Draft CubicBezCurve

Description
The Draft CubicBezCurve command creates a Bézier Curve of the third degree (four points required).

The Bézier Curve is one of the most commonly used curves in computer graphics. This command allows you to create a continuous spline made up of several 3rd-degree Bézier segments, in a way that is similar to the Bézier tool in Inkscape. A general Bézier curve of any degree can be created with the Draft BezCurve command.

The Draft BezCurve and the Draft CubicBezCurve commands use to define the position and curvature of the spline. The Draft BSpline command, on the other hand, specifies the through which the curve will pass.



Usage
See also: Draft Tray, Draft Snap and Draft Constrain.


 * 1) There are several ways to invoke the command:
 * 2) * Press the button.
 * 3) * Select the option from the menu.
 * 4) For the following Mouse Navigation Models a keyboard key has to be held down:
 * 5) * If you are using OpenInventor Navigation the key must be held down throughout the command.
 * 6) * If you are using Gesture Navigation the key must be held down for each click-hold-release sequence, but is also possible to keep this key held down throughout the command.
 * 7) Pick the first point in the 3D view and hold the mouse button (1), this is the first endpoint.
 * 8) Drag the pointer to another point in the 3D view and release the mouse button (2), this is the first control point.
 * 9) Move the pointer to another point in the 3D view, pick this point and hold the mouse button (3), this is the second endpoint.
 * 10) Move the pointer to another point in the 3D view to adjust the final curvature of the segment and release the mouse button (4), this is the second control point.
 * 11) You now have one Bézier curve of the 3rd degree.
 * 12) Optionally repeat the process of clicking and holding (5), and dragging and releasing (6) to add more segments.
 * 13) Each subsequent segment will use the second endpoint and second control point of the previous segment as its first endpoint and first control point respectively.
 * 14) Press  or the  button to finish the command.

Options
See Draft BezCurve.

Properties
See Draft BezCurve.

Scripting
See also: Autogenerated API documentation and FreeCAD Scripting Basics.

See Draft BezCurve for general information. A cubic Bézier is created by passing the option  to.

For each cubic Bézier segment four points must be used, of which the two extreme points indicate where the spline passes through, and the two intermediate points are control points.
 * If only 3 points are given, it creates a quadratic Bézier instead, with only one control point.
 * If only 2 points are given, it creates a linear Bézier, that is, a straight line.
 * If 5 points are given, the first 4 create a cubic Bézier segment; the 4th and the 5th points are used to create a straight line.
 * If 6 points are given, the first 4 create a cubic Bézier segment; the 4th and the other two points are used to create a quadratic Bézier segment.
 * If 7 points are given, the first 4 create a cubic Bézier segment; the 4th and the other three points are used to create a second cubic Bézier segment.
 * In general, the last point in a group of four is shared with the following three points maximum to create another Bézier segment.
 * To have smooth curves, with no straight segments, the number of points should be or, where  is the number of segments, for.



Example: