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Variation Specifies the number of frames by which the life of each particle
can vary from the norm.
Subframe Sampling Turning on any of the three check boxes below helps
avoid particle "puffing" by sampling particles at a much higher subframe
resolution, instead of the relatively coarse frame resolution. Depending on
your needs, you can do this over time, over motion, or over rotation. "Puffing"
is the effect of emitting separate "puffs" or clusters of particles, rather than a
continuous stream. This effect is especially noticeable when the emitter is
animated.
■ Creation Time Enables the addition of a time offset to the equations of
motion that prevents puffing in time. This setting has no effect with the
Object Fragments particle type. Default=on.
■ Emitter Translation If the object-based emitter is moving in space,
particles are created at integral times at positions along the geometry's
path between renderable positions. This prevents puffing in space. This
setting has no effect if Object Fragment particle type is on. Default=on.
■ Emitter Rotation If the emitter is rotating, turn this on to avoid puffing
and produce smooth spiral effects. Default=off.
IMPORTANT Each additional subframe sampling check box that you turn on
progressively increases the necessary computation. In addition, the methods
are listed in order of least amount of computation to most. Thus, Emitter
Rotation is more costly than Emitter Translation, which is more costly than
Creation Time.
Particle Size group
These spinners specify the size of the particles.
Size This animatable parameter specifies the target size for all particles in the
system, depending on the type of particle:
■ Standard Particles The major dimension of the particle.
■ Constant The dimension, in rendered pixels, of a Constant type of
particle.
■ Object Fragments No effect.
Variation The percentage by which the size of each particle may vary from
the norm. This is applied to the Size value. Use this parameter to get a realistic
mix of large and small particles.
3052 | Chapter 14 Space Warps and Particle Systems