38 lines
1.1 KiB
Raku
38 lines
1.1 KiB
Raku
my $width = my $height = 255; # must be odd
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my @light = normalize([ 3, 2, -5 ]);
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my $depth = 255;
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sub MAIN ($outfile = 'sphere-perl6.pgm') {
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spurt $outfile, "P5\n$width $height\n$depth\n"; # .pgm header
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my $out = open( $outfile, :a, :bin ) orelse .die;
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$out.write( Blob.new(draw_sphere( ($width-1)/2, .9, .2) ) );
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$out.close;
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}
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sub normalize (@vec) { @vec »/» ([+] @vec »*« @vec).sqrt }
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sub dot (@x, @y) { -([+] @x »*« @y) max 0 }
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sub draw_sphere ( $rad, $k, $ambient ) {
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my @pixels[$height];
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my $r2 = $rad * $rad;
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my @range = -$rad .. $rad;
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@range.hyper.map: -> $x {
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my @row[$width];
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@range.map: -> $y {
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if (my $x2 = $x * $x) + (my $y2 = $y * $y) < $r2 {
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my @vector = normalize([$x, $y, ($r2 - $x2 - $y2).sqrt]);
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my $intensity = dot(@light, @vector) ** $k + $ambient;
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my $pixel = (0 max ($intensity * $depth).Int) min $depth;
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@row[$y+$rad] = $pixel;
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}
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else {
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@row[$y+$rad] = 0;
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}
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}
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@pixels[$x+$rad] = @row;
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}
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flat |@pixels.map: *.list;
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}
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