$|=1;
use PDL;
use PDL::Graphics::TriD;
use Time::HiRes qw(sleep);
# use PDL::Dbg;
# PDL::Core::set_debugging(1);
$size = 100;
$a = zeroes(float,$size,$size);
$res = $a->copy;
$resc0 = $res->clump(2);
$resc = $resc0;
$resi = xvals $resc;
$inds0 = $resi;
$re00 = 2*(xvals $a)->clump(2)/$size-1.5;
$im00 = 2*(yvals $a)->clump(2)/$size-0.5;
$re0 = $re00;
$im0 = $im00;
$im = $im0; $re = $re0;
$im2 = $im; $re2 = $re;
for(1..60) {
        $rp = ($resc == 0) * ($im2 ** 2 + $re2 ** 2 > 2) * $_;
        $resc += $rp;
        if(1) {
                $inds = ($resc == 0)->which->long->sever;
                $inds1 = $inds0->index($inds)->sever;
                $inds0 = $inds1;
                $re0 = $re00->index($inds1)->sever;
                $im0 = $im00->index($inds1)->sever;
                $re = $re->index($inds)->sever;
                $im = $im->index($inds)->sever;
                $resi = $resi->index($inds)->sever;
        # Use inds1 here so that resc propagates back only one step.
                $resc = $resc0->index($inds1);
        }
        $re2 = $re ** 2 - $im ** 2;
        $im2 = 2 * $re * $im;
        $re2 += $re0;
        $im2 += $im0;
        $re = $re2; $im = $im2;
        nokeeptwiddling3d();
        my $r = $res/max($res);
        imagrgb [$r,1-$r,$r] if $_ % 2 == 0;
        sleep 0.05;
}