Child hair particles turned wrong way through mesh

[bkol]

I’ve been trying to figure this out for two days and can’t seem to find any answers online. I’m trying to make a simple sheath with hair particles coming out the side. I’ve used a vertex group for density, and I’ve tried many combinations of settings. The parent particles come out fine, but when I add child particles, some of them are pointed in the wrong direction and go through the mesh. I can’t find a reason for it. I’ve applied all transforms, and all faces are pointing the correct way.  I’m attaching the blend file. If anyone has any thoughts, I would greatly appreciate it. Thanks in advance!

[spikeyxxx]

Your .blendis missing, you can only post a link to your file, when you upload it to Dropbox or GoogleDrive, or so…

Maybe, you have a situation like this:

using Simple Children with a roundness of 1, places the children on an imaginary sphere with set Radius around the Parent. The Children (blue) are still all pointing up, but some of them ‘start’ below the Parent (green)…

[bkol]

Ah, sorry, here is a google drive link: https://drive.google.com/file/d/1lFWZGDjlMPFsoBNRS4-Q6d2R-Z85fJsI/view?usp=sharing

I’m actually uses interpolated children

[spikeyxxx]

That seems to be, because of the way Blender calculates the interpolation of the Child Hairs. With only one Hair:we get:

But with more Hairs:

we get:

Not only do some Hairs go through the Mesh, but some Hairs are also shorter!

Apparently Blender considers a Hair going in opposite (World) direction to have an opposite (negative) length…

I’d call this a bug, but the system is going to be replaced/overhauled anyway (if I understand correctly). 

It’s not some kind of Setting that you can change, you didn’t do anything wrong.

What you could do, is to not use Children, simply more Parents…

Or use two Particle systems, one for each side….you can use strips that you Shrinkwrap to each side as Emitters.

[spikeyxxx]

Or even using one Particle System, something like so:

[bkol]

Ah, thank you! I took your suggestion, and it works fine now.

[Author]

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