Ticket #4001 - Sketcher trimming issue with arcs

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uwestoehr
Posts: 745
Joined: Sun Jan 27, 2019 3:21 am

Ticket #4001 - Sketcher trimming issue with arcs

Postby uwestoehr » Sun Jun 02, 2019 12:36 am

I noticed random behavior when trimming arcs in a sketch and think this is a bug.

When trimming 2 intersecting arcs the trimming fails when the endpoint of one arc is coincident with the second arc. Moreover the trimming cannot be undone.

To reproduce open the attached file:
Sketch-cut-problem.FCStd
(3.75 KiB) Downloaded 8 times
and trim the upper ends of the arcs so that only one arc segment would be left. The interesting thing is that the result cannot be foreseen and that in all cases the trimming cannot be undone.
Here is one try:
icmL0Omf4U.gif
icmL0Omf4U.gif (507.31 KiB) Viewed 228 times
but sometimes I end up with 2 arc segments not intersecting each other but being connected in one point.

So am I doing something wrong or is it a 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)
Last edited by Kunda1 on Wed Jun 05, 2019 11:42 pm, edited 1 time in total.
Reason: Prepended ticket number to thread title
chrisb
Posts: 18784
Joined: Tue Mar 17, 2015 9:14 am

Re: Sketcher trimming issue with arcs

Postby chrisb » Sun Jun 02, 2019 7:28 am

Abdullah wrote:ping
abdullah
Posts: 3174
Joined: Sun May 04, 2014 3:16 pm

Re: Sketcher trimming issue with arcs

Postby abdullah » Sun Jun 02, 2019 11:49 am

uwestoehr wrote:
Sun Jun 02, 2019 12:36 am
So am I doing something wrong or is it a bug?
Of course, it is a bug. I confirm the repeatability.

Please make a ticket in the tracker with a link to the thread so that the file does not get lost.

Trimming relies on a buggy OCCT function. It has been reported to OCCT, but not fixed yet.

There is some code in FreeCAD that tries to compensate for this OCCT bug. Maybe it can be improved to handle this case.
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uwestoehr
Posts: 745
Joined: Sun Jan 27, 2019 3:21 am

Re: Sketcher trimming issue with arcs

Postby uwestoehr » Wed Jun 05, 2019 11:08 pm

abdullah wrote:
Sun Jun 02, 2019 11:49 am
Please make a ticket in the tracker with a link to the thread so that the file does not get lost.
I created now issue #4001.
Many thanks for having a look. Let's cross fingers that the next OCCT release comes soon.
chrisb
Posts: 18784
Joined: Tue Mar 17, 2015 9:14 am

Re: Ticket #4001 - Sketcher trimming issue with arcs

Postby chrisb » Thu Jun 06, 2019 6:58 am

From my point of view we could well wait for OCC, but it would be great if FreeCAD can handle the undo.