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Re: Do SoViewingMatrixElement and SoViewVolumeElement break bounding bo

To: Chester Liu <cht@xxxxxxxxxxx>
Subject: Re: Do SoViewingMatrixElement and SoViewVolumeElement break bounding box cache?
From: Gavin Andresen <gavin@xxxxxxx>
Date: Thu, 16 Nov 2000 19:13:59 -0500
Cc: info-inventor-dev@xxxxxxxxxxx
In-reply-to: <3A1440EF.FB733492@xxxxxxxxxxx>
References: <200011161931.LAA95625@xxxxxxxxxxxxxxxxxxxx> <OE27S0qPzg9uV54Ogdd000001ac@xxxxxxxxxxx>
Sender: owner-info-inventor-dev@xxxxxxxxxxx

     const SbViewVolume & viewVol =
             SoViewVolumeElement::get(action->getState());

     const SbMatrix & viewMat =
SoViewingMatrixElement::get(action->getState());


The separator reports that the bounding box cache (used for
render culling) is being invalidated.  If I comment out these
lines of code, it's fine.

Why?

The ViewingMatrix and ViewVolume change whenever the camera moves, so if your GetBoundingBox method relies on them, then the bbox cache SHOULD be invalidated.

Does the bbox cache get invalidated if you don't move the camera (or resize the window, which also changes the ViewVolume), but instead just have a fixed camera with an animated object NOT underneath that Separator?


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