I have a set of edges from a graph, and would like to expand it with all edges that share a vertex with any edge. How could I do this efficiently with boost::graphs?
The only way I've been able to come up with is the naive solution of extracting all the source and target vertices, using boost::adjacent_vertices to get all adjacencies and then creating all the new edges with boost::edge. Is there a better way of doing this?
Context: The graph vertices are centroids of a terrain triangulation, the edges connect vertices whose corresponding triangles are adjacent (so sort of a dual graph). The set of edges I'm looking to expand corresponds to inter-triangle paths which are blocked, and the blocked area is expanding. The area is sort-of circular, so most of the edges I'll see using my naive approach above will already be part of the set.
Instead of considering all adjacent vertices in each step to generate the new edges, use a property map to mark edges already encounterd. Thus, you need to consider unmarked edges in each step only. A vertex is marked after adding all edges incident to it to your set.
Given the fact that the internal data structure used by boost::graph is either an adjacency list or an adjacency matrix, I do not think that any further improvement is possible.