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Author Topic: No light on back of a face ! !  (Read 9571 times)

beyond_3rd_dimension

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No light on back of a face ! !
« on: April 13, 2008, 09:17:21 pm »
I am not sure anyone had face this problem before or not. I searched the 0.97 Preview forum but couldn't find any topic related to it.

I made a tunnel to represent a corridor then I put a light and a camera inside. When I rendered the scene with ART I could not see any light. But when I use Scaline I can see the light. Then after some more experiment I found that, only the front of the face can reflect lights with ART. I had to Flip Normal the faces of my corridor to fix this.

your comments please.

beyond_3D
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hihosilver

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Re: No light on back of a face ! !
« Reply #1 on: April 13, 2008, 10:52:00 pm »
That makes sense.  I don't think the ART raytracer supports double sided materials.  Realistically, the back of a face should not be rendered, in fact, they aren't rendered in games.  That's why there is a "flip normals" command, because you want the normals facing you.  You don't want to be looking at the wrong side of the face.  Still, scanline renders the back because it supports double sided materials which enables you to make a different texture for each side of a face, therefore making it somewhat of a double sided normal kind of thing.
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CobraSpectre

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Re: No light on back of a face ! !
« Reply #2 on: April 13, 2008, 11:01:32 pm »
You may be able to use the shell tool it give it an object faces on the inside of a mesh.
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beyond_3rd_dimension

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Re: No light on back of a face ! !
« Reply #3 on: April 14, 2008, 05:10:08 pm »
hihosilver: Thanks.. now it's making sense to me as well..

CobraSpectre: Shelling.. Why didn't I think of that before ?? thanks a million...

- beyond_3D -
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Steve

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Re: No light on back of a face ! !
« Reply #4 on: April 19, 2008, 04:38:59 pm »
The ART raytracer doesn't flip a surface's normal whtn it's pointed away from the light.  That causes problems for some of the more advanced materials and isn't really realistic.  (There are no infinitely thin surfaces in the real world which is what the scanline renderer is assumong.)

As CobraSpectre pointed out the shell tool is a good way to gove thes objects some thickness.
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