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226 Chapter 11: Space Warps and Particle Systems
Inter face
The user interface appears in the parameters panel,
ontherightsideoftheParticleViewdialog.
Test True When group
Transit ion Per iod Ends —When on, the par ticles test
True at the end of the specified transit ion period,
andbecomeeligibleforredirectiontothenext
event. When off, part icles will not go to the next
event, even if wired. Tur n off to disable the test
aspect of Go To Rotation. Default=on.
Transition By group
Determines how the software applies the specified
timing, defined by the Time and Variation values.
Default=Event Duration.
Thepossibleoptionsare:
•
Absolute T ime—Time refers to the overall time
of the system. Each par t icle will reach its target
orientation at the frame number specified by
Time.
•
Par ticle Age—Timereferstothetimeelapsed
since the birth of the particle. Each particle will
reach its target orientation when its age reaches
the value specified by Time.
•
Event Dur ati on—Timereferstothetimeelapsed
since the p article entered the current event.
Each particle will reach its target orientation
when it has been in the current for the number
of frames specified by Time.
Duration—The number of f rames particles should
take to reach the target orientation. Default=30.
Variation—The number of frames by which
Duration can vary r andomly. Default=0.
To obtain the actual time to the target orientation
for each particle, the system multiplies the
Var i a t i o n v a l u e by a r a n d o m numbe r b e t w e e n
-1.0 and 1.0, and then adds t he result to the
Duration value. For example, if Duration=60 and
Variation=20, then the time to target or ientation
for e ach particle would be b etween 40 and 80
frames.
Target Rotation group
When you use an orientation-type operator with
Go To Rotation, this setting lets you determine
whether the test sets the target orientation on a
one-time or ongoing basis. Default=Constant.
Co nstant—Defines that t he orientation-type
operator sets a constant orientation for a particle.
Forexample,whenusingaRotationoperatorset
to an orientation matrix other than Speed Space
Follow, the Go To Rotation operator would acquire
the target orientation only once, and then use it
as its goal.