(open)[HOU-4498]simple merge of two materials renders wrong in IPR

[Morbid Angel]

I have a really basic scene, where I have alembic loaded twice, once for paper material once for the lid material (by using object selection to isolate parts I need), I assign different materials to each part. One needs to be solid paper material one needs to be refractive/plastic lid material. I then merge them and produce one output.
Renders fine with regular render.

However when I use IPR it looks like this:


It seems the IPR cannot process refractive part of the material?

[chakarov]

Hello Morbid Angel , I can't reproduce the issue on my side. Can you share more info about your OS, Houdini and V-Ray versions ? Or share the abc/hip file.

[chakarov]

Hello again Morbid Angel , I've reproduced and reported the problem. As workaround, I can suggest you to use different V-Ray Material Builders for different geometries instead of targeting different nodes in the same builder.

[chadstevens]

Yeah, I had this problem a while ago, the ipr doesn't seem to support rendering multiple material outputs from 1 material buider.

So I either use multiple material builders or a multi-id material node to apply different materials to different parts of the model using a string attribute (I usually create a s@material attribute) then you can use the pattern ID in the multi-id material node and set it to material in the attribute and set the patterns to the names you give each part.

See attached image.

[Morbid Angel]

Hello again Morbid Angel , I've reproduced and reported the problem. As workaround, I can suggest you to use different V-Ray Material Builders for different geometries instead of targeting different nodes in the same builder.

Thanks, yes of course we can. However you have to understand complexity of our scenes. In this simple example sure. However in more complex scene we have something like this. The model is split into many sub groups to which a shader is assigned. It is much much easier to have all those shaders inside one builder thus having the ability to share materials, textures etc without having to jump from one builder to another.

[bdancer]

> It is much much easier to have all those shaders inside one builder thus having the ability to share materials

I've fixed that particular issue with IPR however this setup will not work correctly:
1. if user selects the builder itself the first found output will be used (whatever HDK's OP_Network::getOpsByName() will return as first element).
2. all outputs will have the same scene_name (because we use builder's scene_name and we won't change this) thus the same value in material cryptomatte.

[Morbid Angel]

Thanks Bdancer. In a more complex setup what would be your recommended workflow? Yes we can have material builder per node, but it seems counter intuitive?

[bdancer]

> In a more complex setup what would be your recommended workflow?

Well, I'm just pointing out some current restrictions of such a workflow.
I could add aditional ROP (or output node) parameters to define which node name to use for Cryptomatte (if you have issues with that).

[Morbid Angel]

Yes we do have issues with that since in our cache the cryptomatte will be just one. Having an ability to control it would be great. With that said we have used vrayObjProp node with objectId to define the cryptomatte number but that means manually setting that and is not ideal.