B-spline and periodic B-spline

The feature creates a free form spline curve in the current Sketch.

To add a new B-spline to the Sketch:

  1. select in the Main Menu Sketch - > B-spline item or

  2. click bspline.icon B-spline button in the Sketch toolbar.

To add a periodic B-spline to the Sketch:

  1. select in the Main Menu Sketch - > Periodic B-spline item or

  2. click bspline_p.icon Periodic B-spline button in the Sketch toolbar.

Creation of B-spline curve

../_images/bspline_creation_panel.png

Click in the view to specify the control polygon of B-spline curve. The curve will be shown after the second point is initialized. To stop adding new poles, click Esc button or Apply the operation.

TUI Command:

Sketch_1.addSpline(degree, poles, weights, knots, multiplicities, periodic)
Parameters:

  • integer – degree of B-spline.

  • array – list of poles [(x1, y1), (x2, y2), …].

  • array – list of weights for corresponding poles.

  • array – parametric knots of B-spline curve.

  • array – multiplicity of each knot.

  • boolean – True mentions that the B-spline curve is periodic.

Returns:

Result object.

Each parameter is optional.

Result

Created B-spline curve appears in the view.

../_images/bspline_result.png

Non-periodic B-spline created

../_images/bspline_periodic_result.png

Periodic B-spline created

See Also a sample TUI Script of Create Sketch B-spline operation.

Modification of B-spline curve

../_images/bspline_modification_panel.png

Modification panel for B-spline curve

The following options are provided to modify the already created B-spline curve:

  1. Change weight of each pole.

  2. Add new pole.

The new pole is added after the current by pressing on the corresponding add_pole.icon button. The default weight for the new pole is 1.

Note: adding the new pole after the last for non-periodic B-spline will not change the last point of the curve to avoid modification of full sketch.