Computer aided design (CAD) software delivered by vendors is seldom complete.
Customizing and/or developing new software is inevitable. A recent survey indicates
that most companies purchase or write custom computer aided design software tailored
to their specific needs. Design of such software requires the development of modeling
tools for the creation of CAD geometry. This research investigates the capabilities of
the proposed graphics standard, PHIGS plus, as a geometric modeling interface in CAD
that off-loads many basic modeling functions to PHIGS. Specifically, how the B-spline
modeling capabilities of PHIGS plus can be enhanced through the use of a new
modeling interface prototype is examined. This prototype consists of a proposed
graPHIGS modeling toolbox based entirely on PHIGS plus concepts. The prototype
provides functionality to easily create B-spline curves and surface geometric entities
based on data points and continuity constraints. Functionality is also included to easily
perform modeling operations on B-spline surfaces such as intersection and trimming.
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