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228 Chapter 11: Space Warps and Particle Systems
For example, if Offspring #=20 and Variation=10,
then the actual number of offspring for each
particle would be between 18 and 22.
Sync B y—Choosethetimeframetousewhen
animating Rate, Step Size, Offspring #, and
Va r i at i o n :
•
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 Duration—Any keys set for parameters
are applied to each particle starting when it first
enters the event.
Restart Particle Age—When on, sets the age of
each newly spawned particle at 0. When off,
each spawned p article in herits its parent’s age.
Default=on.
Speed group
Lets you specify the speed of spawned p art icles
in absolute terms or relative to the parents ’ speed,
with optional random variation. The direction of
a spawned particle is always in relat ion to that of
itsparent,butyoucansetaDivergencesothey
eventu ally spread out. Default=Inherited.
In Units—Choose this to specif y the speed of
spawned particles in system units per second.
Default=100.0.
A positive value inherits the parent ’s direction; a
negative value reverses it.
Inher ited—Choose this to specify each spawned
particle’s speed as a percentage of its parent’s
speed. Default=100.0
A positive value inherits the parent ’s direction; a
negative value reverses it.
Variation—The amount by which a spawned
particle’s speed can vary randomly. Default=0.0.
To obtain the actual speed for each spawned
particle, the system multiplies the Variation value
by a random number between -1.0 and 1 .0, and
then adds the result to the p article’s speed as
specified or inherited. For example, if a par ticle’s
speed is 100 units/second and Variation=20, then
the tested value for each particle would be b etween
80 and 120 units/second.
Divergence—When on, spreads out the stream
of spawned part icles. Use the numeric setting to
define the extent of the divergence in degrees.
Range=0 to 180. Default=0.
Size group
Scale Factor—The amount of uniform scaling to
apply to each spawned particle, as a percentage of
its parent’s size. Default=100.0.
Variation—The amount by which a spawned
particle’s scale can vary randomly. Defau lt=0.0.
To obtain the actual scaling for each spawned
particle, the system multiplies the Variation value
by a random number between -1.0 and 1 .0, and
thenaddstheresulttotheScaleFactorvalue.For
example, if Scale Factor=100 and Variation=20,
then each spawned particle would be between 80
and 120 percent of its parent’s size.
Uniqueness group
The Uniqueness setting enables r andomization of
the Spawnable result, when less than 100.0, as well
as of the Variation values.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.