Spline (Control Points)
Toolbar / Icon:
Menu: Draw  Spline  Spline (Control Points)
Shortcut: S, P
Commands: spline  sp
Description:
Draws spline curves from control points. Nonuniform rational BSplines
(NURBS) with homogeneous weighting factors are the only splines that are
supported.
Procedure:
 Choose the degree of the spline in the options tool bar. Supported degrees
are 2 (quadratic bspline) and 3 (cubic bspline). The higher the degree, the
'smoother' the curve becomes.
Note that a quadratic bspline requires by definition at least 3
control points while a cubic bspline has at least 4 control points.
 Check the 'Closed' check box in the options tool bar if you want to create
a closed spline. Closed splines are continuous closed loops.
 Specify the control points. After defining the third (for quadratic
bsplines) or fourth (for cubic bsplines) control point, a preview will be
shown. You can remove the last control point again by clicking the 'Undo'
button in the options tool bar.
Example for two open splines (quadratic and cubic):
Example for two closed, periodic splines (quadratic and cubic):

