Double sided polygons question

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# 1 21-03-2012 , 03:30 AM

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Hi again. Just a general question about polygons in Maya.

So for I've been merrily modeling away and my polygons appear to be double sided (shaded and visible from both sides), and I've not given this any thought, but should I?

In a program like Lightwave, unless you make a polygon double sided it is one sided, and it's normals face outwards. Sometime you get flipped polygons that need to be corrected.

I know that Maya has a bunch of Normals tools so it must also be a thing to look out.

My object seems to render okay but is it important to establish the unified normals of all objects and how do I see that when they are double sided to begin with?

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# 2 21-03-2012 , 03:45 AM

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Turn off two-sided lighting in your panel shading menu. Then the wrong side will show black. Yes, in general even though they look double-sided, polys only have one normal direction, which may cause problems when they are reversed, or doing funky stuff.

-stwert

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# 3 21-03-2012 , 03:46 AM

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Yes, surface direction is important for things like merging verts, boolean operations and pretty much all the same reasons as Lightwave. To turn off two-sided lighting press the lighting drop down and uncheck two-sided lighting. I do this as a matter of habit whenever I start modeling as it can be tricky to figure out why some operations fail because of incorrect surface directions.

Cheers,
Rick

"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675

Last edited by ctbram; 21-03-2012 at 03:52 AM.

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# 4 21-03-2012 , 03:47 AM

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Oops Dave types faster then me apparently user added image

"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675

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# 5 21-03-2012 , 03:49 AM

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Neither of us may have an avatar, but our names aren't even close...

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# 6 21-03-2012 , 03:53 AM

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Doh Sorry Stew I saw the gold medal and for some reason thought Dave

"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675

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# 7 21-03-2012 , 05:11 AM

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This forum is awful fast on the answers, thanks both of you. I had quite a number of black objects which are now reversed. 2 sided lighting will remain off forever more.

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# 8 21-03-2012 , 09:09 AM

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i'm quite new here, but i think this is a more efficient solution for your problem.
Ok, with this enabled you can't see "behind" some faces because the shading is visible only in the semi-space "containing" the face normal... but this is a possible solution anyway..

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# 9 21-03-2012 , 02:16 PM

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Doh Sorry Stew I saw the gold medal and for some reason thought Dave

Originally Posted by ctbram

It's a bronze... why don't you just rub it in. user added image

Andrearastelli: Yeah, you can also uncheck double sided in the render stats in the AE. But I guess it depends if you want the wrong side to be black or invisible. I'd rather leave double-sided on and just check the normals, but it's a matter of preference. I wonder if it affects render times?