2009

Interface
The user interface appears in the parameters panel, on the right side of the
Particle View dialog.
The first interface element is a drop-down list that lets you choose the type
of measurement to test:
■ Velocity Magnitude Tests the particle velocity, in system units per second,
without consideration of direction. This is the default test type.
■ Velocity X/Y/Z Tests the particle velocity on the specified axis, in system
units per second, using the world coordinate system.
An example of this option would be with fireworks: As the particles move
upward, their velocity on the world Z axis is positive. When the reach the
top of their trajectory and begin to move downward, their velocity on the
world Z axis slows to 0, and then becomes negative. If you choose Velocity
Z and Is Less Than Test Value, and set Test Value to 0.0, you can send
particles to another event at the moment they begin to move downward.
■ Acceleration Magnitude Tests the particle acceleration (change in
velocity), in system units per second per second, without respect to
direction.
■ Acceleration X/Y/Z Tests the particle acceleration (change in velocity)
on the specified axis, in system units per second per second, using the
world coordinate system.
■ Steering Rate Tests the circular component of particle travel in degrees
per second, without consideration of rotation or spinning.
2996 | Chapter 14 Space Warps and Particle Systems