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The user interface appears in the parameters panel, on the right side of the
Particle View dialog.
Control By ... The drop-down list at the top of the parameters panel lets you
choose whether to send particles to a target by specifying the speed and
acceleration, or by specifying the amount of time they should take.
Alternatively, by choosing No Control, you can test particles' distance from
a target.
■ Control By Speed Specify speed and acceleration settings for the particles
to follow while traveling to the target. Use the Control By Speed group to
set the parameters.
■ Control By Time Specify time-based settings for the particles to follow
while traveling to the target. Use the Control By Time group to set the
parameters.
■ No Control With this option, Find Target functions only as a proximity
test. When a particle comes within the specified distance of the target, the
particles become eligible for redirection to the next event.
NOTE When you choose No Control, the Find Target test does not affect
particle speed or direction.
Test True If Distance To group
These settings let you choose which distance the Find Target test measures
and specify the measured distance. You can choose Target Pivot or Target
Point, and specify a distance with the Is Less Than setting.
Target Pivot Measures the distance between the particle and the target pivot.
If the particles are directed to the outside of the target and the Is Less Than
value is small, this condition might never be satisfied.
Target Point Measures the distance between the particle and the
target point
on page 2978.
Is Less Than When particles are closer than this distance from target pivot
or point, they test True and become eligible for redirection to the next event.
Measured in scene units.
NOTE If you set Is Less Than to 0, the particles might never test True. This might
be desirable for an animation of, for example, bees buzzing around a flower but
not landing on it. In this case, you might want to use a low value for Accel Limit
so the bees don’t circle too close to the flower.
2974 | Chapter 14 Space Warps and Particle Systems