I'm currently playing around with unity and tried to create a room in blender and import it to unity. The room is a non-manifold mesh (on purpose) - because nobody is going to see that room from the outside and I wanted to save polygons.
The render result looks nice in blender, but in unity the room looks pretty ugly and I realized that the normals are wrong (if i recalculate normals in unity it looks OK)
I tried to recalculate the normals in blender but it started to flip around faces and calculated the wrong normals (for flipped faces).
Now my question: Is there a way to recalculate normals without blender trying to "fix" (flip) some faces or is blender not designed to work with non-manifold meshes (which are pretty usefull in games)