[vtkusers] problem of polydata manipulation

[pagen_ivan at sohu.com]

hi, everyone:
   I have a polydata contain triangles.
   Now I want to add vertex according to every edge of the polydata, so I must manipulate the geometrical and topological imformation. Then I have the following problems:
   1)How can I get every edge of the polydata. If I just use getcell I can only get the triangles.
   2)If I could get the vertex I need, then one triangle will be divided into four, so the connectivity of the vertex will change.Is there any simple way to change the connectivity information of the data?
   Thank you!

                                                Ivan from Beijing, China