Convert to MSH ASCII format, meshio-ascii crashes

[russell-sealand]

Is there a way to convert directly to Gmsh MSH format in ASCII rather than binary? I have tried to use meshio-ascii following a successful conversion of an STL file to MSH, however it always crashes.

PS C:\temp> meshio-ascii.exe output.msh
File size before: 14.13 MB
Traceback (most recent call last):
  File "c:\users\user\appdata\local\programs\python\python38\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "c:\users\user\appdata\local\programs\python\python38\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\user\AppData\Local\Programs\Python\Python38\Scripts\meshio-ascii.exe\__main__.py", line 7, in <module>
  File "c:\users\user\appdata\local\programs\python\python38\lib\site-packages\meshio\_cli\_ascii.py", line 31, in ascii
    gmsh.write(args.infile, mesh, binary=False)
  File "c:\users\user\appdata\local\programs\python\python38\lib\site-packages\meshio\gmsh\main.py", line 102, in write
    writer.write(filename, mesh, binary=binary, float_fmt=float_fmt)
  File "c:\users\user\appdata\local\programs\python\python38\lib\site-packages\meshio\gmsh\_gmsh41.py", line 357, in write
    _write_entities(fh, cells, tag_data, mesh.cell_sets, mesh.point_data, binary)
  File "c:\users\user\appdata\local\programs\python\python38\lib\site-packages\meshio\gmsh\_gmsh41.py", line 502, in _write_entities
    physical_tag = tag_data["gmsh:physical"][matching_cell_block[0]][0]
KeyError: 'gmsh:physical'

[gdmcbain]

There is a direct route from STL to ASCII MSH; pass the --ascii flag to meshio-comvert. I suspect though that the real difficulty here is one of the many associated with writing the current default MSH 4.1; can you get away with the legacy MSH 2.2? If so, specify the --output-format more precisely, viz. "gmsh22".

[gdmcbain]

Actually MSH 4.1 works fine; e.g. taking Sphericon.stl as input:

meshio-convert -o gmsh -a Sphericon.stl Sphericon.msh 

gives an ASCII MSH 4.1 that Gmsh seems happy with.

[gdmcbain]

I confirm though that

meshio-convert -o gmsh Sphericon.stl Sphericon-a.msh 
meshio-ascii Sphericon-a.msh

raises the same KeyError: 'gmsh:physical' that you reported. That is a bug, but one that you can avoid with --ascii.

[gdmcbain]

That might be #956.