Animation Objects - Interactive Web-Based Virtual Reality with Java 3D - page 132

Chapter VII
Animation Objects
IntroductIon
We have discussed important Java 3D objects that are basically static in the last few chapters.
Starting from this chapter, we will be looking at universe and objects that are dynamic in
nature. Specifically, we will discuss issues on animation and interaction in this and the
next chapter, respectively.
As well demonstrated by popular interactive computer games, animation, and inter-
action are crucial in making a Java 3D world more interesting. Technically, animation is
associated with changes in graphical objects and images as time passes without any direct
user action, while interaction corresponds to any such change in response to an action or
input from the user (Tso, Tharp, Zhang, & Tai, 1999).
In any virtual reality or game application, animation and interaction are often crucial
and critical. Through animation, the user is able to have a more realistic feel of the real 3D
objects through looking at the object at different angles and perspectives. Through interac-
tion with these objects, the user will become more integrated into the virtual 3D world in
the same way as sensing our own reality in the real world.
Under Java 3D, the “behavior” class is used to define and control both animation and
interaction. However, note that the behavior class is an abstract class and cannot be directly
used (Stromer, Quon, Gordon, Turinsky, & Sensen, 2005). Instead, there are three classes
that extend the behavior class and that are commonly used. They are the “interpolator,”
the “billboard,” and the “level of detail (LOD)” class. Furthermore, we can create a new
behavior class by extending the behavior class to fit any special need.