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162 Chapter 11: Space Warps and Particle Systems
particles’speedcanchangeinordertomatchthe
speed of the operator icon. Default=100.0.
If the operator icon changes speed or direction
rapidly, increase this value to let the particles
follow it more closely.
Tip: UsealowerAccelLimitvalueforsmooth
motion, and a highe r value when greater accuracy
is needed, such as when the particles should hit
a small target. You can a nimate this settin g (use
Sync By > Event Duration) to specify different
appropriate values, depending on the required
results.
Influence % Determines the mix of the previous
speed w ith the speed of the operator icon.
Default=100.0. Range=0.0 to 100.0.
At the default value of 100, the speed is cont rolled
only by that of the icon. At 0, the icon speed
doesn’t affect particle speed at all. At in-between
values, the mix proportion is determined by the
Influence % value.
Speed Va r iat ion—Enables random variation of the
particles’ speed, so they don’t all move at exactly
thesamerateastheicon.Turnthison,andthen
set the minimum and maximum percentages of
variation. Default=off.
Using Speed Variation can help keep the particles
from bunching up as they travel along the
animation path. Note, however, that each
individual par ticle’s speed doesn’t vary; it travels
at a constant speed.
Min % /Max % Set the minimum and maximum
percentages, respect ively, of particle speed
variation. Default=50.0 (Min %), 100.0 (Max %).
For example, if you set Min % to 50 and Max % to
200, the particles will vary in speed b etween half
and two times the speed of the icon.
Use Icon Ori entationApplies animation of the
icon’s orientation to the particles.
By default, Speed By Icon controls particle motion
only by animation of the icon’s position. If you
turn on Use Icon Orientation, the software also
applies rotation of the icon to the particle motion.
In essence, this motion is circular, and its extent
dependsonthedistancebetweeneachparticleand
the icon. Default=off.
The best way to understand how this works is by
using it. To try out Use Icon Orientat ion, see
this
procedure (p age 2–160)
.
Steer Towar ds Tra jector y Particles farther away
than the Distance value from the icon are moved
directly toward the icon. Default=off.
Distance—Sets the dist a nce b etween the particles
and the operator icon beyond which Steer Towards
Trajectory takes effect. Default=10.0.
Parameters Animation group
If you animate the operator settings, the software
can begin applying this animation to all particles
as of the start frame of the animation or the first
frame of the current event, or to each par ticle
based on its age. For instance, if you set Sync By
to Part icle Age, and set Speed Var iation keys at
frames 0 and 30, then the s oftware will animate
the speed var iation for each particle born while
the event is active between its birth and its 30th
frame of existence. Alternatively, if you set Sync By
to Absolute Time, the speed variation is animated
from frame 0 to frame 30 of the animation, even if
no particles are in the event at that time. Or, if you
set Sync By to Event Duration, the speed variation
animation is applied to each particle as of the time
that it enters the event. For further information,
see
Animation Offset Keying group (page 2–155)
.
Sync B y—Choose the time frame for applying
animated parameters:
Absolute T ime—Any keys set for p arameters are
applied at the actual f rames for w hich they’re
set.