Sketcher WB: moving destroys hexagon

[bejant]

There is a square in the polygon list,

I even looked before I posted, I don't know how I missed it.

but especially for that it would be good to have a specially constrained with verticals and horizontals.

That one has its own place in the Sketcher Geometries toolbar...

[chrisb]

This is a really important concept that probably should be featured in the comprehensive tutorial Chris has authored.

You are very right. I thought it was there, but it isn't

The sketcher solver has no idea that it is a polygon, it just analyzes the constraints together with the move operation and computes a solution that conforms with the constraints.

Polyline, Rectangle, Polygon and Slot are only Shortcuts, and I see absolutely no need to change that. However, I see that it might be useful to have different sets of constraints for these constructs.

[chrisb]

That one has its own place in the Sketcher Geometries toolbar...

You mean the rectangle? That lacks the equality to be a square - easy to add manually, but it still has to be done.

[bejant]

The sketcher solver has no idea that it is a polygon, it just analyzes the constraints together with the move operation and computes a solution that conforms with the constraints.

The appearance of shapes is just a convenient grouping of elements with constraints and has little or no impact on the sketch solving process.

Well, I can move a Regular Hexagon by dragging any white edge and it maintains the hexagonal shape without collapsing into something else, so I don't think that using the Sketcher > Move Geometry tool should permit the hexagon to morph into some other shape. From what I see the Sketcher > Move Geometry tool by itself doesn't delete or add Constraints, in the OP example no Constraints have been deleted or added, so I think it is reasonable that the user expects the polygon to remain a polygon of the same shape.

Sketcher > Move Geometry wiki page, while I have it handy:
https://www.freecadweb.org/wiki/Sketcher_Move

[GeneFC]

I think this is closely related to the mostly eliminated problem of "sketch flipping." Moving a short distance seems to work, even when grabbing a single element. Moving a large distance fails.

If you read the wiki carefully it says nothing about maintaining the original shape, only the constraints. Also, it says the operation moves the selected elements and says nothing about the unselected elements.

I agree that in many cases the user would expect the move to keep the shape intact, but that is not what the description says.

If I select all the elements of the hexagon it can be moved completely intact, any distance or direction.

Sounds like a feature request, or at least an expanded description in the wiki, rather than a bug report.

Gene

[chrisb]

I think this is closely related to the mostly eliminated problem of "sketch flipping." Moving a short distance seems to work, even when grabbing a single element. Moving a large distance fails.

That's exactly what is happening. If you draw a hexagon and take a point at the right and you apply a distance constraint which moves it far to the left, you experience the same collapsing into a square.

So it has nothing to do with the move tool.

[bejant]

I think this is closely related to the mostly eliminated problem of "sketch flipping." Moving a short distance seems to work, even when grabbing a single element. Moving a large distance fails.

That's exactly what is happening. If you draw a hexagon and take a point at the right and you apply a distance constraint which moves it far to the left, you experience the same collapsing into a square.

Ok, now I agree.

[abdullah]

The moving of geometry has already been discussed above. I can only confirm that if a geometric element is moved so that the solver fulfils the constraints, then the software is doing what the user is asking it to do. Of course, it shall be possible to come back to the original situation undoing the action. That is a bug.

PR:
https://github.com/FreeCAD/FreeCAD/pull/3536

[uwestoehr]

PR:
https://github.com/FreeCAD/FreeCAD/pull/3536

Many thanks, it fixes the Undo issue for me.