Subject: Re: [boost] [Review Request] Inclusion of the Boost.Polygon Voronoi Library
From: Andrii Sydorchuk (sydorchuk.andriy_at_[hidden])
Date: 2012-05-21 18:15:39
On Mon, May 21, 2012 at 7:33 PM, Jeffrey Lee Hellrung, Jr. <
jeffrey.hellrung_at_[hidden]> wrote:
> I may have some suggestions on how to implement this user data, but yes,
> Luke's suggestion looks to be the simplest solution. Andrii, do you have an
> example use case for storing the data in situ with the voronoi primitive
> objects? Looking at a concrete use case might help ground the discussion.
>
There are two examples on data association usage:
1) Basic tutorial (non-practical examples that shows how to use this
functionality):
http://svn.boost.org/svn/boost/trunk/libs/polygon/doc/voronoi_basic_tutorial.htm
Section: "Associating User Data with Voronoi Primitives".
2) Voronoi visualizer:
http://svn.boost.org/svn/boost/trunk/libs/polygon/example/voronoi_visualizer.cpp
Uses depth first search to remove Voronoi edges outside of the polygon
bounds.
The data field is used to mark edges as visited (I added some comments):
void remove_exterior(const VD::edge_type* edge) {
if (edge->data()) // visited edge, don't proceed
return;
edge->data(&edge); // mark edge as visited
edge->twin()->data(&edge); // mark twin edge as visited also
const voronoi_diagram<double>::vertex_type* v = edge->vertex1();
// if the edge doesn't have endpoint or is not primary stop
if (v == NULL || !edge->is_primary())
return;
// recursively run dfs for each Voronoi edge around current edge endpoint
const voronoi_diagram<double>::edge_type* e = v->incident_edge();
do {
remove_exterior(e);
e = e->rot_next();
} while (e != v->incident_edge());
}
While this example doesn't directly associate any data with Voronoi
edges, it shows additional usage of this field that appeared to be
practical.
Regards,
Andrii