STEP export: Wrong device placement for models with non-zero transform

[xotho]

VERSION / OS / ENVIRONMENT

LibrePCB Version: 1.1.1-unstable
Git Revision: 4d05a63
Build Date: 2024-05-06T08:58:42
Build Author: LibrePCB CI
Qt Version: 6.6.2 (built against 6.6.2)
CPU Architecture: x86_64
Operating System: Windows 11 Version 23H2
Platform Plugin: windows
TLS Library: OpenSSL 3.0.12 24 Oct 2023
OCC Library: OCCT 7.7.2

SUMMARY

Exported 3D-STEP show a PCB where a component mounted on BOTTOM side of the PCB is turned 180 degree.
In the LibrePCB all is shown correctly instead.

Wrong location about exported:

Right position shown in LibrePCB:

[ubruhin]

I don't understand from the pictures what is wrong. It doesn't even look like the same PCB is shown in both pictures 🤔

Can you please post the whole project (or send it to the contact email address on the website)?

[xotho]

Dear ubruhin,

check the following images, ( I removed some components ):

exported and imported in FREECAD or PTC:

1. is the right view in LIBREPCB, 2) is the wrong view imported in FREECAD or PTC.

Should be clear I think.

Do you need more ?

[ubruhin]

I still cannot reproduce this, it would be very helpful to have your project for investigation. If you send it (as *.lppz export) to the contact email on our website, I'll handle it confidentially.

[xotho]

Pls Check contact Email.

take care

[ubruhin]

Got it, and can reproduce it! Thank you!

[xotho]

Great. Thank you 2 U.

[ubruhin]

OK this is really strange... The affected STEP model is a bit unusual because it contains a rotation of 180°, as shown in the FreeCAD object inspector:

But of course also this unusual case needs to be supported properly by LibrePCB. However, after exporting the PCB to STEP, this rotation is lost on the package:

I don't know why this happens, but I realized it can be fixed with a small change (see #1401). The output structure is then as expected:

And even the label "DEV1:1" is now correct, although this makes absolutely no sense to me. Also the change in #1401 makes no sense to me, but at least I didn't experience any negative impact on several projects I tested. That's the mystery of the OpenCascade API which I still don't understand at all...

I think we can go with this change for now and if any new issue pops up in future we have to investigate it again.

@xotho would be nice if you could test your complete project with the nightly build of #1401 (should appear in ca. an hour) and report here if the exported STEP is now correct.