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• Birth and Death Values: Specifies starting and ending spin degrees used to animate
each particle’s rotation over its lifetime. The spin amount generated by this option for
a specific particle at a specific time is added to the pre-existing particle spin (defined
in the Cell Controls section of the Emitter Inspector). When this option is selected, the
Spin At Birth and Spin At Death parameters become available.
• Custom: When Increment Type is set to Custom, a mini-curve editor appears that allows
you to customize the spin of the particles over their lifetime. Click the disclosure triangle
to display the mini-curve editor in the Inspector. For more information on using
mini-curve editors, see Mini-Curve Editor.
Spin Rate: Allows you to define how quickly each particle spins and the direction of the
spin. Positive values spin particles faster over time and in a counterclockwise direction;
negative values spin particles slower over time and in a clockwise direction.
Spin At Birth: Determines the initial spin of the particles when they are created.
Spin At Death: Determines the spin of the particles at the end of their lifetime.
Custom Spin: This group of parameters appears when Increment Type is set to Custom.
Use this mini-curve editor for more precise control over the Spin of particles in your
particle system.
• Custom Spin: Use this control to adjust the value of the selected keyframe in the
mini-curve editor. This parameter appears when Custom is selected in the Increment
Type pop-up menu.
• Over Life: Use this slider to adjust the position of the selected keyframe in the life of
the particle. This parameter appears when Custom is selected in the Increment Type
pop-up menu.
HUD Controls
The HUD contains the Increment Type pop-up menu, and the Spin Rate, Spin At Birth,
and Spin At Death parameters.
Viewing Animated Emitter Curves in the Keyframe Editor
When you animate an emitter or cell parameter using keyframes, a curve describing that
animation appears in the Keyframe Editor. The selected object determines which curves
appear in the Keyframe Editor (when Animated is selected from the pop-up menu in the
top-left corner of the Keyframe Editor):
• Select the emitter to display animated emitter parameters such as Position and Rotation
(in the Properties Inspector) or Emission Angle and Range (in the Emitter Inspector).
• Select the cell to display animated parameters such as Birth Rate or Angle (in the Particle
Cell Inspector).
720 Chapter 14 Working with Particles