2009

than recalculating the particle action. This is particularly useful with large or
complex particle systems, where playback, and particularly backtracking, are
slow because of the large amount of processing required. With caching on,
the particle system needs to be calculated only once for each frame, and
thereafter playback and moving among frames is significantly faster.
To cache an entire flow, add a Cache operator to the global event. To cache
an individual local event, add a Cache operator to it.
To determine how best to implement caching in your particle system, turn
on Particle View > Track Update > Update Progress, and then play the
animation or go to a frame relatively distant from the current frame. Observe
the particle diagram, and watch for events with actions that highlight longer
than a fraction of a second, or events with more activity than the rest. Any
such events could benefit from caching.
NOTE Use no more than one Cache operator per event, unless you’re using two:
one set up for viewports, and the other for rendering. Similarly, don’t use global
and local Cache operators in the same flow, unless one is set up for viewports,
and the other for rendering.
TIP When using real-time playback, if playback isn't fast enough, you can use the
Cache operator to speed it up. For best results, set the Viewport integration step
to the same value as the real-time playback speed, and set cache sampling to
Integration Step. For example, if the real-time playback speed is set to 1/4x, then
the Viewport Integration Step for viewport should be also set to 1/4 Frame, and
the Cache operator Sampling parameter should be set to Integration step. Thus,
because real-time playback is showing four times as many frames per second, and
the Cache operator has stored four times as many frames per second, the two are
synchronized. If the real-time playback speed is set to 2x or 4x, set the Viewport
Integration Step to Frame.
Procedures
Example: To use the Cache operator:
1 Start or reset the software, and then add a Particle Flow system.
2 Open Particle View.
3 In Particle View, go to Options menu > Track Update and turn on Update
Progress.
This lets you monitor calculation of the particle system by highlighting
actions in Particle View as the system executes them.
2936 | Chapter 14 Space Warps and Particle Systems