Introduction to Maya - Rendering in Arnold
This course will look at the fundamentals of rendering in Arnold. We'll go through the different light types available, cameras, shaders, Arnold's render settings and finally how to split an image into render passes (AOV's), before we then reassemble it i
# 1 05-12-2021 , 01:28 PM
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Join Date: Feb 2012
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Two normals for one face?

So I have been rummaging around the World of Warcraft's 3D model files and came across reddragonshrine_tree05 which is a red leafed tree. The way they do their leaves is just a simple "tripod" polygon that is three triangles back to back to back. Or, another way of thinking of it is if you have a square, cut it diagonally, then extruded that diagonal to be a third triangle.

Anyway, I noticed that when displaying the normals for faces that all of the faces have normals on both sides. So that "tripod" polygon is only three faces, but has six normals. I have tried to replicate it using just about every normal operation imaginable and have gone through both the shader, mesh, and shape node attributes, comparing every single thing to just a plain object to see if anything has been checked to cause this. But I have been unable to figure it out.

If I try to reverse a normal, it goes to being just one normal, but if I reverse again, it goes back to two. I wondered if double-sided meshes were the cause of this, but it appeared that double-sided is checked by default on the node.

It doesn't seem to have any effect on how the texture is displayed, so I'm not even sure what the point of it is. But I was curious if anyone knew why this is the case. Any ideas?

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