Graphics Programs Reference
In-Depth Information
An Overview of Dynamics and Maya Nucleus
Dynamics
is the simulation of motion through the application of the principles of physics.
Rather than assigning keyframes to objects to animate them, with Maya dynamics you
assign physical characteristics that define how an object behaves in a simulated world.
You create the objects as usual in Maya, and then you convert them to
dynamic bodies
.
Dynamic bodies are defined through dynamic attributes you add to them, which affect
how the objects behave in a dynamic simulation.
Dynamic bodies are affected by external forces called
ields
, which exert a force on
them to create motion. Fields can range from wind forces to gravity and can have their
own specific effects on dynamic bodies. You'll learn how to use fields later in this chapter.
In Maya, dynamic objects are categorized as bodies, particles, hair, and fluids.
Dynamic bodies are created from geometric surfaces and are used for physical objects
such as bouncing balls.
Particles
are points in space that have renderable properties and
that behave dynamically. Particles are used for numerous effects, such as fire and smoke;
they're also useful in tons of other situations and, as such, are a specialty of their own for
professional animators. We'll cover particle basics in the latter half of this chapter.
Hair
consists of curves that behave dynamically, such as strings.
Fluids
are, in essence, volu-
metric particles that can exhibit surface properties. You can use fluid dynamics for natu-
ral effects such as billowing clouds or plumes of smoke.
Nucleus, which was introduced in Maya 8.5 with nCloth, is a more stable and inter-
active way of calculating dynamic simulations in Maya than the traditional dynamics
engine. Nucleus speeds up the creation and increases the stability of some dynamic
effects in Maya, including particle effects and cloth simulation (through nCloth).
In the Maya 2009 release, Autodesk introduced nParticles. They're closely related to
traditional particles in Maya but have been made easier to create and manage, requiring
less explicit expression controls than before.
We'll introduce nParticles (instead of traditional particles) later in this chapter; how-
ever, soft bodies, hair, nCloth, and fluid dynamics are advanced topics and won't be
covered in this topic.
Rigid and Soft Dynamic Bodies
The two types of dynamic bodies are rigid
and soft.
Rigid bodies
are solid objects, such as
a pair of dice or a baseball, that move and rotate according to the dynamics applied. Fields
and collisions affect the entire object and move it accordingly.
Soft bodies
are malleable
surfaces that deform dynamically, such as drapes in the wind or a bouncing rubber ball.
In brief, this is accomplished by making the surface points (NURBS, CVs, or polygon ver-
tices) of the soft body object dynamic instead of the whole object. The forces and collisions
of the scene affect these surface points, making them move to deform their surface.
In this section, you'll learn about rigid body dynamics.
