Julia set
use Image::PNG::Portable;
my ($w, $h) = 800, 600;
my $out = Image::PNG::Portable.new: :width($w), :height($h);
my $maxIter = 255;
my $c = -0.7 + 0.27015i;
julia($out);
$out.write: 'Julia-set-perl6.png';
sub julia ( $png ) {
^$w .race.map: -> $x {
for ^$h -> $y {
my $z = Complex.new(($x - $w / 2) / $w * 3, ($y - $h / 2) / $h * 2);
my $i = $maxIter;
while (abs($z) < 2 and --$i) {
$z = $z*$z + $c;
}
$png.set: $x, $y, |hsv2rgb($i / $maxIter, 1, ?$i).reverse;
}
}
}
sub hsv2rgb ( $h, $s, $v ){
my $c = $v * $s;
my $x = $c * (1 - abs( (($h*6) % 2) - 1 ) );
my $m = $v - $c;
[(do given $h {
when 0..^1/6 { $c, $x, 0 }
when 1/6..^1/3 { $x, $c, 0 }
when 1/3..^1/2 { 0, $c, $x }
when 1/2..^2/3 { 0, $x, $c }
when 2/3..^5/6 { $x, 0, $c }
when 5/6..1 { $c, 0, $x }
} ).map: ((*+$m) * 255).Int]
}
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