2024-01-09 Render & Cycles Meeting


  • Brecht Van Lommel (Blender)
  • Lukas Stockner (Blender)
  • Nikita Sirgienko (Intel)
  • Xavier Hallade (Intel)
  • Patrick Mours (NVIDIA)
  • Brian Savery (AMD)
  • Christophe Hery (Meta)


  • OpenImageDenoise:
    • A new release with CUDA driver and Metal support is expected in about 2 weeks, which should be in time for Blender 4.1.
    • A message informing the user if CPU or GPU denoising is being used would still be good to add.
    • Brecht still needs to look into changes to retain the primary CUDA context. From discussion it seems like this should be ok even if multiple renders are working simultaneously, but needs testing.
  • BSDF nodes: there are a few open pull requests to extend these with new closures added for the Principled BSDF. Lukas will review.
  • Curves: Brecht works on adding support for rendering more curve types (B-Spline, Bezier, Linear) to better support files imported from Alembic and USD, which are not all Catmull-Rom. Unclear still how compatible we can get these across GPUs, especially Linear.
  • Adaptive Sampling: Lukas is finishing a master thesis about guiding adaptive sampling using error estimated by the denoiser, and showed a demo with some early results.
  • Bump mapping: Christophe mentioned that using a factor 0.1 to reduce the ray differential size worked well in tests to improve bump mapping detail. Brecht will test adding it in Cycles.
  • Intel GPU: support for the new hardware architecture would be good to backport to 3.3 and 3.6 LTS branches. A pull request can be made for that so it gets tested on the builbot first.
  • AMD GPU:
    • Changes were made to add ROCm 6 compatibility. These are not strictly needed anymore right now, as in the end the new AMD driver will ship with a ROCM 5 dll. This avoid users needing to upgrade to a recent Blender build. But it will be helpful to take advantage of ROCm 6 in the future.
    • There are some issues on Linux, where depending on the distribution and/or configuration the HIP shared libraries can’t be found. Brian will look into this, maybe it involves adding extra search paths, maybe HIP packaging can be improved.

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.


I assume this is 6 weeks, but it would be good if this was updated with the correct timeline.

Out of interest, does this also include investigating adding a layer node, or adding a layer input to supported nodes?

Thanks, corrected.

I only asked Lukas to review your pull requests and look at bug reports.

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