Bonjour Celine,

Everything depend of what kind of result you want : do you want the
coordinate of the polygons that describe the outline ? or do you just want
to draw the pixels that form this outline ?

For the pixels, there is a way : use 2 additional clipping planes to your
scene, before you draw the scene : they should be near each other, and
parallel to the one you really want. Set them up to have everything you will
draw outside of the 2 planes clipped by the hardware, and you will get a
'cut' of your scene on the screen (Am I clear ??).

Write to me (and copy to that ng also) if you still don't understand, I can
also explain in French.

Vincent Cantin