Surface Tab

The Surface tab handles mesh binding and groom transfer operations. It lets you bind hair to animated meshes, transfer grooms between different characters, and control how hair follows surface deformation.

What It Does

The Surface tab provides:

  • Mesh binding - Attach hair to scalp/body mesh
  • Animation following - Hair follows animated mesh deformation
  • Groom transfer - Move hair from one character to another
  • Auto-rebind - Automatically update binding when mesh changes
  • Surface binding data - Stores UV coordinates and barycentric weights

Think of it as the glue that connects your hair to your character, ensuring it moves naturally with animation.

Current Binding Info

This section shows the status of your current hair system:

Source Mesh

  • The mesh your hair is currently bound to
  • Usually the character's head/scalp

Guides

  • Number of guide curves in the system
  • Shows if guides are properly created

Binding Status

  • ✓ Computed - Binding data exists
  • Not computed - Need to compute binding

Transfer Groom

Transfer hair from one mesh to another - perfect for moving hairstyles between characters.

Target Mesh Selection

Mesh Dropdown

  • Lists all available meshes in the scene
  • Type to search for specific mesh
  • Excludes the source mesh (can't transfer to itself)

Eyedropper Button (👁)

  • Pick target mesh from viewport selection
  • Select a mesh in Blender, then click eyedropper
  • Automatically fills in the target mesh

Refresh Button (↻)

  • Refresh the mesh list
  • Use after adding new meshes to scene

Transfer Modes

UV Coordinates

  • Best for meshes with matching UV layouts
  • Transfers based on UV position
  • Most accurate when UVs are similar
  • Recommended for same character, different topology

Nearest Point

  • Transfer to closest surface point
  • Works for any mesh topology
  • Good for similar shapes
  • May distort on very different shapes

Nearest Normal

  • Match surface orientation
  • Considers normal direction
  • Better for curved surfaces
  • Preserves hair direction

Projection

  • Project along original normal direction
  • Good for similar poses
  • Handles slight shape differences
  • May fail on very different shapes

Transfer Options

Preserve Length

  • Keep original strand length after transfer
  • Recommended: ON
  • Prevents hair from stretching or shrinking

Preserve Shape

  • Keep relative CV positions (groom shape)
  • Recommended: ON
  • Maintains styled hair shape

UV Tolerance

  • Tolerance for UV coordinate matching
  • Range: 0.001-0.5, default 0.01
  • Only used in UV Coordinates mode
  • Increase if transfer fails to find matches

Max Distance

  • Maximum search distance for nearest point modes
  • Range: 0.1-100.0, default 10.0
  • Increase if hair disappears after transfer
  • Decrease for more precise matching

Transfer Workflow

  1. Prepare Source
  • Style hair on source character
  • Ensure binding is computed
  1. Select Target
  • Choose target mesh from dropdown
  • Or use eyedropper to pick from viewport
  1. Choose Mode
  • UV Coordinates for same character
  • Nearest Point for similar shapes
  • Nearest Normal for curved surfaces
  1. Set Options
  • Enable Preserve Length and Preserve Shape
  • Adjust tolerance/distance if needed
  1. Transfer
  • Click "Transfer Groom" button
  • Wait for transfer to complete
  • Hair appears on target mesh

Auto-Rebind Settings

Automatically update hair binding when the source mesh changes.

Auto-rebind on mesh modification

  • Enabled by default
  • Rebinds when mesh is modified (subdivision, sculpting, etc.)
  • Ensures hair stays attached correctly
  • Disable for manual control

Update strand orientation

  • Reorient strands to match new surface normals
  • Enabled by default
  • Keeps hair perpendicular to surface
  • Disable to preserve original direction

Rebind Now Button

  • Manually trigger rebind operation
  • Use after major mesh changes
  • Applies current preserve settings

Animation Binding

Make hair follow animated mesh deformation (armature, shape keys, lattice, etc.).

Enable animation following

  • Enabled by default
  • Hair follows mesh animation
  • Disable for static hair on animated character

Binding Status

  • Shows if animation binding is computed
  • ✓ Computed - Ready for animation
  • Not computed - Need to compute

Compute Animation Binding

  • Calculate binding data for animation
  • Do this at rest pose for best results
  • Required before animation will work
  • Only needs to be done once

Clear Button

  • Remove animation binding data
  • Use if binding becomes corrupted
  • Recompute after clearing

Animation Binding Workflow

  1. Pose Character
  • Set character to rest pose (T-pose or A-pose)
  • Ensure armature is at frame 0
  1. Compute Binding
  • Click "Compute Animation Binding"
  • Wait for computation to complete
  • Status changes to "✓ Computed"
  1. Animate
  • Animate your character normally
  • Hair automatically follows deformation
  • Works with armature, shape keys, lattice, etc.
  1. Troubleshooting
  • If hair doesn't follow: Clear and recompute
  • If hair lags: Check mesh has no modifiers after hair
  • If hair explodes: Recompute at rest pose

Common Workflows

Transfer Hair Between Characters

Same Character, Different Mesh:

  1. Use UV Coordinates mode
  2. Enable Preserve Length and Shape
  3. Set UV Tolerance to 0.01
  4. Transfer

Different Characters, Similar Shape:

  1. Use Nearest Point mode
  2. Enable Preserve Length and Shape
  3. Set Max Distance to 10.0
  4. Transfer
  5. Adjust hair if needed

Very Different Characters:

  1. Use Nearest Normal mode
  2. Enable Preserve Length
  3. Disable Preserve Shape (may need restyling)
  4. Increase Max Distance to 20.0
  5. Transfer
  6. Restyle hair as needed

Animated Character Setup

Initial Setup:

  1. Create hair on character at rest pose
  2. Style hair completely
  3. Click "Compute Animation Binding"
  4. Test animation - hair should follow

After Mesh Changes:

  1. Modify mesh (sculpting, subdivision, etc.)
  2. Auto-rebind triggers automatically
  3. Or click "Rebind Now" manually
  4. Animation binding persists

Troubleshooting Animation:

  1. Clear animation binding
  2. Return character to rest pose
  3. Recompute animation binding
  4. Test animation again

Technical Notes

  • Binding uses UV coordinates and barycentric weights
  • Animation binding stores per-vertex deformation data
  • Auto-rebind monitors mesh modification events
  • Transfer operations preserve strand attributes
  • Binding data is saved with Blender file
  • GPU-accelerated for fast computation

Common Issues

Transfer Fails

  • Check target mesh is different from source
  • Increase UV Tolerance or Max Distance
  • Try different transfer mode
  • Ensure target mesh has valid UVs (for UV mode)

Hair Doesn't Follow Animation

  • Compute animation binding at rest pose
  • Check "Enable animation following" is ON
  • Clear and recompute binding
  • Ensure mesh has armature/deformation

Hair Explodes After Transfer

  • Reduce Max Distance
  • Use Nearest Normal mode instead
  • Check for mesh scale issues
  • Recompute binding

Auto-Rebind Not Working

  • Check "Auto-rebind" is enabled
  • Try manual "Rebind Now"
  • Ensure mesh modification is detected
  • Check Blender console for errors

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