I have a simulator where time can go forward or backward and I am
integrating an osgParticle system which draws line particles. My
particle lifetimes are under 1 second.
I am looking for suggestions on the following problems:
When I jump ahead in simulation time (by a week, for example) the
currently live particles stick around for that week plus their remaining
lifetimes. I would expect them to die immediately because the delta
time that just elapsed is much greater than their lifetimes.
When I jump backwards a similar issue occurs. But as I jump back in
time before the simulation time when the particle system was
initialized, the start and end of the particle lines seem to grow apart
until I have enormously long particles (presumably from the parent node
moving with time). Only going past the start time again resolves the
issue. I would expect particles to work normally at any time in my
simulation as long as time is going forward.
When time is in reverse weird things happen as well, but less severe. I
would be fine if nothing drew while time is reversed since obviously
there is no way to easily reverse a particle system.
So... I've tried turning off the particle system node while time is
jumping but it doesn't resolve anything. I've tried modifying
osgParticle to kill the particles when dt is zero (since negative dt is
not allowed by the particle updater). I then get no particles at all
until time is again after the startup time, which is some improvement.
But I don't see what is storing the particle system initialization time
or why.
Wondering if anyone has any ideas.
Thanks!
Rob
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