Re: [JAVA3D] Views, Canvas3D and frame syncing

[CAZOULAT Renaud CNET/DIH/REN]

Hi Mr Kendall,
Don't be desesperate, you're not alone :~)

> 1) I need to be able to run a target frame rate - namely 30hz
> - not the
> default of absolutely the fastest Java3D can run
The only not too consuming solution I found is to add a sleep in postSwap of
canvas3D
Of course you could use a fake behavior and put the sleep on it's
wakeupsomethink callback.

> 2) I need to control when  the buffer swap happens, but you can not
> implement swap() in Canvas3D because it is final.
>     The docs say that the "View" object syncs the frames and
> then swaps
> all of it's Canvas3D's, but I need to sync and swap based on other
> timing information (i.e. sync from network data). How can I do this?
Synchronization with other timing informations is *very* difficult. But try
the new beta version to discover that it could be worst than now ;-)

> 3) Determine the accuracy of the frame timing.  In any best attempt I
> could code, the smallest fluctuation from frame to frame for the same
> scene averaged 2/10 second on a brand new dual Pentium III
> 550.  I think
> that this is partly due to the fact that NT's threads' or
> Java threads'
> have some minimum resolution no matter how fast the machine
> is (is that
> correct?).  Should I implement my own waiting cycles (i.e. don't use
> sleep()) to be sure of accurate timing?
This one is easy to answer : do not expect more than 1/10s in
System.currentMillis.
Be happy, it's worst in 95/98 ;-).

Another problem you will probably run into is the number of times the
postSwap method
is called for one update (you can safely divide by 4).

> Is there a advanced Java3D mailing list.
I haven't heard about such a list but it is a *very* good idea.
What about creating one ?

renaud

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