STICKY SPLINES - DEFINITION AND MANIPULATION OF SPLINE STRUCTURES WITH MAINTAINED TOPOLOGICAL RELATIONS

This paper describes an augmentation to the spline concept to account for topological relations between different spline curves. These topol ogical relations include incidence relations, constraining the extreme s of spline curves to other spline curves, and also more general geome tric relations, for example, involving the tangents of spline curves i n their extremes. To maintain these incidence relations, some spline c urves may have to be transformed (translated, rotated, scaled), or eve n deformed (i.e., the shape of the curve may change) as a result of mo difying other spline curves. A data structure and algorithms are given to implement the propagation of these transformations and deformation s.Based on the augmented spline concept, to be called sticky splines, both a script system to represent spline structures and an interactive system for editing drawings while automatically maintaining their top ological structure are presented.