Adjust Normals for Unity

Hey Blenders,

i have work on a project very long and now i want to load it into unity…
But i have a hugh problem with the normals. some walls are not shown in unity.
I recalculated the normals ( inside also)
but it did not help. Now are different walls missing.

Can you help me?
i attach the blender file so ou can have a try :stuck_out_tongue:

Best regardslecture_theatre.blend (2.28 MB)

Whenever you have an edge that doesn’t connect exactly two faces, you have a non-manifold mesh: Blender can’t decide where’s “inside” and where’s “outside”. In edit mode switch to vertex or edge selection and go Select -> Non Manifold. Borders of the mesh are ok, but any sections that connect more than two faces are not.

If you want to make walls, either make them proper solid walls, or keep them disconnected from the rest of geometry. You also have some ngons in that model, I wouldn’t expect it to be game-friendly.