gistfile1.txt

multi method KnotVector.N0_index(Int $p, $u, KnotBasisDirection $direction = Left)
{
    given $direction
    {
        when Left { UpperBound(@.knots, $u) - $p - 1; }
        when Right { LowerBound(@.knots, $u) - $p - 1; }
        when Reasonable { die "Must specify Left or Right for KnotBasisDirection"; }
    }
}

multi method Nubs.Direction($t, KnotBasisDirection $direction)
{
    return $t < ([+] self.ParameterRange) / 2 ?? Left !! Right 
        if ($direction == Reasonable);
    return $direction;
}

multi method Nubs.evaluate($t, KnotBasisDirection $direction = Reasonable)
{
    my $n0 = $.knot_vector.N0_index($.degree, $t, Direction($t, $direction));
    return [+] ($.knot_vector.N_local($n0, $.degree, $t)
                >>*<< @.control_points[$n0 .. ($n0 + $.degree)]);
}