9.5.2

380 • CHAPTER 7
OBJECTS MENU • PARTICLES • 381
Seed
Seed is used to create the pattern of the particle stream. If you copy an emitter, you’ll notice that
both emitters generate exactly the same pattern. If you want each stream to be unique, set the Seed
of each emitter to a different value. For example, a seed value of 1 will create a completely different
stream than a seed value of 0.
Lifetime
Gives the length of time a particle will be visible. For example, if ying sparks are set to be visible for 20
frames, the particles will disappear after this time. This value also controls the length of the animation
sequence in the Timeline. Variation adds a deviation factor to the Lifetime value; i.e. individual particles
can live for a longer or shorter time, according to the size of the Variation value.
Speed
Indicates the speed of the individual particles, in units per second. The higher you set the value, the
longer the particle stream will be displayed in the viewport. Variation introduces randomness to the
speed. A value of 100% can make individual particles twice as fast, or twice as slow.
The speed can be set to 0. This can be useful if the emitter is animated, such as
travelling along a spline, and you want the emitter to leave a trail of particles
behind. Negative values can also be used. The emitter will then emit the
particle stream in the negative Z direction.
Rotation
Species the amount by which the particles will revolve around a spatial axis. Variation adds a
deviation factor to the value.
End Scale
Denes the nal size of the particles relative to their starting size. A value of 0.5, for example, will
shrink the particles to half their initial size. Variation denes a variable factor for the scaling so that
the particles are sometimes larger or smaller at the end of the animation.
Tangential
If this option is disabled, the local Z-axis of the individual object particles will always be aligned with
the Z-axis of the emitter. If the emitter orientation is animated, the local axes of each particle will be
rotated if necessary to maintain this relationship. When Tangential is enabled, object particles are
emitted with their Z-axis aligned with the emitter’s Z-axis, but the orientation of each particle’s local
axis does not change as the emitter’s orientation changes.