3D >> 2D coordinates

hi, im working on a project at the moment with papervision 1.7b
im running MovieScene3D with a few Planes scattered randomly all facing the camera.
i would like to add movie clips over the 3D scene based on the coordinates of the planes. more precisely, i need to convert 3D coordinates into 2D coordinates on the screen.
if anyone has done this before or has any idea on how it can be done, can you please point me in the right direction.

cheers.
julaps

_______________________________________________
Papervision3D mailing list
Papervision3D@...
http://osflash.org/mailman/listinfo/papervision3d_osflash.org