8

Speed By Icon Operator 159
as Path Constraint. See the follow ing procedure
for an example of this.
The par t icles’ motion is now under the
influence of the animated icon.
3. Set the Speed By Icon parameters. With the
icon selected, you can do this in the Modify
panel.
In general, the default Icon Animation > Sync
By settin g, Event Duration, works best. It
causes the icon animation to be applied to the
part icles within the time frame of the event
containing the Speed By Icon operator.
Example: To send par ticles along a path:
1.
Reset the software, and then add a Particle Flow
system in the Perspective viewport.
2. OntheCreatepanel,chooseShapes>Splines>
Helix, and then, in the Perspective viewport, at
the center of the grid, c reate a helix shape. Then,
on the Parameters rollout, set the following:
•Radius1=100
•Radius2=20
•Height=20
•Turns=3
•Bias=0
This wi ll serve as the particle p ath.
3. Move and rotate the Particle Flow source icon
so that it’s at the sta rt of the helical path, and
aimed along the path, as shown. Get the base
of t he arrow as close as possible to t he star t of
the path.
4. Open Part icle View (press 6).
5. In Event 01, click the Position Icon operator
and set Location to Pivot.
This causes the particles to be emitted in a thin
stream.
6. Insert a Speed By Icon operator at the end of
Event 01.
The operator icon appears at the world orig in.
7. Select the operator icon, and then, from the
Animation menu, choose Position Controllers
>
Path C onstraint (page 2–380) .
Whenyoumovethemousecursorintothe
view por t, a rubber-band line joins the cursor
to the icon.
8. Select the Helix object.
The command panel switches to the Motion
tab, and the controls indicate that the software
has applied a Position List controller to the
icon, with the listed controllers being a Position
XYZ and a Path C onstraint. You can delete
theformerifyoulike,butitdoesn’tmakeany
difference for the purposes of this procedure.
9. CloseParticleView,andthendragthetime
slider back and forth between its extents a few
times.