2009

Interface
The user interface appears in the parameters panel, on the right side of the
Particle View dialog.
Speed The particle speed in system units per second. Default=300.
A positive Speed value moves the particles in the direction determined by the
Direction setting; a negative Speed value moves the particles in the opposite
direction.
NOTE Speed sets each particle's speed once only: when the particle enters the
event (or is born, in the case of a birth event). If you animate the Speed value,
particle speed does not vary: rather, each particle is given a constant speed equal
to the current Speed value when it enters the event.
Variation The amount by which particle speed can vary, in system units per
second. Default=0.0.
To obtain each particle's speed, the system multiplies the Variation value by
a random number between -1.0 and 1.0, and then adds the result to the Speed
value. For example, if Speed=300 and Variation=100, then each particle's speed
would be between 200 and 400.
Direction group
The Direction drop-down list lets you specify which way the particles go after
they're born. Default=Along Icon Arrow. In most cases, the actual direction
also depends on the icon orientation. The primary exception is when Position
> Location is set to Pivot.
2874 | Chapter 14 Space Warps and Particle Systems