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(Blackwell Publishing Ltd and the Eurographics Association, 1985)

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(Blackwell Publishing Ltd and the Eurographics Association, 1985) Arnold, David B.; Hall, Gillian; Reynolds, Graham J.

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.

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Polygonal Clipping of Polylines

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Matthew, A.J.

A Fortran routine is presented for clipping a polyline to the inside or outside of a polygon, the boundary of the polygon being treated as part of the inside. There is no limitation on the number of sides of the polygon or vectors of the polyline, and no working storage is required. The polygon may have sides that intersect and vertices or sides that coincide with each other.

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Arbitrary Area Filling in a Fast Procedure

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Ying, Dao-Ning; Feng, Xing

A representation for area filling is described which allows shading of an area that may have both straight lines and circular arc edges and include holes within its boundaries. For efficiency an elimination algorithm which has a waiting line list and a currently active line list is adopted. For calculating intersections, a more time saving method is used. The algorithm and some practical examples are discussed. The main features of the algorithm are execution with high speed and less storage requirement. The program is written both in BASIC and FORTRAN 77 and could be executed on a microcomputer such as APPLE II, IBM-P/C etc. The sample outputs shown in this paper are generated by the APPLE II with high efficiency.

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Better Understanding through Formal Specification

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Duce, D. A.; Fielding, E. V. C.

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.

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Calendar of Events

(Blackwell Publishing Ltd and the Eurographics Association, 1985)

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EUROGRAPHICS 86 TUTORIALS: August 25-26 1986

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Hopgood, Bob

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Computer Animation and Art Slide Competition

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Rambert, Patrick

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A Survey of Electronics R and D in the USA

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Prince, M.D.

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EDITORIAL

(Blackwell Publishing Ltd and the Eurographics Association, 1985)

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Manufacturing Models of Biomedical Objects via CAD/CAM and GKS

(Blackwell Publishing Ltd and the Eurographics Association, 1985) Reumann, K.; Giebel, G.; Mildenstein, K.

Picture generating methods like tomography have drastically improved the possibility for the conception of biomedical objects in living humans. They have proved to be of major significance in surgical planning. Computer Aided Design (CAD) methods based on tomography are in the research phase for the three-dimensional reconstruction and display using computer graphics for even better visualization. We provide a method beyond that by manufacturing physical three-dimensional models via the Graphical Kernel System (GKS) and Computer Aided Manufacturing (CAM) methods. This kind of method is very well suited for visualization in some application areas. Moreover it yields physical models which can be manipulated in the preoperative phase. Lastly a physical bone model can be a substitute for the original object.

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An Interpolant with Tension Defined over Triangles

(Blackwell Publishing Ltd and the Eurographics Association, 1985) de Floriani, Leila; Dettori, Giuliana

A C1 interpolation scheme is described, which is defined over triangular grids. The interpolant is computed on the basis of curves with tension, which permit local control over the shape of the resulting surface.