2024-06-11 Render & Cycles Meeting


  • Brecht Van Lommel (Blender)
  • Sergey Sharybin (Blender)
  • Lukas Stockner (Blender)
  • Iliya Katushenock
  • Nikita Sirgienko (Intel)


  • For 4.2:
    • High priority report about Apple Mac AMD/Intel Metal render
      • No big changes anticipated, can look into solving it now. Brecht and Sergey will sync-up offline to coordinate the fix.
    • There are other high-priority issues which needs to be looked into.
    • Brecht is looking into OSL crash on GPU. Possibly related to the new drivers.
    • Updates for the manual for the new features (blue noise, i.e.). Lukas is looking into it, but might need help with the manual setp.
    • Lukas will check on the release notes as well, ensuring all the recent development is documented there.
    • Still to come: pixel index hashing for the blue noise to improve the look of the noise. Lukas is working on it.
  • On-going:
    • ReSTIR:
      • Not much progress
      • The meeting went into discussion of cons/pros of evaluating multiple closures. Some papers suggest to only handle one closure, but it might give negative impact on the noise in other cases.
      • There is correlation issues with branched RNG and 1 sample. Lukas is aware of it and will try to fix it for 4.2.
    • Weizhen is looking into motion blur issue related on custom normals
      • For smooth vertex normals copy algorithm from Blender
      • Copy all normals from Blender
    • Lukas is looking int ellipse light sampling (improves noise for elliptic lamps)
      • Weizhen found reference implementation, which simplified development.
      • Coming along very well!
      • All the neat numerical tricks to keep computation cheap in the GPU
    • Path trace device and denoiser need to be checked in more places to properly report error on the UI.
    • Check for errors during BVH builder, and stop builder and rendering when an error occurred.
    • The meeting discussed floating point precision related reports. The conclusion is: needs to be handled on the case-by-case basis.
  • For 4.3
    • The meeting went over possible topics to focus on for the next Blender 4.3 release.
    • There is surely plenty to do, with a small team.
    • The most well-defined topics will go to a Cycles workboard after the meeting, so people can assign tasks to them.

Practical Info

This is a weekly video chat meeting for planning and discussion of Blender rendering development. Any contributor (developer, UI/UX designer, writer, …) working on rendering in Blender is welcome to join and add proposed items to the agenda.

For users and other interested parties, we ask to read the meeting notes instead so that the meeting can remain focused.