Blender 4.4 introduces Slotted Actions. In a nutshell, slots make it possible to store the animation of multiple “things” in the same Action.
What are Slotted Actions?
In Blender 4.3, an Action was just a “dumb bag of F-Curves”. Anything that gets an Action assigned will be animated by the same F-Curves.
Slotted Actions have a separate “dumb bag of F-Curves” for each slot. Anything that gets an Action assigned can choose which slot it gets animated by.
A slot is just a label stored by the Action. It has two components:
- the display name (like “Suzanne” or “Cube”), and
- the type it is meant to animate (
OBJECT
,CAMERA
,SCENE
, etc.).
This combination (name+type) is unique, so you can have an Object slot named “Camera” and a Camera Data slot also named “Camera”. Like always in Blender, the next one of those will become “Camera.001”.
Examples of Typical Usage
- Object and Object Data together: one action “CameraAction” could have two slots:
- for the camera object (animating location & rotation), and
- for the camera data (animating focal length & focus distance).
- Object, Mesh, and Shape Key parameters together: basically the same as above, where one “CharacterAction” could have three slots:
- for the mesh object (animating location / rotation /scale)
- for the mesh data (animating remesh voxel size)
- for the shape key (animating blend values)
- Object rig: where one “character” consists of multiple objects parented together. Each object can have its own slot in the same Action.
- Brick wall physics simulation: a brick wall can consist of hundreds of individual objects. These can all be using the same Action, consisting of a slot per brick.
How to use Slotted Actions
There are three ways in which you can use slotted Actions:
- Explicitly: Assign an Action, but do not pick a slot yet. When you start keying, Blender will create a new slot in that Action, to hold your keys. With this, you have full control over which Action your keys will go into.
- Automatically: Blender will automatically make certain data share the same Action. For example, when you start keying a Camera Object, this will create an Action with a single slot. When you then key its Camera Data, that will use the same Action, and create a second slot for the camera data. This is also done for other combinations, like Material/World/Scene and their Shader Node Tree.
This only happens if there was no Action assigned yet, so you can use the explicit method above if you do not want this automatic behaviour. See the release notes for more detailed information about the auto-assignment. - Afterwards: If you’ve keyed multiple objects, and then decide they should actually be using the same Action, you can merge Actions. Select the objects you want to merge. Then go to the Action editor, Action menu, and choose Merge Animation. For more info on how this works exactly, see the Action Menu chapter in the manual.
What does not happen?
Because this is the first release with slotted Actions, it was decided to not automate too much. This avoids the feel of “hard to understand magic”, at the cost of having to do more manually. These things were deliberately chosen not to implement in Blender 4.4, and to wait until a wider audience has had the chance to use slotted Actions in practice.
- Select multiple objects & press
I
to key them. This still creates separate Actions, one per object. You can either use the “Explicitly” or “Afterwards” approaches (described above) if you want them to share Actions. - Action assignment only assigns that one Action, on that one thing. So when you assign an Action to the Camera Object, you may see “(unassigned)” behind the slot name of the Camera Data. In the Camera properties there is another Action selector (since Blender 4.3) that you can use to also assign the same Action to the Camera Data.
- Similar to the previous point, switching Actions does not mass-switch all users of that Action.
So if you feel that these are stupid, and could be better, you’re in the right place. See below.
Already Foreseen Improvements
These improvements are already in our minds. Even though they’re not yet planned (as in, no date has been picked yet at which development would start), we do want them. In no particular order:
- Simplify the Action selectors. Currently a Material + its node tree can have separate Actions (and will have, if you animated them in Blender 4.3 or earlier). When they do have the same Action assigned, it would be nice if the selectors would collapse, to show only a single Action selector and
two slot selectors. - Pinning Actions in the Action editor. Currently the Action editor still works like it did before, and only shows the Action of the active object. It would be useful to be able to view any Action there, without assigning it to any object.
- Operators to manage switching Actions: #133725: Anim: switching assigned action on multiple data-blocks together
What to give feedback on?
Blender 4.4’s behaviour is intentionally kept quite simple. There are ideas for streamlining the workflows, and for making things happen more automatially. And in order to automate the right things, and still ensure people have full control over their animation, we want to know about your experience.
First and foremost: please try to work with slotted Actions for a while, before giving feedback. Also read through the entire feedback thread, and if somebody else already voiced your idea, give them a . This will make it much easier for developers to go through the thread and see which views are shared among a wide range of people.
These are some questions that we would love to see different points of view on:
- When keying multiple objects simultaneously (and they do not have an Action assigned yet), should that make them share an Action, always? If not, should this be a user preference? If so, what should the default value for that preference be?
- The “Automatically” case above makes certain types of data share the same Action by default. Should a similar kind of system also be in effect when switching Actions? And what should happen when you do want them to have different Actions? Is that even necessary for Blender to support?
- What is missing / unexpected / counter-intuitive?