Corrupted .obj file if to_obj() function was ran more than once

[adambgnr]

It is a nice feature of Geomeppy that it can translate .idf files to .obj files. What I have noticed is that the generated .obj file sometimes turns out to be weird. There are faces in it without vertices (lines only with an "f" in them. See attachment).

How to reproduce:

• Start python (e.g. IPython in a shell)
• Run some script with geomeppy idf.to_obj() function. - the obj file will be fine this time.
• Run the script again (e.g. because you have changed some parameter) - the obj file will be weird
• Close python (close IPython)
• Start python again
• Run the script - the obj file will be fine this time again.

It seems this only happens, if you run the idf.to_obj(), then run it again, without restarting the python kernel (this can easily happen if you use Python in a scripty way, i.e. executing line by line in a shell with IPython, or you work in some integrated IDE, like Spyder).

Any ideas what might cause this?

obj_files.zip