Support name tags for multi-tiles in Corona bitmap

[romullus]

Recently i discovered that you can load multi-tiles in V-ray bitmap by using name tags: https://docs.chaos.com/display/VMAX/VRayBitmap I think it's brilliant idea and would love to see something similar in Corona bitmap. I'm aware that 3ds Max has dedicated multi-tile map, but it's retarded and buggy and it doesn't look that autodesk has plans to fix it in foreseeable future - i saw bug reports as old as 2019 and it still isn't fixed in the latest versions!

[maru]

Could you explain why this feature is interesting to you and in what exact cases you would use it? Honestly the description sounds a bit cryptic to me without knowing some specific examples how it can be used.
I will also get in touch with the V-Ray team. Hopefully they can share some ELI5 with me and maybe some examples how it can be used.

Thanks in advance for the additional info.

[romullus]

Sure, so basically it makes life so much easier for someone who works with UDIM, or other multi-tile formats. You don't need to load tens, or sometimes hundreds of individual textures and set-up their tiling according to their place in UV space, you just load single texture, replace part of its name with <UDIM> tag and the renderer automatically does rest of the work for you. Super easy and convenient. I see that V-Ray implementation has some drawbacks, like inability to show UDIM textures in asset tracker, but it's a price that i'm willing to pay, since 3ds Max multi-tile implementation isn't perfect either and it has at least one serious bug that practically renders it useless.

[maru]

So let's say that you have a model of a car and textures in a special UDIM format. You can then texture the car using a bunch of UDIM textures with the special tag in one go, instead of having to manually apply each texture to a different area / material ID.
Is that right or does it work in a different way?

[romullus]

Yes, that's right, but there's nothing special in the textures, except their naming. What's rather special, is the mesh objects, more specifically their UVs - they have to be prepared for UDIM workflow. But that has little to do with Corona, it is already perfectly capable to deal with UDIMs, name tags would just make users life much more convenient.

[maru]

Yes, that's right, but there's nothing special in the textures, except their naming.

Do you mean the file names or the names of textures in the material editor in 3ds Max? (or something else?)

So how I understand it so far is that these are the requirements:
- textures with special naming (waiting for clarification)
- mesh objects with special UVs prepared for UDIM workflow
- support in Corona <-- we have it working partly, but having these name tags would make life much easier

Do you have any special mesh like this that we could experiment on, or could you point me to some place where they can be downloaded/bought?

[romullus]

File names. They are created by texture authoring software automatically, so the rendering app would know how to map them on the object correctly. If you want, you can read more about UDIM naming convention and workflow here: https://learn.foundry.com/modo/901/content/help/pages/uving/udim_workflow.html but in essence each UDIM texture must end with four digits part, that serves as an address to its place in UV space. As i said before, Corona already supports UDIMs when they are loaded through Max's multi-tile map, but V-Ray bitmap has nice option where you can load single texture from particular UDIM set, replace those four digits with the tag <UDIM> in its name (inside material editor) and V-Ray then automatically would load all needed UDIM textures and correctly map them on the object at render time. That's super convenient for the user, as there's no need to mess with tens of textures at once.

I wouldn't ask for this feature if multi-tile map would work as it should, but it doesn't, because... Autodesk.

P.S. there are other multi-tile naming conventions, besides UDIM and V-Ray bitmap tags support them as well.

Do you have any special mesh like this that we could experiment on, or could you point me to some place where they can be downloaded/bought?

I will try to author some sample asset with UDIM textures over weekend and will send it your way.

[maru]

Thanks a lot Romullus for your explanation and sample files. This is now logged.

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