As mentioned in this previous topic, the fbx import pipeline is in a weird place as Interchange has a bugged material instance parent property, making the older pipeline preferable in a lot of cases.
I need to import several OBJ meshes (in the hundreds), meaning I cannot afford to go and manually change the parent for each imported material. I am therefore using the legacy (Interchange.FeatureFlags.Import.OBJ false) pipeline.
Legacy mostly works, but doesn’t seem to handle normal maps correctly. With Interchange, despite the wrong parent material, the normal map is correctly identified from the “bump” keyword in the .mtl file, and added as a normal map to the material. With legacy however, I’m getting the correct material and texture as expected, but no sign of the normal map.
Here are the settings used:
As well as the Blueprint of the parent material in question:
If I later edit the material instance to add the normal map manually, it looks as expected, so it’s an issue in the import step, and likely not due to the parent material.
Is there a specific setting to consider when importing normal maps? Considering the lack of normalization, is it perhaps that “bump” is not the right keyword to use in the .mtl file? I did try using “map_bump” and “map_Kn” to no avail.
Thank you very much for any pointers you might have on this issue.
As a last note, perhaps a bit of a rant; Do we seriously need to wait until 5.8 for a fix on something this significant, which is unintended behavior in the first place? The engine ignoring the parent material should have been picked up and fixed during development of the new import pipeline, not versions later- Was it not properly tested?
This is making me seriously question the development and release process of Unreal Engine.