Lines disappear--They were getting culled.

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Brian Furtaw (brian++at++sgi.com)
Thu, 14 Nov 1996 11:24:37 -0500

Well I solved the problem of the disappearing lines, the Geoset which contained
the lines was getting culled. At first I came to the concullsion that my
bounding box was not getting updated properly because of the way I specify the
vertices in my LineSet. So I added, (cable is a pfGeoset)

    // now I need to recalculate the munged bbox
    pfBox *bbox = new pfBox();
    bbox->around(cablecoords, 11);
    //apply a new bbox to the pfGeoset for the cable
    cable->setBound(bbox, PFBOUND_STATIC );

That fixed the problem with the bounding box, but the lines kept dissappearing.
I was puzzled I knew the bounding box was correct I could see it on the screen
when the lines were visible. I use the APP_CULL_DRAW mulitprocessor model and
to propagate the LineSet geometry down the pipe I had to use a pfCyclebuffer.
So I came to the conclusion that maybe my bounding box calculation was not
properly sync'd with the pipe. So I did this, (geode2 is a pfGeode)

    // disable culling for this node
    geode2->setTravMask(PFTRAV_CULL, 0, PFTRAV_SELF|PFTRAV_DESCEND, PF_SET);

which turns culling off for the pfGeoset (cable) in the previous example. It
fixed the problem, but unfortunately it only proves that the geometry was in
fact being culled. My question now is how can I debug this futher?

Brian

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Brian Furtaw  (brian++at++sgi.com)	
VisSim  Technical  Consultant
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