Maya 2017 Vray "Bifrost options" attributes

[scorpes]

There is a export particles/density attribute on the bifrost foam but I don't know how to use it with UserScalar. Tried particleSamplerInfo as well with no luck. Any idea how to render the foam with density as user scalar connected to the opacity of a vray material? It doesnt work by putting the density as vrayUserScalar.

[scorpes]

I'm kinda in a hurry, any solutions? Otherwise I need to switch to Arnold (preferably not )
Chaosgroup on holidays? Sounds like it, normally instant replies?

[yolov]

Yes, we were closed for a few days around Christmas and we will be again for New Year's Eve, there's a message on the chaosgroup website.
Sorry we didn't get to you earlier.

UserScalar is used to pass scalar (float) values from one attribute to another. Can you expand a bit on exactly what you need to do and if possible, share a simple scene that we can try and tweak to help you get there?

[scorpes]

No whorries If you check the bifrost foam, there is an opacity channel where you can set it to density. I'm trying to export that opacity channel to a vray material. With Arnold, you can use a "aiUserDataFloat" (attribute set to "density") which is the same as "vrayUserScalar" connected to the opacity of a material. But I cannot get it to work with Vray. There is a vray bifrost options attribute on the foam where you can set: export particles and export density. So I was hoping, I can you use that option with a vrayUserScalar?

[ydm]

Creating the foam brings up two new nodes in the scene: the foamShape and the foamMaterial, right? Can you please point us to where exactly is the problematic attribute?

[ydm]

Actually can you please send us a scene? Attach it here or, if you prefer, send it to yordan.miladinov@chaosgroup.com . Cheers!

[scorpes]

Happy new year! I attached a image to explain what I 'm looking for. I can provide you my scene but it's using a cache of 400GB which costs 2 days to simulate. .
I can make you a simple ball throw into the water scene? Or just pick an Bifrost example scene from the content browser.

[ydm]

Happy new year! I get it now. Let us check and we'll get back to you shortly.

[scorpes]

What's time-frame to implement this? I need to make a decision which renderer we are going to use for our project.

[scorpes]

Yordan?...

[Paul Oblomov]

Well, if it is urgent - convert foam to prt and then use ply2vrmesh. It will convert your particles to vrmesh, then you can attach any shader you like. Tho, you have to specify point size, coz there's no size mult for vrmesh particles.

[ydm]

Yordan?...

Well, I'm sorry it's taking so long, but there's no genuine way to export the opacity channel. I have the idea to write a specific C++ node for you that takes the created bifrost nodes and, using their parameters, computes the density on its own and outputs it. Not my primary task, so, if you can wait a little bit more, I'll investigate if it's possible or not.

[scorpes]

Thank you, worth waiting for! In the mean time I'm gonna test the ply2vrmesh

[ydm]

Alright, let us know if it works or not.

[Paul Oblomov]

Btw, there would be some scale problems with exported prt. You have to adjust the scale also with point size. If I'm not mistaken - prt scale would be like 1/mvs. Smth like that