Abstract The‘linetype’attribute in GKS and PHIGS is required to cover a wide variety of renderings of the polyline primitive. The results are strongly implementation‐dependent, widi virtually no user control. Splitting‘linetype’into a one‐dimensional‘line‐pattern’and a two‐dimensional‘line‐picture’gives much greater flexibility, without the need to go through a registration process for every new style. The line‐picture attribute, consisting of a single glyph repeated at intervals along a linear primitive, can answer many requirements in draughting for process industries, and should also be applicable elsewhere.

Abstract Hershey's “Repertory of Occidental Fonts” is well known in the field of computer graphics, as a set of character‐forms which is superior to the cruder representations used when space was at a premium. This paper gives a method of extending Hershey's format to include true curves, thus giving near typographical quality.

Abstract This paper presents formulae and results from a practical implementation of a conic arc specified in terms of its end‐points and other descriptors, based on the three numeric factors, bulge, shear and squash, described in an earlier paper. The parametric form for the derivative is given, from which are found the normals from a given point to the arc, and formulae for splitting off one or more parts from it. A method of chordal approximation for plotting purposes is also presented, and the effects of applying transformations are discussed.

No abstract available.