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754 Chapter 9 Using the Replicator
Once you have replicated a layer, you can quickly change the shape of the pattern and
animate its elements by animating the replicator parameters. You can also use
behaviors to animate many of the replicator parameters. In addition, the replicator has
a special behavior that allows you to animate the pattern’s elements in sequence over
the pattern.
The Difference Between a Replicator and a Particle System
Although the replicator and particle systems share many of the same parameters,
they are very different tools. While both use layers (shapes, text, images, and so on) as
cell sources and generate elements from those cells along or within a shape such as a
circle, line, or spiral, the cells are used differently by each tool. A particle system uses
the cell source as the “mold” for the particles that are generated by the emitter. As
mentioned in Chapter 8, “Working with Particles,” if you imagine that a garden hose is
a particle system, the nozzle acts as the emitter, while the water represents the flow
of particles. Particles are animated over time by default—they are born, move away
from the emitter, and die. The particle system is not designed for pattern-based
replication purposes.
In a replicator, elements are not emitted (they do not have “birth rate,” “life,” or
“speed” parameters) like particles. The replicator simply builds a pattern of static
copies of a source layer in a shape and arrangement that you specify. Although the
replicated layers (elements) are static by default, the replicator parameters can be
animated. In a simple example, a star shape is used as the source and replicated
along the outline of a circle. The Offset and Color parameters can be keyframed so
the stars travel around the circle while changing color.
The replicator also has a special behavior called Sequence Replicator that allows you
to sequence parameters, such as position, scale, and opacity, over the pattern of
elements. How the animation moves through the replicator pattern is determined by
the build style or origin of the replicator, as well as the parameters of the Sequence
Replicator behavior. This behavior works very similarly to the Sequence Text behavior.
For more information on using the Sequence Replicator behavior, see “Using the
Sequence Replicator Behavior” on page 821.