**Toolbar / Icon:**

**Menu:** Draw > Spline > Spline (Control Points)
**Shortcut:** S, P
**Commands:** spline | sp

**Description:**

Draws spline curves from control points. Non-uniform rational B-Splines (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 b-spline) and 3 (cubic b-spline). The higher the
degree, the 'smoother' the curve becomes.

Note that a quadratic b-spline requires by definition at least 3 control points while a cubic b-spline 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 b-splines) or fourth (for cubic b-splines) 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.
- Hit escape or click the right mouse button after setting the last point to confirm the spline shape.
- You can now create another spline or right-click again to terminate the tool.

Example for two open splines (quadratic and cubic):

Example for two closed, periodic splines (quadratic and cubic):