Add support for FreeCAD (.FCStd) files

[mwestphal]

Is your feature request related to a problem? Please describe.
FreeCAD has a specific format consisting of an archive of brep file and xml files, lets add support for it

Describe the solution you'd like

• Investigate the format
• Design a solution to be able to open it

Notes
https://wiki.freecad.org/File_Format_FCStd

[mwestphal]

Freecad discord may be helpful here, @Meakk and myself are on it.

[ChristosT]

Hi @mwestphal :)

I would enjoy to give this a go !

This is what I have in mind:

1. use libzip or libarchive to open the FCStd (zip) archive in memory. If there is another library for handling .zip files already we can skip this but looking into the /include of the f3d-superbuild I didn't see anything.
2. for each brep file in the archive use vtkF3DOCCTReader with a vtkResourseStream with the stream pointing to the file handler/data pointer from above.

suggested steps:
a. add libzip/libarchive into f3d-superbuild
b. create a new reader that returns vtkMultiBlockDataSet/vtkPartitionedDataSetCollection/vtkPartitionedDataSet (any preference for f3d?) using vtkF3DOCCTReader internally for each brep file in the archive.

Let me know what you think!

[mwestphal]

Hi @ChristosT , funny seeing you here :)

Anyway, I think i might delay this a bit if VTK add vtkCompressedResourceStream like described here: https://discourse.vtk.org/t/adding-support-for-opening-any-archived-single-file/16254

Until I know what VTK will do with this, I'd rather wait a bit.

In any case libarchive seems definitely to be the right choice, and the reader should output vtkPartitionedDataSetCollection.

[ChristosT]

Indeed this looks like a much cleaner and more general solution. It makes sense to wait then I agree.