5

Note: The Affect Subobjects checkbox only appears in the Behaviors Inspector when the
Throw and Spin behaviors are applied to a group that contains multiple objects, such as
a group, particle emitter, or text.
Applying Parameter Behaviors to Emitter or Cell Parameters
As with all objects in Motion, you can apply Parameter behaviors to the parameters in
the Emitter or Particle Cell Inspector.
To apply a Parameter behavior to an emitter or cell parameter
Do one of the following:
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Drag a behavior from the Parameter category in the Library onto an emitter or cell in the
Layers list or Timeline. In the Apply To section of the Behaviors Inspector or HUD, choose
an option from the Go pop-up menu.
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Select an emitter or cell in the Layers list or Timeline, then choose a Parameter behavior
from the Add Behavior pop-up menu in the toolbar. In the Apply To section of the
Behaviors Inspector or HUD, choose an option from the Go pop-up menu.
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In the Emitter or Particle Cell Inspector, Control-click a parameter, then choose a Parameter
behavior from the shortcut menu.
Using Particles Behaviors
The Particles category in the Library contains two behaviors specifically for use with the
cells or emitter in a particle system:
Scale Over Life
This behavior lets you grow or shrink the particles in a system over the duration of each
particle’s life. It has one main parameter and three optional parameters that appear
depending on the selected Increment Type.
Parameters in the Inspector
Increment Type: Choose an option from this pop-up menu to determine which method
is used to resize particles over their lifetime. There are four options:
• Natural Scale: Specifies starting and ending scale percentages used to animate each
particle’s size over its lifetime. Natural Scale uses an exponential curve to allow the
animation to progress slowly when the scale values are small, and speed up when the
values are large. This creates the illusion that the scaling is occurring at a constant
speed. When Natural Scale is selected, the Scale At Birth and Scale At Death parameters
become available.
• Rate: Specifies a steady rate at which particles change size over their entire lifetimes.
When Rate is selected, the Scale Rate parameter becomes available.
718 Chapter 14 Working with Particles