Bones & IK
The bone tool builds a real skeleton on flat artwork: a chain of bones, a skinned mesh, and both forward and inverse kinematics. After Effects has no equivalent.
The pieces
| Piece | What it is |
|---|---|
| Bone | A segment with a length and a rotation, parented to the previous bone |
| Chain | A sequence of bones — an arm, a tail, a leg |
| Skinning | Linear blend skinning: each mesh vertex is influenced by nearby bones, weighted |
| FK | Forward kinematics — rotate a bone, everything downstream follows |
| IK | Inverse kinematics — move a target, the chain solves to reach it |
| Controller | A posing handle linked to a bone or IK target, read by the solver directly |
Two IK solvers are live: a closed-form two-bone solver, and FABRIK for longer chains.
Start with a preset
Before drawing anything by hand, check whether a preset fits. Biped and quadruped presets build bones, IK chains and controllers in one operation.
They are in the Rigging dropdown and in the command palette (Ctrl/⌘ + Shift + P) — both driven by the same preset definitions, so the two routes cannot drift apart.
What you get is an ordinary rig. Move the bones, delete a chain, re-bind the weights: nothing about a preset-built skeleton is locked or special.
Workflow
Pick the tool
Ctrl/⌘ + B, with a riggable leaf layer selected — a single shape or image layer.
Draw the chain
Click to place the root, then click again for each subsequent joint. The BoneOverlay draws the bones, joints and IK targets on the canvas.
Bind
The mesh is skinned to the skeleton. Each vertex picks up weighted influence from the bones near it, so the artwork deforms smoothly across a joint rather than tearing at it.
Pose
FK: rotate a bone and its children follow. Good for tails, antennae and anything whose motion originates at the root.
IK: add a target at the end of the chain and move the target. The solver finds joint angles that reach it. Good for arms and legs, where you care about where the hand or foot ends up and not about the elbow angle.
Keyframe
Poses are keyframeable. Set the playhead, pose the rig, and keys are written.
Use IK when the end of the chain has a job — planting a foot, holding a prop. Use FK when the motion travels outward from the root — a whipping tail. Most character work uses both, on different limbs.
Switching a chain between IK and FK
You do not have to choose once. IK/FK mode is per chain, and the conversion preserves the pose — the limb does not jump when you switch.
The mode is itself keyframeable, so a leg can be IK while the foot is planted and FK while it swings, which is the standard way to animate a walk without fighting the solver.
Controllers
A controller is the posing layer: a handle you grab instead of grabbing bones. It links to a bone or IK target and the solver reads it directly.
If you know DUIK, this is the same idea built against a real rig model rather than against nulls and expressions — which is why it links to a rig field instead of driving one through a chain of expressions.
Controllers deliberately do not drive puppet pins. DUIK does that only because After Effects has no skeleton to link to; here there is one.
Weights
Binding auto-assigns weights by distance. Two ways to fix what it got wrong:
| Tool | Use it for |
|---|---|
| Weight-paint brush | Broad strokes — this whole region belongs to the forearm |
| Pick Vertex on the bone overlay | One vertex, typed as a number, when a single point tears |
The numeric editor is the one that closes the last gap against DUIK and Rive: brush-only weight editing cannot fix a single bad vertex without disturbing its neighbours.
CPU and GPU skinning
Both paths exist and produce the same result — the deformed mesh is normalised before it reaches the renderer, so the GPU path does not drift from the CPU one.
Editing the rig
The Rigging inspector tab holds chain editing, IK targets and pose controls. Every edit is a single undo step.
Bones or puppet?
| Bones | Puppet |
|---|---|
| Jointed, articulated motion | Squashy, organic, cloth-like motion |
| A defined skeleton exists | No obvious skeleton |
| You want IK — “put the hand there” | You want to grab and pull |
They are not either/or — a bone rig and a puppet rig compose on the same layer, over the same mesh. Skeleton for the limbs, pins for the cape. See Puppet pins.
Related
- Rigging a logo
- The assistant’s
create_skeleton_rigandpose_skeletontools: Tool reference