Add 3mf export and import

[lvk88]

This PR addresses issue #1032 adds the possibility to export and import meshes in 3MF format to and from meshlab. This is a minimum working solution.
Features:

• Imports separate meshes from the 3MF as separate meshes into the open document
• It is able to read color and texture data from the 3MF file and use them in the imported mesh
• When importing colors, the entire triangle is colored with the p1 property found in the 3mf file (see 3MF spec here). The most complete solution should be face wedge coloring, but I couldn't get it working unfortunately
• When importing textures, face wedge textures are used
• Exporting single meshes into 3MF file works. Exporting multiple meshes does not work.

I tested the solution on Ubuntu 22.04. with GCC12 and Windows with MSVC 2019.

All files from the 3MF example repo under the core folder can be opened (https://github.com/3MFConsortium/3mf-samples/tree/master/examples/core)

Colored and textured files from the 3MF example repo (https://github.com/3MFConsortium/3mf-samples/tree/master/examples/material) can be opened, except those with multiprop prefix. These files also crash the built in 3D viewer of windows.

[alemuntoni]

Thank you very much @lvk88!! I'll look into this in the next few weeks (I can't test it on macos right now).

[alemuntoni]

The 3mf importer works as expected on mac x86_64, but not on arm64 :( I'll try to check why, but on my mac I am having troubles even on compiling lib3mf :(

[alemuntoni]

@lvk88 is there any reason why you used lib3mf 2.2.0 (which is 3 years old)? Could it be possible to update to 2.3.2?

[lvk88]

Hey @alemuntoni ,

The 3mf importer works as expected on mac x86_64, but not on arm64 :(

Oh no 😢 . I can try to fix that, I just need to get an arm Mac from somewhere. I'll see what I can do. What exactly doesn't work? It doesn't compile, it doesn't link, or it compiles links and crashes? If it doesn't compile, could you tell me the compiler and its version that you are using on Mac? If we are lucky I can reproduce the issue with the same compiler but on x86 without having to find a Mac.

is there any reason why you used lib3mf 2.2.0 (which is 3 years old)? Could it be possible to update to 2.3.2?

The reason is that when I started working on the feature last year, 2.3.2 was not out yet. Since then, the new release came out. I will check if the whole thing still works with the newer version and get back to you in the next days.

[alemuntoni]

It doesn't compile, it doesn't link, or it compiles links and crashes?

It's kind of strange. On github actions runner it seems to build correctly, but then the app bundle is damaged (I did not checked why yet). Then I tried to build it on my mac but I get build errors caused by old cmake code that has been removed on newer versions.

The reason is that when I started working on the feature last year, 2.3.2 was not out yet. Since then, the new release came out. I will check if the whole thing still works with the newer version and get back to you in the next days.

Ok, then I think that upgrading to the new version should be the first thing to do. Then I can try to make it working on mac, if there are still some errors.

[alemuntoni]

Let me know if you have time to upgrade it and make it working at least on linux and windows, otherwise I think I could try to do it next week! Thanks again!!!

[lvk88]

I think I will be able to do the upgrading on the weekend, should not be a big issue. Even though my first try with commit 56951e0 seems to have failed 😃

[lvk88]

I updated lib3mf to 2.3.2 and tested on Ubuntu and Windows with the example files from the 3mf repos. Still seems to work. I didn't test very extensively, though. @alemuntoni let me know if it helps with the Mac issue

[alemuntoni]

The latest version of lib3mf builds fine on my mac m1, thanks @lvk88!!
I was still getting the error on macos m1 ("MeshLab is damaged and can't be opened"), and I just found that it was caused by the app bundle not being signed (PRs do not get access to github actions secrets).
I guess I'll always hate Apple and its non-transparency policy on not let the user know what's actually happening.

Anyway, thank you very much for this PR!! :)

[lvk88]

Awesome, I'm glad that it all worked out 🎉

I guess I'll always hate Apple and its non-transparency policy on not let the user know what's actually happening.

Oh, haha, I share your frustration.

Thanks for the review and merging 😄