MoExtrude along Hair Splines

[reading-card]

I’m trying to extrude polygon selections of a mesh along hair splines, following an example in the C4D help: Extrude Deformer/ Object Properties/ Sweep Spline). However, I can’t make it work. Also tried another method using the connect object to connect the hair mesh with the target mesh. It works only partly because of the different distances between the connecting points. Here is a scene with the two approaches:
https://www.dropbox.com/s/dhsfxg8uz6dre7p/hair%20mesh%20connect%2Cextrude%201.c4d?dl=0
It would be fantastic if there is a workaround or a way to use the Extrude Deformer for this purpose. Many thanks for any hint!

[Dr. Sassi]

Hi reading-card,

Thank you very much for the project file and for using Dropbox.

I do not have the Arnold Render, but perhaps this works in any render engine.
CV4_2023_drs_23_HApi_01.c4d

I use an Object (Cylinder) here as an Instance. The object's shape is based on the Hair Material Thickness settings, and I left the settings as you had them set.

All the best

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[reading-card]

Thank you for your prompt reply. the c4d file link prompts an error: "/topic/369/moextrude-along-hair-splines/error Not Found - You seem to have stumbled upon a page that does not exist. Return to the home page".
Did you find a way to connect the root mesh points of the Hair Cylinder to the model? I am looking for a way to have both in one mesh and then add Subsurface to have a smooth transition between the mesh and the hair roots. So that the hair look like spikes extruding from the mesh. Thank you!

[Dr. Sassi]

Hi reading-card,

Here is the link from our Cineversity Cloud server:
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2023_PROJECTS_DRS/20230329_CV4_2023_drs_23_HApi_01.c4d.zip

The Hairs sit on a polygon. This polygon is pushed with the MoExtrude. Hence why I used the Hair Instance option here. Perhaps replace the Cylinder with a four-side Cylinder and rotate the Axis by 45.
With The SDS options, you can pull the connections of the main body a little bit more.
https://help.maxon.net/c4d/2023/en-us/Default.htm#html/TSDS.html

I have so far not found a stable option to get Hair-Splines driving the MoExptrude. One test was even with MoSpline as a "bridge".

If you need them flexible, perhaps rig the Object and have the "tentacles" dynamic.
Another option would be to use a Pose Morph and animate the Tentacles.
Or point-weight them and have a deformer working on those.

All the best

[reading-card]

Thank you! Yes, generating a hair instance or square is the common approach. But I was trying to connect the roots of the hair mesh with the object mesh. It partly works with the "test connect" example in my file, but the connection object messes up other parts of the mesh. Is there a way to restrict the "connect" to edge or point selection to affect only those points which need to be connected? I've seen a "connect" object node, but could not manage to assign a selection to it. Haven't even figured out how to import a selection tag into the node editor...

I understand the rig workaround, but need to stay procedurally.

[Dr. Sassi]

Hi reading-card,

The key problem would be that the Polygon where the Root is will be lifted. Hence the results look somewhat chaotic.
If you could connect the points of the hair instances with the "main body", then the Polygon would be inside of it. Meaning you have three polygons sharing a single edge. This will not provide excellent results.
There is, of course, the idea of having two "main bodies" animated in the same way, preferably via PLA.
With this, one would have the Root information, and the other would receive the results. However, the Hair instances are generated, and I'm unclear on how to combine them and have those working with SDS.

Hence my suggestion with the Joint Rig.

Cheers