sub position {
    my($i) = @_;
    my $e = int sqrt (--$i);
    my $r = $i - $e*$e;
    if($e & 1) {  # $e is odd
        if($r <= $e) {
            $x = ($e+1)/2;
            $y = ($e-1)/2 - $r;
        } else {
            $x = ($e+1)/2 - ($r-$e);
            $y = -($e+1)/2;
        }
    } else { # $e is even
        if($r <= $e) {
            $x = -$e/2;
            $y = -$e/2 + $r;
        } else {
            $x = -$e/2 + ($r-$e);
            $y = $e/2;
        }
    }
    return ($x, $y);
}

##</code><code>##

my $edge = 100;

use GD;
# create a new image
my $im = new GD::Image($edge+2, $edge+2);

my $white = $im->colorAllocate(255,255,255);
my $red = $im->colorAllocate(255,0,0);

# make the background transparent white
$im->transparent($white);

# This is mine :-)
# plot the points
my $edge_squared = $edge * $edge;
for (my $i = 1; $i <= $edge_squared; $i++) {
    if($i % 16 == 0) {
        my($x, $y) = position($i);
        $im->setPixel($edge/2+$x, $edge/2-$y, $red);
    }
}

# Save the image file
open PNG, ">result.png" or die "Can't write to file: $!";
# make sure we are writing to a binary stream
binmode PNG;

# Convert the image to PNG and save it
print PNG $im->png;