using Performer callbacks

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Thomas Hudson (hudson++at++cs.unc.edu)
Wed, 22 May 1996 11:38:44 -0400 (EDT)

I'm having some really strange behavior from Performer callbacks that
I was hoping somebody on here could explain. For debugging, I've
attached cull and draw callbacks to just about every node in my scene
graph. What I see is (when singleprocessing):
  root cull callback is called
  root draw callback is called
  root cull callback is called
    culling descends graph
  root draw callback is called
    drawing descends graph
    drawing *doesn't* necessarily reach leaves

Now, my real bug is the fact that most leaves are only being drawn
on some frames, despite the fact that all the culls are forcing
pfCullResult(PFIS_MAYBE | PFIS_TRUE | PFIS_ALL_IN). Every cull
callback is called, and the draw callbacks on all the pfGroups
are called, but some pfGeode draw callbacks aren't called
*on every frame*.

However, what I think people are more likely to be able to help
me with is the very beginning. Why are there extra calls of the
root cull and draw callbacks before we begin the traversal? At
this time there isn't anything I'm doing that must be done exactly
once per frame, but I do have some fairly expensive calculations
there.

Thanks for any advice.

Tom
UNC Walkthrough and Modeling groups
// hudson++at++cs.unc.edu

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