Support Material not generated for local minimum overhangs

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I haven't explored this much, but it just happened to me again today, and has happened before, where I'm slicing a model that has an overhang that slopes down, creating a local z-axis minimum point, and support is not generated for that section.

The one today comes down to a point, so parhaps Cura only checks the angles of the faces, and since there are no angles over my support setting, it doesn't generate support, despite the fact that it is going to start printing this section in mid-air? Or perhaps the generated support material is too small that it rounds to 0?

The two long hair braids on this piece, for example (overhang set to 80 deg):

http://www.thingiverse.com/thing:184723/#files

even set to 45 deg, the support misses the very tip, the lowest point still will print on mid air.

 

[Daid 306]

The one today comes down to a point, so parhaps Cura only checks the angles of the faces, and since there are no angles over my support setting, it doesn't generate support, despite the fact that it is going to start printing this section in mid-air? Or perhaps the generated support material is too small that it rounds to 0?

 

Both. Cura only checks the angles, and does some "small area removal" (it's actually doing other stuff, area removal is a side effect)

The support generation code is pretty bad right now. And I hope to improve it in the future.