CoCreate OneSpace Designer - Commands Reference Manual

BSPLINE_CON terminate action

BSPLINE_CON specifies a B-spline using a series of control points.

Syntax


                    +-----------<------------+
                    v                        |
--->(BSPLINE_CON)---+--->|data position|--->-+------>
                    |                        |
                    +--->(:CLOSED)--------->-+
                    |                        |
                    +--->(:OPEN)----------->-+
                    |                        |
                    +--->(:ORDER)--|number|--+
                    |                        |
                    +--->(:BACK)----------->-+

Options

The following options are available to create your B-spline.

:CLOSED - closes the B-spline creating tangency and curvature continuity at the first control point. Curvature continuity is only achieved with an order of no less than 3.
This option acts as a toggle with :OPEN.
:ORDER - increases the control you have over the ultimate shape of your B-spline. The default B-spline order of 4 creates a curvature continuous curve that follows its control polygon as closely as possible.
You can set a minimum order of 3, and there is no maximum value. However, a high order decreases the performance, and increases the possibility of wiggles along the curve.
:BACK - deletes the last control point specified.

When to use

Use this action to create a planar freeform B-spline curve anywhere in your active workplane.

A series of control points attract the curve you are creating, that is, they form a guideline for the curve. Every fluctuation in the control polygon, results in a fluctuation in the B-spline curve. In addition, the first and last control polygon segments define the tangent at the ends of the B-spline curve.

You can align either end of the B-spline with an existing element, if you know its tangent. The new B-spline can have tangent continuity at the end point.

No two directly subsequent control points may be coincident.

Example

The following parameter sequence specifies the control points to define a B-spline.

BSPLINE_CON 100,100 100,73 75,73 35,27 COMPLETE