2020-09-29 Blender Rendering Meeting


  • Brecht Van Lommel (Blender)
  • Jeroen Bakker (Blender)
  • Kévin Dietrich (Blender)
  • Lukas Stockner
  • Patrick Mours (NVIDIA)
  • Stefan Werner (Tangent)
  • Mark Theriault (Tangent)
  • (Other Tangent developers, I forgot to write down all the names, apologies)


Background on changes in Blender development organization

  • Blender development team and the number of external contributors is growing, to scale we are attempting to better organize smaller teams, in this case for rendering.
  • Brecht will lead the Rendering (Cycles & Eevee) team.
  • Another goal is to get external contributors more closely involved, and this weekly meeting is a good place to synchronize.
  • The goal of this meeting is to better organize rendering development, both for Blender Institute developers and other contributors, providing a place to solve problems and communicate things that fall through the cracks in asynchronous communication.

Improving cooperation in code review and bug fixing

  • Brecht asks for more help with code review, bug fixing, so the burden is not only on Blender Institute developers to finish and make patches ready for the Blender core and fix bugs.

Status of ongoing projects

  • Cycles public API and Alembic procedural
    • Detail in these tasks:
    • Under development by Kévin, API changes are incrementally going into master. The goal is to end up with a public API that is well documented and hides internal details.
    • Feedback from developers integrating Cycles into other software is welcome, since this significantly affects them, but in the end should lead to simpler implementations.
  • hdCycles
    • Goal of Tangent is to both support Hydra in Blender and support using Cycles in other software
    • Priority for Tangent to get working in the near term. For the Blender Institute the focus is on more gradual USD integration in a way that is future proof, and helping external contributors (NVIDIA, Tangent, …) get their improvements compatible with and integrated into core Blender.
  • Tangent priorities for production rendering
    • Volume rendering
      • Issues with overlapping volumes
      • Improved volume stepping using algorithms like delta tracking
      • Better performance in general
    • Motion blur
      • Quaternion interpolation issue
      • Issues with particles / hair
        • New particles and hair should take these issues into account. Likely involves velocity attribute on geometry rather than trying to figure out correspondence between frames in the Blender to Cycles exporter? Unclear what exactly can or needs to be done with the current system.
    • Tangent animation will provide more detail on the issues and proposed changes.
  • Lukas is looking into tile stealing for better work distribution in combined CPU and GPU rendering.
  • More projects to be discussed next week.

When and how to meet

  • This will become a weekly meeting, at the same time (Tuesday 2PM Amsterdam time).
  • We can always scale back and make it bi-weekly if there is not enough to discuss.
  • Meeting notes will be public. We want every developer (or UX designer, …) contributing to rendering in Blender to be able to join, but it’s undecided yet how to organize this in practice.

So will there be a USD/Hydra delegate in Blender’s viewport & officially supported from the BF or only for Tangent? because you guys weren’t so keen at first to go that direction.

1 Like

It would be a good feature to support in official Blender releases. But until there is a concrete plan and it goes on the roadmap for Blender Institute developers, there isn’t more to say on this besides what is in the meeting notes.