[Hill: 379-385. Foley & van Dam: p. 239-242]
View Volumes
View volumes are used for:
- clipping objects which will not project onto the image
- restricting the domain of z for visibility calculations
A perspective view volume:
An orthographic view volume:
Clipping operations could be carried out directly based upon the view volumes
defined, but is simpler using a canonical view volume. The coordinate
system is referred to as the normalized device coordinate system or
NDCS.
OpenGL Canonical View Volume
The transformation from VCS to NDCS can be conveniently viewed as
part of the projection transformation, as we shall see shortly.
Viewport Transformation
- NDCS to DCS
- simple translate and scale