[fixed] Ticket #3968 - moving features in Part Design can delete tip

[uwestoehr]

FC 0.18 has a new feature that when moving design features in Part Design behind the current tip, it asks you if the moved feature should be the new tip.
The implementation has a bug because not all design features can hold the tip and in these cases you end up without any tip breaking the part design.

Take for example the attached file:
- use the Part Design WB
- right-click on the Datum plane and select to move object after another object
- move it after the sphere
- FC will now ask you "Do you want to want the last feature to be the new tip?"; say Yes.

result: the body gets broken because there is no longer any tip since a datum plane cannot hold the tip.
To fix this, FC must only ask to reset the tip for design features that can hold the tip.

OK to report this as bug?

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16110 (Git)
Build type: Release
Branch: (HEAD detached at upstream/releases/FreeCAD-0-18)
Hash: f7dccfaa909e5b9da26bf50c4a22ccca9bb10c40
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: German/Germany (de_DE)

Mod Edit: Updated thread topic with ticket number

[Vincent B]

With the 0.19, I attach the datumPlane on the sphere (inertial mode). Freecad doesn't ask to change the tip, nothing becomes broken.

[kisolre]

Same happens if you try to move a sketch - you are asked to move the tip and this again gives error in the body.

Code: Select all

OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.16624 (Git)
Build type: Release
Branch: master
Hash: 222ae7305fdf1097e4ef3d050f69dff47dbd8786
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: Bulgarian/Bulgaria (bg_BG)

[uwestoehr]

Same happens if you try to move a sketch - you are asked to move the tip and this again gives error in the body.

Thanks for testing. Yes, the bug is triggered by all design features that cannot hold the tip.

I reported this now as issue #3968.

[uwestoehr]

With the 0.19, I attach the datumPlane on the sphere (inertial mode). Freecad doesn't ask to change the tip, nothing becomes broken.

The bug is about moving a sketch, datum object or whatever cannot hold a tip. During the work with FC this appears quite often when rearranging design features. For example in the file where I discovered the bug, I have more than 50 features in the design tree and to keep the overview I have to rearrange them to new positions.
My datum planes are purposely not attached to a feature but to the xyz base planes.

[chrisb]

This behaviour is indeed an issue. The most natural workaround seems to be simply to answer "no" to the question if it should be made the new tip. As it can easily be repaired by setting the correct tip I would classify it as minor issue, but the classification doesn't seem to have too much impact anyway. It just shouldn't be forgotten.

Edit: The issue gets repaired by itself when a new feature is added.

[uwestoehr]

The most natural workaround seems to be simply to answer "no" to the question

Sure, but how should you know that? Answering Yes seemed reasonable. It cost me some time to figure out why my body got broken since I did not immediately noticed it after the moving. And due to Murphy's law I encountered short before a delivery deadline.

Edit: thanks for the hint that the issue gets repaired by itself when a new feature is added. I missed this since I only worked with a sketch afterwards and then it stays.

[chrisb]

The default is "no". So I think it's not too serious. It seems to be reasonable to stick to the default, if a user doesn't know what the Tip and changing it means.