Trying to make the Russian Double Eagle today and noticed that when you make faces with F, Blender sometimes makes the UV face the other way. I know I can flip it, but why does it do this? Is it something I can prevent? Not really a big deal, just wondered if anyone out there might have that random bit of knowledge.
Hi Simo.Haya,
I’m not 100% sure but it could be from the face normals direction? I only mention this because face normals often get flipped when creating new faces.
Honestly I’ve never noticed this but next time I’ll remember to be aware of it.
I am interested in this as well. I don’t know what causes it either, but it happens quite often when I am doing retopology in certain situations, but your example shows a flat surface, and doesn’t apply to my situation. Like you said, not a big deal, but I would like to get through a bit more, if not all, without having to flip faces.
I think you didn’t created this by extruding a plane or mesh but by extruding a point and drawed a grid like template which you then “polygonized” by selecting points and pressing F2, right? Well points by itself (in math) doesn’t have a normal , even if blender is showing them (it only asumes that they are pointing away from (0,0,0) ). So if you press F2, Blender is making a polygon based on the selected point and it’s edges and guessing a normal if there is no neighboured polygon which already have a normal. As a result if you don’t extrude from existing polygons or “grow” your polygons from an already established mesh you can have these jumbled normals (Strg-N is your friend if the polygons have “meet”).
Or in short: you already (believe to) know what the normals would point to while blender (and math) doesn’t.
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just select all in edit mode, and press CTRL+N
. Thanks 
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