mbrot2.p6

#!/usr/bin/env perl6

#
# XXX This code is broken for a presentation and doesn't generate a correct image
# or (on some systems like Mac) doesn't work at all
#

use v6;
use SDL2::Raw;

my int $width = 320;
my int $height = 240;

my $hwidth = ($width /2).Int;
my $hheight = ($height/2).Int;

my int $wid = 4;
my (int $xcenter, int $ycenter) = (-1,0);

constant SDL_WINDOW_SHOWN = 0x00000004;

my $t0 = DateTime.now.Instant;

SDL_Init(VIDEO);

my $window = SDL_CreateWindow("Mandelbrot",
SDL_WINDOWPOS_CENTERED_MASK, SDL_WINDOWPOS_CENTERED_MASK,
$width, $height, SDL_WINDOW_SHOWN);

my $render = SDL_CreateRenderer($window, -1, 1);
SDL_SetRenderDrawColor($render, 0, 0,128, 0);
SDL_RenderClear($render);
SDL_RenderPresent($render);


#
# don't do this .. SDL2 isn't thread safe
#

   $PROCESS::SCHEDULER=ThreadPoolScheduler.new(initial_threads => 0, max_threads => 2, uncaught_handler => Callable);

await do for ( 0..$width) -> int $xcoord {

    start {
        for ( 0..$height-1) -> int $ycoord {

            my $ca = ($xcoord - $hwidth) / $width * $wid + $xcenter;
            my $cb = ($ycoord - $hheight) / $width * 1 * $wid + $ycenter;

            my ($res, $i) = mandelbrot($ca + $cb * i);

            my $hcolor=128;
            $hcolor=10*$i if $i;

            my $color;
            if !$res.defined {
                $color = (0,0,0);
            }  
            else {
                if $i < 5 {
                    $color = (0, 0,128);
                } elsif $i > 5 and $i < 7 {
                    $color =  (0, 0, $hcolor);
                } elsif $i > 7 and $i < 10 {
                    $color = (0, $hcolor, 0);
                } else {
                    $color =  ($hcolor,0, 0);
                }
            }
            plot($render, $xcoord, $ycoord, $color);

        }                   
    }                   

}

SDL_RenderPresent($render);
say DateTime.now.Instant-$t0 ~ " sec(s)";
prompt("wait..") unless %*ENV{'MBROT_BATCH'};
SDL_Quit();

sub plot($render, $x,$y,$c) {
    my ($c1, $c2, $c3) = $c; # XXX
    SDL_SetRenderDrawColor($render,$c1,$c2,$c3,0);
    SDL_RenderDrawPoint($render, $x, $y);
    SDL_RenderPresent($render);
}

sub mandelbrot(Complex $c) {
    my $z = $c;
    for (1 .. 20) -> $i {
        $z = $z * $z + $c;
        return ($z,$i) if $z.abs> 2;
    }
}