PK_ERROR_code_t     PK_FIN_ask_oriented_curve
(
--- received arguments ---
PK_FIN_t            fin,          --- a fin

--- returned arguments ---
PK_CURVE_t   *const curve,        --- the curve (possibly PK_ENTITY_null)
PK_LOGICAL_t *const orientation   --- the fin orientation with respect to its
                                  --- curve
)


This function returns the curve and orientation of the given fin, if any.


If orientation is PK_LOGICAL_true, then the fin direction is parallel to the
curve tangent, otherwise it is anti-parallel.

If the fin has no curve (for example, a non-tolerant fin) then curve is
returned as PK_ENTITY_null, and the value of orientation is unspecified.