[vtkusers] Modifying vtkPolyData

[Jordi Gutiérrez Hermoso]

Okay, in reference to this thread (and a belated thanks to the answers therein):

     http://old.nabble.com/Update-vtkDelaunay2d-object-td27697718.html

I am still stuck. Indeed, the vtkPolyData object can be just gotten
from the output of the vtkDelaunay2D object, but *still* want to know
how can I modify vtkPolyData. The idea is to update the z-coordinates
in order to generate a movie of a moving surface, a vibrating
membrane, for example.