In an effort to make the fastest possible particle system we need a few questions answered.
1) What is the best Geometry mode to use when you need to have variable length GeometryArrays? Should it be copy mode or by-ref mode? As it was explained to me by Kelvin, using by-ref means no hardware T&L, because by-ref doesn't use vertex buffers/display lists. We are currently using the copy mode and using setValidVerexCount() to emulate a variable length array. But don't believe it is working correctly because performance is apparently effected not by the setValidVertexCount, but by the size of the array, meaning if I make the array to have 100 particles, but show only one it runs as though there are 100. This may be an incorrect observation at this time because test has not been absolutely thorough. But if I knew the underlining operations, I would have to set all these tests.
2) What if changes are made to every coord, every frame? In copy
mode, will all those sets() create a vertex buffer/display list bottleneck?
Or does it have no effect? If we are making this many changes, this
often is by-ref better.
I think a thorough explanation of the underlining operations and implications
of using copying or by-ref Geometry mode is crucial to developers putting
out the best possible apps using Java3D. I know the philosophy expressed
in the online information and API spec is to only think Objects and not
Polys, but the truth is, systems are not there yet and how we use Java3D
can make a big difference in execution performance. Without more
info on this stuff, we are flying blind, and getting the information on
a case by case basis is wasting your time having to deal with each individual
apps goals. This could all be eliminated if you would just publish
the actual implementation design and techniques, instead of the generic
high level Java3D view.
Failing to release this information but exposing it piecemeal on this
list is making it more difficult and time consuming to develop.
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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
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