Setting up UV direction I have created a hallway in Blender, and then I applied "Smart Unwrap":

The unwrap doesn't look absolutely perfect, but I thought it would do the job.

Then I exported the model as an fbx and imported it into Unity.
In Unity, I applied a material to it which has a texture assigned.

For some walls it looks fine, but for some walls, the direction of the UV map is changed for some reason, and the texture doesn't look right:



How could I set up the "direction" of the UVs in Blender and not just hope that it will work out alright (which it obviously doesn't)?

Thank you very much!
When you do Smart UV Project you can generate UVs with islands.  Then you can select the pieces that need to be rotated and rotate them by pressing R 90 Enter.  You can also scale the pieces generated by pressing R 90 Enter.