9

Particle Flow 109
Pa rt icle Fl ow
Particle Flow is a new, extremely versatile and
powerful par ticle system for 3ds Max. It employs
an event-driven model, using a special dialog
called Particle View (page 2–125).InParticleView,
you combine individual operators (page 3–985)
that describe particle properties such as shape,
speed, direction, and rotation over a per iod of
time into groups called events (page 3–935).Each
operator provides a set of parameters, many of
which you can animate to change particle behavior
during the event. As the event transpires, Particle
Flow continually evaluates each operat or in the list
andupdatestheparticlesystemaccordingly.
To achieve m ore substantial changes in particle
properties and behavior, you can create a flow
(page 3–942). The flow sends particles from event
to event using tests (page 3–1021),whichletyou
wire (page 3–1033) events together in series. A
test can check, for example, whether a particle
has passed a certain age, how fast it’s moving, or
whether it has collided with a deflector. Particles
that pass the test move on to the next event, w h ile
thosethatdon’tmeetthetestcriteriaremaininthe
current event, possibly to undergo other tests.
Note: Operatorsandtestsareknowncollectively
as actions (page 3–903).
Following are the principal sections in the Particle
Flow docum entation:
Using Particle Flow (page 2–109)
Par t icle Flow User Interface (page 2–125)
Actions (page 2–141)
The P
article Flow Tutorials.
See also
Non-Event-Dr iven Particle Systems (page 2–237)
Using Par ticle Flow
Particle View (page 2–125) is the primary interface
forbuildingandmodifyingParticleFlowsystems.
The first event in the system is always a global
event, whose contents affect al l particles in the
system. It has the same name as the Particle Flow
source icon. By default, the g lobal event contains
asingleRenderoperatorthatspecifiesrendering
properties for all particles in the system. You can
add other operators here to have them act globally,
such as Material, Display, and Speed. When you
use a n operator globally, be sure not to use the
same operator locally (that is, in any other events
in the system) to avoid potential conflicts.
TheglobaleventalsoservesastheParticleView
representation of the particle system. You can
create a new system by duplicating this event,
or by adding an Empty Flow or Standard Flow.
Conversely, if you clone the Particle Flow icon in a
viewport,oraddanewPFSource,thenewsystem
appears in Particle View as well.
The second event is called the birth event,because
it must contain a Birth operator. The Birth
operator should exist at the top of the birth event,
and in no other place. The default birth event also
contains a number of operators that act locally to
specify properties of particles while in that event.
The default particle system provides a basic global
event and birth e vent that serve as a useful starting
point for creating your own system. If you like,
you can instead star t with an empty system that
lets you build a particle system from scratch.