Apple Motion 2 Tutorials - Manual (Page 193)

Tutorial 4 Working With Particles 193
To use the star shape as a particle cell source:
1 With the star object selected, press E.
A new particle system with a duration of 300 frames is created.
2 Play the project (press the Space bar).
Since the particles are so large, the system quickly becomes a solid white mass. But
with a few changes, you can make the background more distinct.
3 In the Layers tab, double-click the name of the emitter, Emitter. Type a new name, Stars,
then press Return.
Next, soften the edges of the star shape, to create a more interesting (and visible)
effect. You can soften the edges of a shape by increasing the Feather parameter.
Modifying the Cell Source
First, alter the original object, then change the cell source to modify the emitter in
order to more clearly see what the emitter is doing.
To feather the star object:
1 In the Layers tab, select the original 5-sided star shape.
The shape has the shape icon next to it, and is highlighted below.
When a particle system is created, the cell source is automatically turned off. In order to
edit the Feather parameter, the cell source shape must be active.
2 Turn the shape on by clicking the checkbox next to the 5-sided star shape in the On
column of the Layers tab.
3 In the Dashboard (press D or F7), adjust the Feather parameter to 32.
Now the edges of the particles are feathered.
4 Turn the 5-sided star shape off.
Changes made to a cell source change all the cells in the particle system.
One of the reasons that it is difficult to see what the emitter is doing is because the
particles are too large. Make them smaller.