Alpha Matte of Maya Fluids In V-Ray 3.0?

[TRFX]

New to V-Ray.

I'm having a hard time figuring out how to get a clean alpha matte of just my fluid sim portion of a project. I have other objects that have object_ids which is fine but object ids are not supported for fluids in V-Ray it seems. I can get a render pass of just the fluid if I add an Atmospheric_Effects pass in V-Ray but this isn't what I want. I want a true alpha matte of the fluid. Any help would be greatly appreciated.

Tobias

[ivaylo.ivanov]

I think the closest thing is to use material id, but it's not exposed in the extra attributes yet. You can use python post translate:

from vray.utils import *
 
l=findByType("PhxShaderSim")
l[0].set("material_id", AColor(1.0, 0.0, 0.0, 1.0))

Of course it's a bit limited. We think to add Atmospheric Alpha RE.

[TRFX]

That worked nicely to get me a color matte of the fluids. Thank you very much for that. I'll see how well it works at the compositing stage. I'm worried about the transparency of the color in certian areas being seen as a different value of red in the compositor and thus not yielding a production quality matte. I'll post it here when done.