The Specification and Implementation of GKS Application Software in ADA (R)

One of the most important uses of (interactive) computer graphics is as one of the tools available to a User Interface Management System (UIMS) for a variety of user-computer environments (UCE). Typical UCEs in vogue are Programming Support Environments (PSE), Expert System Builders (ESB), Office Automation systems (OAS). This paper concentrates on the conceptual relationship that exists between the users on the one hand and computer systems on the other. Such relationships are to be seen in the context of specific application domains. The two standards, GKS and Ada, are chosen to be the background against which the argument for a Software Methodology based on the Abstract Data Type approach, is presented. This has significant implications for a GKS binding to Ada and the development of GKS application software written in Ada. A collection of colour models is considered in detail.
Ada(R) is a registered trademark of the U.S. Government, Ada Joint Program Office.     

GKS certification—An overview

The rapid emergence of GKS implementations indicates the widespread acceptance of GKS as an international standard for computer graphics. It is essential however if the interests of the standard are to be preserved, that there be a feasible means of validating GKS implementations to ensure that adherence to the standard is maintained. This paper describes an overall methodology for GKS certification, and outlines in more detail the validation of data returned by GKS to an application program. Validation of output generated by GKS is discussed in general terms in this paper, and in more detail in other papers in this issue.     

GKS in Pascal

The design of the Pascal interface to the Graphics Kernel System is discussed and illustrated. The principles underlying the binding are given and examples show how some of the major features of GKS will look in Pascal. The examples cover graphical output, setting primitive representation, graphical input and inquiries.     

Evaluation of Standard Graphics Packages

In order to compare the quality of different implementations of GKS, the ISO0 standard for computer graphics, an evaluation method for GKS implementations is presented. It is based upon several groups of criteria. One group of criteria is concerned with performance, by which we understand here the memory requirements and time requirements for programs using GKS functions. A program that measures the performance of GKS packages is presented. Results of this evaluation method with several commercially available GKS implementations are described in summary. A checklist for evaluation of standard graphics packages is added as an appendix.     

A verifier for checking the conformance of programs with the GKS standard

A software development tool is introduced which allows to check the corrections of programs using the Graphical Kernel System (GKS). Such graphical application programs are checked whether their use of GKS functions is syntactically correct and conforms with semantic rules given by the GKS definition. Like the PFORT verifier for FORTRAN programs, this tool greatly reduces development time for GKS programs.     

A Multi-Microprocessor GKS Workstation

Implementers of graphical application sytems hesitate to interface their applications to the GKS standard not only because GKS functionality seems to be less suffcient for a particular application but also because the use of GKS-as it is offered in portable software implementions-uaually means a loss of system performance. This article describes an installation of GKS on a multi-microprocessor that is based on functional distribution principles as well as on the object-oriented distribution of a graphics system. The main concepts and advantages of a GKS workstation using more than one processing unit with at least one output pipeline are described. The flexibility of this approach opens a perspective view to a GKS workststion that is configurable to application requirements.     

A practical strategy for certifying GKS implementations

The question of how to validate GKS implementations is crucial to the success of GKS as an international standard for computer graphics. This problem has been addressed by a series of certification workshops sponsored by the EEC. A basic strategy for testing GKS implementations is outlined and progress towards the development of a test suite is reported.     

Formal Specification in the Revision of GKS: An Illustrative Example

The first ISO/IEC standard for computer graphics, the Graphical Kernel System (GKS) was published in August 1985. In accordance with ISO/IEC procedures, GKS is now being reviewed and revised. This paper describes how formal specification techniques are being used by the authors to analyse key parts of proposals being made for changes to the framework of GKS to bring the standard into line with the requirements of applications and the operating environment likely to be found in the mid-1990's.     

Filling Complex Polygons by Region-Fill Methods on Raster Graphics Terminals

A method is described for filling polygons according to the GKS Fill Area definition on terminals that provide only region-filling capabilities. The advantages and disadvantages of using this algorithm in GKS device drivers are considered.     

Functional conformance testing of graphics software using a configurable reference system

This paper introduces a scheme for conformance checking of GKS implementations with the given GKS standard specification[1] based on functional black box testing. Specific testing problems caused by the nature of graphics systems and a solution are presented. Thereby emphasis is laid on a software generation technique which allows to configure reference implementations from a suitable specification of GKS. The reference implementation is used to produce correct reference data the contents and formats of which are adjusted for the particular candidate implementation.     

GKS-the standard for computer graphics

GKS is about to be ratified as the first international standard for computer graphics. It will provide a unique base on top of which portable graphical applications software can be built. This paper traces the history of GKS and describes its main concepts.     

ADA† and NIL: Two Concurrent Languages for GKS

The Graphical Kernel System (GKS) has become an international standard in graphics programming and attempts are now being made to integrate it with multiprocessing, possibly in distributed systems. It is therefore necessary to consider new programming languages able to support distributed implementations of GKS. Among them, Ada and Nil are considered here, since they are particularly suitable for concurrent programming. They are compared and evaluated in those specific tools which may provide data safety, system reconfigurability, and availability to distributed programming. The structural philosophies of the two languages are emphasized and reconfigurable implementation schemata for GKS in both of them are then suggested.     

On Implementing Parallel GKS

This report investigates the problems involved in implementing the GKS 2D graphics standard in Occam. Whilst some of the detail is language specific, similar problems arise with implementations in any parallel system and the paper therefore has wider relevance. The main problems were found to be the lack of data types in Occam, parallel calls to the GKS implementation (which assumes a sequential command stream) and implementing a truly parallel GKS kernel. None of these problems appears to be insuperable, particularly if a preprocessor is used to overcome the potential communication and network conflicts which are possible in a parallel graphic system.     

At Last an ISO C Binding of GKS

The C⁴ bindings of GKS1 and other semantic computer graphics standards like GKS–3D² and PHIGS³ are long overdue. While GKS was completed in 1985 and GKS–3D² (and PHIGS³) became an international standard in 1988, none of their C bindings could be standardized, for the simple reason that the C language itself was not a standard. Instead, a host of de facto GKS/C bindings⁹ appeared.
This paper will give the flavour of the ISO C binding^5,6 of GKS; the main features will be outlined.
1983 CR Categories: D.3.0,I.3.0,I.3.4.     

Realization and Application of an Intelligent GKS Workstation

This articles summarizes the work at SIGMEX Systems Limited from its origin in 1982 just prior to the publication of the draft of the International Graphics Standard, GKS. This article covers the original concept of the GKS workstation as defined in the Standard, its realization, the practical implications, and the real-world application of the resulting intelligent workstation device.     

The Formal Specification of Level la of GKS

In this paper the formal specification of a part of level la of GKS is given in the algebraic specification language OBJ. It shows that it is possible to produce a formal specification of a substantial part of GKS which is of manageable size and complexity specifying the appropriate level of abstraction of the system and using a suitable formal technique.     

Standards in computer graphics

GKS, which recently became the International Standards Organization (ISO) standard for computer graphics programming, is the first of a set of interlocking graphics standards. This paper outlines the important ideas behind GKS, describes its relationship with other standards and discusses the benefits of standardization.     

An interactive FORTRAN 77 program using GKS graphics for 2.5 D modeling of gravity and magnetic data

An interactive 2.5 D gravity and magnetics modeling program has been written for an ICL PERQ 2 workstation using FORTRAN 77 and GKS graphics. All of the available hardware and software input devices are utilized through GKS to produce an easy-to-use menu-driven program. A large number of functions are controlled by the software in order than the user can concentrate on the model. A range of options also are provided for manipulating the observed anomaly. The use of FORTRAN 77 and GKS should make the program easily portable to other computer systems and graphics devices. The modular form of the program should facilitate readily further development including optimization and real time modeling, given a more powerful computer with high-speed graphics.     

3D extension to GKS

The Graphical Kernel System GKS has [1] been established as the first standard in the field of Computer Graphics covering two-dimensional (2D) graphics. Now work is going on to develop standards in related areas. One important effort is the extension of GKS for three-dimensional (3D) graphics. This paper will briefly overview the history of standardization efforts with respect to 3D graphics and then report the current activities of various national and international standardization bodies for extending GKS to 3D. Then the paper will concentrate on GKS-3D [2], a proposal for a 3D extension of GKS which is developed by the Dutch standardization committee NNI in close collaboration with the International Organization for Standardization ISO/TC97/SC21/WG2. Technical work is expected to finish in 1985. Scope and purpose of this future 3D standard and goals of the design are given and the functionality of the 3D extension is described in some detail. As technical work on GKS-3D is going on, changes may occur to the standard document. The major issues will be surveyed and trends will be sketched.