Single sided object in vray?

[vazap]

Hi.

I'm trying to backface cull specific objects in vray. I've just noticed vray doen't take into account the "Double sided" and "Opposite" attributes in maya. And that the "Double sided" option in VRayMtl only tells vray whether to light the back facing faces or not, but they are still rendered. How do I tell vray not to render back facing faces on specific objects? (The render settings option applies to the whole scene)

On a same note, is there a way to flip faces at render time (equivalent to maya's Opposite option), other than actually reversing normals?

Thanks,

Vania

[Morbid Angel]

Did you try vray2sided mtl?

[vazap]

I have it in mind, but it's such an awk

[vazap]

Oops sorry, new to this forum...

I have it in mind, but it's such an awkward, unpractical way to determine single/double sided-ness I thought there'd probably be a more conventional way. Ideally a shape vray attribute would seem a logical choice. Or an object properties attr... I'm hoping there's something similar in there somewhere I didn't find.

In some cases, complex scenes with lots of objects and shading group displacement, using a shader for this purpose can be troublesome. But thanks for the reply

Vania

[tashko.zashev]

Hi,

You can try with V-Ray 2 sided material where the back material is fully refractive with IOR 1.0.

I'm posting an example scene:
Example_.zip

[vazap]

Thanks Tashko.

I had considered using the 2 sided material. However you might agree with me that it is not a very practical way of doing things. I'm afraid that in the case of a displaced object render times might not be optimized using a shader for single sidedness. But mostly, it is just very inconvenient to have to go through shader assignment for this purpose. If many objects for example share a common shader that involves shading group assignment (displacement, volume), these will have to be created twice, for single and double sided objects. Wouldn't it make a lot more sense using a vray attribute (or even maya's) to determine this per object? Is this something you would consider putting on the to do list?

Cheers,

Vania

[ivaylo.ivanov]

I think we have this issue in the "to do" list, but it's not from the trivial ones.

[vlado]

I'm afraid that in the case of a displaced object render times might not be optimized using a shader for single sidedness.

I'm not sure about that one - V-Ray will always displace an object, regardless of the sidedness of the material applied to it.

Best regards,
Vlado