B-Spline Shapes

The B-Spline shape is a shape defined by a sequence of points and interpolated using the B-Spline interpolation method with a user selected degree of the curve. The degree of the curve specifies the number of points needed for a single segment on the curve. B-Spline shapes allow the creation and editing of higher degree than cubic shapes, with more than two control points.

The B-Spline shape is non-destructive and the points remain editable with the Node tool, and the interpolation degree can be changed in the Shapes panel. To create actual curves from the shape, use the Convert to Curves command.

Drawing B-Spline Shapes

B-Spline shapes can be drawn using the B-Spline tool from the application toolbox:

• Select the B-Spline tool from the toolbox.
• Click with the mouse to place the first point of the shape.
• Move the mouse to the position of the next point and click+drag to place the next point.
• Repeat the above point placement sequence using the tool.
• The points will be interpolated using the B-Spline interpolation.
• Depending on the interpolation degree, a number of points are used as control points, while every degree number point will be a node on the shape.

The B-Spline shape is a non-destructive shape where the interpolation degree can be changed by the user.

Editing B-Spline Shape

The Node tool can be used to interactively edit the points of the B-Spline shape:

• Select the object with a B-Spline shape.
• Select the Node tool from the application toolbox.
• The nodes and control points of the shape, and lines connecting these points, are shown as an indicator.
• Drag the points in a similar way as when editing paths.
• To insert a new point, click on the inner part of a line connecting two points and press the Plus key.
• To remove a point, select the point with the node tool and press the Delete key.
• Inserting or removing points will shift the node or control point role of the remaining points.

B-Spline Shape Properties

The B-Spline shape interpolation degree can be changed in the Shape panel when the shape is selected, or in the B-Spline view, either from the shape panel, or when editing a shape style.

• Degree - Set the interpolation degree of the B-Spline shape.