A class of algebraic–trigonometric blended splines

This paper presents a new kind of algebraic–trigonometric blended spline curve, called xyBxyB curves, generated over the space {1,t,sint,cost,sin2t,sin3t,cos3t}{1,t,sint,cost,sin2t,sin3t,cos3t}. The new curves not only inherit most properties of usual cubic B-spline curves in polynomial space, but also enjoy some other advantageous properties for modeling. For given control points, the shape of the new curves can be adjusted by using the parameters xx and yy. When the control points and the parameters are chosen appropriately, the new curves can represent some conics and transcendental curves. In addition, we present methods of constructing an interpolation xyBxyB-spline curve and an xyBxyB-spline curve which is tangent to the given control polygon. The generation of tensor product surfaces by these new spline curves is straightforward. Many properties of the curves can be easily extended to the surfaces. The new surfaces can exactly represent the rotation surfaces as well as the surfaces with elliptical or circular sections.