Clumping gathers fibres into clumps, the way real fur and hair gather into tufts and locks, especially when wet. It's one of the most important nodes for making fur look natural. You can stack several Clumping nodes, from large clumps to small, to build up detail.
Each clump has a centre fibre, and the fibres around it are pulled towards it. The clump centres come from one of two places:
- Without a second input, the node picks some of the fibres being clumped to be the clump centres, spaced by the Clump Radius. This is the quickest way to start.
- With a second input, every fibre in it becomes a clump centre, which gives you full control over where the clumps are. A typical setup is a second Scatter node with a lower density and Lock Density turned on (so the clumps don't change when you change the viewport or render density), followed by a Grow node, and the same Comb as the main fibres, so the clumps follow the groom.
| Input | Accepts | Description |
|---|
| 0 | Fibres | The fibres to clump. |
| 1 | Fibres | Optional. Fibres to use as the source of the clumps. Every fibre in the first object of this input becomes a clump. They need per-fibre rest positions, lengths, root IDs and strandu, as fibres from a Grow node have. Without this input, the node picks clumps from the fibres being clumped. |
Parameters
| Parameter | Description |
|---|
| Weight | The overall amount of clumping. |
| Weight Random | Randomizes the clumping weight of each fibre. |
| Clump Weight Random | Randomizes the weight of each clump, so whole clumps vary in strength. |
| Clump Radius | The rough size of the clumps. Without a second input, this sets the spacing of the clumps picked from the fibres. It's also the distance limit for Within Radius clump selection. |
| Clump Selection | Which fibres clump: By Fibre Length (the default) clumps fibres within a fibre's length of a clump's root, Always clumps every fibre, and Within Radius clumps fibres within the Clump Radius of a clump. |
| Fly Away | How many fibres stay out of the clumps. The higher the value, the more stray hairs, for a frizzier look. |
| Obey Parting | When on (the default), and both the fibres and the clumps come from a parted groom through a Comb node, each fibre only clumps to a clump in its own parting region. |
Shape
| Parameter | Description |
|---|
| Attraction | How strongly fibres are pulled towards their clump. |
| Enable Opposing Attraction | Turns on Opposing Attraction. |
| Opposing Attraction | The attraction for fibres on the far side of the clump's flattening axis, so the two sides of a flattened clump can be attracted differently. |
| Flatness | Flattens the clump's cross-section. |
| Flatness Random | Randomly reduces the flatness of each clump. |
| Base Attraction / Tip Attraction | How strongly fibres are attracted to the clump at their root and their tip. |
| Attraction Bias | Biases the attraction along the length of the fibres. |
| Twist | Twists the fibres around the clump. |
| Twist Random | Randomizes the twist. |
| Rotation | Rotates the clump's flattening axis around the clump, in full turns from -1 to 1. Only has an effect with Flatness or Opposing Attraction. |
| Rotation Random | Randomly reduces the rotation of each clump. |
Geometry
| Parameter | Description |
|---|
| Length Handling | Depending on your graph, a fibre can be longer than its clump (especially when you use guide curves), which can give stray-looking hairs. Set this to Conform If Longer to make fibres that are longer than their clump conform to its length, or leave it at Do Nothing. |
| Maintain Length | When on, each fibre keeps its original length after it's clumped. |
| Obey Weight | With Conform If Longer, takes the Weight into account for fibres that are longer than their clump. Fibres with a weight of 0 are left alone and keep their length. |