#!/usr/bin/perl
# grat --- set up graticule lines
# Author: Dan Jacobson https://www.jidanni.org/
# Copyright: https://www.gnu.org/licenses/gpl.html
# Created: 2023-09-03T11:01:01+0000
# Last-Updated: 2023-09-27T19:58:32+0000
#     Update #: 7
#
#set up graticule lines
use warnings q(all);
use strict;
#do only one dimension (only N/S, only E/W),
#because the axes might not be perpendicular anyway,
#e.g., Highland Park, IL.

die "ARGS: Xmin Xmax Ymin Ymax Increment AXIS(0/1)" unless @ARGV==6;
my ($increment, $axis)=@ARGV[4..5];
die "0 will cause loop, dude" unless $increment;
my @range;
for (0,1){
    $range[$_]=[shift, shift];
    my $v=$range[$_][0];
    warn "Are you sure you want $v min, that are not a clean \$increment?"
	if $v % $increment;
}
my @letter=([qw/W E/],[qw/S N/]);
for(my $i=$range[$axis][0]; $i<=$range[$axis][1]; $i+=$increment){
    printf ">-L%d%s\n", abs $i, $i?$letter[$axis][$i>=0]:join "",
	reverse @{$letter[$axis]}; #reverse, so sounds more English
    for my $m(0,1){
	my @t=($i,$range[!$axis][$m]);
	printf "%d %d\n",
	    $axis?reverse @t:@t;}}