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Item A Survey of GKS and PfflGS Implementations October 1988(Blackwell Publishing Ltd and the Eurographics Association, 1989) Wyrwas, K.M.; Hewitt, W.T.Item Mass-Spring Simulation using Adaptive Non-Active Points(Blackwell Publishers Ltd and the Eurographics Association, 1998) Howlett, P.; Hewitt, W.T.This paper introduces an adaptive component to a mass-spring system as used in the modelling of cloth for computer animation. The new method introduces non-active points to the model which can adapt the shape of the cloth at inaccuracies. This improves on conventional uniform mass-spring systems by producing more visually pleasing results when simulating the drape of cloth over irregular objects. The computational cost of simulation is decreased by reducing the complexity of collision handling and enabling the use of coarser mass-spring networks.Item Surface Graph Sketching(Blackwell Science Ltd and the Eurographics Association, 1996) Hutchinson, D.; Lin, F.; Hewitt, W.T.The production of patterns and designs upon surfaces has received only limited attention, with texturing techniques being accepted as adequate. Texturing, however, can be a very unsatisfactory and clumsy method of producing complex and accurate designs upon a surface, even more so with surfaces such as NURBS where a texture may appear very much distorted when mapped to a surface. This paper introduces a new approach called surface graph sketching which draws upon ideas from planar graph sketching for the construction of complex curve networks across parametrically defined surfaces. Surface curves can be created by a number of methods and stored in the parameter space of the surface thereby allowing intricate and more importantly accurate surface designs to be created. Regions of the surface may be assigned a property such as colour or texture, or cut away to produce holes. Surface graph sketching has a number of applications, in the design of trimming curves, surface patterning and texture map definitions.Item AN INTERACTIVE DEBUGGER FOR PHIGS(Eurographics Association, 1990) Howard, T.L.J.; Hewitt, W.T.; Larkin, S.The Programmer’s Hierarchical Interactive Graphics System (PHIGS) is an International Standard for integrating application modelling and interactive computer graphics. With PHIGS, application models are constructed from hierarchical data structures called structure networks, which may be edited interactively. While structure networks are in principle straightforward to create, organising and managing them correctly is in practice a much more difficult proposition. One of the main difficulties arises from the atomic nature of the traversal process by which structure networks are interpreted for display. This paper draws an analogy between structure network traversal and programming language execution, and presents the PHIGS Debugger, a development tool for PHIGS applications. The PHIGS Debugger supports interactive incremental traversal of structure networks and debugging of the PHIGS Centralised Structure Store, and is a component of the PHIGS Toolkit, an emerging set of portable integrated tools for PHIGS environments. 1Item Workshop Report Curves for Computer Graphics Standards(Blackwell Publishing Ltd and the Eurographics Association, 1990) Hewitt, W.T.