Hello, I wanted to use the new hair system to put some feather cards on my character, but I have a problem : when the character moves, it seems that the tilt of the curves is not recalculated. I’m no pro at geo nodes though, and since I don’t really understand why and how the problem happens, I could use a liltte help to fix it !
feathers when in rest pose :
when the ear rotates (but it happens when the head or whole body rotate too):
the node tree that makes the cards :
I’d like the feathers to not rotate on themselves when the character mesh is deforming, and I’d prefer to keep the cards as a hair system
This works for me:
For y-aligned feather:
Constrain feathers so y is along -z and point x along tangent… instead of tilting the curve tilt the feather with transform node. GN modifier needs to be after the armature.
Good luck!
Thanks for the answer! That could be a good solution for an array of feather meshes, but alas it doesn’t work for hair curves 
The nodes I’m using work for the grooming part, but due to the “set position” node in my tree and the fact that the system groups the realized instances in a single mesh, it’s not possible to use the “transform geometry” node or the “rotation” of the instances node.
The only option left is to work around the original curves’ tilt ( or tangent, not sure). That or converting the groom to a mesh and using something like Surface Deform, but that’s plan B.
It’s totally doable: Simple wing rig1.blend (100.6 KB)
The trick is to have a reference curve deformed by the same armature acting as a tangent reference.
Good luck.
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Oh I see ! This solution would be perfect if it also allowed to deform the feathers along their respective hair curve, so I can groom them 
Could it be possible ?
Right now the final groom looks like this, the hair curves have 7 points
The reason I stubbornly use a set position node on the realized instances is because it’s the only way I found to make them accurately deform along the hair curves
(they have the exact same point count / indexes as the curves’ profile)
But if I could use your solution + curve the feathers that’d be top notch 
Thanks for your time and help !
the Y-align to tangent in my example does that for 2-point hairs… to perform a full deform you may wanna check out higgsas’ node collection - there is a node-group in there that does a deform along a curve. My guess is that it would have to be done after the initial align like in my example… I suspect that requirement, although doable, will be a challenge to get right.
Good luck.
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Yea, seems like I’m forced to make a choice here, oh well…
I’ll check out higgsas’ nodes
Anyway, thanks a lot !
