An Algorithm for Adding Draft Angle to B-spline Surfaces

Abstract

An algorithm for adding draft angles to B-spline surfaces is described. The algorithm modifies the control net of the surface in order to satisfy the draft angle conditions. The draft angle conditions are based on simple vector products performed on the quadrilaterals of the control net. The algorithm minimizes the total displacement of the control points in such a way that the draft angle conditions will be satisfied everywhere on the surface. The algorithm is demonstrated with some examples.