Once you post the code I will endevor to have detailed feedback within a
week.
David Yazel
Cosm Development Team
> ----------
> From: Shawn Kendall[SMTP:[EMAIL PROTECTED]]
> Reply To: Discussion list for Java 3D API
> Sent: Wednesday, October 25, 2000 1:40 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [JAVA3D] Particles System and GeometryArrays
>
> Each particle is parallel but not necessarily coplanar. Specifically,
> they all
> turn to face the view, but can be at any location.
> This is somewhat different than the billboard behavior. Billboarding will
> turn
> to face the ViewPoint, which means that for each billlboard they must
> comute
> there own rotation because the rotation is related to their location. The
> trick
> with particles is that they all turn to be MATCH the View's rotation, so
> it only
> needs to be computed once. Lemme me know if you would like more details.
>
> If I understand you correctly, I believe the particle cylinder you
> describe
> would work fine.
>
>
> "Yazel, David J." wrote:
>
> > Shawn:
> >
> > Does each particle in the system have to be coplanar? Would it be
> possible
> > to assemble the particles in a cylinder around a point and rotate the
> > particles, keeping each particle facing the image plate?
> >
> > Dave Yazel
> > Cosm Development Team
> >
> > > ----------
> > > From: Shawn Kendall[SMTP:[EMAIL PROTECTED]]
> > > Reply To: Discussion list for Java 3D API
> > > Sent: Tuesday, October 24, 2000 9:24 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: [JAVA3D] Particles System and GeometryArrays
> > >
> > > <<File: particle-by-ref.jpg.jpe>>
> > > Ok, kudos to Uma and Kelvin for helping me work through this one!
> > > Thank you, thank you.
> > >
> > > Here is a short explanation of what we are doing and the results.
> > >
> > > We implemented a "Particle System" (I prefer Manager, it's not really
> a
> > > system) in Java3D.
> > > Our first attempt was simple using TransformGroups, Shape3D's and
> > > behaviors for every particle object.
> > > This works, but of course, is way to slow. However, it is no too slow
> > > because of Java3D or something else, it is simply because using many
> > > Transforms and Behaviors is going to be expensive.
> > >
> > > In gaming, a particle system is usually two classes may be even one,
> the
> > > particle, and the particle updater or manager.
> > > We reviewed several straight OpenGL and D3D particle systems before
> > > implementing our second system. All of the systems we found only use
> a
> > > Quad or TriStrip for each particle. When that is the particle's
> geometry,
> > > optimizations can be set up to take advantage, so only TWO full vector
> > > transformations need to be computed for the entire system to be
> > > "BillBoarded" correctly. So we knew we would try this technique using
> no
> > > TransformGroups, one Shape3D, and one Behavior. To do it right we
> needed
> > > to get as close to the GL_TRIANGLE level that we could in Java3D.
> With
> > > help from Uma and Kelvin, we have implemented two different version,
> one
> > > using the direct set methods in GeometryArray and one using the by-ref
> > > mode of GeometryArray.
> > >
> > > First off all, both methods where orders of magnitude faster than the
> > > multiple TransfromGroup/Shape3D/Behavior method. We still had some
> > > rendering problems, but that is practically fixed in the pre-beta.
> > > Second, once the by-ref method was up and running we got another 100%
> > > increase in frame rate (for our particular particles test case anyway
> and
> > > on a GeForce H/W T&L). Needless to say it was much faster and looks
> > > great!
> > >
> > > Now making a particle system like this is not nearly as versatile as
> the
> > > full TransfromGroup/Shape3D/Behavior system. It can only do
> billboarded
> > > and usually alpha textured quads. This is the classic particle engine
> in
> > > games. Sometimes you need real geometry that had independent
> rotation,
> > > etc. I call that Debris (from my simulation days) so we are planning
> to
> > > keep the original system and improve it to complement the particle
> system
> > > when that kind of look is wanted.
> > >
> > > I attached a picture for fun.
> > > For those interested, I plan on writing all of this up more formally
> with
> > > code and benchmarks soon.
> > >
> > > --
> > > ___________________________________________________________
> > >
> > > Shawn Kendall Full Sail Real World Education
> > > Course Director 3300 University BLVD
> > > Real Time 3D for Gaming Winter Park FL 32792
> > > [EMAIL PROTECTED] http://www.fullsail.com
> > > ___________________________________________________________
> > >
> > >
> >
> >
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>
> --
> ___________________________________________________________
>
> Shawn Kendall Full Sail Real World Education
> Course Director 3300 University BLVD
> Real Time 3D for Gaming Winter Park FL 32792
> [EMAIL PROTECTED] http://www.fullsail.com
> ___________________________________________________________
>
> ==========================================================================
> =
> To unsubscribe, send email to [EMAIL PROTECTED] and include in the
> body
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> [EMAIL PROTECTED] and include in the body of the message "help".
>
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