#!/usr/bin/perl

use strict;
use GD;

my $numColors = 128;
my $size = 200;
my ($XMIN, $XMAX) = qw(0 1);
my ($YMIN, $YMAX) = qw(0 1);
my $POINTS        = 3 + int(rand(6));

my $xfact = ($XMAX - $XMIN) / $size;
my $yfact = ($YMAX - $YMIN) / $size;

# allocate some colors
my @colors;
my $img = new GD::Image($size, $size);
for (my $i = 0; $i < $numColors; $i++) {
    push @colors, $img->colorAllocate(1, 1, $i * (256 / $numColors));
}

my (@xs, @ys);

# Pick some random points
for (1..$POINTS) {
    my ($xrand, $yrand) = (rand(), rand());
    for my $xoffset (-1..1) {
        for my $yoffset (-1..1) {
            push (@xs, $xrand + $xoffset);
            push (@ys, $yrand + $yoffset);
        }
    }
}

# Calculate screen
for (my $yi = 0; $yi < $size; $yi++) {
    my $y = $YMIN + $yi * $yfact;
    for (my $xi = 0; $xi < $size; $xi++) {
        my $x = $XMIN + $xi * $xfact;
        my ($best, $good) = closest($x, $y, \@xs, \@ys);
        $img->setPixel($xi, $yi, $colors[int($numColors *
                                             ($best / $good))]);
    }
}

binmode STDOUT;
print $img->png();

sub closest {
    my ($x, $y, $xs, $ys) = @_;
    my ($dist, $best, $good);
    for (my $i = 0; $i < @$xs; $i++) {
        $dist = sqrt(($x - $xs->[$i])**2 + ($y - $ys->[$i])**2);
        if    ($i == 0 || $dist < $best) { ($good, $best) = ($best, $dist); }
        elsif ($i == 1 || $dist < $good) { $good = $dist; }
    }
    return ($best, $good);
}