PK_FACE_ask_oriented_surf

PK_ERROR_code_t     PK_FACE_ask_oriented_surf
(
--- received arguments ---
PK_FACE_t           face,   --- a face

--- returned arguments ---
PK_SURF_t    *const surf,       --- the surface (possibly PK_ENTITY_null)
PK_LOGICAL_t *const orientation --- the face orientation with respect to its
                                --- surface
)


This function returns the surface and orientation of the given face.


If 'orientation' is PK_LOGICAL_true, then the face normal is parallel to the
surface normal, otherwise it is anti-parallel.

If the face has no surface then 'surf' is returned as PK_ENTITY_null, and
the value of 'orientation' is unspecified.