Created
August 23, 2010 15:14
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左上が北緯90°東経0°、右下が南緯90°西経0°なメルカトル図法の地図データから、「黒」の点(海岸線?)の緯度経度を計算し、2次元配列に納め、JSONで出力。出力した結果は、地球儀描画に用いる。
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#!/usr/bin/perl | |
use strict; | |
use warnings; | |
use Math::Round; | |
use GD::Image; | |
use JSON; | |
use 5.010; | |
my $image = GD::Image->newFromPng("worldmap.png"); | |
my ($width,$height) = $image->getBounds(); | |
my @coast; # 海岸線を表す点のリスト | |
for my $x (0..$width-1) { | |
for my $y (0..$height-1) { | |
my $index = $image->getPixel($x, $y); | |
my ($r, $g, $b) = $image->rgb($index); | |
if ($r == 0 && $g == 0 && $b == 0) { | |
my $degx = nearest(0.01, $x / $width * 360); | |
my $degy = nearest(0.01, ($y - $height / 2) / $height * 180); | |
push @coast, [$degx, $degy]; | |
} | |
} | |
} | |
print "var coast="; | |
print encode_json(\@coast); | |
say ";"; |
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