PK_ERROR_code_t  PK_VERTEX_make_blend
(
--- received arguments ---
PK_VERTEX_t      vertex,        --- vertex to be blended
double           radius,        --- blend radius
PK_LOGICAL_t     local_check,   --- whether local checking required

--- returned arguments ---
PK_EDGE_t *const edge,          --- new edge
PK_VERTEX_t      vertices[2]    --- new vertices
)


The given vertex of a sheet or wire body is replaced by a circular blend
producing one new edge and two new vertices.


Specific Errors:
    PK_ERROR_general_body          Vertex is from a general body
    PK_ERROR_invalid_bodies        Vertex is from an invalid body
    PK_ERROR_solid_bodies          Vertex is from a solid body
    PK_ERROR_wrong_number_edges    Not two edges at vertex
    PK_ERROR_cant_blend_vertex     Blending cant be done
    PK_ERROR_blends_overlap        Blends would overlapp
    PK_ERROR_blends_intersect      Blends would intersect
    PK_ERROR_wrong_surface         Surface not suitable


Blends a vertex from a sheet or a wire body with the given radius.

Only two edges should meet at the vertex, and these two edges must share a
common plane.  If the face between the two edges has a surface then it must
be planar. A circular blend is created between the two edges.

If the two edges at the vertex are parallel so that the profile of the body
is smooth across the vertex then that vertex will be ignored.

If any loop on a face is excluded from the face by a blend then this loop
will be removed from the body.

The blend edge and the two new vertices are returned.

This function is not supported for a vertex on a general body.