2020-10-27 Blender Rendering Meeting


  • Brecht Van Lommel (Blender)
  • Kévin Dietrich (Blender)
  • Jeroen Bakker (Blender)
  • Clément Foucault (Blender)
  • Lukas Stockner
  • Patrick Mours (NVIDIA)
  • Stefan Werner (Tangent)



  • Socket API. Changes were reverted due to motion blur tests failing and crashing in other areas, Kévin will investigate and update the patch.
  • OptiX BVH refit. Patch by Kévin is ready for review, Brecht and Patrick will review.
  • Custom properties as geometry attributes. Brecht works on refactoring the kernel changes to avoid performance regressions.
  • Regression tests on GPU devices. Brecht works on adding a CMake option to run the regression tests on GPU devices. It will be for manual testing to start with, a mechanism to keep reference images updated for multiple devices needs additional infrastructure. Brecht will create a task on developer.blender.org for this.
  • NanoVDB. Patrick still looks into further optimizations for half float, hold off on asking platform maintainers to commit libraries.
  • Tile stealing (D9324). Brecht reviews.
  • Multiple BVH types. For mixed CPU/GPU rendering and networking rendering we need to support building multiple BVHs. This is the reason OptiX does not yet support CPU + GPU for example, and why CUDA/OpenCL + CPU uses a slower BVH on the CPU.
    Lukas proposes to build BVH from packed primitives which would work for network rendering. This would require significant refactoring, needs investigation to see if it’s feasible. Other possibility would be to send over the scene graph now that it’s becoming a more generic nodes + sockets system, though this would be significantly different architecture than current network rendering.
  • Network render. Lukas gets closer to being able to post a patch with improved network render. Initial patch will not solve some more complex issues like OptiX support or fast transmission of textures.

Eevee & Viewport

  • BGL compatibility after Vulkan refactor. Clément fixed known bugs, so unless more unexpected issues come in we should be fine for 2.91.
  • 2.92. Clément will make tasks for new features planned to be worked on, and expects to have time to transition from bug fixing to 2.92 development.
  • Eevee: Cryptomatte. Jeroen has an initial implementation of Cryptomatte passes.
  • Color management: Jeroen still works on color management bugs related to the image drawing refactors (new or already existing).

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.