Free-form splines combining NURBS and basic shapes

► C2 tensor-product bi-cubic NURBS and G2 bi-cubic rational splines are automatically joined into one unified C2 spline surface. ► The G2 splines can exactly represent basic shapes such as (pieces of) quadrics, surfaces of revolution, tori and cyclides. ► We also explain how to join bi-quadratic rational G1 splines and C1 NURBS.