Improving interactivity within a virtual sculpting environment

Computer animators find that maintaining control of the shape of deformable objects during motion is sometimes difficult. This paper describes a system called "Gargoyle" which provides improved support in this area; it concentrates particularly on the form of interaction between user and computer. In Gargoyle, an object is sculpted at several predefined key positions which are associated with particular values of the parameters defining the surface. This allows the object to be animated by parametric interpolation in the conventional way. Within a two-handed, stereoscopic environment, an object is modelled, by "holding" it in one hand, while the other hand uses the mouse to sculpt the object (as if it were made of clay) using a "point and click" technique, rather than the conventional "pick and drag" approach. Several tools are available, and with each click of the mouse, the current tool is applied to the surface at the indicated point. The algorithms underlying the tools are outlined and various objects which have been sculpted using them are described.