Apple Motion 3 - Manual (Page 707)

Chapter 8 Working with Particles 707
For example, you can create a particle system that simulates an explosion by offsetting
the appearance of three different types of particles. First, dense white particles emerge
from the center. Half a second later, more diffuse orange particles appear around a
larger area. One second after that, small sparks emerge from underneath both of these
layers as they fade away.
You can offset a cell in the Timeline or mini-Timeline to start before the emitter. This
creates a “preroll” in which the particle simulation starts before the particles are drawn.
For more information on adjusting the timing of layers in the Timeline, see “ Using the
Timeline ” on page 321.
About Rasterization and Groups
Some operations, as well the application of certain filters or a mask, cause a group to
be rasterized. When a group is rasterized, it is converted into a bitmap image. Because
all particles live in groups, this affects how particles interact with other objects within
your project. For more information on rasterization, see “
3D Compositing ” in the Motion
Supplemental Documentation PDF.