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152 Chapter 11: Space Warps and Particle Systems
Divergence—
Defines the range of variation (in
degrees) for spin-axis orientation. The actual
deviation is calculated at r andom within this
range. Unavailable for the R andom 3D option.
Default=0. Range=0 to 180.
Uniqueness group
The Uniqueness setting affects the r andomization
of spin rate var iation, spin axis with the Random
3D option, and Divergence with the other options.
Seed—Specifies a randomization value.
New—Calculates a new seed using a r andomization
formula.
Scale Operator
Particle View (page 2–12 1) > Click a Scale operator in an
event or add a Scale operator to the particle system and
then select it.
The Scale operator lets you set and animate
par ticle size during an event, with optional
random variation. Options for how scaling and
animation are applied give this operator a great
deal of flexibility.
Procedure
Example: To animate particle scale:
This procedure g ives an overv iew of animating
particles to g row for 30 frames, remain at full
size for the next 30 frames, and then shrink for
30 fr ames. It also gives an option for having the
particles pulsate in size during the middle period.
To follow this procedure, you should b e familiar
w ith the basic usage of Part icle Flow and Tr ack
View.
1. SetupadefaultParticleFlowsystem. Setthe
Shape operator to Sphere, and set the Display
operator to Geometry.
2. AddaSendOuttesttoEvent01.
3. Add a new Scale operator to the event display,
creating a new event. Set the new event’s
Display operator to Geometry, and make sure
it’s a different color than the one in Event 01.
4. Wire the Send Out test in Event 01 to Event 02.
5. In the Event 02 > Scale operator, set Type to
Absolu te, and animate the Scale Factor values
from 10 to 100 over f rames 0 to 30. In the
Animation Offset Keying group, set Sync By to
Event Duration.
6. AddanAgeTesttoEvent02.SetittoEventAge,
set Test Value to 30,andVariationto0.
In this event, particles grow from 10 percent of
their original size to full size over the first 30
frames of their existence, which is the same as
their duration in the event. At that point, they’ll
be eligible to move to the next event.
7. Use a new S cale operator to create a new event,
Event03.Setthenewevent’sDisplayoperator
to Geometry, and make sure it’s a different
color than the others.
8. Wire the Age Test in Event 02 to Event 03.
9. In the Event 03 > Scale operator, Set Type to
Absolute, and in the Animation Offset Keying
group, set S ync By to E ven t Duration.
10. Copy and paste the Age Test as an instance from
Event 02 to Event 03.
Part icles in Event 03 remain at full scale for 30
frames, and then move on to the next e vent.
11. Use a new Scale operator to create a new event:
Event04.Setthenewevent’sDisplayoperator
to Geometry, and make sure it’s a different
color than the others.
12. Wire the Age Test in Event 03 to Event 04.
13. In the Event 04 > Scale operator , set Type to
Absolu te, and animate the Scale Factor values
from 100 to 10 over f rames 0 to 30. In the
Animation Offset Keying group, set Sync By to
Event Duration.