From: Brian Furtaw (brian++at++sgi.com)
Date: 12/19/2000 06:48:46
With that many billboards and DCSs you are probably taking a huge time
hit for performer scenegraph housekeeping. Was the implementation to
slow with pfBillboards or did you just for go the pfBillboards for the
pfDCS implementation? You will probably be better off creating a
pfFlux'd geoset to hold all your billboards and use the CPU to orient
them toward the eye. A good example of this can be found at
http://www.dorbie.com/#_cch2_886177090, the application is called
Billboard. Using this method you will eliminate the Performer scenegraph
housekeeping overhead.
Merry Christmas,
Brian
Mark Evans wrote:
>
> I have a complex scene with a lot of billboards (more
> than 5K) and therefore I didn't use pfBillboards but
> instead pfDCSs - to be able to modify the rotation
> angle selectively, based on distance.
> I have a function that computes the angle of rotation
> for every pfDCS (associated with a billboard), and
> also
> sets this angle in the pfDCS matrix - so everything is
> done in this function. The function takes aprox. 7 ms
> every frame, yet, the frame time increases by aprox 22
> ms - and the statistics reports that the App step
> duration is increased by this amount.
> My question is: where does the difference (22 ms - 7
> ms) come from? Is it because Performer recomputes the
> bounding boxes/speres for the pfDCSs that have the
> rotation modified from one frame to another? Is there
> other reason? Does the pfBillboard bring advantages
> over using pfDCSs for many billboards?
>
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