use strict;
use warnings;

use List::Util qw/min max/;
use Image::Magick;

# 歩く回数
my $count = 10000;

sub _walk { int(rand(3))-1; }

# 歩いて範囲を測定
my @current = (0,0);
my @area = (@current, @current);
my @footmarks;
for my $fm (map { [_walk, _walk] } 1 .. $count) {
  $current[0] += $fm->[0];
  $current[1] += $fm->[1];
  $area[0] = min $area[0], $current[0];
  $area[1] = min $area[1], $current[1];
  $area[2] = max $area[2], $current[0];
  $area[3] = max $area[3], $current[1];
  push @footmarks, [@current];
}

# 軌跡を書く
my $grid = 8;
my $lsize = 2;
my $img = Image::Magick->new;

$img->Set(
  size=>join(q/x/, map { ($_+1) * $grid } $area[2]-$area[0], $area[3]-$area[1])
);
$img->Read(q/xc:white/);
$img->Draw(primitive => q/polyline/, stroke => q/black/, strokewidth => $lsize,
  points => join(q/ /, map { join q/,/, map { $_ * $grid + $grid/2 } @$_ }
                       map { [$_->[0]-$area[0],$_->[1]-$area[1]] }
                       @footmarks)
);

# start地点にバッテン
$img->Draw(primitive => q/line/, stroke => q/red/, strokewidth => $lsize/2,
  points => join(q/ /, map { join q/,/, map { $_ * $grid } @$_ }
                       map { [$_-$area[0], $_-$area[1]] }
                       0, 1)
);
$img->Draw(primitive => q/line/, stroke => q/red/, strokewidth => $lsize/2,
  points => join(q/ /, map { join q/,/, map { $_ * $grid } @$_ }
                       map { [$_->[0]-$area[0], $_->[1]-$area[1]] }
                       [1,0], [0,1])
);
$img->Write(q/rwalk.png/);