Glossary
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## Glossary

arena

  A portion of memory shared by OpenGL Performer processes.

billboard

  A slice of a geometry that rotates with the viewer so that the entire geometry appears rendered, even though only a slice of it has been rendered.

channel

  A view of objects in a scene, based on the location and orientation of the camera in the scene viewing frustum.

cull

  Eliminates all geometries out of view from rendering.

clip texture

  Virtualizes MIPmapped textures using hardware and software support, so that only the texels in the region close to the viewer (known as the clipped region) need to be loaded in texture memory. (Also known as ClipMap.)

dynamic shared object (DSO)

  An object that can be shared between applications at run time.

dynamic link library (DLL)

  The Microsoft Windows equivalent of a dynamic shared object (DSO).

frustum

  Computer-generated objects can be projected into an artificial viewing area, called a frustum. A frustum is in the form of a truncated pyramid, shown in Figure 5-3, between the base of the viewing volume, called the far plane, and the near plane.

heap

  A portion of memory reserved for graphics.

libpf

  The pf Performer library; a higher level library that relies on libpr.

libpr

  The pr Performer library containing basic Performer tools.

libpfdu

  The du Performer library containing database utilities, helpful for loading scene graphs.

load

  (1) Transferring from disk to memory. (2) The processing burden of rendering a frame, and can be defined as the rendering time divided by the desired frame period.

model view

  Same as object space.

node

  A class derived from pfNode. A node can be part of a scene graph.

object space

  A coordinate system in a subsection of a scene graph. Also referred to as model view.

Perfly

  The demonstration program distributed with OpenGL Performer.

pipe

  Renders the visual data, contained in the viewing frustum, to a window.

scene graph

  A hierarchy of nodes. The hierarchy specifies the order in which the nodes are processed.

stress

  Stress is directly related to the graphics load; the more complex the display, the higher the system stress.

texture mapping

  Applies textures, such as the appearance of an orange, to the surface of a geometry.

traversal

  An scene graph action, such as a draw action, going from one node to another.

viewing frustum

  A truncated pyramid defined by the near and far clipping planes, and by the horizontal and vertical field of view. See Figure 4-3. Only those shapes in the frustum are visible to the viewer.

viewing volume

  The viewing volume is the pyramid, shown in Figure 5-3, formed between the eyepoint and the vertical and horizontal field of view.

viewport

  A viewport refers to each channel in a window.

world space

  The coordinate system of the root node, in which all shapes in a scene graph can reside.

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