Visualize boost graph topology after layout algorithm is performed - boost

Question

I am using fruchterman_reingold_force_directed_layout algorithm on my graph
to get a cluster free layout. Below is code for my vertices and edge
using RectTopology = boost::rectangle_topology<>;
using point = RectTopology::point_type;
class MyVertex{
public:
MyVertex(){ myObject = NULL; }
Mybject* myObject;
point position;
std::string name;
};
class MyEdge{
public:
MyEdge(){ myLine = NULL; }
MyLine* myLine;
double weight;
};
//Boost graph defination
using graphT = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, MyVertex, MyEdge>;
using vertexT = boost::graph_traits<graphT>::vertex_descriptor; //Define Vertex
using vertexIt = boost::graph_traits<graphT>::vertex_iterator; //Vertex Iterator
using edgeT = boost::graph_traits<graphT>::edge_descriptor; //Define Edge
using edgeIt = boost::graph_traits<graphT>::edge_iterator; //Edge Iterator
forcedDirLay(){
boost::minstd_rand gen;
RectTopology rect_top(gen, 0, 0, 1, 1);
boost::random_graph_layout(myGraph, boost::get(&SLDVertex::position, myGraph), rect_top);
boost::fruchterman_reingold_force_directed_layout(myGraph, boost::get(&SLDVertex::position, myGraph), rect_top);
}
Imagine now I have a graph and perform my layout algorithm which all works fine
and I have position info for every vertices.
How can I visualize each vertex where they end up after layout algorithm
finished ? Is there a way to get position info to Dot file and I can visualize
Dot file ?
I have a function to convert my graph to dot file but don't know how
to get position info to dot
file. Thanks in advance.
GraphToDotFile(){
std::ofstream dot(".\\graph.dot");
boost::write_graphviz(dot, myGraph,
boost::make_label_writer(boost::get(&MyVertex::name, myGraph)));
dot.close();
}

Answer 1

You can use dynamic properties to add graphviz attributes, see the example:
https://www.boost.org/doc/libs/1_74_0/libs/graph/example/graphviz.cpp
The attributes that specify the position in graphviz are here:
Position of node, or spline control points.
For nodes, the position indicates the center of the node. On output,
the coordinates are in points.
In neato and fdp, pos can be used to set the initial position of a
node. By default, the coordinates are assumed to be in inches.
However, the -s command line flag can be used to specify different
units. As the output coordinates are in points, feeding the output of
a graph laid out by a Graphviz program into neato or fdp will almost
always require the -s flag.
When the -n command line flag is used with neato, it is assumed the
positions have been set by one of the layout programs, and are
therefore in points. Thus, neato -n can accept input correctly without
requiring a -s flag and, in fact, ignores any such flag.
Valid for: Edges, Nodes.

Answer 2

The neato -n trick works like a champ.
Adding a bit to the above,
yourProg produces graph.dot; then
neato -n -Tpng graph.dot >graph.png
You may have to fiddle with yourProg to make sure that graph.dot has all the required attributes, units are correct, etc. You can produce a tiny example by hand, then
dot -Tdot tiny.gv >tiny.dot
and compare the two .dot files