Virtual Reality and Java 3D - Interactive Web-Based Virtual Reality with Java 3D - page 2

(Rhyne, 1997). Very often, this is supplemented by the need for an interactive graphical
user interface that captures user inputs through appropriate mouse, window, and widget
functions. In terms of applications, computer graphics is an important subject in digital
media technologies, scientific visualization, virtual reality, arts, and entertainment.
The basic theory for computer graphics can be found in the references by Pokorny
(1994), Hearn and Baker (2006), and Foley, Dam, Feiner, and Hughes (2006). Very simply,
in 3D computer graphic application, the components in a particular scene are often defined
by using mathematical relationships or geometries. Specifically, these involve the use of
graphical primitives that correspond to basic geometrical shapes for constructing graphical
scenes. Each primitive may have many attributes including size and color.
To create 2D graphics, primitives such as line, circle, ellipse, arc, text, polygon, and
spline are frequently used. For more complicated 3D applications, the primitives employed
may include cylinder, sphere, cube, and cone. The main purpose of using these primitive-
based representations is to speed up rendering in real-time. This is especially important
in scenarios involving a large scale virtual world.
Since most display devices are 2D in nature, the projection or transformation of a 3D
world on a 2D screen is an inherent process in most applications. This is not a trivial task,
especially when there is a need to create immersive 3D effect by using lighting, volume,
and shadowing techniques.
While the use of static 3D graphical primitives may satisfies the requirements in
some cases, the ability for the user to interact with virtual or real objects in a 3D world
are needed in a lot more applications. As examples, interactive 3D graphics can provide
us with the capability to interact with movable objects or scenes, for exploring complex
structures, and to better visualize time varying phenomena and architecture design. In
general, with realistic interaction included in a 3D world, we arrive at what is commonly
known as virtual reality.
To create 3D computer graphical applications, a variety of programming tools may be
needed depending on the type of applications and hardware support available. A commonly

Figure 1. OpenGL rendering pipeline

IMAGING PATH

Unpack
Pixels

Pixel
Operation

Image
Rasterization

Image

Frame
Buffer

Texture
Memory

Fragment
Operations

Display List

GEOMETRY PATH

Unpack
Vertices

Vertex
Operation

Geometric
Rasterization

Geometry