Apple Motion 2 - Manual (Page 611)

Chapter 8 Working With Particles 611
Note: Not all behaviors instantly activate an object when applied. For example, when a
Throw behavior is applied to an object, the Throw Velocity parameter must be adjusted
before the object moves.
Applying Behaviors to Cells
Simulation behaviors that are applied directly to cells are in turn applied to each
individual particle generated from that cell. This can result in some extremely complex
animations as dozens of particles move according to the behaviors you’ve defined.
Behaviors applied to cells have no effect on the position of the emitter. Parameter
behaviors on a cell only affect particles when they are created.
To apply a behavior to a cell:
m Drag a behavior from the Library to a cell in the Layers tab or Timeline.
The behavior is applied to the cell, and all particles generated from that cell begin to
move according to the parameters of the behavior.
Tip: If you do not see your expected result when applying behaviors to particle cells, try
turning the Affect Objects parameter on or off, or selecting a different option from the
Affect pop-up menu. These parameters determine whether the entire object (such as
the particle emitter) or its components (such as the particle cells) are affected by the
behavior and how an object interacts with surrounding objects, respectively.
Note: The Affect Objects checkbox only appears in the Inspector when the Throw and
Spin behaviors are applied to an object that contains multiple objects, such as a layer,
particle emitter, or text.
The Particles Behavior Category
There is one category that contains a behavior specifically for use with the cells or
emitter in a particle system. The Particles category contains the Scale Over Life
behavior. 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 Increment Type option that’s chosen:
Increment Type: Choose which method is used to resize particles generated with a
particle effect. There are three options to choose from.
• Rate: Specifies a steady rate at which particles change size over their entire lifetimes.
A Scale Rate parameter appears in the Inspector (and becomes available in the
Dashboard), allowing you to define how quickly each particle changes size. Positive
values grow particles over time, while negative values shrink particles over time.
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