##</code><code>##

#!/usr/bin/perl

use Tk;

$top=MainWindow->new();
$canvas=$top->Canvas(width=>300, height=>245)->pack();

$origin_x=110;
$origin_y=70;
$PI=3.141592635;
$circle_radius=5;
$path_radius=0;

for ($angle=0; $angle<=180; $path_radius+=7, $circle_radius+=3, $angle+=10)
{
    $path_x=$origin_x+$path_radius*cos($angle*$PI/90);
    
    $path_y=$origin_y-$path_radius*sin($angle*$PI/90);
    
    $canvas->create('oval', $path_x-$circle_radius,
    			    $path_y-$circle_radius,
    			    $path_x+$circle_radius,
    			    $path_y+$circle_radius,
    			    -fill=>'yellow');
    			    
    $canvas->create('line', $origin_x, $origin_y,
    			    $path_x, $path_y,
    			    -fill=>'slategray');
    
    sleep(1);    			    
}
		    
MainLoop();