Apple Motion 2 Tutorials - Manual (Page 212)

212 Tutorial 4 Working With Particles
Because the default Orbit Around parameters are pulling the particles around Big Star
strongly, the other simulations are not as evident. Move Big Star to the lower-left corner
of the Canvas.
What you now see is a complex interaction of simulations, using Gravity, Edge Collision,
and Orbit Around. These simulations, used together, produce something much more
complex than what you could achieve in the same amount of time with keyframing. In
addition, the interactions automatically adjust as objects are moved and parameters
are changed. Experiment with the parameters of the various simulations to watch their
interaction.
The final step is to spin the Big Star object.
To add a Spin behavior to Big Star:
1 In the Layers tab, select Big Star.
2 In the Toolbar, click the Add Behavior icon, then choose Basic Motion > Spin.
3 In the Behaviors tab of the Inspector, change Spin Rate to 300 degrees.
Big Star spins, as if driving the orbit of the particles.
4 Save your project (press Command+S).
All done!