pub fn crossing_orientation(
first: Line,
second: Line,
a: Point2,
b: Point2,
) -> Result<Option<Sign>, ExactError>Expand description
Which side of the directed line a -> b the crossing of first and
second lies on: Sign::Positive for left.
Returns Ok(None) when the lines are parallel (no single crossing).
The crossing point is never rounded, so a crossing that lies exactly on
a -> b reports Sign::Zero.