PHIGS中NURBS曲线曲面方法及应用

非均匀有理Ｂ样条（ＮＵＲＢＳ）曲面由于在复杂零件的设计制造中的表现出众多的优点，从而在ＣＡＤ／ＣＡＭ系统中得到广泛的应用。本文在介绍ＰＨＪＧＳ中ＮＵＲＢＳ曲线曲面方法及特点的基础上，讨论了ＮＵＲＢＳ曲线的次数、节点矢量及权的选取。并结合造型系统的开发，提出了一种基于ＮＵＲＢＳ曲线曲面的准Ｂ Ｒｅｐ造型方法，最后，给出了在ＩＢＭＲＩＳ／６０００ ３２０Ｈ工作站上实现的应用实例。     

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.     

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.     

Triangle Sets in PHIGS PLUS: a Valuable Link with Finite Element Modeling

At the ISO/IEC editing meeting on PHIGS PLUS1 in Villars sur Ollon, Switzerland from 9 to 14 September 1990, an additional output primitive was added to PHIGS PLUS: TRIANGLE SET 3 WITH DATA together with its 2D shorthand. The principal reason for that addition was that only triangular primitives admit uniquely defined interpolation of data (colours, normals, etc.) across the facet.
However, an additional advantage of this new primitive is its value for the visualization of scientific computing results. It corresponds in a very pleasant way with the Finite Element Method using piecewise linear blending functions on a triangular partition of the function domain.
In this paper, an outline will be given of the possible use of this function by Finite Element engineers.
1983 CR Categories: G.1.1, G.1.2,I.3.2,I.3.5,I.3.7, J.6.     

基于图形标准PHIGS的用户界面的设计与实现

ＰＨＩＧＳ是一种面向程序员的层次式交互图形系统国际标准，其特点是使用户能方便地描述三维图形，并在最大程度上独立于硬件环境开发应用程序。本文在介绍ＰＨＩＧＳ国际标准人机交互功能的基础上，根据用户界面设计的基本原则，充分利用ＰＨＩＧＳ所提供的种类功能函数，提出了更为灵活和实用的用户界面设计方法，并在ＩＢＭ ＲＩＳ／６０００图形工作站上结合图形仿真软件的开发实现。     

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.     

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。