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After separate: 2 curves, 1 action
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--- Operating System ---
Linux Mint 13 64-bit

--- Blender versions tested ---
2.68.0 r58536
2.68.5 r60361

--- Short description of error ---
When animating curves' Bevel Factor, after a "separate" operation, the resulting curves have both the same action and it cannot be unlinked.

--- Steps to reproduce the error ---
1) Add curve and set its bevel with any depth (Properties editor > Object Data panel > Geometry section > Bevel)
2) animate its (End) Bevel Factor (e.g.: move to frame 1, set Factor to 0, insert keyrame [i key]; move to frame 10, set Factor to 1, insert keyframe)
3) enter edit mode, select 2 nodes (control points) and split or duplicate it
4) then press P to separate it into a different curve object
5) Try to change animation keyframes (in the Dope Sheet) for one object and it will change for the other.

Using the outliner is possible to see both objects have the same action under its object data (the action is not relative to the object, but to its data).
There is no way to unlink that action, or change it without affecting the other curve.



Event Timeline

P.S.: there is one way to unlink it, by right-click on the animation data in the outliner and selecting "unlink".

I would have expected the Action data block to show up in the action editor. This works fine for objects, there you get a "2" button indicating the 2 users after separating mesh data into a second object which then shares the action, and you can make it unique or unlink. But for some reason the context update in Action editor only uses actual object data, not the animated curve data.

@Aligorith: this happens in actedit_get_context:

if (ac->obact && ac->obact->adt)
saction->action = ac->obact->adt->action;
saction->action = NULL;

Would it hurt to allow actions from other non-Object contexts in the editor? I think we need better ways to access anim data in non-object blocks.

This is currently a known limitation that's been on the todo for quite a while.

I'm not entirely against allowing the Action Editor to be used for assigning/editing actions attached to levels other than object. However, I also think that it's not a good idea to try and do anything "clever" like guessing which context a user wants to assign an action to, at least not without providing a clear indicator of what level they're currently editing, otherwise we get problems like users thinking that they're assigning an action to one context when in fact they're assigning to another.

There are really 2 parts to addressing the problem here:
1) How do we present the ability to choose which level we're dealing with?
2) How to reliably detect and manage which levels we present to users based on current selections. - Ultimately, we may just fall back to the same technique here as what the Properties Editor and what the old IPO Editor did, though in both of those cases, there are some really iffy situations currently when switching between two objects with totally different types (and hence, a large number of contexts become invalid in one, but are valid in the other, and vica versa).

@Joshua Leung (aligorith), shall we consider this a bug? Otherwise i'll move it to TODO.

Julian Eisel (Severin) closed this task as Archived.Feb 3 2015, 2:28 PM

Added note in the Todo list for now.