my $part = $part_order[ floor(($colournum-1) / 3) ];
die "huh colour $colournum?" unless defined $part;
return 0 unless $part =~ m/[$wparts]/o;
my $part = $part_order[ floor(($colournum-1) / 3) ];
die "huh colour $colournum?" unless defined $part;
return 0 unless $part =~ m/[$wparts]/o;