DXF export has flipped arc's even with recent PPA

[jpieper]

I have a sheet metal part, that when exported to DXF, has a random subset of 180 degree circular arcs flipped. I've found a number of references to this problem in the past, each of which has had some kind of fix applied. I don't know if this is exactly a regression or some new problem. The dxf stuff is set to auto-download in the Draft preferences, and has a timestamp of today, 2015-06-06, in my .FreeCAD directory.

Am I doing something wrong, or is there a workaround I can use?

freecad_view.png (135.29 KiB) Viewed 1472 times

librecad_dxf_view.png (83.82 KiB) Viewed 1472 times

Previous bugs describing a seemingly identical issue all of which are documented as being fixed.
* http://www.freecadweb.org/tracker/view.php?id=1653
* http://www.freecadweb.org/tracker/view.php?id=1590
* http://www.freecadweb.org/tracker/view.php?id=1513

OS: Ubuntu 14.04.2 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.4928 (Git)
Branch: master
Hash: d8f63bcfd10301f3d1e141cced4370f0782238d0
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[triplus]

As for fixing this probably Yorik will take a look. As for workaround you can still use workaround i mentioned in issue report.

• Select Shape2DView object in Tree View and use Draft Downgrade tool on it.
• Select all edges and use Draft Convert to Sketch tool.
• Part Design -> Part Design -> Merge sketches tool

Try to export that crated sketch to DXF. Probably 4 horizontal lines should be removed first for DXF export and 4 vertical ones will need to be repaired as it looks like are lost at conversion.

[yorik]

This is a recurrent problem... Fir some reason I never manage to fix it completely...
Another workaround is to separate everything into single edges with the Draft Downgrade tool.

[triplus]

This is a recurrent problem... Fir some reason I never manage to fix it completely...
Another workaround is to separate everything into single edges with the Draft Downgrade tool.

Sometimes this does work but often the conversion to sketcher geometry fixes it. For example only using Draft Downgrade tool on Shape2DView object won't fix the issue in attached file. I was thinking what could be that difference involved that would affect DXF library in a way it flips Draft Arc in one direction and then again the same converted Draft Arc to Sketcher geometry in the other direction? Is there any additional check involved or what could be the cause? Does sketcher geometry (arc) have any additional info DXF library (or something else affecting DXF library) does use? I am not sure sketcher is "perfect" as in the past if i remember correctly i did get flipped arcs (sketcher geometry) but usually this is how i "workaround" the issue. Or is this more or less a question of "luck" and sometimes one method works and then again the other one?

[cox]

I know the path module is not ready for testing, but might this shed som light on some common library having a problem.

Flipping seams random and resizing the pocket has in many occasions flipped the circles the correct way

flipp.png (69.54 KiB) Viewed 1410 times

OS: "Arch Linux"
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.5465 (Git)
Build type: Unknown
Branch: makepkg
Hash: 347fe6217111569866fd83a4796d3d65e4e75dfe
Python version: 2.7.10
Qt version: 4.8.7
Coin version: 3.1.3
OCC version: 6.9.0

[yorik]

oh no, inverted arcs in Path too!!!!

[f3nix]

Hi!

I'm having the same problem:

FreeCAD_0.16.png (121.46 KiB) Viewed 1347 times

OS: Debian GNU/Linux 8.1 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.5070 (Git)
Build type: Unknown
Branch: master
Hash: 418cefd7ee4d02d584c5a871f07104683606787b
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.9.0

Cheers,
Mateusz

[ickby]

Yorik, is there somewhere a collection of all files which have shown this inverted arc problem?

[cox]

Just a thought, could this be a variable type (signed / unsigned) problem.

Looks like there could be a 50-50 chance of having the arcs invert

[f3nix]

I've tested the export in:

OS: Debian GNU/Linux 8.1 (jessie)
Word size: 64-bit
Version: 0.14.3702 (Git)
Branch: releases/FreeCAD-0-14
Hash: b3368125c63289ec8ce9faec2b2ae4c78d436406
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
SoQt version: 1.6.0a
OCC version: 6.7.0

And the arcs are ok.

FreeCAD_0.14.png (98.85 KiB) Viewed 1326 times

Cheers,
Mateusz