Converting obj model and calculating tangent and binormal

I’m trying to load an obj file into Panda3D, but I can’t get the normal maps to work as the obj file doesn’t contain tangents/binormals, and obj2egg won’t create them.

I’ve tried loading the obj file directly in Panda3D with “self.loader.loadModel” and also tried first converting to an egg file with obj2egg. I’ve tried the -tbnall and other -tbn* options without any luck, I don’t get any errors but the resulting egg file never has any tangents or binormals. I’ve tried with a couple of obj files with the same result, eg.

Any idea what I’m doing wrong or how I should be importing this model?

I can open it in Blender and then export it using YABEE, which does work fine, but I’m wondering why the -tbnall option for obj2egg seems to do nothing?