Meta-Attributes for Graphics Collection Classes

摘要

Graphics syustems such as GKS, PHIGS, or GEO++ differ mainly in the way graphics entities can be grouped into collections and how attributes can be assigned to them. Besides the concept of collecting graphics primitives, the predominant structuring concept, additional constructs are used to filter out, select, or group specific subsets of the whole set of graphics objects. The paper introduces basic mechanisms to collect graphics entities and to assign attributes. These mechanisms are defined on a meta-level allowing one to extend a low level kernel and to interpret systems such as PHIGS, GKS-R, or GEO++ as special cases of one flexible system.