5.5

538Motion User Guide
For example, you can create a particle system that simulates an explosion by offsetting
the appearance of different types of particles. First, dense white sparks emerge from the
center. Half a second later, more diffuse orange blast particles appear around a larger
area. One second after that, hot smoke emerges from underneath both of these layers, and
smoky remains are left as the particles fade away.
You can offset a cell in the Timeline or mini-Timeline so that the cell starts before the
emitter. This creates a “pre-roll” in which the particle simulation begins before the
particles are drawn.
For more information on adjusting the timing of layers in the Timeline, see Intro to the
Timeline in Motion.
Using graphics in particle systems in Motion
Creating a particle system from scratch begins with designing the particles you want it
to emit. You can use any image, shape, text, or movie supported by Motion as a source for
a cell.
Still images
Particle systems that use still images as their cell sources render in real time much faster
than systems that use video or animation clips. A still image is often all you need to create
a compelling particle system.
Use the following guidelines when creating graphics for use as particles:
• Graphics size: If you’re not sure what size you want your particles to be, it’s a good idea
to make your graphics larger rather than smaller. Increasing the size of particles beyond
the size of the original graphic can introduce unwanted artifacts. One caveat, however,
is that the larger the cell source size, the slower your playback performance.
• Particle edges: The quality of the edges of your graphics can be extremely important for
creating convincing particles. Soft, translucent edges might look better than hard, over-
defined ones.
• Object color: By default, particles are created using the original colors of the source
image used as the cell. If necessary, you can tint the emitted particles using the Color
Mode controls in the Emitter and Particle Cell Inspectors. Choose between tinting all
particles with a single color or creating a gradient tint that changes color over time. You
can also choose to apply a gradient preset to the particles (see Use a gradient preset in
Motion). Tinting particles applies the tint color uniformly over the entire particle system.
• Alpha channels: Always create graphics that you want to use as cells with predefined
alpha channels. For more information on importing files with alpha channels, see Alpha
channels in Motion.