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Timing group
Timing parameters control the "birth and death" rates of emitted particles.
At the bottom of the Timing group is a line that displays the maximum
sustainable rate. This value is based on the Render Count and the lifetime of
each particle. To be precise:
maximum sustainable rate=Render Count/Life
Because the number of particles in a frame never exceeds Render Count, if
the Birth Rate exceeds the maximum rate, the system will run out of particles,
pause until some die off, and then start again, generating bursts or spurts of
particles.
Start Number of the first frame where particles appear.
Life The lifetime of a particle, in number of frames.
Birth Rate The number of new particles born per frame.
If this is less than or equal to the maximum sustainable rate, the particle
system generates an even flow of particles. If it is greater than the maximum
rate, the particle system generates particles in bursts.
You can animate the Birth Rate parameter.
Constant When on, Birth Rate is unavailable and the birth rate used equals
the maximum sustainable rate. When off, Birth Rate is available. Default=on.
Turning Constant off does not mean that the birth rate varies automatically;
the birth rate remains constant unless you animate the Birth Rate parameter.
Emitter Group
The emitter specifies the area where particles appear in the scene. It has a
geometry you can display in viewports, but it isn't renderable.
The emitter is displayed as a rectangle with a vector pointing out of one side.
The vector shows the direction in which the system emits particles.
You set emitter parameters in the Emitter group of the particle system's
Parameters rollout.
Width and Length You implicitly set the initial value of these parameters
when you drag in a viewport to create the emitter. You can adjust the values
in the rollout.
The space occupied by the particle system at any given time is the result of a
combination of its initial parameters (size of the emitter, and speed and
variation of emission) and any space warps that have been applied.
3024 | Chapter 14 Space Warps and Particle Systems