The Priority Tree, a HL/HSR Approach for PHIGS

The Programmer's Hierarchical Interactive Grahics System (PHIGS) specifies an interface for programming device-independent computer graphics applications. PHIGS provides a powerful data grouping mechanism, called the PHIGS structure, that may be used to model the geometry of 3D objects. Hidden Line/Hidden Surface Removal (HL/HSR) is a required process to produce realistic solid views of the modeled objects. Modeling clip is an essential process for viewing a clipped portion of the modeled objects. A technique is presented that provides HL/HSR and modeling clip as added utilities to PHIGS. The technique is based on the Binary Space Partitioning (BSP) tree (sometimes called priority tree), and involves a back to front sorting of the primitives of a PHIGS structure network to another PHIGS structure. Modeling clip is achieved by limiting the sorting to those primitives in a specified clip ping region of the object space. The resulting structure when displayed on a raster device produces a realistic view of the possibly clipped object that was originally modeled by the PHIGS structure network.     

A critical evaluation of PEX

PEX, the PHIGS extension to the X Window System, is evaluated in the context of assumptions inherent in the PHIGS output, modeling, input, user interface, and system environment models. Problems not previously discussed arise when examining PEX this way. The problems not only pertain to the implementation of PEX, but also to implementing a 3-D library in a distributed windowing system in general. The University of Illinois PEX implementation serves as a reference to discuss the solutions proposed     

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.     

基于PHIGS的层次图形数据库系统

程序员级的交互式层次图形系统支持动态的交互和层次结构的组织。实现图形系统的一个重要方面是图形模型的数据结构。本文论述了一个集中式图形数据库的设计与实现，该系统是一个实验性的基于ＰＨＩＧＳ的层次数据库系统。其设计的特点是此数据库可以被若干个应用程序共享。     

GosiP: A GKS3D Shell for PHIGS

Gosip is an implementation of a GKS-3D level 2c interface to PHIGS. It allows GKS applications to run on PHIGS platforms, offering performance and portability across a wide range of high-performance 3D workstations. Compatibility of the standards is reviewed. A selection of design solutions is given for the problems of error processing, non-retained primitives and attribute management. The concepts of Workstation Display Session and atmbute state are introduced. Some comments are made on implementation dependencies, performance and portability.     

PHIGS: A Standard, Dynamic, Interactive Graphics Interface

The Programmer's Hierarchical Interactive Graphics System (PHIGS) is a draft standard for computer graphics programming. PHIGS is useful for applications that manipulate complex displays of 2D or 3D data in a highly interactive environment. This is done through the hierarchical data organization and flexible editing capabilities provided in PHIGS. This article describes the goals and underlying model of PHIGS, reviews its capabilities, and provides some brief application examples. The similarities and differences of PHIGS and GKS are discussed.     

GKS Programming in a PHIGS Environment

GKS is an international standard for the functional interface to 2D graphics, whilst PHIGS is currently an ISO work item for 2D and 3D graphics. In addition, PHIGS allows improved control over structuring graphics data in the system. With a new work item, the upwards compatability from GKS to PHIGS is being called into question. This paper is an attempt to give direction to these discussions by listing the implications of introducing a software layer between a GKS application program and a PHIGS environment on which this application is to be run. It is intended to highlight differences between the systems and to answer questions such as, “How compatible?”, “Is it possible?”, “How much does the software layer have to do?”, etc.     

A Library for Developing PHIGS Programming Tools in a PEX Environment

The merger of three-dimensional graphics with the X Window System has recently been standardized by adapting PHIGS, the Programmer's Hierarchical Interactive Graphics System, to the X Window System with PEX, the PHIGS Extension to X. The standard programming library for PEX has been defined to be identical to PHIGS PLUS allowing PHIGS programs to port directly to the X environment. X uses a client server model to run applications as client processes which communicate with a server to perform graphical display and input. For improved performance, the PEX extension defines new server resources to reduce network traffic and to take advantage of graphics hardware existing on high-end servers. A side effect of this distributed model of computation is a distribution of PHIGS structures leading to a relaxation of the exclusive access which a PHIGS application usually maintains over its Central Structure Store. We exploit the distributed nature of a PEX/PHIGS client's Central Structure Store to provide access to it for other applications besides the originating PEX/PHIGS client. We refer to these other applications as tools since one of our primary goals is to create development tools for PHIGS programmers. Rather than concentrate on particular debugging tools, we focus upon easing the process of actually developing tools. Our goal is to supply a collection of routines which can be used by PHIGS programmers to create custom tools or other programs which require access to the graphics data of remote PHIGS processes. Our Tool Development Library provides the PHIGS programmer a small number of management routines which orchestrate the connection and mapping to the data of one or more remote PHIGS applications. Manipulation of remote PHIGS structures is accomplished just as easily as local operations and is performed using standard PHIGS calls. The remote application being accessed requires no changes to its source code. Obvious uses for the Tool Development Library are in the construction of PHIGS tools such as structure browsers, editors and debugging aids. Less obvious is the potential for developing collections of cooperating graphics applications which share graphics data.     

A Robust Distributed Adaptive Finite Element Program for Coupled Fluid-Structure Problems

This paper describes an implementation of an adaptive finite element program for coupled fluid-structure problems using a network of workstations. A pool of task programming paradigm suitable for a heterogeneous distributed workstation environment is presented. The issues of load balancing and fault recovery are explored. Numerical results for this distributed programming paradigm are presented and compared with sequential and parallel programming models.     

基于重用方法的软件开发环境

软件重用方法是提高软件生产率和质量、缓解软件危机的重要手段 .实施该方法的关键是提供一个帮助开发者实现软件重用的支撑环境 .为此 ,我们在 SUN工作站上设计并实现了一个基于可重用性的软件开发环境 RSDE.本文介绍了该环境的设计、实现和特点     

Parallel 3D Delaunay Triangulation

The paper deals with the parallelization of Delaunay triangulation algorithms, giving more emphasis to pratical issues and implementation than to theoretical complexity. Two parallel implementations are presented. The first one is built on De Wall, an Ed triangulator based on an original interpretation of the divide & conquer paradigm. The second is based on an incremental construction algorithm. The parallelization strategies are presented and evaluated. The target parallel machine is a distributed computing environment, composed of coarse grain processing nodes. Results of first implementations are reported and compared with the performance of the serial versions running on a Unix workstation.     

Integrating PHIGS and User Interface Systems

The past five years has seen an explosion of rich and effective user interface management systems and toolkits and an increase in the expectations regarding application portability. Nearly a decade old, the PHIGS input model is inadequate in the face of this variety. "Fixing PHIGS" input would be a long and arduous task. Instead, PHIGS should be adapted to cooperate, not compete, with user interface systems. This can be done in two ways. An application can use both PHIGS input and input from a user interface system to accomplish its goals. Alternatively, an application can use input only from a user interface system, but in this case it needs utilities in PHIGS to gain access to information only PHIGS can supply. Specifically the utilities are needed for application-initiated picking and for coordinate mapping.     

Ray Tracing and Graphics Standards

Existing standards for three-dimensional graphic representations are unable to produce any realistically shaded images (except PHIGS PLUS, which provides discrete shading only). Ray Tracing or Radiosity are not taken into account up to this time. This article is intended to show one way to integrate the Ray Tracing technique into the pipeline of the graphics standards GKS-3D and PHIGS. No modifications of the viewing concepts are required by our implementation.     

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.     

Top Draw: A Structure Network Visualiser for PHIGS

The Programmer's Hierarchical Interactive Graphics System (PHIGS) is an International Standard for computer graphics. PHIGS provides a flexible mechanism for creating hierarchical models from collections of directed acyclic graphs known as 'structure networks'. In practice, the combination of powerful data structuring facilities and the ability to dynamically edit structure networks can lead to a potential complexity which makes models difficult to manage and maintain reliably.
This paper presents TopDraw , a portable programming tool for visualising PHIGS structure networks, by automatically documenting their topology using diagrams. Drawing tidy representations of graphs algorithmically is a difficult problem, and most existing systems are large, complex and speciallsed The alternative approach taken in TopDraw is to use a fast, straightforward algorithm supplemented when necessary by an interactive 'tidief. A novel feature of TopDraw is that the diagrams it produces are themselves PHIGS structures, which the application may edit and manipdate as required. TopDraw is a component of the PHIGS Toolkit , an emerging set of portable integrated tools for PHIGS environments.     

A persistent graphics facility for the ICL PERQ

The facilities of the PS-algol programming language are described in this paper to show how they may be used to provide an integrated programming support environment. The persistent store mechanism and the secure transaction facilities provide the basic environment in which an integrated system may be implemented. In particular the paper makes use of the data type picture of PS-algol to show how such an environment may be built for a graphics system ideal for use with a medium range computer workstation. An implementation of a picture editor on the ICL PERQ workstation is described to show the utility of the system.     

Wsh—a new command interpreter for unix

WSH is a window managing command language interpreter (shell) for the UNIX operating system. This interface increases a user's power to communicate with UNIX by providing a process management environment based on an integrated virtual terminal-shell design. Unlike conventional shells, WSH affords its user the ability to monitor and communicate with multiple processes within a single display context. Windows represent virtual terminals in the WSH design, and as such are device-independent abstractions of real terminals. Since the design of the virtual terminal environment is based on UNIX's TERMCAP terminal database facility, WSH is portable across all versions of UNM supporting this feature. WSH requires neither alteration of existing UNIX facilities nor special display devices. The current implementation runs on a Digital VAX 11/780 under Berkeley UNIX 4.1 environment.     

Industrial workstation design: a systematic ergonomics approach

For the design of an industrial workstation, ergonomics guidelines are presented in a systematic manner. The guidelines provide a conceptual basis for a good workstation design. In a real world design situation, the implementation of the recommendations or guidelines needs the matching of the population anthropometry with the various components of the workstation. Adequate posture, work height, normal and maximum working areas, lateral clearance and visual requirement are determined for the intended user population. The procedure for determining the workstation dimensions and layout has been explained. The importance of building a mock-up of the designed workstation and its evaluation with representative subjects is emphasized. A case problem (supermarket checkstand workstation) is discussed to illustrate the workstation design procedure.