45d038181a
This commit improves NURBS knot generation by adding proper support for the combination of the Bezier and cyclic options. In other cases the resulting knot doesn't change. This cyclic Bezier knot is used to create accurate accurate "Nurbs Circle", "Nurbs Cylinder" primitives. "Nurbs Sphere" and "Nurbs Torus" primitives are also improved by tweaking the spin operator. The knot vector in 3rd order NURBS curve with Bezier option turned on (without cyclic) is changed in comparison to previous calculations, although it doesn't change the curve shape itself. The accuracy of the of NURBS circle is fixed, which can be checked by comparing with mesh circle. Tessellation spacing differences in circular NURBS is also fixed, which is observable with the NURBS cylinder and sphere primitives. These were causing seam-like effects. This commit contains comments from Piotr Makal (@pmakal). Differential Revision: https://developer.blender.org/D11664