Sketcher Ticket #3793 - Reference Constraints toggle to driving on edit

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hatari
Posts: 69
Joined: Fri Jul 22, 2016 10:56 am

Sketcher Ticket #3793 - Reference Constraints toggle to driving on edit

Postby hatari » Thu Jan 24, 2019 3:57 pm

In the latest FC0.18, every time I edit a (blue) reference constraint in the sketcher, after leaving the dialogue window it turns into a (red) driving constraint.
I suppose this is a bug?

Consequences are, that if you have a fully constrained sketch and eventually want to name some of the reference constraints, you can't do it. After editing, the constraint still has no label and I get the message

"Dimensional constraint - Negative datum values are not valid for the constraint with index $some-number"

and then, since the sketch is now overconstrained:

"Not allowed to edit the datum because the sketch contains conflicting constraints"

cheers, hatari

OS: Ubuntu 18.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15697 (Git)
Build type: Release
Branch: master
Hash: dedaa807629ab25cf32977d30bf7610f1346aff7
Python version: 2.7.15rc1
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)

Mod edit: added ticket issue #3793 to thread title
openBrain
Posts: 4874
Joined: Fri Nov 09, 2018 5:38 pm

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby openBrain » Thu Jan 24, 2019 4:04 pm

Hi,
May you provide the file ?
hatari
Posts: 69
Joined: Fri Jul 22, 2016 10:56 am

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby hatari » Thu Jan 24, 2019 4:33 pm

It works in any file, I think. Anyway, here's a model. I worked in Part Workbench (I have the same problem in Part Design, however)
sketcher_err.FCStd
(6.37 KiB) Downloaded 22 times
openBrain
Posts: 4874
Joined: Fri Nov 09, 2018 5:38 pm

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby openBrain » Thu Jan 24, 2019 4:47 pm

OK, see it.
I'm not sure it's a bug. Actually FC behaves by changing reference dimension to driving dimension as soon as you try to edit it.
This doesn't sound completely idiot, as there is no obvious reason why editing reference dimension. Reference dimension only displays a value calculated from driving constraints & dimensions thus it hasn't to be changed manually by user.

My only clue here is that maybe you are mixing the reference dimensions of FC's sketcher with reference dimensions as they are used typically in conventional 2D drafting softwares or in TechDraw WB when generating the 2D drawings from 3D model. ;)
GeneFC
Posts: 1654
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby GeneFC » Thu Jan 24, 2019 4:49 pm

I see the same problem. I think this came up in the forum a month or two ago, but I do not have the reference. I recall that it was considered a "feature", but I could be remembering incorrectly.

Gene
GeneFC
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Location: Punta Gorda, FL

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby GeneFC » Thu Jan 24, 2019 4:53 pm

openBrain wrote:
Thu Jan 24, 2019 4:47 pm
Actually FC behaves by changing reference dimension to driving dimension as soon as you try to edit it.
You are correct that it does not make much sense to try to change a reference constraint, since it is really a measurement, not a constraint.

However, silently creating a real constraint can be dangerous to the model.

Gene
User avatar
meme2704
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Location: Vosges

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby meme2704 » Thu Jan 24, 2019 4:56 pm

Hi
Do you have blue lines, but does it also switch the constraint tools in blue with the blue buttons in the constraints toolbar?
hatari
Posts: 69
Joined: Fri Jul 22, 2016 10:56 am

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby hatari » Thu Jan 24, 2019 5:01 pm

[This doesn't sound completely idiot, as there is no obvious reason why editing reference dimension
Of course. But I don't want to edit the reference, only to label it. And then it makes no sense that my sketch brakes/ is overconstrained and I'm not allowed to label it.
My only clue here is that maybe you are mixing the reference dimensions of FC's sketcher with reference dimensions as they are used typically in conventional 2D drafting softwares or in TechDraw WB when generating the 2D drawings from 3D model. ;)
No I don't think so. I want to know e.g. the length of the circumference of the sketch without putting it on a drawing. I think this is not uncommon nowadays (see PMIs). ;)
openBrain
Posts: 4874
Joined: Fri Nov 09, 2018 5:38 pm

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby openBrain » Thu Jan 24, 2019 6:11 pm

hatari wrote:
Thu Jan 24, 2019 5:01 pm
[This doesn't sound completely idiot, as there is no obvious reason why editing reference dimension
Of course. But I don't want to edit the reference, only to label it. And then it makes no sense that my sketch brakes/ is overconstrained and I'm not allowed to label it.
You told it ... and I forgot during the time I was replying... My mistake :!: Indeed this leads to a weird behavior where you can't label a reference dimension. Maybe it's a bug, maybe it's a feature. :) But in this last case, FC probably shouldn't display the labeling textbox.
My only clue here is that maybe you are mixing the reference dimensions of FC's sketcher with reference dimensions as they are used typically in conventional 2D drafting softwares or in TechDraw WB when generating the 2D drawings from 3D model. ;)
No I don't think so. I want to know e.g. the length of the circumference of the sketch without putting it on a drawing. I think this is not uncommon nowadays (see PMIs). ;)
I'm not really sure FreeCAD is currently ready for this. ;)
chrisb
Posts: 29062
Joined: Tue Mar 17, 2015 9:14 am

Re: Sketcher - Reference Constraints toggle to driving on edit

Postby chrisb » Thu Jan 24, 2019 6:32 pm

This behaviour is indeed a bit confusing. You can label the blue reference constraints with the right click menu in the constraints list in the panel.
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