Hair Guides

Hair Guides gives a character’s hair its own bones. Draw a curve through each clump of hair (a ponytail, a spike, the bangs), and the node turns every curve into a chain of joints hanging from the head, then weights the hair around it to that chain. Put it after Auto Rig.

What it does

After Auto Rig, the hair is weighted to the head, so it moves as one stiff piece with it. Hair Guides adds a chain of joints inside each clump you mark. The hair around each chain now follows that chain, so the chain can swing on its own.

The mesh comes out exactly as it went in. What changes is the rig it carries:

Each guide becomes Joints per guide joints, spaced evenly from the guide’s root to its tip (after Center in volume has moved it into its clump), named Hair_01_1, Hair_01_2 and so on (guide 1, joints 1, 2, …).
The first joint of each chain hangs from a joint of the skeleton. On Auto that is the joint whose bone passes nearest the guide’s root, usually the head. You can pick another joint per guide.
The hair is weighted to its chain by the same bone heat Auto Rig uses, so the weights follow the surface: a clump binds to the chain inside it, and the scalp blends into the head. Only the hair takes the chains’ weight: on a character whose hair and head are one mesh, the face, brows and ears beside it keep exactly the weights Auto Rig gave them, as does every point the hair chains don’t reach.
Draw each guide through a clump that stands clear of the face. A lock fused flat against a cheek can’t be told apart from the cheek, so a guide through it moves the cheek too; leave such a lock unguided and it moves with the head.

The new joints come after the skeleton’s own, so any clips already on the rig keep playing. In those clips the hair joints stay at rest: they move with the head but don’t swing yet.

Drawing the guides

Wire a Curve node into the Guides input and draw one contour per clump of hair. Each contour is one guide:

Start at the root. The first point you draw is the root, where the hair leaves the scalp. The chain runs from there to the guide’s last point, the tip.
Draw on the hair. To draw on the character, display Hair Guides and select the Curve node: the curve editor works over the displayed character, so the surface snap lands your points on the hair.
Center in volume (on by default) then moves each guide into the middle of its clump: every point steps inward, across the guide, to halfway between the surface you drew on and the hair’s far wall. Where the hair lies over the head, the guide stops halfway to the scalp; it never sinks into the skull. No point moves deeper than about a sixth of its guide’s length, so on a character whose hair and head are one surface a guide sinks just under it instead of to the middle of the head. A point with no hair near it, or on an open sheet with no far wall, stays where you drew it.
Off, the joints sit exactly on the curve. Turn Center in volume off when you have placed the guide inside the clump yourself, for example by moving its points from a side view.

A guide belongs inside the mesh. If part of a guide still runs outside it, the node still adds its joints but shows an amber note naming the guide, because the hair there may not follow it.

While the Curve (or Hair Guides itself) is selected, the viewport draws every chain over the character: a dot on each joint, an arrow on each root pointing down the chain, and red on every stretch that runs outside the mesh. The chains redraw after each edit, so you can drag a point until its red disappears.

Checking the result

Display Hair Guides and switch the viewport to the Rig view. The hair chains are drawn with the rest of the skeleton; click a hair joint to see which part of the hair it moves.

The Hangs from list in the parameters shows one row per guide. On Auto, a row names the joint Auto picked, for example “Auto (Head)”. Pick another joint to override it.

Where to put it

Hair Guides needs a rigged mesh: put Auto Rig before it. Add Animation can come before or after it. Like Add Animation, keep it near the end of the chain: a node that reshapes the mesh after it drops the rig.

Two Hair Guides nodes in a row both add their chains. The second numbers its guides on from the first, so no two joints share a name.

Inputs

Mesh character

A rigged character: the output of Auto Rig (or a node after it that keeps the rig).

Curve guides

The guide curves. Each contour is one guide, drawn from the root at the scalp to the tip, on or through its clump of hair.

Outputs

Mesh

The same mesh, its rig carrying one joint chain per guide and the hair weighted to it.

Parameters

Parameter	What it does	Default
`Joints per guide`	How many joints each guide becomes, spaced evenly from root to tip.	5
`Center in volume`	Moves each guide into the middle of its clump of hair, so one drawn on the surface ends up inside.	On
`Hangs from`	For each guide, the joint its hair hangs from. Auto picks the joint whose bone passes nearest the guide’s root.	Auto for every guide