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204 Chapter 11: Space Warps and Particle Systems
This is a compromise method of operation, and
can be used with renderers that cannot handle all
particles in a single mesh, but can deal w ith groups
of particles of a certain size.
Mesh Count—The maximum number of mesh
objects that Particle Flow will send to the renderer.
Particles p/Mesh—The number of p articles that
each mesh object will com prise.
Mesh Per Par ticle—Sends the renderer a separate
mesh for each particle.
This is the least efficient method of operation, but
might be required by certain renderers.
Note: With the default scanline and mental ray
renderers, this method does not support rendering
of particles born after the start of the rendered
framesequence.Ingeneral,useMeshPerParticle
only with renderers that require it.
Script Operator
Particle View (page 2–121) > Click Script Operator in an
event or add a Script Operator to the particle system and
then select it.
The Script operator enables control of particles
within the Particle Flow system using a MAXScript
script. The script can use any program
functionality available to MAXScript.
When you add a new Script operator, it contains a
defaultscriptthatslowsparticles,andthen,when
they are slow enough, splits off the first 50 particles
into a stream traveling in a negative direction on
the world X axis, and the remainder traveling in
theoppositedirection.
Tip: You c an use MAXScript to a lign particle scale
w ith the underlying bitmap, thus providing a
“scale bitmap” function. This requires a sandwich
with three operators: two Script operators, and a
Speed By Surface operator in between. The first
Script operator reads the current speed vector into
the MXVec tor channel, thus caching the current
speed. The Speed By Surface operator changes the
speed according to the underlying bitmap. And
the second Script operator reads the speed channel
into a temporar y var iable, restores the speed from
the MXVector channel (the cached value), and
uses the temporary variable to define the scale.
This way, the or iginal speed is restored, and the
scale value is defined by the bitmap.
Interfa ce
The user interface appears in the parameters panel,
on the right side of the P article View dialog.
Edit S cr ipt—Clickthisbuttontoopenthecurrent
script in a MAXScript Editor window.
For detailed information about the MAXScript
utility, open the MAXScript Reference, available
from Help menu > MAXScript Reference.
Uniqueness group
The Uniqueness setting provides a randomizat ion
seed that the s cript can use or ignore.
Seed—Specifies a randomization value.
New—Calculates a new seed using a randomization
formula.
Fl ows
The flows category contains two operators for
creating initial particle system setups. These are: