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Cache Operator 193
upper-left corner of the map, and W is useful only
w ith three-dimensional maps, in which context
it spe cifies depth.
Sync B y—Choose the time frame for applying
animated parameters. For further information, see
Animation Offset Keying group (page 2–155) .
•
Absolute T ime—Any keys set for parameters are
applied at the actual f rames for which they’re
set.
•
Particle Age—Any keys set for par ameters are
applied at the corresponding frames of each
particle’s existence.
•
Event Duration—Any keys set for parameters
are applied to each particle starting when it first
enters the event.
Channel group
The Channel setting determine s whether the
mapping is applied to a map channel or to a vertex
color channel.
Ma p Channel —The mapping is applied to the
specified map channel.
Ver tex Color Channel—The mapping is applied to
the particles’ vertex color channel.
Show M a p In Viewport —The map coloring is visible
in the viewports.
Other
Cache Operator
Particle View (page 2–121) >ClickCacheinaneventor
add a Cache operator to the par t icle system and then
select it.
The Cache operator records and stores particle
states to memory. When it’s in effect, the first time
you play or go to a frame, the particle motion
up to and including the frame is calculated and
recorded in the cache. Thereafter , playing the
frame or any previous f rames uses the data in
the cache, rather than recalculating the particle
action. Thisisparticularlyusefulwithlargeor
complex particle systems, where playback, and
particularly backtracking, are slow because of the
large amount of processing required. W ith caching
on, the particle system needs to be calculated only
once for each frame, and thereafter playback and
movingamongframesissignificantlyfaster.
Tocacheanentireflow,addaCacheoperatorto
the global event. To cache an individual local
event, add a Cache operator to it.
To determine how best to implement caching in
your p art icle system, tur n on Particle View >
Track Update > Update Progress, and then play the
animation or go to a frame relatively distant from
thecurrentframe.Observetheparticlediagram,
and watch for events with actions that highlight
longerthanafractionofasecond,oreventswith
more activity than the rest. Any such events could
benefit f rom caching.
Note: UsenomorethanoneCacheoperatorper
event, un less you’re using two: one set up for
viewp orts, and the other for rendering. Similarly,
don’t use global and local Cache operators in the
same flow, unless one is set up for viewpor ts, and
the other for rendering.
Tip: When using real-time playback, if playback
isn’tfastenough,youcanusetheCacheoperator
to speed it up. For best re sults, set the Viewport
integration step to the same value as the rea l-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 View por t
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