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Manual - Blender 2.41

[edit] NLA Editor

[edit] Description

You use the NLA (Non Linear Animation) Editor to mix actions and IPOs of objects to make a composite animation. Both Object Ipos and Actions can be blended. Every object may have only one composite animation. You can think of it this way: the Action editor says WHAT the bones are supposed to do, and the NLA Editor says WHEN they are supposed to do it. In addition, you can position the object and key its location using the NLA while in the NLA Editor, in order to say WHERE the action is supposed to occur.

The NLA Editor works in two different modes. In the "Action" (single) mode only the current active action is played. To play combined action use the "NLA" (combined) mode.

In the NLA Editor you see a representation of all Objects with either Actions or Ipos. On a per Object basis, you can add "Action Strips" with ⇧ ShiftA; you can add as many Actions as you like, allowing you to mix different Actions to non-destructively edit timing and relationships. Each Object can have only one active Action, which is displayed in the Action Editor. This active Action is the one which will receive any new keys you insert, and whose keys you can directly edit.

When strips are inserted, they start at the current frame. When a strip is added, it becomes the active strip. The current active strip is always drawn in yellow. Clicking on a strip itself or on the left-hand bars will make the strip active. Using the sript properties panel, you can control how long the action takes to execute, or what portion of an action is to play.

You add new Ipo-Keys to the active Action, you can directly edit these Keys (delete, move). The objects you select in the NLA window are selected also in the 3D window. Be careful! Deleting keys in the NLA also deletes them from the Action, and from the underlying IPO curves as well.

Ipo's for objects - and also for armature objects - can be converted to Actions in the Ipo window with ⇧ ShiftC (or from the Strip Menu (Convert Action to NLA strip)

De-Link Actions before starting:

Before entering the NLA, ensure that any object you want to control using the NLA is de-linked from its action. Otherwise, that action will want to play on its own. To de-link, in the Action Editor, be sure Fake User is enabled and press the X button on the header. The Action will remain in memory (for you to call in using the NLA) but will not force the object to perform it. Note also that Actions designated for use in the NLA should start at frame 1, for convenience.

Image 9: Representation of different objects, actions and IPOs in the NLA Editor window.

1) An object is only shown in the NLA editor window if it has Ipos, an action, or NLA strips. The top-most horizontal bar for an individual object shows the Object's name to the left, and any Object Ipo "keyblocks" (the diamonds that represent keyframes) on the right. (Image 9 - the "Lamp" has only object Ipo's, and no Actions).

2) The button to the immediate left of the Object name toggles Blender between evaluating the entire NLA and displaying the results in the 3D window, or only evaluating the active Action (Image 9 - "Camera" is in "Action" mode, while "AR-right" and "AR-left" are in "NLA" mode). Note that this icon is only displayed when NLA strips are present for the object.

3) Immediately below the first Object bar, the active Action is shown, and the "keyblocks" for the Action's Ipo's.

4) Finally, the "Action Strips" are drawn. The active Action Strip is indicated with a black dot icon. Clicking on a Strip itself or on the left-hand bars will set a Strip to being the active Action.

[edit] NLA Strip Options

[edit] Description

Strips are added and shown in an indented fashion. when you Add Action Strip, a popup window allows you to choose from available Actions defined. Add Blank Action creates a new action, by default named "ObAction". To rename it, use the Action Window. The name of the overall action is the name of the armature or object. Below that is an indent strip that shows the name of the currently selected strip and all of the ipo keys for that strip. Indented beneath that are all the loaded action strips.

The example image shows an NLA window for armature Crane in Action mode. The RMB selected strip is ArmCycle, and it has two keys. The white diamond at the current frame (green line) shows that there is a keyed position there. The orange diamond at frame 21 is the currently selected frame (it is ready to be Grabbed and moved, or X deleted).

There are two modes for the editor: Action mode and NLA mode. The mode is shown by the icon at the head of the strip: "drowning man" for Action, "mini-strips" for NLA mode. In Action mode, only the action for a single action strip is animated as you scroll through your animation frames. In NLA mode, all strips are animated as you scroll through your animation frames. When you switch to NLA mode, the armature's bones are all recomputed based on keyed IK and FK positions. Any non-keyed bones will revert to their edit position. So, it is a good idea to key all bones (especially IK drivers) at the start of the animation in the default pose.

Recall that to create actions for armatures, you must Add New Action, then Add New IPO strip, or just key the action in the Action window (and an IPO will be added automatically). Also recall that an action can contain motion and IPO curves for many bones. Therefore, it is possible to load two action strips that have two (possibly conflicting) IPO curves for the same bone. For that reason, you have to use the strip's properties to tell Blender which IPO should take precedence, or if it should blend the two actions together. These and other properties are described below.

The selected strip is shown in yellow and has a big dot next to its indent. All keys for that action are shown as diamonds in the indent strip. The window scrolls vertically with LMB -drag the thumb in the right window margin. It scrolls horizontally and vertically via MMB -drag.

Strips are added in order, the last one at the bottom of the list. To move or re-arrange the strips, sue Strip -> Move or the hotkey CtrlPageUp or CtrlPgDn.

[edit] Properties

Image 11: The Transform Properties panel for a strip.

The strip properties control how the generic action is applied to the animation. When working on individual actions in Action mode (the "Drowning Man" is shown), the full action is animated in the 3D Window, not just the action between the Action Start and Action End frames in the properties panel. When you switch to NLA mode, only the action range and repeats, along with the rest of the properties, are used to compute the actual animation. These properties include:

Timeline Range

The first and last frame of the Strip in the timeline. The Strip length is independent from the length of the Action, but the Action will "stretch" to fill the Strip length. This feature allows you to have a generic walk cycle action that spans 40 frames for example. To make your character walk fast, you could enter a 30-frame range; to make him walk slower enter a 50-frame range.

Locked Strip Length

By setting the strips to Locked, NLA will always keep strip length up-to-date with your Action edits so that all keys are included.

• Locked mode is the new default, as it is far superior to the old behavior, but older files will have to be updated manually for this feature to work.
• If you release this lock, you can choose only a part of the action to be included in the strip.
• Action End is not allowed to be less than Action Start, so you cannot reverse an action in the NLA editor.

Blending

The number of frames of transition to generate between this Action and the one before it in the Action strip list.

Repeat

The number of times the Action range should repeat.

• This parameter is ignored if Stride Path (in the Stride Support settings) is enabled.

Hold

If this is enabled, the last frame of the Action will be displayed forever, unless it is overridden by another Action. Otherwise the armature will revert to its rest position.

Add

Specifies that the transformations in this strip should add to any existing animation data, instead of overwriting it.

Stride Path

Repeats the strip along a path (for example, to make a walk cycle)

Disable Path

Temporarily disables the path movement so you can see your action repeating on the spot

Stride

The distance in Blender Units that the strip should be repeated over (the length of the stride)

X/Y/Z

The axis of the stride bone to move the armature along

Stride Bone

The name of the stride bone. See tutorial Stride Support

[edit] NLA Strip Tools

[edit] Description

Edit the properties of the Strips and Keys via the Strip menu:

[edit] Options

Image 10: The Strip menu.

Move Up/Move Down

Page Up or Page Down to change the order of the strips. Strips are evaluated top to bottom. Channels specified in strips later in the list override channels specified in earlier strips.

• Delete

X Deletes a Strip or a Key. Deleting a Strip affects only the NLA editor. However, if you delete a key the position is permanently gone.

Duplicate

⇧ ShiftD Copies a Strip or an Ipo.

Snap to Frame

⇧ ShiftS Snaps start and end of the selected Ipo Strip to frames.

Reset Strip Size

AltS Resets the size of the Strip in NLA to match the chosen range of frames from Action.

Reset Action Start/End

AltS Resets the chosen range of Action frames to include all frames in the Action (this is only necessary if you are not using the new "Locked Strip Length" feature, and is useful for fixing older files or if you have "lost your place" when adding or subtracting frames from Actions).

Grab/Move

G Moves the strip horizontally. With Ctrl you move by frames.

Scale

S The base "point" for scaling is the current frame. By setting the frame you can select whether the end, the beginning, or a point in the middle of the strip shall keep its position.

Manual