PK_ERROR_code_t     PK_EDGE_ask_oriented_curve
(
--- received arguments ---
PK_EDGE_t           edge,   --- an edge

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


This function returns the curve and orientation of the given edge.


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

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