Re: [Boost-users] [Boost Graph Library] larger neighborhood in grid_graph

Subject: Re: [Boost-users] [Boost Graph Library] larger neighborhood in grid_graph
From: Geoff Hilton (geoff.hilton_at_[hidden])
Date: 2011-02-03 10:37:46

On 01/02/2011 6:53 AM, Hannes Schulz wrote:
> Hi all,
>
> i recently discovered grid_graph and found it quite useful so far.
>
> However, I would prefer a larger neighborhood in the graph (e.g. 8 instead of
> 4 for 2D; 26 instead of 6 in 3D). I already started looking into copying and
> modifying grid_graph.hpp accordingly, but cannot entirely anticipate the
> complexity of the problem. Therefore I decided to ask here first:
>
> - Why did the developers restrict grid_graph to "orthogonal" neighborhoods?
>
> - Is a modification of grid_graph worth it, or am I going to throw away
>    everything anyway and should start over anew instead? (without the wrapping
>    overhead, which I do not need)
>
> Thank you very much!
>
>    Hannes

I agree, in my case the movement is restricted to 45 degree (along 8 
cardinal directions) rotations with a 135 degree forward-facing point of 
view (ie, move forward, turn left or right), with the right number of 
dimensions the vertex addressing was suitable as-is, but out-edge 
traversal had to be reworked. I read in the documentation that the 
decision was made for the graph abstraction to consist of both vertex 
and edge traits (ie. within boost::graph_traits), I believe this is one 
case though where I feel having separate vertex and edge traits classes 
(which graph_traits might then bring together into one binding 
interface) to allow customization only of edge traversal would have been 
nice.

Thanks,
Geoff