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FACTFILE

FOR

Blender

DIFFICULTY

Intermediate / Advanced

TIME TAKEN

One day

ON THE CD

Full-size screenshots

Blend file for Proog

Textures

Blend files for stages

2,15, 21 and 26

ALSO REQUIRED

More supporting files can

be found on our website

Turn a simple walk cycle into a stroll with style! Improve your character animation in our Blender masterclass,

which makes use of genuine rigs from the movie Elephants Dream, provided on the CD BY BASSAM KURDALI

successsteps toW

alk cycles are one of the staples

of 3D character animation. Yet its

all too easy to end up with bland,

robotic movements. In this tutorial,

you will learn how to create a walk with personality,

keyframing and refining a basic movement cycle, then

layering secondary animations over the top.

For this, we will use Blenders NLA Editor (Nonlinear

Animation Editor). It works just like a video editor, but using

animation strips instead of video clips. Each strip representsinstances of an action that can be moved, scaled in time or

layered on top of other strips. This allows you to create an

action that contains one walking cycle, while the strip itself

contains as many cycles as are required for your character to

walk along the path you have assigned to it. The repetitive

nature of the cycling can be offset by using additive action

strips to alter the motion, or by adding other strips to layer

different actions on top of the walk.

In the tutorial, well be using Proog, the lead character in

the worlds first open source animated film, Elephants Dream.

First, well keyframe a basic walk cycle and make the action

loop properly, then put him on a path and add some actions and

layer animations on top of his walk. Finally, well look at some

of the extra cloth animation controls the character rig contains.

Dont worry too much about Proogs coat until the very last step

of the tutorial to look good, it needs some hand tweaking.

The walkthrough is intended for readers who already have

some familiarity with both Blenderand the basic concepts

of animating a walk cycle. If you get stuck, refer to the

annotated screenshots on the CD. The disc also contains a set

of numbered scene files that will enable you to pick up the

tutorial again at the corresponding steps, and more are availablefor download from www.3dworldmag.com/stoppress .

The Proog model itself is the genuine rigged character

from the movie, and is available under a Creative Commons

attribution licence, so it can be used for any project you like.

Most of the tutorial can be completed in Blender 2.41,

which is included on the disc. However, some of the advanced

steps require Blender 2.42, which should be a free public

download from www.blender.org by the time you read this.

Bassam Kurdali is a freelance animator. He recently finished

work as Director/Animation Director on Elephants Dream

www.freefactory.org

BLENDERBLENDER

054 | 3D WORLD3D WORLD August 2006

TDW80.t_blender 054TDW80.t_blender 054 6/6/06 12:58:326/6/06 12:58:32


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ON THE WEBBonus scene files andfinished walk animationwww.3dworldmag.com

ON THE CDBlender 2.41 (seenote in introductionabout version 2.42)

SEE PAGE 82

Animating better walk cycles | TUTORIALS

August 2006 3D WORLD3D WORLD | 055



3/6

STAGE ONE |Creating a sneaky-looking walk cycle

Launch Blenderand adjust the panels until you have

Action, NLA and IPO Curve Editors, a 3D Viewport,

buttons and timeline windows onscreen. Split and

join panels by hovering the mouse over their edges and

right-clicking. Move the edges by clicking and dragging. Drag

down the top menu bar, select Edit Methods and, under Auto

keyframe, select Available, drag the bar up and hit [Ctrl]+[U].

01Load Proog: choose File > Open or [F1] and browse

to where you extracted the files from the CD. Select

stage_2.blend and hit [Enter]. If you want to keep

you current layout, deselect Load UI at the bottom of the file

selection window, otherwise you will get the same UI layout

saved with the file. Note: the full-size screenshots are on the

CD, so dont worry about reading the tiny annotations above!

02

Pose the torso in the same way as you posed the foot

in Step 3: select control bones, rotate and/or move

them until you like the contact pose. The cage-likebodybase control can be used to move and rotate the entire

torso; the rest of the spine (body, back, neck and head) can

be rotated independently (body can also be translated, but

well just rotate it). If you rotate, key Rot; if you move, key Loc.

05

Pose the arms and shoulders by rotating and keying

rotations so that the right arm is forward and the

left is backward. Rotate the palm, thumb and finger

bones. The fingers and thumbs are each controlled by one

bone: rotating it rotates the finger, scaling causes the finger

to curl. Key each digits rotation and scale. ([Shift]-select

multiple bones and key them together to save time).

06

EXPERT TIPSetting up contact pointsWell create the walk cycle in one

place using pose-to-pose techniques.

Imagine that youre animating a

character walking on a treadmill,

with each planted foot rolling back,

when planning the poses. You can

plan the cycle between any of the

key poses, but the simplest way is to

start from the contact positionswhere the front foot just begins to

touch the ground, then do the

passing position (where the back

foot passes the front). Finally, do the

down position and the up position.

These last two give a sense of

gravity and force to the walk cycle.

i

For the first contact position, drag the Frame Marker

to frame one, then go to the Side View in the 3D

Viewport. Select and move Proogs left foot half astep forward and a touch inwards. Dont lift it on the Z-Axis!

Rotate it so his toes are pointing up and turned out. (Pronate

by rotating on the Y-Axis.) Press the [I] key and select LocRot

to set a keyframe.

03Heres a little trick: select the left foot, press the

down arrow on the 3D Viewport header (Copy Pose),

then the small upwards icon with the pink arrow(Paste Mirrored Pose). The right foot is now in the mirrored

position of the left foot, so move the right foot backwards,

zero its X and Y rotation, then key it with the [I] key.

04

EXPERT TIPUsing manipulatorsUse manipulators for positioning,

rotating and scaling. These can be

turned on and off with the hand iconin the 3D Viewport, and the buttons

to choose translate, scale or rotate

can be [Shift]-clicked to select more

than one at a time. The drop-down

menu with the options Global,

Local, Normal and View selects the

alignment of the manipulator axis.

Generally, Normal is the most useful

for posing bones, since it aligns with

the axis of each bone. You can also

use hotkeys to constrain motion in

the 3D Viewport by pressing the axis

letter after initiating a transform.

i EXPERT TIPThe layers providedProogs armature has 16 visibility

layers that help minimise the clutter

in the 3D Viewport, Action Editor andNLA Editor. The first layer contains

his body and leg bones; the second

has his left arm FK controls; the

third, his left arm IK controls; and the

the fourth, his left palm and finger

controls. The fifth, sixth and seventh

layers control his right arm and hand

in the same way. The stride bone is

on layer eight, and the facial controls

are on layer nine. Layer 11 has cloth

fix-up controls. Other layers contain

bones that you shouldnt animate

and are supposed to be hidden.

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TUTORIALS | Animating better walk cycles



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Go to frame 5 (or the first down position in the

action). In the 3D Viewport, select the stride bone

and press the [I] key and select Loc to key its

location. Click on Stride Root in the Armature Bones panel.

Move the bone L_stride until it lines up with the back of

the left heel in the side view. L_stride is just a marker, so

it doesnt matter if its keyed.

13Go to the last frame in which the left foot is in

contact with the ground (in my case, frame 34

this may differ depending on the tweaks you

applied in Step 12). Move the stride bone in the Y-Axis until

the L_stride triangle is aligned with the back of the left heel.

Dont move or key L_stride itself; just the stride bone.

14

Thats the first pose done! Save time by pressing the

VCR-style record button in the timeline; this turns

on Auto-Keying. Select all the bones posed so far

and select the Copy Pose arrow in the header. Then move the

frame counter 24 frames forward, and hit the Paste Mirrored

Pose arrow; another 24, and hit the Paste Pose arrow. You

now have the character skating between contact positions.

07Now the passing position (frame 16). This is where

the back foot passes the front foot in the middle

of the cycle. Lift the right foot up and make sure to

remove the X and Y rotation on the left foot, but dont move

its location. Pose the hips and other body parts as shown

above, and then select all the bones that are keyed here.

Copy the pose, go to frame 40 and Paste Mirrored Pose.

09

STAGE TWO |Making Proog walk along a path

Select the left foot and go into the IPO Curve Editor

window (make sure its set to show Pose IPOs), then

click on the label LocY. Select the Y location curve

and hit [Tab] in the IPO Curve Editor, then select the Bezier

handles between frames 1 and 24 and press [V] to make

that section straight. Do the same for the right foot between

frames 24 and 48.

08

EXPERT TIPHow this method worksWhile posing Proog to create the

walk cycle, think of the stride bone

(see Step 13) as a conveyor belt

moving backwards that the character

walks on. When applying the stride

to a path, Blendercycles the action

and uses the stride bone to control

the speed of the cycles.

The stride bone itself remains

stationary on the path for every

cycle of the action. This makes the

character move steadily forwards

along the path. You need to key the

first and last frame of the action on

the stride bone itself for this to

work correctly.

i

Next, create the up position of the foot: the highest

one after the passing position. Try to create a sense

of Proog pushing his weight up and forward whileon his resting leg. Again, Copy Pose and Paste Mirrored Pose

to get the mirror of the pose done. Now delete all the extra

location keys within straight segments of the feet IPO curves.

11We can continue to break down the walk into poses,

or do straight ahead runs on the feet, head, arms, and

neglected body parts such as fingers. Break apartthe motions of joints (try to get the hands and fingers to trail

the arms, and so on) to limber the motion up. Tinker with the

Action Editor and 3D Viewport until the movement looks good.

12The first down position is frame 5. Clear X and Y

rotation of the left foot and rotation of the ankle

and toe, select them and press [I] > Available. GetProogs weight over his front foot and swing the arms further

than in the contact pose. Paste Mirrored Pose on frame 29.

Straighten the foot curves between down and contact poses.

10

STAGE ONE (Continued) |Creating a sneaky-looking walk cycle


Animating better walk cycles| TUTORIALS



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Select the stride bone and, in the IPO Curve Editor,

select its Y Location curve. In the header menu,

select Curve > Extend Mode > Extrapolation. The

curve becomes a straight line. Go to frame one, put the mouse

in the IPO Curve Editor window and press [I] to insert a key.

Do the same at frame 49 (the last frame of the action). In the

Action Editor, delete the original stride bone keys at 5 and 34.

15

In the 3D Viewport, press [Ctrl]+[Tab] to take the

armature out of Pose Mode, select the path, then

[Shift]-select the armature and hit [Ctrl]+[Alt]+[C]

and add a Follow Path constraint to the armature. In the Panels

window, select the Object buttons, go to the Constraints

panel, and make sure the CurveFollow button is pressed the

follow (Fw) direction is in -Y, and Z is the Up vector.

20

Tweak the speed of the movement by clicking on

the path and going to an IPO Curve Editor, then

editing the speed curve as shown above. Change

the Strip End time to the end of the animation, and adjust the

end frame of the animation. And thats it! Youve got Proog

walking!

21

STAGE TWO (Continued) |Making Proog walk along a path

Check that the right foot matches up with the stride:

simply use the R_stride marker and line it up with

the back of the right heel in any frame in which

the right foot is in contact with the ground. The R_stride

should remain aligned in all other ground-contacting frames,

otherwise the right foot needs to be adjusted.

16

Select proogskel. If you havent named the

action, do so now. Delete the link to the action by

clicking the x next to its name in the Action Editor.Mouseover the NLA Editor and add ([Shift]+[A]) the action as

a strip (or mouseover the NLA window and press [Alt]+[C] to

convert the action to an action strip). Make sure that youre in

NLA Mode (see the Expert Tips box after Step 21).

18In the NLA Editor, hit [N] to get the strips Transform

Properties window, if it isnt already visible. Check

the Stride Path option, and make sure the StrideBone option has the stride bone name, and that the axis

for the striding is the Y-Axis.

19To create the path on which Proog will walk, hit

[Spacebar] while in the 3D Viewport. Select Add >

Curve > Path. Press [Tab] once to go to Object Mode,then press [Alt]+[G] followed by [Alt]+[R] to clear its location

and rotation. Press [Tab] again to go into Edit Mode and edit

the path until you achieve something you like the look of.

Dont make it too extreme or the walk cycle will break.

17

EXPERT TIPSwitching between modesWhen adding new objects, Blender

automatically enters Edit Mode on

that object. This allows you to edit

vertices/bones in sub-object level.

Blenders working modes are

accessible via the pop-up menu in the

3D Viewport header, or via hotkeys.

They consist of, in order: Object

Mode, Pose Mode (armatures mustbe in Pose Mode before they can be

animated), Edit Mode, and modes for

weight and face painting on meshes.

To toggle Edit Mode on and off, use

[Tab], and to toggle Pose Mode

(this is only available for armatures),

use [Ctrl]+[Tab].

i

EXPERT TIPSingle actions vs stripsTo display a single action rather than

a strip, click on the button in the

NLA Editor next to the name of thearmature. When the button shows

the Action Editor icon, the armature

displays only the results of that

actions keys. When it shows the NLA

Editor icon, the armature displays the

results of NLA strip animations. For

path-based animation to take place,

you must be in NLA Mode or the

armature will only display the result

of one motion cycle. If youre editing a

single action, you can use the toggle

to capture the NLA-based state at any

frame and key it in your action.

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TUTORIALS | Animating better walk cycles




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Before starting to create the action, select and key

the bones you intend to animate (the head, neck,

back, shoulders and arm bones, including the hands)

at the last and first frame of the action. This allows you to

blend the action from the current animation without having

to use the Blendin/Blendout feature.

24

To finish off, refine the cloth animation. Select all

the strips in the NLA Editor by pressing the [A]

key once or twice. Move them roughly 30 frames

in and dont forget to edit the speed curve of the path as

before. Now, bake the cloth simulation by clicking on the

ProogSoftProx object on layer 15, and in the Physics buttons,

bake the simulation over the range of the animation. The

cloth can be tweaked further by moving (and keying) the

cloud of empties on scene layer nine. Proogs armature

(proogskel) and jacket armature (proogjakskel) have

controls on armature layer 11 to animate the collar and

sleeve manually. And thats it: youve learned to keyframe

a walk cycle, refine it, and added secondary motions. Now

experiment for yourself to develop the animation further.

STAGE THREE |Layering more actions on top of the walk

You can also add an entirely new action and edit it

on top of the NLA animation. Lets make Proog peer

around. Go to the Action Editor, which currently

shows whatever action is active, click on the x to the right

of the name, then on the arrows for selecting an action,

and choose ADD NEW from the menu. Call the new action

something descriptive: we simply called it peer.

23Now lets refine the animation. To add another

action on top of the path animation, [Shift]+[A] in

the NLA view (with Proogs armature selected) and

add an action by name. Select the crouch action and click the

Add button, then make the Blendin and Blendout 15 frames

or so. Proog will now crouch a bit as he walks.

22

In the left column of the NLA window, hit [Alt]+[C]

to convert the action to a strip. You can continue

to edit from here while viewing the results in the

3D Viewport. Over the range of the action, the new keys

replace the underlying walk, which is usually what you want.

Experiment with what youve learned so far to keyframe a

suspicious peering action for Proog for yourself.

25 26

EXPERT TIPAnimating the faceYou can also add facial animation!

In the proogskel armature on layer

nine are Proogs facial controls.

The controls (nicknamed bots) are

mostly location controls, and are

locked, allowing them to move only

in useful ways. Move around the blue

shapes and youll see their effect on

the face. You can scale botbrowmid

and botnarrow to wrinkle the brow

and purse the lips. The green eyelid

controls can only be rotated about

their X-Axis to raise and lower each

eyelid. The eyetracker (shaped like

a pair of sunglasses) controls the

direction in which Proogs eyes point.

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Animating better walk cycles| TUTORIALS


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