[osg-users] Recognizing currently seen polygons / vertices?

[Ariasgore]

Hello,

I am trying to render a scene and then recognize all currently seen polygons 
(or even vertices) of a loaded model. I require not only the node precision 
but polygons or better vertices.
Basically I believe (but do not know) that I need to get hold of the 
z-buffer after a successfull depth test for a frame and extract the vertices 
out of it but I don't know how.

thanks