# Undefined normal vector by converting .blend file

I hope my first post here isn't that much off-topic. Well, I had some times ago an project with Ogre3d. My designer used Blender. When ever he made a model for me, it looked in the Blender window fine, as far he didn't entered the UV-map mode. (I'm not quite sure anymore, but the mode had something to do with texture mapping)

If he did so, some surfaces were randomly CCW or CW rendered. Even if he did

Mesh > Faces > Flip Normals

It didn't change anything. But this wasn't the main problem at all, the main problem was, when we used the .blend to .mesh exporter this behaving kept and the mesh file I used in ogre also had randomly surfaces back and front culled. We weren't able to find any solution till now.

So now I ask here if maybe anyone could explain whats our problem and how we can solve it.

And I'm sorry for that lack of information but I'm not working together with my designer anymore.

• Did you try Recalculating the normals? (Tab> edit mode A> select all Ctrl+N> recalculate normals) – gandalf3 Sep 24 '13 at 20:01
• Worked so far in Blender it self, But can't test it right now in Ogre. I will let it you know when I have tested it after exporting into Ogre. – Zaibis Sep 24 '13 at 20:44