8

Particle Flow 105
Pa rti cle Fl ow
Particle Flow is a new, extremely versatile and
powerful particle system for 3ds Max. It employs
an event-driven model, using a special dialog
called
Part icle View (page 2–121) .InParticleView,
you combine individual
operators (page 3–1079)
that describe particle propert ies such as shape,
speed, direction, and rotation over a period of
time into groups called
events (page 3–1029) .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 operator in the list
andupdatestheparticlesystemaccordingly.
To achieve more substantial changes in part icle
properties and behavior, you can create a
flow
(page 3–1036)
. The flow sends particles from
event to event using
tests (page 3–1115) ,whichlet
you
wire (page 3–1127) 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, while
thosethatdon’tmeetthetestcriteriaremaininthe
current event, p ossibly to undergo other tests.
Note: Operatorsandtestsareknowncollectively
as
actions (page 3–997) .
Following are the principal sections in the Particle
Flow documentation:
Using Particle Flow (page 2–105)
Part icle Flow User Interface (page 2–121)
Actions (page 2–137)
The introductory tutorial (page 2–108) ,andthe
remaining P
article Flow Tutorials.
See also
Non-Event-Driven Particle Systems (page 2–233)
Using Par ticle Flow
Part icle View (page 2–121) is the primar y interface
forbuildingandmodifyingParticleFlowsystems.
The first event in the system is always a
global
event
, whose contents affect all particles in the
system. It has the same name as the Particle Flow
source icon. By default, the global event contains
asingleRenderoperatorthatspecifiesrendering
properties for all part icles in the system. You can
add other operators here to have them act glob ally,
such as Material, Display, and Speed. When you
use an operator globally, be sure not to u se 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 Par ticle 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 part icle system provides a basic global
event and birth event that serve as a useful starting
point for creating your own system. If you like,
you can instead start with an empty system that
lets you build a particle system from scratch.