1. Computer Animation Ying Zhu Georgia State University
Walk Cycle, Action Editor, and NLA Editor

2. Walk cycle A walk cycle generally consists of four key poses Contact
Recoil
Passing
High-point
See
Let Blender interpolate between these poses

3. Create a walk cycle The process
At the start frame, create the “rest” pose. Select all the bones that have been moved, press I to insert a key frame.
Increase frame number. Create the “Contact” pose. Select all the bones that have been moved, press I to insert a key frame.
Increase frame number. Create the “recoil” pose. Insert a key frame.
Increase frame number. Create the “passing” pose. Insert a key frame.
Increase frame number. Create the “high-point” pose. Insert a key frame.
Repeat the above process until the character reaches the original contact pose.

4. Create a walk cycle
Select a bone (or bones), open the IPO Curve Editor
Choose “Pose” IPO type
You’ll see the IPO curves for the bones

5. Copy and paste poses In Pose mode, select Pose menu and choose
Copy Current Pose
Paste Pose
Paste Flipped Pose
“Paste Pose” is useful for copy and paste the same pose in a walk cycle
“Paste Flipped Pose” is useful for creating mirrored pose in a walk cycle
E.g. reversed leg position
Can also use the copy/paste icons

6. Combine walk cycles with path
Two ways to create a walk cycle
Move the character forward while you create the walk cycle
Create the walk cycle without move the character forward
In latter case, you can attach the armature with a path
Create a path
Select armature and then the path, press ctrl + P
Choose “normal parent” (not “follow path”)
The character will walk along the path

7. Action Editor
Three editors are used in creating complex character animation
IPO Curve Editor
Action Editor
NLA Editor
Each is built on top of another and handles a different level of task

8. Action Editor IPO Curve Editor deals with the animation of each bone
A user creates a pose and insert a key frame
An IPO curve interpolates between key frames
In Action Editor, you can create individual “action”
An action is a sequence of poses that serve a purpose (e.g. walk, wave hand, rest, etc.)

9. Action Editor
To create an action you create a sequence of poses and insert key frames
In Action Editor window you’ll see a number of channels
Each channel represents a bone
A diamond marker is a pose marker
Each vertical line represents a complete pose
Along the time line, pose markers are interpolated by the IPO curves
to see them you need to switch to IPO curve editor

10. Action Editor
If you see a pink strip between two markers, it means there is no change in pose between these two markers

11. Action Editor You can give each action a meaningful name
To add a new action, click on the button next to the action name and select “ADD NEW”
Then you create another set of poses and insert key frames, and so on.

12. Action Editor
For a character, each action is defined by a set of bones and their individual IPO curves
An IPO curve is defined by a set of key frames markers and the curve that interpolates them
You can create many (simple) actions for a character

13. Action Editor
Then you may want to composite these actions to create complex animations
Configure the sequence of actions
Decide when each action is played on the timeline
Determine how the actions blend with each other
To do this you need to use the Non-Linear Animation (NLA) editor

14. NLA Editor NLA stands for “Non-Linear Animation”
NLA Editor is a level above the Action Editor
It allows you to organize and mix the actions you created in the Action Editor
Organize actions along time line
(If you see a blank window when you enter NLA Editor, press Home or Shift + MMB to scroll the window up and down.)

15. NLA Editor
Select an armature, move the green line to the starting frame, press Shift + A to add an action strip
Choose an action from a list
These are the actions you created in the Action Editor
You can move and scale the action strip
Press Shift + A to add more action strips
Organize them along the time line to create a logical sequence of actions

16. NLA Editor Action strips may overlap at some point
E.g. “wave hand” in the middle of a “walk cycle”
In many cases, you want one action to ease into another action
E.g. walk  run  walk  rest

17. “Ease in” and “Ease out” in NLA
How to set up “ease in” and “ease out”?
Place two action strips so that the end of one action overlaps with the start of the next action by a number of frames (e.g. 15-frame overlap)
Right click to select the first action
Press N to bring up the “Transform Propoerties” menu
Press “Auto-Blending”
In the “In” field, type in the number of overlapping frames (e.g. 15)

18. “Ease in” and “Ease out” in NLA
How to set up “ease in” and “ease out”? (Cont.)
Right click to select the second action
Press N to bring up the “Transform Propoerties” menu
Press “Auto-Blending”
In the “Out” field, type in the number of overlapping frames (e.g. 15)

19. NLA Editor The active action is marked in yellow
Right click on the strip to make it active
There is a dot on the left side to indicate active strips
The action strips are evaluated from top to bottom
You can move the action strips up and down to change their priorities

20. Why use Action Editor and NLA Editor?
You can create a complex animation by adjust posing and inserting key frames
You have just one action sequence that contains all the poses
But this is inflexible
Difficult to make changes
Or you can create a number of simple actions and then composite them in NLA Editor
Much more flexible and adaptive

21. Why use Action Editor and NLA Editor?
For example, you may want to create an animation sequence with a character waves, walks, and then runs
Option #1: You can create a single long animation sequence that contains all above
Option #2: You may create three separate actions: wave, walk and run. Then you composite them in the NLA editor

22. Why use Action Editor and NLA Editor?
What if you change your mind and instead want to do a walk, wave and run sequence?
It’s difficult to make the changes with option #1.
It’s easy to make the changes with option #2.