Working with Strand Groups 

A strand group is a whole-number label assigned to a guide or hair strand. Groups let you split a groom into parts and style each part separately, by telling an operator which groups it should affect. For example, you might place a character's fringe in one group and the rest of the hair in another, then add separate styling operators for each.

 

Assigning strands to groups 

The most common way to assign groups is on guides, using the Edit Guides Operator:

1. In the Edit Guides Operator, enter Roots mode and select the strands you want, or use the selection brush in brush mode.
2. Open the strand groups controls and enable the use of strand groups.
3. Choose a group index and assign the selected strands to it, or assign a unique index to each selected strand.

Groups can also be assigned on dense hair (by adding Edit Guides Operator above Hair from Guides Operator), set per strip when using Hair from Mesh Strips Operator, or generated procedurally - by expression, map, or randomly - with the Generate Strand Data Operator.

 

Using groups in operators 

Most operators expose a strand group parameter. The value you enter decides which strands the operator acts on. An empty value or 0 means the operator applies to all strands that have no group assigned; group 0 is the default for ungrouped strands.

 

Strand group patterns 

The strand group parameter accepts more than a single number. You can describe a combination of groups with a compact pattern syntax:

• Single group: 1 affects group 1.
• Multiple groups: 1, 3, 5 affects groups 1, 3, and 5.
• Range: 1:5 affects groups 1 through 5.
• Range with stride: 1:10:2 affects every second group from 1 to 10.
• All groups above a value: +2 affects group 2 and every higher group.
• Exclude a single group: ^4 affects all groups except 4.
• Exclude a range: ^4:6 affects all groups except 4 through 6.
• Combine a single group and a range: 1, 3:5 affects group 1 and groups 3 through 5.

This makes it easy to direct one operator at exactly the strands you intend, without re-assigning groups.

 

Related 

• Working with Strand Channels - per-strand and per-vertex values that drive operator parameters.
• Generate Strand Data Operator - generate groups and channels procedurally.
• Strand Filter Operator - isolate strands for downstream operators.

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