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I'm relatively new to blender. I've found countless videos showing how to weight paint a vertex group or how to create one selecting the vertices and then use the group in the Factor value of many of the Hair Modifiers (such as Noise or Frizz) to mask or blend the effect.

Unfortunately I can't seem to link the vertex group to the Factor properly. Most videos show that simply typing the name of the group in the factor box should work. Not for me. (Blender 3.6.1). I believe it has to be a bug, I can make the vertex groups work for other things such as Distribute Points on Surface, but not for the hair modifiers that already come with Blender.

I repeat: I cannot replicate the workflow as seen in this video at 10:10 https://www.youtube.com/watch?v=gCQN5vNgHiI

So, would it be possible to use a texture image instead? If so, how can I combine this with the already existing hair modifiers?

Edits: Image 1 showing a plane with the frizz modifier. The plane has a vertex group, the name of the vertex group is typed in the Factor field yet the hairs look straight enter image description here

Image 2 showing the vertex group does in fact have information painted enter image description here

Image 3 showing the effect of the frizz modifier when the Factor field shows a single numerical value and not the vertex group name enter image description here I was expecting to see a change in the hairs frizz effect so that the red areas of the vertex group would have more frizz than the blue areas, but that isn't happening.I hope this helps clarify the question

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  • $\begingroup$ Hi. Sorry, your question has too few details to isolate the problem. Add a screenshot of the modifiers and the GN node tree or share a blend file that shows the problem. A vertex group should work. Keep in mind that vertex groups need geometry. A simple default plane does not have enough geometry. The group must be on the surface object (=emitter), while the hair modifiers are on the Curves object. You have to type in the group name in the exact spelling. -- You can use a texture image instead of a vertex group. Here is an example: blender.stackexchange.com/a/296902/107598 $\endgroup$
    – Blunder
    Oct 26, 2023 at 11:51
  • $\begingroup$ Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues. $\endgroup$ Oct 26, 2023 at 11:52
  • $\begingroup$ You can absolutely use a texture image by sampling an UV-mapped image file onto your scalp object. But the issue of the vertex group not appearing should be solved : perhaps you have painted some other object instead of the scalp object ? perhaps you have mistyped the attribute name, or you have tinkered with the bundled node group a bit and broke it. Please describe what is happening. Step-by-step. Expected results ? Actual results ? $\endgroup$
    – Hadriscus
    Oct 26, 2023 at 12:26
  • $\begingroup$ @Blunder that's brilliant, thank you! I managed to make the image mask work following the instructions on your link. $\endgroup$ Oct 26, 2023 at 15:28
  • $\begingroup$ @Hadriscus and Duarte I've added images that hopefully better describe what isn't working with the vertex group. I've managed to workaround the issue using an image texture, but if by any chance you think you can point to what I'm doing wrong with the vertex group method please let me know. It's not the spelling as the screenshots prove. I'm happy to share the blend file too, but I'm not sure which is the best way to do so? $\endgroup$ Oct 26, 2023 at 15:36

1 Answer 1

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In the modifier interface, at the right of the "factor" slider, you can click the spreadsheet icon to let you type in an attribute in place of a single value.

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  • $\begingroup$ Sorry but this is what I'm doing and it's not working. The first image proves it, as you can see I managed to type the name of the vertex group instead of the value and it does nothing. I also noticed, when clicking on the field before starting to type, I see a drop-down list of all attributes available (only 2) and none is the vertex group. This is clearly different from the expected result as shown in the video linked. $\endgroup$ Oct 27, 2023 at 3:24
  • $\begingroup$ My bad I didn't see the first of your three images. I thought you had omitted to toggle from "factor" to "attribute". I don't have a solution for you then. $\endgroup$
    – Hadriscus
    Oct 27, 2023 at 12:02

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