class StraightSkeleton::Split

def viable?
  return false unless @source.active?
  @edge = @nodes.track(@normal).find do |edge|
    (n00, n01), (n10, n11) = edge.map(&:normals)
    p0, p1 = edge.map(&:point)
    next if (point - p0).cross(n00 ? n00 + n01 : n01) < 0
    next if (point - p1).cross(n11 ? n11 + n10 : n10) > 0
    true
  end
end