This can happen when mtllib is absent, points to a non-existing file, or material names are incorrect. In either case it helps the reader differentiate between materials that are actually specified in the file, even if their definition happens to match the default, from materials that were never loaded in the first place.
thisistherk
commented
11 months ago
This can happen when mtllib is absent, points to a non-existing file, or material names are incorrect. In either case it helps the reader differentiate between materials that are actually specified in the file, even if their definition happens to match the default, from materials that were never loaded in the first place.