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Glossary




avatar
The software representation of a person as the person appears to others in a shared virtual universe. The avatar may or may not resemble an actual person.

branch graph
A graph rooted to a BranchGroup node. See also scene graph and shared graph.

CC
Clipping coordinates.

center ear
Midpoint between the left and right ear of the listener.

center eye
Midpoint between the left and right eye of viewer. This is the head coordinate system origin.

compiled
A subgraph may be compiled by an application using the compile method of the root node-a BranchGroup or a SharedGroup-of the graph. A compiled object is any object that is part of a compiled graph. An application can compile some or all of the subgraphs that make up a complete scene graph. Java 3D compiles these graphs into an internal format. Additionally, Java 3D provides restricted access to methods of compiled objects or graphs. See also live.

compiled-retained mode
One of three modes in which Java 3D objects are rendered. In this mode, Java 3D renders the scene graph, or a portion of the scene graph, that has been previously compiled into an internal format. See also retained mode and immediate mode.

content branch
A branch graph that contains content-related leaf nodes, such as Shape3D nodes. No viewing-specific nodes are contained in a content branch.

DAG
Directed acyclic graph. A scene graph.

EC
Eye coordinates.

frustum
See view frustum.

group node
A node within a scene graph that composes, transforms, selects, and, in general, modifies its descendant nodes. See also leaf node and root node.

HMD
Head-mounted display.

image plate
The display area; the viewing screen or head-mounted display.

immediate mode
One of three modes in which Java 3D objects are rendered. In this mode objects are rendered directly, under user control, rather than as part of a scene graph traversal. See also retained mode and compiled-retained mode.

IID
Interaural intensity difference. The difference between the perceived amplitude (gain) of the signal from a source as it reaches the listener's left and right ears.

ITD
Interaural time difference. The difference in time in the arrival of the signal from a sound source as it reaches the listener's left and right ears.

leaf node
A node within a scene graph that contains the visual, auditory, and behavioral components of the scene. See also group node and root node.

live
A live graph is any graph that is attached to a Locale object, or a shared graph that is referenced by a live graph. A live object is any object that is part of a live graph. Live objects are subject to being traversed and rendered by the Java 3D renderer. Additionally, Java 3D provides restricted access to methods of live objects or graphs. See also compiled.

LOD
Level of detail. A predefined Behavior that operates on a Switch node to select from among multiple versions of an object or collection of objects.

polytope
A bounding volume defined by a closed intersection of half-spaces.

retained mode
One of three modes in which Java 3D objects are rendered. In this mode, Java 3D traverses the scene graph and renders the objects that are in the graph. See also compiled-retained mode and immediate mode.

root node
A node within a scene graph that establishes the default environment. See also group node and leaf node.

scene graph
A collection of branch graphs rooted to a Locale. A virtual universe has one or more scene graphs. See also branch graph and shared graph.

shared graph
A graph rooted to a SharedGroup node. See also branch graph and scene graph.

stride
The part of an interleaved array that defines the length of a vertex.

three space
Three-dimensional space.

view branch
A branch graph that contains a ViewPlatform leaf node and may contain other content-related leaf nodes for geometry associated with a viewer.

view frustum
A truncated, pyramid-shaped viewing area that defines how much of the world the viewer sees. Objects not within the view frustum are not visible. Objects that intersect the boundaries of the viewing frustum are clipped (partially drawn).

VPC
View platform coordinates.


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