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#!/usr/bin/perl -w
# Copyright 2010, 2011, 2012 Kevin Ryde
# This file is part of Math-PlanePath.
#
# Math-PlanePath is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 3, or (at your option) any later
# version.
#
# Math-PlanePath is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with Math-PlanePath. If not, see <http://www.gnu.org/licenses/>.
# Usage: perl hilbert-lines.pl
#
# This is a bit of fun printing the HilbertCurve path in ascii. It follows
# the terminal width if you've got Term::Size, otherwise 79x23.
#
# Enough curve is drawn to fill the whole output size, clipped when the path
# goes outside the output bounds. You could instead stop at say
#
# $n_hi = 2**6;
#
# to see just a square portion of the curve.
#
# The $scale variable spaces out the points. 3 apart is good, or tighten it
# up to 2 to fit more on the screen.
#
# The output has Y increasing down the screen. It could be instead printed
# up the screen in the final output by going $y from $height-1 down to 0.
#
use 5.004;
use strict;
use Math::PlanePath::HilbertCurve;
my $width = 79;
my $height = 23;
my $scale = 3;
if (eval { require Term::Size }) {
my ($w, $h) = Term::Size::chars();
if ($w) { $width = $w - 1; }
if ($h) { $height = $h - 1; }
}
my $x = 0;
my $y = 0;
my %grid;
# write $char at $x,$y in %grid
sub plot {
my ($char) = @_;
if ($x < $width && $y < $height) {
$grid{$x}{$y} = $char;
}
}
# at the origin 0,0
plot('+');
my $path = Math::PlanePath::HilbertCurve->new;
my $path_width = int($width / $scale) + 1;
my $path_height = int($height / $scale) + 1;
my ($n_lo, $n_hi) = $path->rect_to_n_range (0,0, $path_width,$path_height);
foreach my $n (1 .. $n_hi) {
my ($next_x, $next_y) = $path->n_to_xy ($n);
$next_x *= $scale;
$next_y *= $scale;
while ($x > $next_x) { # draw to left
$x--;
plot ('-');
}
while ($x < $next_x) { # draw to right
$x++;
plot ('-');
}
while ($y > $next_y) { # draw up
$y--;
plot ('|');
}
while ($y < $next_y) { # draw down
$y++;
plot ('|');
}
plot ('+');
}
foreach my $y (0 .. $height-1) {
foreach my $x (0 .. $width-1) {
print $grid{$x}{$y} || ' ';
}
print "\n";
}
exit 0;
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