Graphics Reference
In-Depth Information
Table
.
.
X
D Viewers
Product
Type
OS
License
Octaga Player
Viewer
Linux, Windows
Commercial
Octaga Professional
Viewer
Windows
Commercial
Flux Player
Plug-in
Windows
Commercial
FreeWRL
Viewer, Plug-in
Java, Linux, MacOS X
GPL-style
Xj
D
Viewer
Linux, MacOS X, Windows
GPL-style
FreeWRLisanopen-sourceX
D/VRMLbrowserandplug-in.Platforms that sup-
port FreeWRL include MacOS X, Linux, Unix, IRIX, and Java. Other plug-ins for
MS Windows are Flux Player, OpenWorlds and Vcom
D Venues. Xj
D is a project
of the Web
D Consortium (Web
D Consortium,
) that focuses on the creation
of a toolkit for VRML
and X
D content written completely in Java. A standalone
viewer is included.
Basic Structure
18.4.2
he first line is the XML declaration, and the second and third lines are the DTD
declaration. he root element of X
D is the
<X3D>
tag (called a node in X
D), with
a
version
attribute that specifies the version of X
D and a
profile
attribute
that specifies the profile. he X
D world is described with the
<Scene>
node, by
arranging its contents appropriately. he default background color is black.
Node and Field
Since X
D uses an object-description format, the world or components consist of
D, multimedia and interactive objects. An object is described by a nest of nodes,
and the parameters of an object are described as fields. New components can reuse
the grouping and prototype of an existing node.
Standard Units and Coordinate System
X
D defines the unit of measurement of the global coordinate system as the meter.
Allother coordinate systems aregenerated fromtransformations based onthe global
coordinate system. he unit of linear distance is the meter. Angles are given in radi-
ans, and time is given in seconds. he color space is specified by three real numbers
(RGB) between
and
, e.g.,
'1 0 0'
for red.
X
DusesaCartesian, right-handed andthree-dimensional coordinate system.By
default, the viewer is positioned along the positive z-axis, looking in the z-direction
withthe+y-axisdirectedupwards.Amodelingtransformation(
<Transform>
and
<Billboard>
) or viewing transformation (
<Viewpoint>
) can be used to alter
this default projection.
