Consider this Custom Group:

It adds a line segment to existing path of the "Lazer", by raycasting towards a default geonode cube using provided position, direction and index of a face to ignore. Then it passes the information needed for the next line segment. Since there's no recursion in Geonodes, a setup like this has to be chained like so:

(the Cube visible in wireframe mode has been added outside this setup)

So if the above works, why doesn't the below?

Apparently, it works for the first evaluation, but then fails. I have done some more investigation, but haven't yet gained a full, satisfactory explanation, and I don't want to suggest a potentially wrong answer, so here it goes, do you know what's going on?

Is this the real bug? Is this just design?

A workaround is easy (and this could be a part of an answer…):

But the question is why the workaround is even needed, what's the logic (and fully understanding the logic might result in a better solution).

  • $\begingroup$ Maybe a good fit for another question, but while I test various workarounds, I find myself in this situation: i.imgur.com/nP8i0eC.png - how could possibly the 0 or 1, plus 2, become less than 2? $\endgroup$ Jul 9, 2023 at 19:47
  • $\begingroup$ Most likely it was a recently fixed bug, can you check in new versions? $\endgroup$
    – mod nop
    Jul 15, 2023 at 21:12
  • $\begingroup$ @modnop the above was originally tested on stable 3.6 from 27 jun, which version do you have in mind? Is there a newer 3.6 or do you mean 4.0? There's a .blend file link in the question btw. $\endgroup$ Jul 16, 2023 at 9:22
  • $\begingroup$ Yes, 4.0. Example file also work correct in today 4.0. $\endgroup$
    – mod nop
    Jul 16, 2023 at 10:10
  • 1
    $\begingroup$ Then it's a duplicate of projects.blender.org/blender/blender/issues/109341 $\endgroup$
    – mod nop
    Jul 16, 2023 at 11:37

1 Answer 1


Feels like a design for me TBH, but i am not completely sure. I would just create a named attribute and update it with every step, than use than named attribute as an input inside a node group, so you do not have to pass it inside a simulation zone


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