typedef PK_LOGICAL_t (*PK_BODY_blend_propagate_f_t)
(
--- received arguments ---

PK_EDGE_t       edge,               --- potential propagation edge
PK_POINTER_t    external_data       --- external application data

);



This is the type definition for an external evaluator function to be used
by PK_BODY_fix_blends in determining whether to propagate blended edges.
The function itself is provided by the application.


Given an EDGE a function of type PK_BODY_blend_propagate_f_t should return a
logical indicating whether the blend is to propagate onto that edge or not.