#!/usr/bin/perl
## Sierpinski's Triangle ##
use Tk;

$width = 800;
$height = 500;
my $main = MainWindow->new();
my $canvas = $main->Canvas( -width=>$width, -height=>$height, -background=>"black");
$canvas->pack( -expand=>1,-fill=>'both' );


# the coderefs take ( x, y )

@iterative_set = (

sub{ my @pt = (400,50); return(  ($pt[0] + $_[0] )/2,
 ( $pt[1] + $_[1] )/2 ) },
sub{ my @pt = (50,400); return(  ($pt[0] + $_[0] )/2,
 ( $pt[1] + $_[1] )/2 ) },
sub{ my @pt = (750,400); return(  ($pt[0] + $_[0] )/2,
 ( $pt[1] + $_[1] )/2 ) },

);


# start coordinates
$x = 40;
$y = 400;
$iter = 0;

# weed out transients
while( $iter++ != 100 )
{

( $x, $y ) = $iterative_set[ int rand 3 ]->( $x, $y );

}


$iter = 0;
while( $iter++ < 10000 )
{

( $x, $y ) = $iterative_set[ int rand 3 ]->( $x, $y );
$canvas->createRectangle(
int $x, int $y, int $x, int $y, -outline=>undef, -fill=>'white' );

}

MainLoop;