I work on addon for UV box mapping. In my addon I need to check face normal to sort X,Y or Z oriented faces. By following this topic I found how to compensate object rotation by multiplying object matrix to face normal vector.
Now issue with object scale. On image - object scaled by Z to 0.1, face normal look almost straight to up to Z but mesh data still return normal as if object not scaled.
Question is - how to compensate object scale to get "true" face normals? Blender do it somehow under the hood when showing Normal Gizmo for selected face so how can I get same result.