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Material Frequency Operator 189
If this value is the same as the rate at which
particles enter the event, then one ID is assigned
per particle. If it’s lower, then multiple particles
aregiventhesameID,orifit’shigher,thenthe
software increments the assig ned ID faster than
1perparticle.
For instance, if particles enter the event at intervals
of 1/60 of a second, and Per Second=30, then
each pair of particles will b e assigned the same
ID. Or if particles enter the event at intervals of
1/15 of a second, and Per Second=30, then the ID
is incremented (or changed randomly) twice per
part icle.
Per Pa r ti cle—Sets the number of p articles that must
appear b efore material ID assignment changes.
For example, If you set Per Particle=3, the material
ID changes every three particles.
If you set Per Par ticle to a number less than 1.0,
the s oftware then moves through the sub-material
list more rapidly than one (or more) particle per
ID.Thatis,thesoftwaredividesthisvalueinto
1.0, and adds the result to the current material ID
to obtain the next one. For example, with eight
sub-materials, if you set Per Particle=0.33, and
usetheCycleoption,thefollowingseriesofIDs
willresult:1,4,7,2,5,8,3,6,1,...Ingeneral,this
option is useful only with the Cycle option.
Loop—When on, a nd the last ID has been assigned,
the software loops back around to the first ID
and continues the cycle. When off, the software
assigns the last cycle ID to all subsequent particles.
AvailableonlywiththeCycleassignmentmethod.
Default=on.
For example, say you want the first eight particles
that enter the event to use different materials, and
all subsequent particles to use a ninth material.
To do s o, you would create a nine-sub-material
Multi/Sub-Object material and assign it to the
Material Static operator. Turn on Assign Material
ID, choose the Cycle assignment method, a nd set #
Sub-Materials=9. For Rate, use the default settings
of Per Particle and 1.0. Lastly, turn off Loop.
Uniqueness group
The Uniqueness se tting varies the sequence of
assigned IDs with the Random option.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Material Frequency Operator
Particle View (page 2–125) >ClickMaterialFrequencyin
an event or a dd a Material Frequency operator to the
particle system and then select it.
The Material Frequency operator lets you
assignamaterialtoanevent,andspecifythe
relative frequency with which each sub-material
appears on the particles. Typically, the material
is a Multi/Sub-Object or other compound
material, and you specif y the f requency by
setting a percentage for each of up to 10 different
sub-materials (or material ID). The software
assignsIDstoparticlesinarandomsequence,
based on these percentages. You can also use other
materials that use sub-materials, such as Double
Sided and Top/Bottom.
See also
Materials and Mapping in Particle View (page
2–186)
Material Static O perator (page 2–187)
Material Dy namic Operator (page 2–191)