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230 Chapter 11: Space Warps and Particle Systems
• True When D ecelerat es—Returns a True value
whentheparticlevelocityisdecreasinginvalue.
Test True if Particle Value—Lets you specify whether
the test passes particles on to the next event if
the speed test succeeds or fai ls. Avai lable 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 quantit y, but you
canchooseIsLessThanTestValueaswell. For
example, if you use the Velo city Magnitude test
type and set Test Value=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 part icles
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 unit 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 p article, the
system multiplies the Variation va lue by a random
number between -1.0 and 1.0, and then adds the
result to the Test Value setting. For example, if Test
Value=300 and Variation=10, then tested value for
each particle would be between 290 and 310.
Sync B y—Choosethetimeframetousewhen
animating Test Value and Var iation. For f urther
information, see
Animation Offset Keying group
(page 2–155)
.
•
Absolute T ime—Any keys set for parameters are
applied at the actual f rames 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 D ura tion—Any keys set for parameters
are applied to each particle starting when it first
enters the event.
Uniqueness group
The Uniqueness setting enables r andomization of
the test value variation.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Split Amount Test
Particle View (page 2–121) > Click Split Amount in an
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 every Nth particle. With a
specific number of particles, the splitting takes
placeonceperevent,butyoucananimatethe
percentage and “every Nth” values to vary the
amount of split-off particles ov er time.