Function robust_geo::orient_3d

pub fn orient_3d(
    a: Vector3<f64>, 
    b: Vector3<f64>, 
    c: Vector3<f64>, 
    d: Vector3<f64>
) -> f64

Calculates the orientation of points a, b, c, d in a space. Returns a positive number if b→c→d defines a left turn when looked at from a, a negative number if they define a right turn, and 0 if a, b, c, d are coplanar.