VRay Proxy Material assignment overrides. What it's?

[iLuso]

Hi!

I create VRay Proxy from alembic, and in VRayMesh node found strange attribute - Material assignment file, and it uses *.xml files. No info in docs, no info any where. What it's, and how it works?

Thanks!

[yolov]

It's a new highly experimental feature that is still in development. It allows you to assign materials stored in .vrscene files onto different objects from an alembic file.
The new parameter that you've noticed actually specifies the location of a .xml file that specifies the "rules" for material assignment based on the obejct path in the alembic file (it only works with alembics). The xml works with wildcards *
Then you need to have a .vrscene that contains the materils (+ procedural textures or paths to bitmaps) and specify where to load the .vrscene from (for now it's only done with post-translate python script).

Here's an example: mtl_assignment_overrides.zip
You'll need to fix the path to the xml in the proxy node and then fix the path to the .vrscene file from the render settings > common tab > post-translate python script. (Note that I've deleted the geometry and settings the "node" plugins from my vrscene, because using appendSceneContent will add all the content from that vrscene file, including the geometry, which I don't want in this case).

Disclaimer: This is still highly experimental and can change at any point!

[Dan Andersen]

Nice, this holds a lot of potential!

A few ideas (I know this is early days so maybe you're already way ahead):

- Include support for regular expressions in the pattern
- Allow assignment by other attributes than object name. For example by vrayUser attributes on objects.
- One of the things that make vrayUser attributes so successful in my opinion, is that they are evaluated hierarchically, so you can have global attributes assigned to top transforms that are then overridden by attributes further down the hierarchy. Are these shader assignments evaluated by the same logic?

[yolov]

Thanks for the input. Yes, we do have a few things in mind for this feature, although it's really early to tell where it's going.
We'll keep your input for consideration.

[vlado]

- One of the things that make vrayUser attributes so successful in my opinion, is that they are evaluated hierarchically, so you can have global attributes assigned to top transforms that are then overridden by attributes further down the hierarchy. Are these shader assignments evaluated by the same logic?

The proxy will use the first rule that matches a given Alembic path. So you if you make sure to list the more specific rules first, you can control the override order.

Best regards,
Vlado

[FSGFX]

this sounds a bit like materialX...
is there any similarity..?

[vlado]

Not that I'm aware of. MaterialX defines the shading networks themselves, not how they are assigned to scene objects.

We also want to override other properties of objects like visibility, matte ID, matte/shadow on/off, displacement, subdivision etc. I don't think MaterialX deals with these.

Best regards,
Vlado

[iLuso]

Wow! Sounds great!
Can you do similar feature for vrayscene? It's be perfect if we can export to vrayscene geometry at once, and after set shading by this method!

[vlado]

Can you do similar feature for vrayscene? It's be perfect if we can export to vrayscene geometry at once, and after set shading by this method!

Most of that can already be done in the latest nightly builds and in V-Ray 3.5 using the VRayScene override snippet that we added recently, although it requires some technical knowledge about how .vrscene files work.

Best regards,
Vlado

[iLuso]

Most of that can already be done in the latest nightly builds and in V-Ray 3.5 using the VRayScene override snippet that we added recently, although it requires some technical knowledge about how .vrscene files work.

Yes, we already use it for override all materials inside vrayscene, and it's very useful. But for production it's difficult, because if we import vrayscene in many shots and after that want to change materials by override snippet we must change, we must open all of them and set it. If we use reference, we can catch problems with reference edits, because we use override snippet in another task. But if we have Material assignment file for vrayscene we set xml file at once, and after that can update it external as we what, and this is perfect! And if we have additional parameter enable/disable it, it's will be brilliance!

And as additional, will be perfect if vrayscene have possibility like a vraymesh(vrayproxy) to set preview file and use it as gpu mesh! Because vrayscene inside mesh often is too huge for display it all, and preview faces give not nice representation.

[yolov]

You can load snippet overrides from file to the vrayScene node in Maya. You can test it with a nightly, actually.

[iLuso]

Hi!
I trying to use this feature in new project. It's looks very nice for large scenes building. I can get very light maya scenes, and use separate GPU mesh for viewport.
But I have one huge problems! I can't use view dependent subdivision by enable vraySubdivEnable in mesh or in vrayDisplacement node. Because when I enable it all assignments materials are missed. And I don't understand how fix pattern name for fix it. Please help!

[yolov]

Ah, sounds like a bug, I'll make a note for the developers. Thanks for the report.

[iLuso]

Oh, It's great. Hoping it's fast

[iLuso]

Hi!
Any news about fix this bug?