Qgis network analysis why find vertex return always -1

Question

I'm trying to compute the shortest path between points using the QGIS networkanalysis library. But the graph.findVertex always return -1.

Basically what I'm trying to do is : 1/ Given a set of points, create a grid. The size of the grid is define by the poins bounding box 2/ transform all the cells' grid to point (centroid) 3/ For each cell's centroid compute the shortest path with the set of points

My script works fine with no error, but the graph.findVertex() function always return -1. It's like my points are not tied to the graph...

My code is available on pastebin : http://pastebin.com/u6n4tSkz

Do you know what I'm doing wrong ?

Answer 1

Check if your graph contains the points you later want to find using findVertex. According to http://qgis.org/api/qgsgraph_8cpp_source.html, the routing graph has to contain the exact point:

72 int QgsGraph::findVertex( const QgsPoint& pt ) const
73 {
74   int i = 0;
75   for ( i = 0; i < mGraphVertexes.size(); ++i )
76   {
77     if ( mGraphVertexes[ i ].point() == pt )
78     {
79       return i;
80     }
81   }
82   return -1;
83 }

Try and check if the tying in makeGraph failed:

Note if tiedPoints[i]==QgsPoint(0.0,0.0) then tied failed.