Function normals_oppose 

pub fn normals_oppose(
    old: &SurfaceGeometry,
    new: &SurfaceGeometry,
    tol: Tolerances,
) -> OgeomResult<bool>

Whether new’s normal points against old’s where they meet, read off the middle of old’s chart: what a restatement reports when it replaces a surface by one of the same points.

Errors

As project_on_surface, and if either surface has no normal there.