[vtkusers] Creating a polydata of edges (lines) from a vtkGraph

[David Doria]

Is there a way to either
1) associate a coordinate with each vertex in a graph/tree?
or
2) create a polydata from a graph/tree where in the process a
coordinate gets assigned a vertex?

I would like to visualize a nearest neighbor graph on a set of 3d
points. Can anyone point me to the right keywords/classes/functions to
do such a thing?

Thanks,

David