PK_SHELL_ask_oriented_faces

PK_ERROR_code_t      PK_SHELL_ask_oriented_faces
(
--- received arguments ---
PK_SHELL_t           shell,             --- a shell

--- returned arguments ---
int           *const n_faces,           --- number of faces (>= 0)
PK_FACE_t    **const faces,             --- faces (optional)
PK_LOGICAL_t **const orients            --- orientations (optional)
)


This function returns the list of faces in the given shell, together with their
orientations with respect to the shell.


Each orientation is given relative to the volume bounded by the shell.
If the orientation is PK_LOGICAL_true, the face's normal points into the shell,
otherwise it points away from the shell.

A face may occur up to twice in the list, with opposing orientations.

The arrays 'faces' and 'orients' are optional. If either one is set to NULL,
its data will not be computed or returned. If both are set to NULL,
the function will only compute the number of faces in the shell (with repeats).