5.1.1

Chapter 14 Particles 519
By default, the rst frame of a new particle system (with a single cell) has one particle. If you
play your project (press Space bar), additional particles are generated and emerge from the
center of the emitter.
By default, new cells emit one particle per frame in all directions (for 30-fps projects), and each
particle moves 100 pixels per second away from the emitter over a lifetime of 5 seconds (150
frames in a 30-fps project).
Note: Use the Initial Number parameter in the Particle Cell Inspector to change the default
behavior so a particle system begins with a burst of particles at the rst frame. For more
information, see Emitter parameters on page 526.
When you create a particle system or modify a parameter of an existing particle system, the
path of each particle is immediately calculated and predetermined. Although the number
and motion of particles might seem random, they are completely predictable based on
that system’s parameters. Playing the same particle system twice with the same parameters
results in exactly the same particle motion. If you want to choose a new predetermined set of
random values, you can change the Random Seed setting repeatedly until you obtain a result
you like.
Multiple cells in a single emitter
When you create a particle system from scratch, you can place multiple cells inside a single
emitter in the Layers list. Doing so lets you create complex compositions with dierent
overlapping particles.
You can add as many cells as you want in a single emitter. Each cell has its own parameters
that govern how particles from that cell are created. When selected in the Layers list, each cell
displays its own Particle Cell Inspector. Particle systems with multiple cells generate particles
from each cell simultaneously, according to each cell’s parameters.
For an example of using multiple cells in a single emitter, see Example 2: Create animated pixie
dust on page 553.
67% resize factor