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NLA Editor

The NLA Editor window (Ctrl⇧ ShiftF12) allows you to do non linear animation in Blender. The idea behind this is similar to the one from non linear video editing, used by most of the video editors (e.g. Blender’s one, but also kdenlive, pitivi, …): the global (NLA) animation is made of small pieces (actions in Blender), which each “make one thing”. These simple actions can be applied to different objects, re-timed, fasten up/slowed down, repeated several times, duplicated at different moments, etc., to create the final complex animation. A bit like simple words (which have each a limited number of meanings) can, once correctly put together, form a complex sentence…

So, NLA is another level of abstraction above Ipo curves and actions. You might ask yourself “why do I need NLA when I can create every animation I need with just Ipo curves”? Well, it’s a question of efficiency and – oddly – simplicity. For small, limited animations, you do can use only Ipo curves, and have no need of the additional complexity provided by the actions and NLA. However, when you begin to work on more advanced and complex animations, you’ll quickly find out that most of these are, as said above, decomposable in small pieces, that are then used several times.

Let’s take an example: the lips movements when a character speaks. You do can create a single Shape Ipo curves animation that matches a whole speech. But in fact, the lips’ movements while speaking can be decomposed in a few basic pieces of animation (around ten or less if you want to keep it raw, more if you want high realism), that are then mixed and blended to match the audio track. So, yes, it takes some time to create these “speak actions”, but then, you can assemble them to match any speech, much more efficiently than if you had to do everything by hand – and even more interesting, if you change a part of the audio track, you do not have to recreate the whole animation, just adjust the strips animating the affected time range…

• The NLA animation is a scene-level datablock, as for example the VSE one, which means that there is only one per scene, that gathers all animations.
• Non-animated objects never appear in this window. However, objects do not have to use actions to be shown – there Object Ipo keyframes are also visible, though you have not much editing options on these…
• The NLA is not so easy to understand and master – take your time, and practice!

Interface

The NLA Editor window, with Object and Shape action strips on Cube_nla object, and Object and Constraints keyframes on Suzanne_nla object (note how you can’t distinguish them…).

The NLA Editor interface is very similar to the Action Editor one, divided in three areas:

The header bar

Here you find the menus, and a few other tools, like the transform snapping type…

The left “list-tree”

This part shows all animated objects in the scene (or only those on visible layers, see below), ordered in a three-levels system:

• The top-level tracks (colored in light gray, and named from their object) represent the objects. These tracks show all keyframes of objects linked to an Object and/or Constraint Ipo datablock (Shape ones are never shown here, and Pose ones are always also actions, so they are shown in sub-strips, see below). The small arrow to the left allows you to expand/collapse the whole sub-tracks set of this object.
• Mid-level tracks (one per top-level ones) show the keyframes of either the action to which the object is linked, or of the current active action track.
• Low-level tracks contain the action strips themselves (only one strip per track!). You can use the small “eye” button to there right to mute them.

A track can be selected (text in white, strip in gray-blue color) or not (text in black, strip in pink-brown color.), use LMB clicks to toggle this state. Note that the whole set of tracks is always selected (i.e. the top-level one, and all its “children”).

The mid- and low-level tracks can also be active – they then have a small black dot to their left. There is only one active track per top-level one (usually the last selected one…). The resulting keyframes of the active track’s action strip are shown in the mid-level track, but also in the Action Editor and Ipo Curve Editor windows that are not pinned: these windows then show you a more detailed view of the action as it will be “played” by this action strip in the NLA. This also implies that once you have added action strips, if you want to have the original action back in your action and/or Ipo curve editors, you must activate the mid-level track in the NLA.

The main area

It contains the keyframes and/or action strips.

As with the other “time” windows, the X-axis materializes the time. The Y-axis has no mean in itself, unlike with the Ipo curve editor, it’s just a sort of “stack” of action strips – each one being shown as an horizontal colored strip.

The keyframes (top- and mid-level tracks) are materialized similarly as in the Action Editor, as light-gray (unselected) or yellow (selected) diamonds. Neighbor keyframes having no difference between them also have the pink (unselected) or yellow (selected) “strip” (not to be mistaken with action strips, see the The NLA Editor window, … picture).

The actions (low-level tracks) are materialized as solid pink (unselected) or yellow (selected) strips, which length represents there effective duration in the NLA animation. Note that muted action strips are crossed out by a thin red line.

View Menu

Apart from the classic window options, we have:

• Only Objects On Visible Layers – A toggle option that only shows the tracks (and hence strips/keyframes) of the objects laying on visible layers.
• Show Seconds/Show Frames (CtrlT) – Whether to show the time in the X-axis as frames or as seconds…
• AutoMerge Keyframes – It seems to be the same option as for the Ipo Curve Editor window…
• Update Automatically – Fine, but update what?
• Lock Time to Other Windows – This is the same option as found in the View menu of the timeline: it allows you to synchronize the horizontal (time) scale of all “time windows” that have this option set.

Then, you have navigation/playback options:

• Play Back Animation (AltA) – Starts the animation playback (same as “play” button in the timeline)…
• Set Preview Range, Clear Preview Range (CtrlP, AltP) – These entries allow you to define/clear a temporary preview range to use for the AltA realtime playback (this is the same thing as the Pr option of the Timeline window header).

Marker Menu

See the Markers page.

Object’s NLA Mode

Object’s NLA Mode.

NLA mode: the three action strips of Cube_nla will be “played” back.

Action mode: only the first ShapeAction_nla action strip of Cube_nla will be “played” back.

An object with action strips in the NLA can be in two modes, selected by clicking on the small icon to the left of its name in its top-level track:

NLA mode (default mode)

Materialized by a small “strips” icon, the objects in this mode use all their action strips to compute their resulting NLA animation. This is the default mode, and generally the one you’ll want to use when rendering your animation!

Action mode

Materialized by the small “man” icon, the objects in this mode use only the active track (action strip) to compute their resulting NLA animation. This is most useful during the animation process, to concentrate on one thing at a time, or check which action strip is creating problems, etc.

Note that in this mode, the active action is fully played, not taking into account the limits that might have been set by the active strip, nor the repeats (its timing are used though, as well as its scaling…).

The other strips are like muted!