#!/usr/bin/perl
use warnings;
use strict;
use Tk::Zinc;

my $width = 200;
my $height = 100;
my $xpos = -10;
my $ypos = -10;

my $mw = MainWindow->new(-background => 'cyan');
$mw->geometry($width.'x'.$height.$xpos.$ypos);
$mw->overrideredirect(1);
my $zinc = $mw->Zinc(-width => $width,
                     -height => $height,
                     -reshape => 1,     #clips zinc 
                     -fullreshape => 1,  #clips $mw and xterm 
                     -backcolor => 'cyan',
                       )->pack;


my $ufo = $zinc->add('curve',1,[[$width/2,0],
                                          [2*$width,0, 'c'],
                                          [2*$width,$height, 'c'],
                                  [$width/2,$height],
                                          [-$width,$height, 'c'],
                                          [-$width,0, 'c'],
                                   [$width/2,0]],

                   -tags => ['bezier1'],
                   -closed => 1,
                   -visible => 0,
                   );

my @portholes;
for(0..8){
my $porthole = $zinc->add('arc', 1, [10+20*$_,40,20+20*$_,50],
                     -filled => 1,
                     -fillcolor => 'white',
                     -visible => 1);

push(@portholes,$porthole);
}

$mw->bind("<Button 1>",sub{Tk::exit});

# using the curve to reshape both TkZinc and Mainwindow widgets  
$zinc->itemconfigure(1, -clip => $ufo);

my $dx = 0 ; my $dy = -1;
$mw->repeat(10,sub {
                    $xpos = $xpos + $dx;
                    $ypos = $ypos + $dy;
                    if(400 + $ypos < 0){$dy = 1; $dx = -1}
                    if(-$ypos < 10){$dx = 1; $dy = 0}
                    if($xpos == 0){$xpos = -10;$ypos = -10; $dx = 0;$dy=-1}


           $mw->geometry($width.'x'.$height.$xpos.$ypos);
           $mw->update;
           });

&Tk::MainLoop;