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How to find faces pointing inward with a python script which uses Blender sdk?

AN example:

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Normally I trigger "backface culling" and select points/face by visual inspection:

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Then I delete the selected geometry, which leaves a hole:

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And finally I do a F-fill:

enter image description here

In short, I'm asking if there's a way to select backfaces without a visual check, using python. There's an answer here by Zeffii, but it is related to a camera view, while I'm looking for something topology-related... Thank you.

EDIT: how I did it.

get the blend

Open the blend, and select the partial sphere:

enter image description here

Now enter select edges, the Select non manifold (ctlr-alt-shift-M), then F or Alt-F for filling it. The result is:

enter image description here

How to heal that?

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  • $\begingroup$ Related blender.stackexchange.com/questions/72647/… $\endgroup$ – kheetor May 8 '18 at 11:19
  • $\begingroup$ Thank you. Sadly recalculating normal has no effect; that face is legitimate, just lies over another one, extruding out into a bad topology... $\endgroup$ – Kabu May 8 '18 at 11:32
  • $\begingroup$ If the problem is not backfacing, you need to logically break down the problem with topology you want to fix before you can find a way to programmatically detect the cases. The geometry is non-manifold, you have edges that only connect to 1 face. Is this what you want to find? $\endgroup$ – kheetor May 8 '18 at 11:39
  • $\begingroup$ I posted some more info. It's not clear to me, I think it's creating overlapping faces with different orientation... $\endgroup$ – Kabu May 8 '18 at 13:11

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