Rigging
Functional rigs supporting intended motion. Clean deformation. Engine-compatible bone hierarchies.
When to Use
- Character/creature deformation rigs
- Mechanical constraint rigs
- Facial expression rigs
- Prop rigs (doors, vehicles, weapons)
- Before any animation work
Workflow
Skeleton Design → Bone Placement → Hierarchy → Constraints/IK → Weight Painting → Deformation Test → Export Prep
Armature Naming
Prefix: ARM_[AssetName]
Bones: [side]_[region]_[name] — e.g., L_arm_upper, spine_01, jaw
Bone Hierarchy
ARM_Character ├── root ├── spine_01 → spine_02 → spine_03 │ ├── L_clavicle → L_arm_upper → L_arm_lower → L_hand │ └── R_clavicle → R_arm_upper → R_arm_lower → R_hand ├── L_leg_upper → L_leg_lower → L_foot → L_toe └── R_leg_upper → R_leg_lower → R_foot → R_toe
IK vs FK
| Use IK | Use FK |
|---|---|
| Legs (ground contact) | Spine (flexible arc) |
| Arms (hand placement) | Shoulder overlap |
| Feet planting | Finger detail |
| Mechanical reach | Whip/tail motion |
Standard: IK legs, FK spine; switchable arms for game characters.
Constraints
| Constraint | Use |
|---|---|
| IK | Limb positioning |
| Copy Rotation | Mechanical sync |
| Limit Rotation | Joint ranges |
| Stretch To | Tentacles, pistons |
| Child Of | Weapon attach/detach |
| Shrinkwrap | Ground contact (use carefully) |
Weight Painting
1. Automatic weights as starting point only 2. Clean weights: normalize per vertex (max 4 influences) 3. Smooth problematic areas (shoulders, hips) 4. Test extreme poses: T-pose, arms up, crouch, jaw open 5. Gradient weights at joints — no hard 1.0/0.0 at bend center
Mechanical Rigs
- Empty objects as control handles
- Constraints instead of weight painting
- Hinge limits match real joint ranges
- Parent hierarchy mirrors mechanical assembly
Facial Rigs
| Approach | Use Case |
|---|---|
| Bone-based | Game characters |
| Shape keys | Cinematics, dialog |
| Hybrid | Hero game characters |
Minimum game facial: jaw open, blink L/R, brow up/down.
Drivers
- Gear rotation sync
- Auto eyelid blink
- Weapon reload mechanism
- Procedural antenna/wire motion
MCP Integration
- Create armature via MCP
- Parent mesh with automatic weights via MCP
- Query bone count and hierarchy
- Validate weight groups via MCP if supported
- Export armature with mesh via export-pipeline
Deformation Test Poses
- T-pose / A-pose (bind pose)
- Arms fully raised
- Deep crouch
- Neck rotation extremes
- Jaw wide open (characters)
Constraints
MUST DO
- Rig after retopology complete
- Name bones consistently
- Limit bone influences to 4 per vertex (game engines)
- Test deformation at extremes before animation
- Document control scheme for animators
MUST NOT DO
- Auto weights without cleanup (hero assets)
- Scale bones in bind pose
- Rig before topology validated
- Skip IK pole targets on limbs
- Mix multiple root bones without documentation
Reference Guide
| Topic | Reference | Load When |
|---|---|---|
| Humanoid rig | references/humanoid-rig.md | Characters |
| Mechanical rig | references/mechanical-rig.md | Props, vehicles |
