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172 Chapter 11: Space Warps and Particle Systems
Parallel To Sur f ace—
Each particle travels parallel
to the nearest face.
To ma ke particles orbit an object, us e this with
Control Speed Continuously, and set appropriate
Continuous Speed Cont rol values (see the
following section).
Divergence—When on, spreads out the particle
stream. Use the numeric sett ing to define the
extent of the divergence. Range=0 to 180.
Default=0. The value can be animated.
This option is unavailable if Control Speed
Continuously is chosen.
Tip: For a fountain-like spray, set P osition >
Location to Pivot, set Direction to Along Icon
Arrow, set Divergence to the desired angle, and
rotate the icon so its arrow points upward.
Continuous Speed Control group
When you choose the Control Speed Continuously
option, these controls become available. Basically,
these controls let the particles move about within
the region of the Surface Geometry object rather
than in a st r aight line away f rom the emitter.
Accel Limit—Sets the maximum acceleration. The
higher this value, the more quickly particles can
turn and change speed.
Tip: UsealowerAccelLimitvalueforsmooth
motion, and a higher value when greater accuracy
is needed, such as when the particles should hit
a small target. You can animate this setting (use
Sync By > Event Duration) to specify different
appropriate values, depending on the required
results.
Unlimited R ange—When on, the surface controls
speed and direction of particles at any distance.
When off, particles must be within a specified
range. Default=on.
Range—The maximum distance, in system units,
between the particles and controlling surface.
The Surface Geometry will not control particles
beyond this distance.
Fa lloff Zone—The d ist ance, in system units,
beyondtheRangevaluewithinwhichtheSurface
Geometry exerts partial control over particles.
The degree of control diminishes from 100% at the
Range distance to 0% at the Range+Falloff Zone
distance.
Animation Offset Keying group
Choosethetimeframeforapplyinganimated
parameters. For an explanat ion, see Animation
Offset Keying group (page 2–158).
Absolute Time—Any keys set for parameters are
applied at the actual fr ames for which they’re set.
Particle Age—Any keys set for parameters are
applied at the corresponding frames of each
particle’s existence.
Event Dura tion—Any keys set for parameters are
applied to each p article starting when it first enters
the event.
Uniqueness group
The Uniqueness sett ing enables randomization of
speed variation, and randomization of direction
w ith the Random 3D and Random Horizontal
options.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Keep Apart Operator
Particle View (page 2–125) >ClickKeepApartinanevent
or add a Keep Apart operator to the particle system and
then select it.
The Keep Apart operator, a member of the Speed
operator family, lets you apply forces to particles