2024-05-06 Grease Pencil Module Meeting

Date/Time: 2024-05-06T14:00:00Z
Link: https://meet.google.com/xxo-tyin-rem
Attendees :

  • Amélie Fondevilla (LFS, Developer)
  • Andry Rasoahaingo (Dedouze, animator)
  • Antonio Vazquez (Developer)
  • Casey Bianco-Davis (Developer)
  • Daniel Martinez Lara (Grease Pencil team)
  • Falk David (Blender developer)
  • Lukas Tönne (Blender)
  • Matias Mendiola (Grease Pencil team)
  • Samuel Bernou (ADV Studio, Dev)
  • Sietse Brouwer (Developer)
  • Yiming Wu (Grease Pencil Line Art)


  • Development updates
  • Python API discussion
  • Drawing attributes API functions

Meeting Notes

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  • GPv3 will not land in Blender 4.2 LTS, it’s now postponed to Blender 4.3.
  • There was a discussion about the Python API for GPv3:
    • Sietse proposed two designs, 1) is behaves almost exactly like GPv2 and 2) follows the data layout of GPv3 more closely. See #116043 - GPv3: Python API - blender - Blender Projects.
    • Both approaches have pros and cons
    • Antonio: Thinks that it would be good to implement 2) and then add helper functions if needed on top.
    • Falk: Also thinks that we should go for 2) but sees the issues with it.
    • Sietse: Wanted to point out that he proposed 1) because it makes it easier for Python developers to think about.
    • Falk: It would be good to have a prototype for 2) so that we can test it and figure out what the pain points are.
  • We talked a bit about the drawing attributes API (#119080 - GPv3: Drawing attribute API functions - blender - Blender Projects):
    • Sietse: Was wondering what the plan is. It’s currently a bit of a pain to deal with attributes as you have to know the name, the domain, the default, etc.
    • Falk: Indeed the plan was to have functions for each of the built-in attributes on the drawing (for reading/writing). This way, the caller doesn’t need to know about any of the things mentioned. The problem is that this does not work when you don’t have a drawing, but e.g. the CurvesGeometry. In this case, we have the same issues as before.
    • This needs to be a bigger discussion about the attribute system in general.
    • Falk: Will schedule another meeting about this with more devs.
  • Antonio: Noticed a weird smoothing behavoir when drawing for longer.
    • Falk: Sounds like a bug. Will investigate further.
  • Antonio: Thinks it would be a good idea to remove the line tool. It’s basicallly the same as the polyline tool.
    • Casey: There are only small differences (in the polyline tool, clicking adds a new point, in the line tool you have to press E; in the line tool, dragging will move the whole line, this does not work in the polyline tool).
    • Falk: Will wait for some more feedback. Otherwise if nobody is against it, we can indeed replace the line tool.
  • Antonio: It would be good to have a way to control the rendered thickness of strokes in pixels.
    • Falk: Agrees. Spent some time on testing if we can have a modifier (geo nodes group) that can change the thickness in camera space and give control over the thickness in the rendered image. Needs more testing.
  • Casey: Was wondering about these settings in the perferences (what are they used for?):
    • image
    • Antonio: These are old settings (probably for the early draw tool). Doesn’t think they are used anymore.
    • Falk: Will check if they are still used. Otherwise we can remove them/replace them by tool settings.

Next Meeting

  • Time/Date: 2024-05-20T14:00:00Z