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QCad User Reference Manual
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22. Splines
CAD Toolbar:
Menu:
Draw - Spline
Command:
spline
Options Toolbar:
Description:
Draws spline curves. Non-uniform rational B-Splines (NURBS) with
homogeneous weighting factors are the only splines that are currently
supported.
Procedure:
- Choose the degree of the spline in the options toolbar. 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 needs at least 4 control
points.
- Check the 'Closed' checkbox in the options toolbar 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 if it was
accidently put in the wrong place by clicking the 'Undo' button in the
options toolbar.
- Click the right mouse button to finish the spline tool.
Figure
32: Open splines with four control
points.
Figure
33: Closed splines with the same
control points.
