Hair instability with collision #59742

System Information
Operating system: Windows 10
Graphics card: Geforce GTX 1070

Blender Version
Broken: 82c3fdd559

Short description of error
If dynamic hair comes in contact with collision object, the hair "explodes."

Exact steps for others to reproduce the error

Open attached file.
Bake hair simulation of cube.
Hair explodes as soon as it contacts suzanne.

Reproduced this with several emitter / collider meshes, particle settings etc.

hair_collision_bug.blend

system-info.txt

Added subscriber: @spiegelball

#65708 was marked as duplicate of this issue

#63502 was marked as duplicate of this issue

Added subscribers: @brecht, @ZedDB

Hair collisions never really worked in the first place. See this example (the left one is the current blender hair physics): https://vimeo.com/200554110

IIRC there are plans to rewrite the particle/hair system. Hopefully problems like these will be solved then.

@brecht should we archive this or leave it as confirmed?

Added subscriber: @Sergey

@Sergey any input?

Added subscribers: @EvertonSchneider, @nacioss

This system has no maintainer currently, so marked as low priority without assignee.

Added subscribers: @iclone, @juang3d, @grosgood, @tomjk

Added subscribers: @sebastian-4, @A-B

@sebastian-4 Parborg (zeddb) Any updates on the particle/hair system rewrite? Are there any ways I can keep track of its progress?

Thanks

Not really, you can see the progress here: https://git.blender.org/gitweb/gitweb.cgi/blender.git/shortlog/refs/heads/functions

Added subscriber: @lichtwerk

Going over hair issues atm (to clear the tracker -- but also to have some input on what the next system has to take care of)

Note that this (explosion) only happens if the Hair Dynamics > Quality Steps are above 1.
There is a (newer) report open just for that, see #65038 (Hair Dynamics: Hair quality steps more than 1 results in increased collision reaction [like a multiplier])
I afaics, this was not the case in 2.79.
Not too familiar with the hair system, but maybe @juang3d can comment if he thinks this is a bug (I think it is)? (have a look at #65038)

Added subscriber: @LucaRood-3

I will check #65038.

In any case Hair collission is flawed because it tries to do tri-tri intersections instead of edge-tri intersection, I spoke about this with @LucaRood-3 about this and he gave me clues on how to fix this, I am not experienced with this at all, but I¡ll try to solve it as soon as I can.

But maybe the #65038 is a different problem because hair quality steps more than 1 should result in better result, not in explosion

This issue was referenced by e52ad1835a

Changed status from 'Open' to: 'Resolved'

Added subscriber: @thechode

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Hair instability with collision #59742