kwokcb/gltf_materialx

glTF / MaterialX Translation Library

You've reached the home of Bernard Kwok

• 🔭 I’m currently open for work on open source projects. The Academy Software Foundation material standard: MaterialX is my primary focus along with it's interrelation with industry standards: Khronos glTF and Pixar USD. Also of focus is MaterialX's interlation with standards such as OCIO (colour management), and shading languages: OSL (Open Shading Language), MDL, and GLSL for both desktop and web rendering.

• Related connections includes:

  • Academy Software Foundation MaterialX: Specification updates, core logic, infrastructure, and shader generation.

  • Khronos glTF and MaterialX: glTF interop and extensions to connect this with MaterialX found.

  • MaterialX Learn : Complimentary site for utilities and learning about MaterialX.

  • Autodesk Fork of MaterialX: Work as technical lead for MaterialX within Autodesk. (sampling)

    • Autodesk Standard Surface: Core definition updates.

    • Some industry presentations can be found on the main MaterialX site

    • 💬 Feel free to connect with me for areas such as: software engineering, design / architacture, project management, remote working, open source / standards.

    • 📫 See my profile and updates on LinkedIn.

gltf_materialx's Issues

Texture transform export (to glTF)

Ensure that filenames are resolved when converting to glTF

Issue

File names may have additional parent qualfiiers such as fileprefix on parent nodegraphs.
These need to be resolved when converting to glTF

Fix

The "resolved" query for filenames should be used.

Notes

• Note that it is not possible to restore the fileprefix from glTF since it does not store such a concept, and resolving means to lose this context information.

Firewall check "__" double underscore names for GLSL variant code generators

It's still possible to create invalid shader declaration names such as "__".
Ideally this should be handled in code gen for GLSL variants as these are illegal.
The prevent can occur on the import side as well.

Convert KHR_materials_pbrSpecularGlossiness

I tried to convert KHR_materials_pbrSpecularGlossiness, but the effect is wrong, I don't know why, can you help me? Here is my conversion using gltf and mtlx
glTF.zip
.

Add a merge MTLX to glTF option

MTLX converted to glTF creates a standalone glTF file.
A merge of this to an existing glTF file is useful to replace existing materials.
Assignments could also be handled.

Sync for 1.38.8

Continuous sync to 1.38.8 until it is out.

Merge C++ Interface into Khronos Branch

Remove glTF materials on conversion to MTLX

Keeping materials in the glTF file can cause unnecessary handling (for Web or other integrations) when they are overridden
by MTLX assignments. Could also occur for USD assignments.

A "clear materials" on glTF files can be added.

Add ORM image merger

Support geometry instancing in MaterialXView

Support named UV sets

Problem

• OpenUSD and other integrations require named uvsets to be used
• glTF uses integer (numbered) sets.

A change has been made to core to support both by changing glTF image nodes to support vec2 texcoord

Fix Proposed

The translation code needs to handle:

• Save: by detecting for connections on texcoord and writing out a set number if on an upstream <texcoord> node. It does not translate upstream named sets provided by <geompropvalue> nodes.
• Load: Create a <texcoord> node if an image uses a non-zero uv sets such as the MultiUVTest test from the sample library.

Sync with 1.38.7

1.38.7 has all local changes required for the distillation pipeline from MTLX to glTF.
When this is released, then no custom build is required anymore.
At this time an official 1.38.7 release from this repo will be stamped out.

Add CPV samples to unit tests

Use MTLX as a submodule

The dependency scheme of using a download is too inflexible relying on major releases for any core updates.
Also exe downloads can be a security issue.
Move to using submodule dependency instead.

Create new Khronos tooling branch

• Sync Khronos MaterialX to head
• Create recreate tooling branch: https://github.com/KhronosGroup/MaterialX/tree/gltf_mtlx_interop
• Add support back in for MaterialXView.
  • Restore load materials from glTF
  • Add save materials to glTF (new)
• Add support in for MaterialXGraphEditor (did not exist before)
  • Load glTF
  • Save glTF graph
• Update copyright notices and licensing
• Add in Python wrappers
• Update to new texcoord based uv set lookup to allow USD named sets to also work with glTF image nodes.

Add Python wrappers