The obj reader looks to support obj "Groups" and "Objects" - it seems that these bring in an OBJ as an aggregate of mesh features.
At the moment it seems like the only way to create something similar is to give the objects a unique appearance name so that the output OBJ separates the meshes. This seems a bit hacky to me.
It also means that it's not really possible to perform a "round trip" with OBJ files which support this group/object feature.
It would be nice to have this supported - either via format attributes or by geometry properties.
Being able to do this would enable output objs to have more value in tools like blender where groups or objects can selected. A use case is in City Models - if Roofs and Walls for example could belong to separate groups then in blender it might be possible to apply materials to all Roofs or Walls.
As it is at the moment the resulting obj will typically just be a single mesh.
