Align Draft working plane with Arch_Axis?

[Roy_043]

I do not understand how to align a Draft working plane with an Arch_Axis. I remember a discussion about this, and there is some dedicated code:
https://github.com/FreeCAD/FreeCAD/blob ... ne.py#L196

Test:

1. Open the attached file.
2. Align the WP with the face of the circle.
3. Select the Arch_Axis in the 3D view.
4. Invoke Draft_SelectPlane.
5. Start the Draft_Line command f.e.
6. Toggle the grid if required.
7. Result: the WP is still aligned with the circle.

[thomas-neemann]

if i want the working plane in a certain position, i create a triangle with draft polygon.

1.png (9.69 KiB) Viewed 829 times

[Roy_043]

Using a Draft_WorkingPlaneProxy would make more sense then. But I am specifically interested in the Arch_Axis option. I need to know how it works because I am working on the documentation of the Draft_SelectPlane command.

[thomas-neemann]

yorik should be able to answer that

[paullee]

This sounds great

In fact, other than laying out 'cosmetically' on a drawing, not sure how ArchAxis actually integrate in a modelling workflow. Anybody has any idea ?

[Roy_043]

You can snap to intersections and endpoints of an Axis System. Other than that I do not know.

[Roy_043]

The algorithm used to check the selected object is a bit complex IMO. And as a result hard to document.

I wonder if it can be simplified:
If subelements are selected: Use those to calculate the plane.
If a single object and no subelements are selected: Use the Placement of that object.

Or would that break exiting functionality too much?