From FreeCAD Documentation
- There are several ways to invoke the command:
- Press the Cubic Bézier curve button.
- Select the Drafting → Bézier tools → Cubic Bézier curve option from the menu.
- The Cubic Bézier curve task panel opens. See Options for more information.
- It is not possible the enter points via the task panel.
- For the following Mouse Navigation Models a keyboard key must to be held down:
- If you are using OpenInventor Navigation the Ctrl key must be held down throughout the command.
- If you are using Gesture Navigation the Alt key must be held down for each click-hold-release sequence, but is also possible to keep this key held down throughout the command.
- Pick the first point in the 3D view and hold the mouse button (1), this is the first endpoint.
- Drag the pointer to another point in the 3D view and release the mouse button (2), this is the first control point.
- Move the pointer to another point in the 3D view, pick this point and hold the mouse button (3), this is the second endpoint.
- 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.
- You now have one Bézier curve of the 3rd degree.
- Optionally repeat the process of clicking and holding (5), and dragging and releasing (6) to add more segments.
- 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.
- Press Esc or the Close button to finish the command.