PK_VERTEX_ask_oriented_edges

PK_ERROR_code_t      PK_VERTEX_ask_oriented_edges
(
--- received arguments ---
PK_VERTEX_t          vertex,            --- a vertex

--- returned arguments ---
int           *const n_edges,           --- number of edges (>= 0)
PK_EDGE_t    **const edges,             --- edges (optional)
PK_LOGICAL_t **const orients            --- edge orientations (optional)
)


This function returns the list of edges at the given vertex, together with
their orientations.


Each orientation is given with respect to the vertex. If the orientation
is PK_LOGICAL_true, the edge points towards the vertex, otherwise it points
away from the vertex.

If closed edges pass through the vertex, the same edge will be returned twice,
each time with opposing orientations.

The output arrays 'edges' 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 edges at the vertex (with repeats).