Simon.Mills++at++esa.int
Date: 08/19/2004 03:03:55
Hi Performers,
I've encountered some issues with pfBillboard while implementing a special
effect. Essentially it means I can't have point rotating, eye space aligned
billboards (mode PFBB_POINT_ROT_EYE) with 10 or more vertices. This is what I
found:
1) pfBillboard mode PFBB_POINT_ROT_EYE does NOT keep the billboard
screen-aligned as it should do unless GL support for sprites if turned OFF
(pfFeature PFQFTR_GLSPRITE). Why not? Unfortunately this is a whole
application setting effecting ALL billboards, not just my ROT_EYE billboards.
It needs to be done on an per-application basis.
2) So, if GL sprites are turned off then if I have 10 or more vertices in my
billboard I get a corrupted billboard. The vertices shoot off to infinity as
it were. I tracked this down to the behaviour of pfSprite which is used
internally by pfBillboard. I suggest this should be checked for.
3) Although pfSprite allows this limit between what is done on the CPU and
what is done via GL to be changed, pfBillboard does not expose this
possibility since its pfSprite is a protected member of its class. No way to
change it then.
It is not a major problem but had me perplexed for a while so I report it
here to other users and the Performer Team.
Finally, platform was Onyx300 IR4, Performer 3.0.2, IRIX 6.5.21m
Regards, Simon
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Simon Mills
Modelling & Simulation Section (TEC-EMM) Tel: +31 (0)71 565 3725
European Space Agency (ESA/ESTEC) Fax: +31 (0)71 565 5420
Postbus 299, 2200AG Noordwijk e-mail: Simon.Mills++at++esa.int
The Netherlands http://www.estec.esa.nl/wmwww/EMM
_______________________________________________________________________
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