8

Particle Flow FAQ 115
How can I make all particles appear in the first
frame while giving them different ages? (page
2–119)
HowcanIspecifythetimeframeinwhich
animated parameters are applied to particles?
(page 2–119)
How can I apply bubble motion to particles? (page
2–119)
How can I branch an e vent to se veral other events?
(page 2–119)
Does it matter wh ich order I put actions in an
event? (page 2–119)
How can I tell which particles are in a certain
event? (page 2–120)
Wh y do my particles lose their material when they
move to another event? (page 2–120)
Can I have an event receive input from multiple
events? (page 2–120)
I changed an operator setting, but it doesn’t seem
to have any effect on the pa rticle system. ( page
2–120)
Can an event be isolated in Particle View and not
connected to anything? (p age 2–120)
General
How does Particle Flow handle time?
ParametersthatmeasuretimeinParticleFlow,
such as
Birth (page 2–139) >EmitStart/Stopand
Age Test (page 2–207) > Test Va lue, are specified
in frames. However, Particle Flow is always aware
of the current system frame rate (fps), and if
you change this rate, it adjusts all time-related
parameters to keep the same timing. For instance,
if you set Test Value to 60 when you’re using the
NTSCframerate(30fps),andthenswitchtoPAL
(25 fps), Par ticle Flow automatically changes the
valueto50,sotheagethat’stestedforisstilltwo
seconds.
On the other hand, rate parameters, such as Speed,
are measured in u nits per second, so they don’t
changewhenyougotoadifferentframerate.
When I go to a different frame, the software
sometimes seems to freeze for a while. What’s
going on?
Most of the animation in Particle Flow is history
dependent; that is, to be able to draw the part icles
in a particular frame, the program needs to know
what happened in all previous frames. Normally,
when you change a parameter value, t he program
needs to recalculate all frames b etween the start
and the current frames. Or, if you go to a different
frame, Particle Flow must recalculate one or more
animation frames. If you go forward, it must
calculate the frames between the current frame
and the one you go to. So, for example, if you just
go to the next frame, relatively little calculation is
needed. But if you go backward, even only by one
frame, it must calculate all frames from the start of
the animation to the frame you go to.
If a lot of calculation is needed, there is a delay.
Meanwhile, the software displays a message like
“PF Source 01 Update xx% (Press Esc to cancel)”
in the status bar, so you can get an idea of how
the recalculation is progressing. If, when you
see this message, you press the ESC key, Part icle
Flow displays an alert with the message “Click
OK to turn off PF Source 01.” If you click OK, the
recalculation stops, giving you the opportunity
to optimize the animation. For example, you
could reduce the number of part icles for testing
purposes. You must turn the source back on to
continue. If you click Cancel, the calculation
continues.
Tip: An easy way to speed up recalculat ion and
rendering of particles is by adjusting the total
number of particles. To do this, select the Particle
Flow source icon, and then go to the Modify panel
> Emission rollout > Quantity M ultiplier group.
Here you can increase or decrease by percentage