The Computational Geometry Column #4

areas of graphical input operations and text operations a s defined by these standards. It has been felt that the GK S input model is poorly suited to the needs of a windowin g environment. I believe, however, that the GKS input mode l as defined in the standards document is simply incomplet e and not fully understood. The original GKS input referenc e model developed at an ISO meeting in England in 1981 doe s satisfy most of the criticisms if properly integrated into th e systems environment. This reference model allow s applications to develop intelligent asynchronous processes fo r handling the input streams. Text is a more difficult situation. The text facilities in th e graphics standards are adequate for including limited amounts of textual material within an image which is primaril y graphical. However, modern PC environments often have a requirement for merging computer graphics and textua l material to produce high-quality combined output. This is n o more apparent than in the desktop publishing applications. I n the PC world. the Postscript language is becoming a de fact o standard for high quality output currently in the hard cop y arena and soon in the display arena. Postscript provides ver y powerful and flexible text manipulation facilities. These hav e been coupled with low-level graphical capabilities which, fo r little apparent reason, are somewhat incompatible with ANS I and ISO graphics concepts. [ believe that considerable benefi t could be derived from attempting to merge the Postscrip t textual capabilities into current ANSI and [SO standard s perhaps in their next revisions. At the same time, th e Postscript graphical capabilities should be replaced by ANS I and ISO standard graphical capabilities. An appropriat e forum might be the study group on graphical text bein g established within the ISO graphics standards committe e SC24. o The PC world is large enough to be independent o f standards not of its own making. Those who espouse this position are hiding their heads i n the sand. Computer graphics is a rapidly expandin g requirement in all fields of computing. The need to for al l levels of the computing community to interact with each othe r in a compatible fashion is clearly established. The bane o f most vendors is the need to convert from one format t o another. Adoption of computer graphics standards …