Unity Rig - Blender Addon

A Blender 4.x addon that creates Unity Humanoid Avatar-compatible animation rigs and converts existing Rigify rigs for Unity export.

Blender's Rigify produces complex multi-layer bone hierarchies that Unity's Humanoid system cannot auto-map. Unity Rig solves this from both directions: building new Unity-native rigs from scratch, and converting existing Rigify rigs to Unity's naming and hierarchy conventions.

Features

• Create Unity metarigs with correct bone names and hierarchy for Unity's Humanoid Avatar
• Full IK/FK switching on arms and legs with blend sliders and snap operators
• Finger controls - 15 bones per hand with per-finger curl, master fist, and spread controls
• Rigify conversion - convert an existing Rigify rig to Unity format (duplicate or in-place)
• One-click FBX export with Unity-optimal settings
• Eye tracking and jaw controls
• Shoulder controls with independent rotation

Requirements

• Blender 4.0 or later

Installation

1. Download or build unity_rig.zip
2. In Blender: Edit > Preferences > Add-ons
3. Click Install from Disk and select unity_rig.zip
4. Enable the checkbox next to Unity Rig

Usage

Creating a New Rig

1. Create the Metarig

From the 3D Viewport in Object Mode:

• Add > Armature > Unity Humanoid (Metarig), or
• Open the N-panel (press N), go to the Unity Rig tab, and click Create Unity Metarig

Options (in the N-panel before creating):

• Include Fingers - adds 30 finger bones (5 fingers x 3 joints x 2 hands)
• Include Eyes - adds eye and jaw bones

This creates a T-pose armature with bones named exactly as Unity expects (Hips, Spine, Chest, LeftUpperArm, etc.).

2. Fit the Metarig to Your Mesh

• Scale the armature in Object Mode (S) to roughly match your character's size
• Enter Edit Mode (Tab) and position individual bones to align with your mesh's joints
• Pay attention to: hip position, shoulder width, elbow/knee placement, hand and finger alignment

3. Generate the Rig

In the N-panel under Unity Rig > Create Rig:

• Choose Default Limb Mode (IK or FK)
• Click Generate Unity Rig

This adds control bones, IK/FK constraints, drivers, widgets, and organizes everything into bone collections. The metarig becomes a full animation rig.

Compatability

This workflow has been tested with Kevin Iglesias' free human movement animations.

Animating

After generating, the rig has three bone layers (Blender bone collections):

Collection	Contents	Visible
DEF	Deformation bones (Unity names, exported)	Hidden
CTRL	Animation controls (what you keyframe)	Visible
MCH	Mechanism bones (IK solver chain)	Hidden

IK/FK Switching

Each limb has an IK/FK blend slider in the N-panel > Unity Rig > IK/FK Controls section:

• 0.0 = IK mode - position the hand/foot target and pole target; the chain solves automatically
• 1.0 = FK mode - rotate each joint (upper arm, lower arm, hand) individually
• Values between 0 and 1 blend between both

Use Snap IK to FK or Snap FK to IK to match one mode's pose to the other before switching.

Finger Controls

• CTRL-Fist-Left/Right - fist property curls all fingers at once (0 = open, 1 = closed)
• CTRL-Spread-Left/Right - spread property fans fingers apart
• CTRL-Curl-{Side}{Finger} - per-finger curl control
• CTRL-{Side}{Finger}{Segment} - individual joint rotation for fine-tuning

Other Controls

• CTRL-Root - moves the entire rig
• CTRL-Hips - hip translation and rotation
• CTRL-Spine / Chest / UpperChest - torso rotation
• CTRL-Neck / Head - neck and head rotation
• CTRL-EyeTarget - both eyes track this target
• CTRL-LeftEyeTarget / CTRL-RightEyeTarget - individual eye targets
• CTRL-Jaw - jaw rotation
• CTRL-LeftShoulder / CTRL-RightShoulder - shoulder rotation

Converting a Rigify Rig

If you already have a character rigged with Rigify:

1. Select the Rigify armature
2. Open N-panel > Unity Rig > Convert Rigify
3. Choose a conversion mode:
   • Duplicate - creates a new clean armature with Unity bone names alongside the original (non-destructive)
   • In-Place - renames bones directly in the existing armature (destructive, no undo beyond Blender's undo stack)
4. Click Convert Rigify to Unity

The converter:

• Maps Rigify DEF bone names to Unity Humanoid names
• Rebuilds the parent hierarchy to match Unity's expectations
• Renames vertex groups on child meshes so skinning transfers
• Remaps animation F-curves to the new bone names

Exporting to Unity

1. Select the rig armature
2. Open N-panel > Unity Rig > Export to Unity
3. Set options:
   • Export Path - where to save the .fbx file
   • Export Animations - include animation data
   • Export Meshes - include mesh children
4. Click Export Unity FBX

The export uses these Unity-optimal settings:

• Only deform bones are exported (CTRL and MCH bones are excluded)
• No leaf bones added
• Correct axis orientation for Unity (Y-up, -Z-forward)
• Scale set to FBX_SCALE_ALL

Importing in Unity

1. Drag the .fbx file into your Unity project
2. Select the imported asset
3. In the Inspector > Rig tab, set Animation Type to Humanoid
4. Click Apply - Unity should auto-detect and map all bones (green checkmarks in the Avatar Configuration)

Bone Hierarchy

Root
+-- Hips
    +-- Spine
    |   +-- Chest
    |       +-- UpperChest
    |           +-- Neck
    |           |   +-- Head
    |           |       +-- LeftEye / RightEye
    |           |       +-- Jaw
    |           +-- LeftShoulder -- LeftUpperArm -- LeftLowerArm -- LeftHand -- [fingers]
    |           +-- RightShoulder -- RightUpperArm -- RightLowerArm -- RightHand -- [fingers]
    +-- LeftUpperLeg -- LeftLowerLeg -- LeftFoot -- LeftToes
    +-- RightUpperLeg -- RightLowerLeg -- RightFoot -- RightToes

Each finger: {Side}{Finger}Proximal > Intermediate > Distal Fingers: Thumb, Index, Middle, Ring, Little (5 per hand, 3 bones each)

File Structure

unity_rig/
    __init__.py              # Addon registration
    bone_data.py             # Bone definitions, hierarchy, Rigify mapping
    utils.py                 # Bone creation, constraints, widgets, drivers
    operators/
        create_metarig.py    # Create Unity metarig template
        generate_rig.py      # Generate full rig from metarig
        convert_rigify.py    # Convert Rigify rig to Unity format
        export_fbx.py        # One-click Unity FBX export
    rig_components/
        root.py              # Root and Hips controls
        spine.py             # Spine chain controls
        head.py              # Head, neck, eyes, jaw
        limb.py              # IK/FK arms and legs
        hand.py              # Finger controls with curl/spread
    ui/
        panels.py            # N-panel interface
        properties.py        # Scene properties

License

MIT