Game Development Reference
In-Depth Information
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Compatibility with existing VRML content, browsers, and tools.
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Extension mechanism to permit the introduction of new features, a quick
review of advancements, and the formal adoption of these extensions into
the specification.
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Small, simple “core” profile for widest-possible adoption of X3D support,
both importing and exporting.
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Larger, full-VRML profile to support existing rich content.
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Support for different encoding procedures, including XML for tight integra-
tion with Web technologies and tools.
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Architecture and process to advance the specifications and technology
rapidly.
X3D addresses the limitations of VRML. It is fully specified, so content will be
fully compatible. It is extensible, which means X3D can be used to make a small,
efficient 3D animation player, or can be used to support the latest streaming or
rendering extensions. It supports multiple encoding and various APIs, so it can
easily be integrated with Web browsers through XML, or with other applications.
In addition to close ties with XML, X3D is the technology behind MPEG-4's 3D
support.
The H-Anim (Humanoid Animation Working Group) model is the most com-
monly used approach to represent human beings. H-Anim is a set of specifica-
tions for description of human animation, based on body segments and connec-
tions. According to the H-Anim standard, the human body consists of a number
of segments (such as the forearm, hand and foot) which are connected to each
other by joints (such as the elbow, wrist and ankle). An H-Anim file contains a
set of Joint nodes that are arranged to form a hierarchy. Each Joint node can
contain other joint nodes, and may also contain a segment node, which describes
the geometry of the body part associated with that joint. Each segment is a
normal VRML transform node describing the 3D shape of the body part (the set
of points that constitutes a 3D surface). The Segments can also have a number
of site nodes, which define locations relative to the segment. The Sites can be
used for attaching clothing and jewelry, and work as end-effectors for inverse
kinematics applications. They can also be used to define eye points and viewpoint
locations. A Segment node may contain a number of displacer nodes that specify
which vertices within the segment correspond to a particular feature or configu-
ration of vertices. H-Anim will be used to describe the gestures.
MPEG-4 (MPEG-4 standard) is a toolkit for developing networked multimedia
applications based on any combination of audio, video, 2D, and 3D content.
Specifically, the MPEG-4 standard was designed for delivering both static and
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