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Chapter 6
Particle Dynamics
W
    shi focus now and cover an aspect of Maya that can be used
to simulate particle dynamics. Maya has engines that can simulate two dierent
aspects of real-world physics. e rst involves the emission of particles, their semirandom
behavior, and their interaction with each other and with objects in a scene. e second
involves the physics of colliding objects, which we will look at in Chapter 11.
Particle dynamics are useful for situations where a large number of small objects are
needed to properly construct a scene. In short, particle dynamics can scale to many
hundreds or thousands of individual particles. is capability can be used to model
smoke, re, rain, and water. Particle dynamics can be used to make realistic cloth as
well. Particles can be used to create eects where each particle is visually distinct or
where the particles seem to form an organic mass where the boundaries of each particle
cannot be identied visually. When we use particle dynamics, we tend to call the model
a “special eect.
e general idea is to create an object, oen called an “emitter,” which will generate
many geometrically identical objects. Typically, we also include a random factor that
causes individual particles to have semi-independent movements and visual qualities, as
we are oen trying to model a chaotic eect.
We can program the emitter to incrementally produce particles over the course of some
number of frames; this is how we might produce rain. But when modeling an ocean, we
might want to generate all the particles but not render them or their movement until the
complete body of water has been made.
USE EMITTERS SPARINGLY
ere are some complications that occur when using particle dynamics in an animated
project. Perhaps the most signicant is that particle dynamics can radically increase render
times. Imagine an ocean scene created with an emitter. Water scenes are oen impressive
visually; the surface can be alive with whitecaps, ripples, and waves. But this means that
the position and appearance (how it reacts to light) of every single particle could poten-
tially change in every single frame. For many of us who are creating animated scenes on

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