Better Understanding through Formal Specification

The Graphical Kernel System (GKS) is now registered as an ISO International Standard for computer graphics programming. One of the major innovations of the Standard is the bundled specification of aspects, a mechanism which gives the applications programmer the ability to tailor the appearance of a picture independently on each of the workstations on which it is displayed, using the capabilities of the workstations. GKS also incorporates the traditional method of individual specification of aspects in which each workstation does the best it can to represent global aspect values. In this paper a formal specification technique, the Vienna Development Method (VDM), is used to describe aspect specification. The GKS model of aspect specification is progressively constructed from simpler models. Properties of these simpler models are formulated and the specifications are proved to conform to these. The properties are then traced through the more complex models. The paper demonstrates the applicability of formal specification to the design of graphics software and the ability of formal techniques to catalyse the deeper understanding of designs.     

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.     

Experiences with implementing GKS on a PERQ and other computers

Driven by a need for a graphics system that would provide a wider range of functions than is common and that would require less support effort when installed on about 50 mainframes, Rutherford Appleton Laboratory has implemented the Graphical Kernel System (GKS). The development project has used PERQ and VAX computers equally. This paper describes some of the design decisions and their effect on the resulting package. In particular, it describes the philosophy of the “workstation interface” and how this provides for devices and systems of greater complexity in the future. The way in which the facilities of the PERQ are matched to GKS concepts is outlined.     

Combining Graphics and Windowing Standards in the XGKS System

In the past few years we have seen the acceptance of standards for both two and three dimensional computer graphics. Also during this time, the workstation community has converged on a common windowing system. This paper discusses the problems encountered in implementing graphics standards such as GKS and PHIGS PLUS within the X Window System environment.     

GKS-9x: Some Implementation Considerations

The Graphical Kernel System (GKS) was published as an ISO standard for computer graphics programming in August 1985. GKS is now undergoing revision in ISO/IEC and at the time of writing the text of the Draft International Standard of GKS-9x was being finalized. This paper presents a way in which a key part of the new functionality in GKS-9x, namely namesets and selection criteria, can be implemented effectively.     

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.     

On developing a GKS driver architecture for raster workstations

The use of raster graphics devices needs adapting to graphics applications. The first graphics standard, the Graphics Kernel System GKS, defines a logical interface on an application and device independent level. The workstation driver maps the logical GKS functions to device functions. First some special raster device facilities are outlined and then it is shown how to use them within the driver. To reduce the amount of driver implementations a common driver concept is sought here, especially for raster devices.     

基于GPSS／H和GKS的FMS物流系统的动画仿真

本文介绍了在ｓｕｎ－３工作站上实现的ＦＭＳ动画仿真系统。该系统在开发Ｓｕｎ－３的ＧＰＳＳ／Ｈ及Ｓｕｎ ＧＫＳ软件的基础上，用Ｃ语言编制全部软件，具有良好的人机接口。利用该系统实现ＦＭＳ的动画仿真，具有易于建模和调试，开发周期短，符合标准化，易于验证正确性和可靠性等特点，为开发研制ＦＭＳ提供了有效的手段。这里着重介绍ＦＭＳ物流系统仿真的建模方法，软件设计以及仿真程序与动画程序的软件接口等。     

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.     

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.     

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.     

Abaqus在把手静态强度分析和优化中的应用

以电脑工作站侧板上的把手为研究对象,应用Abaqus/Standard模块模拟如何优化工作站中把手的结构和材料,使其满足设计需求,并避免工作站的把手在打开侧板的过程中由于强度不够而产生变形甚至断裂失效.     

Algorithms for Handling the Fill Area Primitive of GKS

The fill area primitive of GKS (Graphical Kernel System)¹ is one of the more powerful features which differentiates it from earlier device independent graphics software and systems. Its specification is extremely general in the form of a closed boundary, possibly self-intersecting, and whose interior can be filled in a variety of styles. However a complete implementation of this primitive is very complex. It is difficult to find a single graphics workstation incorporating this primitive in hardware or firmware. Most GKS implementations will have to include software for simulating the appearance of this primitive on the commonly available displays and hard-copy graphics devices. Correct and efficient algorithms are necessary for developing this software. Because of the generality many of the existing algorithms are not directly applicable. In this paper we describe:
1. a new algorithm for clipping a fill area polygon, using what we have named as the Bridge Technique.
2. implementation of a plane sweep algorithm, by Nievergelt and Preparata,² for solid filling and hatching, particularly applicable to vector devices.
3. extension of the plane sweep algorithm for filling with any given pattern on raster as well as vector devices.
The algorithms have been designed to work for all special cases as well. In fact they have been implemented having in mind the fill area set primitive of GKS-3D extension.³ All these algorithms have been very successfully implemented in a commercially available GKS implementation, namely indoGKS.     

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.     

Using GKS Concurrently: a Practical Solution

This paper analyses the use of GKS with concurrent languages, showing the inherent problems that arise when working in a multitasking environment. A theoretical solution and its practical implementation are described.     

New Methods for Improving the GKS Fill Area Output Primitive

The fill area primitive is one of the most powerful primitives of GKS and its derivatives (GKS-3D, PHIGS etc.). Since its specrfication is extremely general, it is important to explore new approaches to achieve higher performance in its implementation. In this paper fast algorithms are presented for special situations, which can be included, together with appropriate tests, into a complete GKS output pipeline. As a result, a speed improvement With a factor of two may be achieved in important practical cases.     

The GKS Input Model in Manifold

This paper describes the specification of the GKS input model in M anifold . The aim of the work reported in this paper was two-fold: first, to review the communication patterns implied by the GKS input model, and second, to evaluate the suitability of the M anifold language as a tool for defining complex dynamic interaction patterns that are common in non-trivial user interfaces.
The GKS input model is also adopted by all more recent ISO graphics standard documents. A more formal scrutiny of the inter-communication of the components of this model, excluding the implementation details of their functionality, is instructive in itself. It can reveal directions for improvement of its shortcomings and for generalization of its strengths for the ongoing effort to define the functionality of future graphics packages.
M anifold is a language for describing inter-process communications. Processes in M anifold communicate by means of buffered communication links called streams and by reacting to events raised asynchronously by other processes. Our experience shows that M anifold is a promising tool for describing systems of cooperating parallel processes. Our M anifold specification of the GKS input model offers a very flexible way to structure user defined logical input devices. Furthermore, it is simple and modular enough to allow easy extensions to include more functionality by local modifications. As such, it can serve as a basis for possible extensions and enhancements envisioned for future graphics packages.
1987 CR Categories: C.1.2, C.1.3, C.2.m, D.1.3, F.1.2, I.1.3, I.3.6, I.3.4.
1885 Mathematical Subject Classification: 68N99, 68Q10,68U05.     

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.