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196 Chapter 11: Space Warps and Particle Systems
This setting determines whether Particle Flow
should update the cache automatically, or let you
do it manually. Default=Always.
•
Always—Chang ing any parameter under
the C ache operator’s purview causes it
automatically to update stored data from the
start of the current r ange (see next parameter)
to the current frame.
•
Manually—Updating occurs only when you
click the U pdate button, or clear the cache and
then move to a different frame.
Range—Sets the frame range within which the
Cache operator operates. Default=Active Seg ment.
•
Co mplete—The software caches the entire
animation.
•
Active Segment—Thesoftwarecachesonly
frames in the active segment, as defined by the
Start Time and End Time settings on the Time
Configuration dialog. This is the frame range
shownonthetrackbar.Youcanalsochange
theactivesegmentbyholdingdownALTand
CTRL and dragging the track bar with the left,
middle, or right mouse button.
•
Custom—The software caches only frames in
the custom range, as defined by the Cache
operator’s Start Time and End Time settings
(see following).
Note: If you cache only part of the animation,
Particle Flow c alculates particle behavior in
subsequent, non-cached frames using the
cached data. For example, if you cache frames
0 to 50, and then jump to frame 60, Particle
flow will calculate frame 51 based on the
cached data, and frames 52 to 60 based on each
previous frame.
Star t/End T ime—The first and last frames
of the range considered for caching when
Range=Custom (see above). Default=0, 30.
Note: Theframerangetimeframeisinabsolute
time; that is, in terms of the entire animation. If
you use a Cache operator locally, and specify a
frame range during which no particles are present
intheevent,ParticleFlowwon’tusethecache.
Sampling—Determines how often the Cache
operator samples and caches the animation.
Default=Every Frame.
•
Ever y Fra me—The software caches animation
data once per frame.
•
Integr ati on S tep—Thesoftwarecaches
animation data at each integration step, using
the Integr ation Step sett ing as specified in
the Use At setting (see above). If Use At is
settoViewport/Render,ituseslowerofthe
two Integration Step values. For example, if
Viewport is set to Half Frame, and Render to
1/8 Frame, the sampling rate would be eight per
frame.
•
Ever y Nth Frame—The software caches
animation data at f rame intervals s pecified by
the N value, below.
N—Determines the frame interval for c aching
when Sampling (above) is set to Every Nth Frame.
Default=5.
Forexample,withNsettothedefaultvalueof
5, the cache stores animation data for every fifth
frame.
Cache Test Res ult s—When caching particle data,
this caches the results of test actions as well.
Default=on.
This is important if Cache is used as a lo ca l
operator, and the next event doesn’t have a Cache
operator. For the next event to work properly, it
should receive particles from the current event.
Those particles result from the activity of a test
action. The Cache o perator can record the test
activity to play it back later.
If the Cache operator is used as a global operator,
thereisnoneedtocachethetestresults. Thisis
because the system has cache data for ever y event,