#! /usr/local/bin/perl -w
use strict;
use POSIX;

my $pixels;
my $inchespercm = 0.39370087;
my $dpi = 600;

my @npa = 
(
  pel( 0.6 ),
  pel( 0.5 )
);

my $width = pel( 29.7 );
my $height = pel( 21.0 );

# -------------------------------------------------

my $offset = $shiftright + ($shiftdown * $width);

sub pel
{
  my($cm) = @_;
  return floor( ( $cm * $inchespercm * $dpi ) + 0.5 );
}

sub makepixels
{
  print STDERR "Making pixels..\n";
  $pixels = '0' x ($width * $height);
  print STDERR "Done.\n";
}

sub setpixel
{
  my($i) = @_;
  substr($pixels, $i + $offset, 1) = '1';
}

sub writepixels
{
  print STDERR "Writing pixels..\n";
  print "P1\n";
  print "$width $height\n";
  my $i = 0;
  while($i < ($width * $height))
  {
    print substr($pixels, $i, 60) . "\n";
    $i+= 60;
  }
}

sub hline
{ 
  my ($sx, $ex, $y) = @_;
  my $i = ($sx + ($width * $y));
  my $j = ($ex + ($width * $y));

  while($i < $j)
  {
    setpixel($i);
    $i++;
  }
}

sub vline
{
  my ($sy, $ey, $x) = @_;
  my $i = ($sy * $width) + $x;
  my $j = ($ey * $width) + $x;

  while($i < $j)
  {
    setpixel($i);
    $i += $width;
  }
}

sub box
{
  my ($tx, $ty, $bx, $by) = @_;
  hline($tx, $bx, $ty);
  hline($tx, $bx, $by);
  vline($ty, $by, $tx);
  vline($ty, $by, $bx);
}

sub donpa
{
  my($npa) = @_;
  my $centre = floor((($width / 2.0) + 0.5));
  
  box($npa, $npa, $centre-$npa, $height-$npa);
  box($centre+$npa, $npa, $width-$npa, $height-$npa);
}

sub main
{
  makepixels();

  box( 0, 0, $width-$shiftright-1, $height-$shiftdown-1);

  foreach my $npa(@npa)
  {
    donpa($npa);
  }

  writepixels();
}

&main();