I am using blender 3.3. and I have been experimenting with Geometry Nodes.

I made a bunch of hair by using an empty hair system and applied its instance to my model via Geometry Nodes. The model requires different colored hair for definite areas. To achieve that I defined areas using vertex groups and duplicated my geometry node group in a modifier stack so that different vertex groups can be assigned to each node group to establish different hair color material on instances of the specified vertex group. To set different materials on hair instances, when I used the (set material) node, hair Instances turned black.

Below is the Image of the nodes group and the result I receive. enter image description here

Then I did some research and came to the conclusion that this is happening because the empty hair system is a curve and not a mesh. So, if I turned my hair curves into a mesh and make an instance out of it then it might be possible to assign different materials to instances.

Therefore I tried to turn the hair curves into mesh -

-First I tried to convert the curves in the node tree by adding (the curve into the mesh node), which shows no outcome and my instance remained black.

-Then the second time I attempted to modify curves in a viewport (Object>convert>Mesh), where again it failed to generate a hair mesh.

I am unable to figure out what I am missing here. Could anyone help me to figure out why my hair instances are turning Black and how to fix it?

*Is it because the hair is curves and not a mesh? or

*there is any problem with the shader editor??

I ran an experiment on this project, here is the link to Blender File.

*Also, there is an error on the duplicate geometry node, which is not there in the original one. It would be much appreciated if someone could tell me why this error is showing up?

enter image description here


1 Answer 1


I asked this question on another forum and received some helpful responses. The solution to my problem is that curves in Blender have no thickness, so to give them material, they need to be converted to a mesh with faces. The Curve to Mesh node, however, only creates a line of edges with no faces by default. To add thickness to the mesh, one needs to input something like a curve circle into the other input of the node.

The post link is available below for anyone who would like to take a look. Post Link


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