UVs don't flip after mirroring geometry

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# 1 30-12-2013 , 05:59 PM

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hello. when i mirror geometry, UVs don't flip. they stay blue, but are not reversed. how can i reverse them? i need it for normal/displacement mapping.

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# 2 30-12-2013 , 06:49 PM

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Here is a snap of the buttons to flip the UV's

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# 3 30-12-2013 , 06:59 PM

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by flipping uvs using "flip" function the uvs turn red and normal/displacement maps don't work as intended.
i have one object with maps for it. now i need a mirrored copy of that object. when i just mirror it and use maps from the original object (uvs of the mirrored object are blue, but not mirrored), the rendered result is wrong.

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# 4 30-12-2013 , 07:53 PM

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How about a pic of your UV layout and the rendered result. Notice how I gave a pic and within seconds you knew it was something else. Same holds true on your side for information. Otherwise I sit here and type all day...

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# 5 30-12-2013 , 08:03 PM

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here's uv layout. it's same for original and mirrored objects.
second picture is the mirrored object with applied with displacement from original one.
last one is the original object with displacement.

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# 6 30-12-2013 , 08:20 PM

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That issue is caused by the normals not being flipped, not because of the UVs.

Imagination is more important than knowledge.

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# 7 30-12-2013 , 08:27 PM

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oh, indeed. i though normals were alright, because "two-sided lighting" is off, but i didn't noticed i switched to viewport 2.0.

now i have additional question - how can i mirror an existing normal map for that case?

Last edited by mickhah; 30-12-2013 at 08:34 PM.

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# 8 30-12-2013 , 10:25 PM

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i tried to invert green channel in photoshop, but got this result:

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# 9 30-12-2013 , 10:35 PM

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XNormal -y conversion. Game engines require the alt setting in some cases so I have to batch this out of Crazybump. That costs money. But XNormal is free and will do it as well.

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# 10 30-12-2013 , 10:44 PM

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as i understood, i have to load high- and low-poly mesh into xnormal and switch +y to -y there. is there any way to invert already existing normal map, rather than render it anew?
i tried to export new map from zbrush with inverted green channel, but still have seams like in the last picture.

Last edited by mickhah; 30-12-2013 at 10:54 PM.

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