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use Math::Trig qw(pi);
$angle = atan2($v2->{y}, $v2->{x}) - atan2($v1->{y}, $v1->{x});
# and normalize the angle to be in the range [-pi, pi]
my $rounds = floor(($angle + pi) / (2 * pi));
$angle -= 2 * pi * $rounds;

my %polygon = map { $_ => 1 } @polygon, @polygon_holes;
@edges = grep { !$polygon{$_} } @edges