First, the finished product, rendered in Octane. Keep scrolling down for how I set up the tools, with descriptions and illustrations.
Here's the full node setup for the entire head groom (no lashes or brows). None of the unusual parenting workflow that Houdini defaults too. Just two nodes with guides and three for the different hair sections. The null is just there to move them all around as a unit if needed.
Here is the template for guides. You can choose to either scatter or plant them. They're converted to ribbons with customizable width and color to match the easy viewing experience of XGen.
Next up, import the guides into a new node and generate the actual hairs. The template includes a space to paint density. Of course you can add any other painted attributes you want.
This one is super important. Clump visualization and a greyscale gradient to make it clear what's going on. Without this it's hard to tell what on earth you're working with. This makes individual hairs and how they're layered obvious so you can go in and work hair by hair if you need to.
From here on out you can put in all the guide processing you want, group hair sections, brush by hand, and add clumping. I like to cache things out to .bgeo every once in a while so the entire tree doesn't have to process when you load the project. The very last node is the width control. This means you never have to recache any groom stuff to update width that was changed downstream. I made a control for global width and hair taper.
And that's it! Fiddle with details to your heart's content, then slap on a hair shader from any renderer (they all recognize the "width" attribute) and you're done! I won't claim this is particularly elegant and I'm sure there's tons of room for improvement. But, I hope it inspires others to dive in to get their hands dirty a bit and customize Houdini. The artistic control is INCREDIBLE and this is all much more stable than XGen, in my experience. Once you get the basic idea of what nodes are needed (hair gen, scalp collider, paint attributes, etc) then it's all pretty straightforward. Definitely worth doing to make for a more pleasant creative experience.
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