLoop();

 sub mydis()
{
  glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
  glClearColor(0,255);
  glClear(GL_COLOR_BUFFER_BIT); 
  &qiu();
}

sub mymouse()
{
	my ($button,$state,$myx,$myy)=@_;
	if ($button==GLUT_LEFT_BUTTON  and $state==GLUT_DOWN)
	{
		   $look=($myx+$myy)/2/400;	
 		   $lookx=($myx-200)/400;
		   $looky=(200-$myy)/400;	        		        		
	}
	print "mouse x:$myx-y:$myy-look:$look\n";
}

sub qiu()
{
  my $x;
  my $y;
  my $z;
  my $c=3.1415926/180;
  glLoadIdentity();
  gluLookAt($lookx,$looky,0.0);
  for (my $phi=-80.00;$phi<=80.00;$phi+=20.00)
  {

      my $phir=$c*$phi;
      my $phir20=$c*($phi+20);     
      glBegin(GL_QUAD_STRIP); 
	  glColor3f($a,$b,$c);
      for (my $theta=-180.00;$theta<=180.00;$theta+=20.00)
      {
          my $thetar=$c*$theta;
          $x=sin($thetar)*cos($phir);
          $y=cos($thetar)*cos($phir);
          $z=sin($phir);
          glVertex3d($x,$y,$z);	
          $x=sin($thetar)*cos($phir20);
          $y=cos($thetar)*cos($phir20);
          $z=sin($phir20);          
          glVertex3d($x,$z);				  
	  }  
      glEnd();	
	  glFlush();
  }
}