USD models - possible to do material override?

[sentry66]

We need to be able to assign different V-Ray shaders to USD models for different looks. These V-Ray shaders are fairly custom and not always USD compliant. Is there a way to assign a material override to USD model so it renders with the custom V-Ray shader? I'm not seeing a way to do this.

Also, will the distance texture ever possibly work with USD models?

[hsz]

Yes its possible. We just did this using USD
I couple of questions,
How are you loading your assets?
Are you working in USD?

[hermit.crab]

If you wish to override a shader within a USD stage, select the object and assign a new material to it (BRDFVRayMtl). This will create a new VRay shader in the USD Stage. Afterward, you can edit it as you wish in the LookDevX Editor.

Regarding the VRayDistanceTex, I need to ask the devs if that's possible. Otherwise, you can always bake it.

[sentry66]

Yeah, we're staging USD files, and then we normally export to .vrscene. We're wanting a workflow where we don't necessarily want to write a new shader to the USD file, but to instead use a regular Maya/V-Ray material and assign it as a vray material override attribute.

I'm hoping there's a way to just read the USD data and when we export to .vrscene that vray can convert the USD to regular vray poly data during export but are still assigned a standard non-USD vray shader.

Maybe it's not possible yet? We have so many vray shaders that use things like distance texture and other non-usd items, or are driven by rigging attributes. Just looking for a way to at least get the speed benefit of USD without having to almost start over with shaders. Even if our custom vray shaders will not work on USD models, when we render in the vray frame buffer, we can temporarily convert those models to "maya data" temporarily via the outliner, then change back when done preview rendering. I'm just hoping there's a way to make it all work for final .vrscene rendering with our custom vray-specific shaders.

[hermit.crab]

Correct me if I've misunderstood - you wish to override a shader in the USD via an attribute? If yes, we've not implemented such an attribute at this point.

Mind if you share your exact workflow to better understand it? Why do you need to convert back from Maya Data? And why not export a .vrscene directly from the Maya Data?

[sentry66]

Thanks. Our team wants to start using USD models for our basic models so files load fast, but we want the full power of vray shading. Right now, we have no way to assign USD models our existing maya vray shaders. We would like a way for that to be possible since it is time consuming to redo vray materials so they work with USD and are limited to what USD shading or MaterialX currently support.

Our workflow currently is stage USD models, and for simple shading, assign a new vray shader via lookDevX. For complex shaders, we have to convert those USD models to maya polygons or bake out as alembic so we can assign our existing vray shaders. We're still very new to working with USD, but have libraries of vray shaders we created that we routinely change for different art looks for clients. We would like to use them with USD data somehow via a material override function so vray knows to render USD with them

[hermit.crab]

I've notified the product owner about the request. For now, you could log the idea to the Ideas Portal so that people can vote on it.

[sentry66]

thanks! I submitted it