2023-05-25 Pipeline, Assets & I/O Meeting

Everyone is welcome on the Google Meet linked below every other Thursday, at 17:00 CEST.

Present: Bastien Montagne, Bogdan Nagirniak, Brecht Van Lommel, Brian Savery, Micheal Kowalski.

The meeting covers the pipeline & I/O module in a broader sense, including some topics hosted in other modules (e.g. some I/O python add-ons, or overrides and .blend file I/O from the Core module).



  • Blender published an update regarding the USD project current status: USD Project Update

  • Michael created a task for 4.0 release targets. The big targets need to be listed there as soon as possible now, these may still need to be missing e.g.:

    • Point instancing.
    • Hydra/MaterialX.
  • Hydra rendering status update and discussion (Brian, Bogdan).

    • The current proposed design: Hydra rendering is handled through a separate rendering add-on in-between Blender data and renderers.
    • It has its own conversion logic, not re-using current USD IO code. This allows the support of incremental/partial updates (using scene delegates) to feed data into Hydra renderers directly from Blender data, without going through a ‘real’ complete USD format export.
    • Bogdan reports that the notes from Brecht from his last review pass have been addressed in the pull request.
    • Brecht notes that the following points should be addressed to move forwards with this project:
      • Have missing features and/or things done differently than from the USD IO code clearly identified and documented.
      • Have a way to check consistency between Hydra handling of data, and the USD IO one (e.g. a simple tool rendering through both the scene delegate system, and by exporting a complete USD file and rendering from this file).
      • There is at least one known difference currently: materials. Hydra uses materialX, while USD IO only supports a basic preview surface.
      • The whole handling of conversion to MaterialX in Hydra delegate is in python now, it would be better to have this as C++ code, such that the logic can easily be shared with other parts of Blender (USD IO being the main immediate candidate).
      • Maybe the current pull request should be split in two, one for Hydra support, and another for materialX support?


  • Bastien reminds that the PLY and OBJ add-ons will be removed from Blender 4.0. The STL C++ I/O code is not yet feature-complete, so the STL add-on will be kept for now.

Next Meeting

The next meeting will be on Thursday 8th June, 17:00 CEST/Amsterdam time (your local time: 2023-06-08T15:00:00Z).

The provisional meeting agenda will be linked in the #pipeline-assets-io-module channel before the meeting.


Topic for this week: Hydra rendering addons if @brecht and others can join

Actually reallized this Thursday is a free day here in the Netherlands… So think we should reschedule the meeting, would propose Thursday next week?

Fine by me. (20 character limit)