topic Re: USD for 3ds Max 0.8 Released in 3ds Max Forum

USD for 3ds Max 0.8 Released

shawnolson — Thu, 08 Aug 2024 19:53:49 GMT

Last week the USD Team released USD for 3ds Max 0.8 that included several new capabilities. Among them are:

Multi-Select and Transform Prims in the Viewport
Zoom Selected on USD Prims
Use USD Cameras from a Stage
USD Controller
Export Progressive Morpher as Blendshape Inbetweens

You can get this update in your Autodesk Account. See the complete release notes on USD for 3ds Max 0.8 here.

(view in My Videos)

Re: USD for 3ds Max 0.8 Released

RobH2 — Fri, 09 Aug 2024 14:15:55 GMT

This is good and appreciated.

But if you want to export to Omniverse, textures won't go with the export. I've been experimenting all week without success. I wrote support to get Max USD 0.7 to be able to effictively commect with Omniverse Composer but they won't give me access to it. Do you know why? Chaos Group and many others, including Maya, provide older versions so we can leverage the technology as our needs see fit. Why can't we Max users get USD 0.7?

Re: USD for 3ds Max 0.8 Released

shawnolson — Fri, 09 Aug 2024 14:54:23 GMT

At this time, we are trying to keep customers on the latest versions to help improve the product. Updating your tool to support 0.8 should be trivial and if you have any specific questions on doing that, let me know and I will try to help.

I cannot give any dates or make specific commitments, but I can tell you that we are internally working on plans to Open Source the 3ds Max USD plugin just as we have for Maya USD and other USD plugins here at Autodesk. If or when that happens, you should have the freedom to fetch and build versions as you see fit.

In terms of your issue of textures, can you explain more about the setup that is failing to export? As long as you are using supported materials (USD Preview Surface, MaterialX or Physical Material by default plus more if supported versions of Arnold/Vray are installed) and maps (BitmapTexture, OSL:Uberbitmap, OSL:BitmapLookup and more if supported versions of Arnold/Vray are installed), the materials and maps should translate. What materials and textures are being used?

Note that if you are dependent on Vray, the Vray nightly builds already support 0.8.

Re: USD for 3ds Max 0.8 Released

RobH2 — Fri, 09 Aug 2024 15:12:54 GMT

I'm using the V-Ray nightly builds and standard V-Ray materials. Here's a thread discussing some of the issues I mentioned here.

https://forums.chaos.com/forum/v-ray-for-3ds-max-forums/v-ray-for-3ds-max-problems/1212405-3dsmax-vray-to-usd

Even as Max 2025 is not supported buy Omniverse yet, Max 2025.2 is supposed to be fully USD implemented via 0.8.0. I'm finding that it doesn't export model textures with standard V-Rays materials either.

Let me go through the things you list and make sure I'm not overlooking something obvious. I've been working on this for two days and having no success but I could be overlooking something right in front of me that I'm just not seeing.

I'll test more and reach out. I really wish I hadn't updated to USD 0.8.0 thus overwriting and losing my USD 0.7.0 code. I had no idea that I would not be able to get that from Autodesk should I want to revert. So now I'm stuck until I figure out why I'm having issues, be it user error or USD 0.8.0 issues.

I'll be back, going to test some things now.

Re: USD for 3ds Max 0.8 Released

shawnolson — Fri, 09 Aug 2024 15:52:59 GMT

Vray Materials are beyond the scope of our support, although we do work with Chaos to build APIs to allow them to hook into our exporter/importer. You have to realize that with renderer-specific materials, you are dependent on the target consumer to also have that renderer installed. For example, a USD file with Vray materials within it will only render correctly when Vray is installed with the application that is rendering the materials. The same with Arnold materials.

If you need to have more portable materials, you should consider using MaterialX. The USD Plugin comes with the MaterialX Material in Max and allows you to generate USD files that reference the MaterialX documents. This is the most compatible method for creating USD assets with portable materials.

Re: USD for 3ds Max 0.8 Released

RobH2 — Fri, 09 Aug 2024 16:09:49 GMT

Understood. Still learning, still experimenting. It's a new pond to splash around in. I think my workflow is sound. I've read and done a dozen or so tutorials and read dozens of posts. I'm need to do more testing to figure out why I'm having the issues I am. Your specific directives are great to have as I double-check. Thanks Shawn.

Re: USD for 3ds Max 0.8 Released

RobH2 — Fri, 09 Aug 2024 19:42:31 GMT

Isn't the point of USD that it exports an agnostic version of the master model/mesh? Meaning, if I have V-Ray running properly on Max and I export a USD to Omniverse (or anywhere really), or just export a USD to any folder, shouldn't the V-Ray material be reconfigured to the USD standards so that any platform that can open a USD will have a model with a reasonable representation of the original material? Same for Arnold, Redshift, etc., as long as the host program, Max in our case, can render the render engine's material, doesn't that get written to a USD format that now has 'no need' for V-Ray, Arnold or any other render engine? Meaning, Omniverse Composer, C4D, UE, iClone, whomever, need not have any specific render engine installed beyond USD support.

My understanding about USD in general, is that it's a way for ANY USD compatible program to read, share and use USD files without having any other render engine installed?

Re: USD for 3ds Max 0.8 Released

shawnolson — Sat, 10 Aug 2024 04:48:52 GMT

No, that is actually very far from the reality of USD. USD is a common framework for how scenes can be described, but it does not provide a way for all descriptions of scenes to be universally understood by everyone. In the specific case of VRay, you have to understand that to render Vray materials, the only renderer that will understand what a Vray material is supposed to look like is the Vray renderer.

You can probably expect all USD-respecting applications to understand base USD data. But anything that is custom on top of it is often going to require an extra layer of interpretation.

My intent is to share some courses this year to help explain the nuances of this. USD is super powerful and robust, but there are many misconceptions about it in the world.

Re: USD for 3ds Max 0.8 Released

RobH2 — Sat, 10 Aug 2024 14:12:33 GMT

Gotcha. Ok, let's try to clear those misconceptions up. If I'm having a hard time with it then certainly new users and students are as well. I'll work on my own and here to help demystify it and see if I can't clear some of the misconceptions up.

Let's start with my first one. I assumed that if I had V-Ray on Max, and the version of V-Ray was USD 0.8.0 compatible, that V-Ray would do the interpreting of it's materials and then write them to the proper USD profile and a USD mesh and material data file would be created that any USD capable software could read. Having been transcribed, V-Ray would no longer be in the picture, its task done and over. What I hear you saying counters what I'm saying. You are implying that somehow V-Ray material read/write capability is still required, even after the USD file has been compiled.

Re: USD for 3ds Max 0.8 Released

shawnolson — Mon, 12 Aug 2024 15:43:01 GMT

There is no USD equivalent of a Vray material. There are only very basic shader capabilities in USD itself. If you want a fully portable material you will likely want to generate and use MaterialX materials, which are intended to be fully transferable between DCCs and renderers.

Arnold and Vray (and other renderers) have many of their own internal ways of building and interpreting shaders, and the way those materials work are built into the renderers--not into USD.

MaterialX is what you should use for portability--but it has historically been missing some of the special shaders that renderers such as Arnold and Vray have. So if you need a very specific shader effect from Vray or Arnold, you will need to stick with those shaders--which means you will only be able to render using that same renderer.

Re: USD for 3ds Max 0.8 Released

RobH2 — Mon, 12 Aug 2024 16:16:44 GMT

I understand all of that. We are miscommunicating. Say I have a Diffuse texture, wood grain photo, I also have a black and white bump map of the grain and I have a roughness texture image. In effect, I have the beginnings of a PBR texture. My expectation from a USD exporter is to take those three textures and create a basic PBR USD material, assign the three textures to the relevant slots and off we go. Each of those three texture components do not care what render engine is being used. They are just jpgs or pngs or whatever. But of course, we all know that, we aren't beginners here.

From what I'm reading, this is how it's supposed to work. 3rd party vendors, Chaos Group, etc., will provide integrations withing their renders in Max to be able to do that. Or, I can just wire them manually. But whether I have V-Raymtl, a Corona base material, an Arnold PBR materials for a standard physical material, it should not matter. The three textures get connected to the 3 relevant slots and get written as USD material that is the beginning of a PBR material. With that basic USD PBR material, I should have some that any program that imports/exports USD can interpret and understand.

What am I missing? There shouldn't need to be a lot of converting and convoluted steps I don't think. The USD exporter should just see the 3 texture maps, know that they are a diffuse, a bump and a roughness and build a USD PBR with them in the correct slots and move on.

Re: USD for 3ds Max 0.8 Released

shawnolson — Mon, 12 Aug 2024 17:50:40 GMT

Our exporter does provide translation of these materials into USD Preview Surface:

USD Preview Surface
Physical Material
PBR (Metal/Roughness)
PBR (Spec/Gloss)

With the materials above, the only accepted maps are:

BitmapTexture
OSL:Uberbitmap
OSL:Bitmap Lookup
Normal Bump (with inputs from above textures)

We will also reference the MaterialX Materials from max nodes in the export.

However, for all other materials, it is up to the specific material developers to provide translations of their materials. In the Max USD Exporter, you will find a Materials section that shows material outputs. At this time, those are MaterialX and USD Preview Surface. We only convert the materials above to USD Preview Surface. Vray, if they choose, can add a translator from their specific materials to USD Preview Surface. If they choose to write that, it is entirely their choice. What Vray does do is, when enabled, the Vray materials get packed into USD in a format that lets Vray render all their complex shading rules.

So if you want to make sure that your materials are transporting into the USD Preview Surface, you need to use the materials listed above as well as turn on the USD Preview Surface output in Materials section of the exporter.

Note that it is possible to bind multiple materials to a USD prim and it will be up to the renderer to choose which to render in what context. For example, a USD Preview Surface may appear in a light viewer, but a full Vray material will be used at render time. This is meant to explain that the system is robust but there is no universal conversion of any complex bespoke materials to USD. For Vray and Arnold, the general use-case is that you are still rendering with Vray or Arnold since they are the only ones that can understand their shader networks. Vray and Arnold implicitly turn on their own shader exports when they are enabled in the plugin configuration and don't appear in the Materials list--meaning that turning on Vray will also generate Vray materials at export.

I hope this helps clarify.

Re: USD for 3ds Max 0.8 Released

RobH2 — Tue, 13 Aug 2024 13:27:21 GMT

Yep, good info. Adding it to my knowledge base. Thank you Shawn.

Re: USD for 3ds Max 0.8 Released

protonmailJFBQC — Tue, 03 Sep 2024 03:52:13 GMT

For some reason the way max exports USD, they don’t appear on my models in Unreal. The texture paths get butchered and these texture nodes get added (last image)

This first image is before I exported from 3ds max. The USD exporters from Blender and Maya don't have this problem. Thanks

Re: USD for 3ds Max 0.8 Released

protonmailJFBQC — Thu, 05 Sep 2024 18:35:29 GMT

bump

Re: USD for 3ds Max 0.8 Released

shawnolson — Thu, 05 Sep 2024 20:19:28 GMT

Max exports materials as a Nodegraph. This is the more advanced way of representing materials. It would be our hope that Unreal adds support for Nodegraphs, as they are a more robust representation of shading networks.

Something we have considered is to create an option in our exporter to use the simpler/more limited material representations in USD, but we have not made a decision on whether that is worth our efforts long-term.

Re: USD for 3ds Max 0.8 Released

protonmailJFBQC — Fri, 06 Sep 2024 00:56:47 GMT

Fair enough. I also wanted to ask about setting up the USD Stage. Is there a stage editor in max? It seems like there's many controls in the reference viewer but in reference viewer I can't add or delete anything, they're for reference only it seems. I can only edit a USD scene by importing it but then I can't add prims or set up anything as a payload or add child objects or references to my USD stage. In Unreal there's a 'stage editor' to do all of this. I don't know if I'm missing a functionality of this plugin. Thanks

Re: USD for 3ds Max 0.8 Released

julien.deboise — Fri, 06 Sep 2024 14:24:27 GMT

If you create a USD Stage object (for example with File>Reference...>Usd Stage) and open it in the USD explorer, there are some edits you can perform from context menus on prims :

We dont have the ability to add references to prims or payloads, but it will come. You can also move prims in the viewport in subobject mode, and edit prim properties from the command panel.

I have written a quick python chaser to fix material export for unreal (dumbing down the export to bypass the node graph connections, technically this violates some rules of UsdShade, but it works, tested the import in Unreal with a collegue just now).

import maxUsd from pxr import Usd from pymxs import runtime as mxs import os, sys, glob class matFixChaser(maxUsd.ExportChaser): def __init__(self, factoryContext, *args, **kwargs): super(matFixChaser, self).__init__(factoryContext, *args, **kwargs) self.stage = factoryContext.GetStage() def isId(self, id , shader): info_id_attr = shader.GetIdAttr() if info_id_attr: id_value = info_id_attr.Get() return id_value == id return False def PostExport(self): try: print("Running Unreal UsdPreviewSurface fix chaser...") all_shaders = [x for x in self.stage.Traverse() if UsdShade.Shader(x)] for prim in all_shaders: shader = UsdShade.Shader(prim) if self.isId('UsdPreviewSurface', shader): # Iterate over the shader's inputs for input in shader.GetInputs(): # Check if the input is connected if input.HasConnectedSource(): # Get the connected path source = input.GetConnectedSource() source_prim = source[0].GetPrim() # The node graph connection... connection_path = source_prim.GetPath() # print(connection_path) # Instead connect to the USD texture 2d that lives inside the node graph. new_connection = connection_path.AppendChild(source_prim.GetName()) # print(new_connection) texture = UsdShade.Shader(self.stage.GetPrimAtPath(new_connection)) input.ConnectToSource(texture.ConnectableAPI(), 'rgb') continue if self.isId('UsdPrimvarReader_float2', shader): varname_input = shader.GetInput("varname") varname_value_attributes = varname_input.GetValueProducingAttributes() primvar_name = varname_value_attributes[0].Get() # Punch in value directly, not from nodegraph... varname_input.Set(primvar_name) except Exception as e: print('Chaser ERROR : %s' % str(e)) print(traceback.format_exc()) return True maxUsd.ExportChaser.Register(matFixChaser, "unrealMatFixer", "Unreal UsdPreviewSurface fix chaser", "Connects straight to textures, bypassing nodegraphs.") def unrealMatFixContext(): extraArgs = {} extraArgs['chaser'] = ['unrealMatFixer'] extraArgs['chaserNames'] = ['unrealMatFixer'] return extraArgs registeredContexts = maxUsd.JobContextRegistry.ListJobContexts() if 'unrealMatFixContext' not in registeredContexts: maxUsd.JobContextRegistry.RegisterExportJobContext("unrealMatFixContext", "Fix USD Preview Surface for Unreal", "Fixes USD preview surface materials for usage in Unreal, avoiding NodeGraphs.", unrealMatFixContext) print("Registered unreal material fixer")

If you run this python script in 3dsMax, it will register a maxUsd chaser (code that runs after the export) and a context to enable it from the UI. Once it is registered, you will have this option in the UI :

You can look at the code to see what it does, basically the nodegraph nodes are just to encapsulate texture node networks. The actual texture node output is just forward to the nodegraph outpout, and materials connect to that. After the "fix" above, the material instead connects directly "inside" the node graph.

Hope this helps!

Re: USD for 3ds Max 0.8 Released

protonmailJFBQC — Fri, 06 Sep 2024 20:51:37 GMT

Wow, this script is amazing and I'm so glad I came here. I'll share this with the Unreal Users who have had this problem. The reason I needed this is so I can seamlessly create my game level in max and as I'm positioning my scene I'll now be able to see the updates instantly in unreal's realtime lighting. The only other things is clicking reload in unreal the scene reloads to an empty USD and needs re-imported. I'm not sure if this is unreal doing this or not.

Re: USD for 3ds Max 0.8 Released

protonmailJFBQC — Fri, 06 Sep 2024 22:41:04 GMT

I spoke too soon. It's still creating the nodes when I export. I don't know if I'm doing something wrong or not.