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I'm still not very familiar with Geometry Nodes and can not figure out how to control individual hair length with them in the new Blender 3.3 Hair system. I've added a new hair object and added some straight hairs in the sculpt mode. Now I want to be able to randomize their length with Geometry Nodes without affecting their direction. I haven't found any node like "Scale Curves" or "Scale Splines", while Scale Elements and Scale Instances nodes don't work with Hair Curves. Transform node affects the whole object. I tried following approaches:

At first I tried to directly Set Position of the hair tips using Noise Texture with indices as X coordinates, but it just randomly moves hair tips all around. I understand the reason but it is not what I am looking for: enter image description here I tried multiplying normals with noise which worked fine for the mesh displacement but I'm not even sure what the normals are for the hair curves. At least it doesn't work: enter image description here I tried to capture Normals from the mesh object as a Named Attribute in all modes to use this attribute as vectors in the Hair Geometry Nodes, but it doesn't affect anything: enter image description here I tried to fix Hair Normal rotation angle but failed: enter image description here I am out of ideas of how to control length of individual hairs. Can anyone help with this please?

UDD. Uploaded .blend file with all 4 Geometry Nodes data blocks in it.

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    $\begingroup$ Could you share your blend file so we don't have to recreate it all? ...because you could just scale the normal vector. $\endgroup$
    – quellenform ♦
    Commented Sep 10, 2022 at 9:04
  • $\begingroup$ @quellenform thanks, I've uploaded project file, and added a link to the post. How do I get a proper normal vector to scale? $\endgroup$
    – Andrey Sokolov
    Commented Sep 10, 2022 at 10:04

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If you want to scale the hair differently along the normals of the surface, you can use the following solution:

enter image description here

Here I use Object Info and Transfer Attribute to bring in the normal of the sphere, and scale this direction vector with a randomly generated value.

But so that only the endpoint of the curves is affected, I use the node Endpoint Selection as selection when moving the points.


(Blender 3.3+)

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  • $\begingroup$ Thank you. This is what I was looking for. $\endgroup$
    – Andrey Sokolov
    Commented Sep 10, 2022 at 10:43

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