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Before you start reading, to help you understand my issue, I am telling that I have copied the code from this link: Dijkstra Shortest Path with VertexList = ListS in boost graph

So.. I am rewriting my program code to use boost, but now when 99% is ready I am stuck with my GPS (for a game). I have a list of nodes, which I added in a way which fortunately was easy to convert to the boost method. The thing I needed to do was just create a vertice variable like this:

Vertex Vx[MAX_NODES];

I copied the typedefs from the link I have given.

The way I add vertices is this:

            stringstream s;
            s << i;
            Vx[i] = add_vertex(s.str(),dgraph);

Where "i" equals an integer number. (eg int i = 9)

And eges are also easy to add. Now, I have my own structured array called "xNode". and eg : xNode[i] holds all the information for X Y Z positions (xNode[i].X xNode[i].Y etc) of the nodes.

Now when using the code snippet from the link I have done this:

// Write shortest path 
std::cout << "Shortest path from " << startid << " to " << endid << ":" << std::endl; 
float totalDistance = 0; 
for(PathType::reverse_iterator pathIterator = path.rbegin(); pathIterator !=       path.rend(); ++pathIterator) 
{ 
    std::cout << source(*pathIterator, dgraph) << " -> " <<     target(*pathIterator, dgraph)
    << " = " << get( boost::edge_weight, dgraph, *pathIterator ) <<     std::endl; 
}

And this is where I am stuck, as "source(*pathIterator, dgraph)" and "target(*pathIterator, dgraph) " Get addresses, but I need the vertice indexes to access xNode[i], i is the NodeID (or well the vertice ID | Vx[i]). How can I do that?

EDIT: I tried to do:

for(PathType::reverse_iterator pathIterator = path.rbegin(); pathIterator !=       path.rend(); ++pathIterator) 
{ 
    for(int i = 0; i < MAX_NODES; ++i)
    {
        if(source(*pathIterator, dgraph) == *((Vertex*)Vx[i]))
        {
            cout  << "  " << i << "  " << endl;
            break;
        }
    }
}

but this just crashes..

Community
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1 Answers1

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With the typedefs from that question, you can use get(boost::vertex_index, dgraph, v) to get the index of v. You can also cache the property map using:

IndexMap vi = get(boost::vertex_index, dgraph);

then use get(vi, v) to get the index for v.

Jeremiah Willcock
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  • Thank you, Finally I did get(vi, source(*pathIterator, dgraph)) and that works great! –  Apr 11 '12 at 18:14