Apple Motion 4 - Manual (Page 620)

Transform Parameters
As a particle system plays, the cells in the system are duplicated, according to the
parameters for that system, to create each individual particle in the Canvas. Because all
particles emerge relative to the position of the emitter (because the emitter can be a
point, a circle, geometry, a sphere, and so on), changing the emitter’s position in the
Canvas also changes the position of every particle in that system.
Origin of particle system
after emitter has been
repositioned
Origin of particle system
The exception to this is if the emitter’s position is animated using a behavior or keyframes.
In this case, particles emerging from the emitter’s position at each frame continue to
move relative to that position, regardless of changes to the emitter’s position in
subsequent frames. This results in a trail of particles following the path of the emitter.
The Attach to Emitter parameter in the Particle Cell tab of the Inspector modifies this
behavior. When set to 0%, the particles are completely independent of the emitter. When
set to 100%, the particles try to keep up with the position of the animated emitter.
Depending on any applied behaviors, such as Drag, the particles may not be able to keep
up with the emitter.
620 Chapter 11 Working with Particles