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Topic: Fly-Out: There are always two sides to a story.

posted by T1T4
archived on 30.4.2002

I am trying to do a fly out of a tube and still see the inside of the tube after I pass through the tube wall. I have a cylinder with the normals flipped as my tube. With the default max render and 2 sided materials off it works the way I need it. With Vray it seems to render everything as if it used 2 sided materials. Is there a way to make Vray render only one side of the material like the scanline render does?

Here is an example of what I am talking about in case it isn't clear enough.

Follow-ups

A: You can use a Double-sided material (not a Standard material with 2-sided turned on, but a Double-sided material type), with one of the sub-materials (the one for the outside) completely transparent.

Q: isn't this going against the way the "standard" material originially created? i mean, the fact that there's a 2-sided checkbox just shows that. i just find it odd that you have to take extra steps to make a material work the way it was intended...
A: I am not really sure that was the way things were intended. The Scanline renderer simply ignores back-facing polygons when rendering (unless they have a 2-sided material) to speed up the rendering process. VRay cannot ignore polygons in this way because a polygon backfacing the camera might still be visible in reflections etc. I consider this to be a renderer-specific feature, and not a material one.

Comment: Using the double sided material with a 100% transparent material for the outside worked perfect. I still think it would be nice if Vray would ignore back-facing polygons if 2-sided is not checked, at least if you are using the standard max materials. If for some reason you needed the back faces to reflect you could always just check the 2-sided option and the problem is solved.

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