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Docs Rigging

Action Bone

Turn a bone's angle into a dial that plays back a whole recorded pose: a mouth that opens as a jaw bone rotates, a hand that curls into a fist.

An Action Bone is not a special kind of bone: any bone can drive any number of actions, with nothing set on the bone itself to mark it as special. What makes an action work is the driving bone's own angle: every pose you record inside the action is tied to a specific angle of that bone, and rotating the bone afterwards, by hand or by IK, plays back the pose that belongs to whatever angle it currently sits at.

Recording an action

Select the driving bone and add an action, either from the Action Bone section in the Properties panel or from the Actions panel (see the Actions panel). This creates the action, drops you into Action Mode, and starts you on a neutral pose so the action does nothing until you rotate the bone away from rest.

  1. Inside Action Mode, rotate the driving bone to an angle you want a distinct pose at.
  2. Pose whatever should change at that angle: the driving bone itself, other bones, a shape's points, its colour, an effect, or a mesh's deform.
  3. Move to another angle and pose again. Only what you actually touch at that angle is recorded; anything you leave alone stays neutral.
  4. Click Apply to save the action and return to your real animation.
Action Mode with the jaw bone rotated open and the mouth shape posed to match, the red Action Mode border around the viewport.
Setting an action up leaves stray marks on the dial. Nudging the driving bone a degree or two while you are getting your bearings records an angle that carries no pose, and one sitting just past rest lands between rest and your real poses, where it swallows part of the bone's travel and makes the action look dead. Celas Studio now tidies the dial for you, both when you Apply and when you open a project, so an action recorded before this and saved in that state comes back working rather than staying quietly broken.

Corrective poses

An action's poses apply on top of the driving bone's own deformation, not instead of it, which is what makes them corrective. Bind a shoulder to a bone and the base deformation gets you most of the way there; an action layered on top can fix exactly the bulge or crease the plain bind missed at a hard angle, without you having to reproduce the bend by hand.

One bone, several layers

An action is not limited to the layer the driving bone sits on. While you are inside Action Mode, pose every layer that should react to this bone's rotation, an eyebrow, a highlight, a whole other shape, and each keeps its own pose recorded against the same dial. One elbow bone can drive the elbow bulge, a sleeve wrinkle and a highlight shape all from the same rotation.

Entering and leaving Action Mode

Entering an action always starts you on the rest pose, whatever frame or pose you were looking at before, so what you see and pose in Action Mode is never contaminated by wherever the playhead happened to be. Your real animation is set aside while you work and restored the moment you leave, however you leave.

Apply vs. Cancel

Apply saves everything you posed back into the action and restores your real animation underneath it. Cancel throws away everything you did in Action Mode and restores your real animation exactly as it was. There is no undo step for a cancel to worry about, because nothing you did in Action Mode was ever meant to stick.

Because two actions on the same shape only record the points, style or parameters each one actually touches, they can drive the same layer from different bones without fighting each other.