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234 Chapter 11: Space Warps and Particle Systems
• Tru e Wh en De cel era tes—Returns a True value
whentheparticlevelocityisdecreasinginvalue.
Test True if Par ticle Value—Lets you specify whether
the test passes particles on to the next event if
the speed test succeeds or fai ls. Available for all
tests except True When Accelerates/Decelerates.
Default=Is Greater Than Test Value.
By default, Speed Test returns True if the value
tested for exceeds the Test Value quantity, but you
canchooseIsLessThanTestValueaswell.For
example, if you use the Velocity Magnitude test
type and set Test Va lue=200 and Variation=0,
and choose Is Less Than Test Value, then particles
will move to the next event only when they travel
faster than 200 units per second. Any particles
traveling 200 units per second or slower stay in the
current event unless they later exceed that speed or
another test returns True.
Test Value—The specific speed or acceleration to
test for. The u nit of measurement depends on the
type of test; see above. Default=300.0.
Variation—Theamountbywhichvaluetestedfor
can vary randomly. Default=0.0.
To obtain the actual test value for each particle, the
system multiplies t he Variation value by a random
number between -1.0 and 1.0, a nd then adds the
result to the Test Value setting. For example, if Test
Va lue=300 and Variation=10, then tested value for
each par ticle would be between 290 and 310.
Sync B y—Choosethetimeframetousewhen
animating Test Value and Variation. For further
information, see Animation Offset Keying group
(page 2–158).
•
Absolute T ime—Any keys set for p ar ameters are
applied at the actual frames for which they’re
set.
•
Particle Age—Any keys set for par ameters are
applied at the corresponding frames of each
particle’s existence.
•
Event Dur at ion—Any keys set for parameters
are applied to each particle starting when it first
enters the event.
Uniqueness group
The Uniqueness sett ing enables randomization of
the test value var i ation.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Split Amount Test
Particle View (page 2–125) > Click Split Am ount in a n
eventoraddSplitAmounttotheparticlesystemand
then select it.
The Split Amount test lets you send a specific
number of particles to the next event, keeping
all remaining particles in the current event. You
can split the particle stream by a specific number
or percentage, or by ever y Nth p ar ticle. With a
specific number of particles, the splitting takes
placeonceperevent,butyoucananimatethe
percentage and “every Nth” values to vary the
amount of split-off particles over time.