Function lyon::tessellation::math_utils::compute_normal

pub fn compute_normal(e1: TypedPoint2D<f32, UnknownUnit>,
                      e2: TypedPoint2D<f32, UnknownUnit>)
                      -> TypedPoint2D<f32, UnknownUnit>

Compute a normal vector at a point P such that x ---e1----> P ---e2---> x

The resulting vector is not normalized. The length is such that extruding the shape would yield parallel segments exactly 1 unit away from their original. (useful for generating strokes and vertex-aa). The normal points towards the left side of e1.