LOCAL SHAPE CONTROL FOR FREE-FORM SOLIDS IN EXACT CSG REPRESENTATION

We present a shape control scheme for free-form solids represented in CSG as Boolean combinations of low-degree algebraic halfspaces. In thi s scheme, we can create manifold solids of arbitrary topology through polyhedral smoothing, and the resulting shapes may be modified by chan ging control points and/or control weights, with each control point an d weight having a local effect. As a solid changes shape, incremental B-rep-CSG conversions are used for fast updates of the corresponding C SG representation. A key ingredient of our scheme, and a main contribu tion of this paper, is an algorithm that uses Kuhn-Tucker conditions t o efficiently compute valid control points. Published by Elsevier Scie nce Ltd