B-spline / NURBS

B-spline / NURBS — an open, clamped uniform knot vector is shown for the selected degree and control-point count. It repeats 0 and 1 degree+1 times, so the curve interpolates its first and last control point. With every weight equal to 1 this is a B-spline. Positive rational weights multiply the basis functions before their weighted normalization; increasing a control point’s weight pulls the NURBS curve toward that point. Drag red points or edit the selected point numerically. The implementation limits the degree to 1 through point count minus 1 and weights to positive finite values.