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194 Chapter 11: Space Warps and Particle Systems
Assign M aterial I D—
When on, the operator
defines a material ID number for each particle.
Default=on.
In general, this should remain on. Particle Flow
uses the material ID with the Particle Age map to
find the par ticle’s other proper ties, including its
life span and current age. And it uses the material
ID with compound materials to know which
sub-material to assign to a particle.
Show In V iewport—When on, the material is shown
applied to the particles in the viewports when the
particles are displayed as geometry.
Assignment Method
The Material D ynamic operator lets you assign
Mater ial IDs to particles in several different ways,
depending on whether you’re using an animated
texture or a compound material. Default=Same
As Particle ID.
Animated Texture group
Same As Par ticle ID—Assigns the same material ID
to a particle as its p a rticle ID. Choose this when
using a material containing an animated texture,
such as a Bitmap, Particle Age, or Particle MBlur
map.
Note: Particle Flow assig ns Particle IDs
consecutively to particles at birth, starting with 0.
AlthoughthehighestpossibleParticleIDisover
2,000,000,000, the highest possible material ID is
65535. Thereafter, the numbering sequence starts
again at 0. Thus, when using a Particle Age map
in a material assigned to the Material Dynamic
operator, for best results, use a total of 65,536
particles or fewer.
Reset Par ticle Age—When on, sets each particle’s
age to 0 when it enters the event.
When using an animated material with a Bitmap
map, turn this on to ensure that the animation
always plays from the first frame.
Randomize Age Offset—When on, the software
varies the difference between the particle age
and the starting material ID at random. The
maximum difference is determined by t he Max
Offset parameter.
Max Offset—The m aximum number of frames by
whichthesoftwarecanrandomlyvaryparticleage.
Sub-Material Rotoscoping group
These settings let you choose the basis on w hich
the operator changes material ID assignments
when using a compound material such as
Multi/Sub-Object, and specify the rate of change.
Material ID—Assigns the same material ID to all
particles. Use the numeric field to set the ID value.
Cycle—Assigns each particle a material ID in
the range 1 to N, where N=# Sub-Materials, in
increasing sequential order. The first ID assigned
is 1, then 2, continuing to increment each by 1
until N; then 1 again, and so on.
Random—Assigns each p article a random material
ID in the range 1 to N, where N=# Sub-Materials.
# Sub-Materials—The h ighest ID number assigned
to particles using the Cycle or Random option.
In general, set this to the same number of
sub-materials in t he Multi/Sub-Object material. If
you set it to a smaller number, the operator w i ll
use only that many sub-materials, starting with the
first and counting upward.
Note: The software automatically sets this value
to the number of sub-materials in the material,
once only, the first time you apply the material
to the operator. Any subsequen t changes in the
material itself, or apply ing a different m aterial to
theoperator,willnotchangeorupdatethesetting.
Rate Per Sec(ond)—Sets the number of times
per second that the assigned material ID is
incremented. If this value is t he same as the rate
at which particles enter t he event, then one ID is