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162 Chapter 11: Space Warps and Particle Systems
If you choose Inherit Previous but no direction
was previously specified, the speed and direction
are undefined; the par ticles don’t move.
Reverse—When on, t he direction is reversed.
Default=off.
Using Reverse is the equivalent of multiply ing the
Speedvalueby-1.Thisoptionisunavailableif
Random 3D or Random Horizontal is chosen.
Divergence—When on, spreads out the particle
stream. Use the numeric sett ing to define the
extent of the divergence, in degrees. Range=0 to
180. Default=0. The value can be animated.
This option is unavailable if Random 3D 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.
Uniqueness group
The Uniqueness setting enables randomization of
speed variation, and randomization of direct ion
with the Random 3D and Random Hor izontal
options.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Speed By Icon Operator
Partic le View (page 2–125) > Clic k Speed By Icon in an
event or a dd a Speed By Icon operator to the particle
system and then select it.
Click a Speed By Icon operator icon in the viewpor t >
Modify panel
Create panel > Helpers > Particle Flow > SpeedByIcon
The Speed By Icon operator lets you use a special,
non-rendering icon to control par t icle speed and
direction.
Speed By Icon operator icon
When you add a Speed By Icon operator to the
particle system in Particle View (page 2–125),the
Speed By Icon oper a t or icon icon appears in the
scene at the world origin (0,0,0). When a nimated,
theoperatoricon’smotionisimpartedtothe
particles. If you delete the icon, the software also
deletes the operator.
Note: If you add Speed By Icon from the Create
panel, Particle Flow creates a separate event for the
operator in the particle diagram.
Wa rn in g : If you delete a Speed By Icon operator icon
in the viewport, you also delete the corresponding
operatorintheParticleFlowsystem.
See also
Speed Operator (page 2 –159)
Speed By Surface Operator (page 2–167)
Keep Apart Operator (page 2–172)
Procedures
To us e the Speed B y Icon oper ator :
1.
Add a Speed By Icon operator to an event. Be
sure to add it after any existing Speed operators
in the event. Alternatively, delete or turn off any
existing Speed operators.
The Speed By Icon operator icon appears at the
world origin (0,0,0).
2. Animate the icon as you would any object. You
can do this manually, or with a controller such