1. Game Design, Development, and Technology
CS 382
Game Design, Development, and Technology
Character Animation
Natural Staging
Walking and Running
Facial Animation
Cloning
Part 5.2

2. Character Animation Squash-and-Stretch
As the central focus in most games, characters require “natural” staging, timing, and motion.
Squash-and-Stretch
The force of impact causes flexible characters to “squash”, while the subsequent recoil causes them to “stretch”.
These deformations are usually the result of volume-preserving scaling and either forward or inverse kinematics.
Part 5.2
Character Animation
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3. Anticipation
To avoid visual disruption due to sudden movement, it is often advantageous to preface a character’s motion with an anticipatory setup.
While the anticipatory version requires extra work to set up the poses associated with the crouch, it’s far superior to the marionette-like liftoff of the non-anticipatory character.
Part 5.2
Character Animation
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4. Overshoot, Overlap, and Follow-Through
At the end of a character’s motion, it is sometimes useful to add some extra touches to prevent an artificial-looking slow and perfect stop.
Follow-through: parts of the character continue to move after the character stops (e.g., shoulders swaying forwards after landing).
Overlap: secondary motion that occurs as a result of the primary motion (e.g., a ponytail swaying after a jump).
Overshoot: moving past the final pose before finally settling into it (e.g., over-straightening the body at the end of the jump).
Part 5.2
Character Animation
Page 148

5. Exaggeration
While subtlety has its place in games, main characters frequently require exaggerated movements in order to effectively relay their emotional states.
Notice that subtle, unexaggerated motion can, in some contexts, be more effective.
In these two animations, the less exaggerated version on top could be interpreted as a more covert, controlled anger.
Part 5.2
Character Animation
Page 149

6. Non-Symmetric Posing
Again, while it’s much easier to model a character with symmetry, such a character tends to look distractingly artificial…
The symmetric character behaves like an automaton, with perfectly synchronized left and right sides.
The character exhibits more personality when the body and face have little symmetry.
By adding some “snap” to the animation (i.e., varying the character’s animated velocity), even more emotion can be demonstrated.
Part 5.2
Character Animation
Page 150

7. The Mechanics of Walking
Animators describe walking as “controlled falling”: a character leans forward, falls slightly, and then is caught by its outstretched foot.
When the feet are fully extended, the hips rotate along the axis of the spine, and, to keep balance, the shoulders swing in the opposite direction.
At the passing position, the hip is pulled out of center by the free leg, causing a counter-rotation in the shoulders.
The arms counterbalance the legs, dragging slightly behind the action; the head bobs slightly from side to side.
Part 5.2
Character Animation
Page 151

8. Running
More than just a fast and highly exaggerated walk, running requires the body to lean forward more and take greater strides.
Unlike walking, running requires there to be moments when neither foot is on the ground.
Also, at the passing position, the grounded foot tends to propel the body upwards.
Part 5.2
Character Animation
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9. Stride, Cadence, and Speed
Game character movement cycles can be defined by four basic components.
Gait: The pattern of the character’s footfalls
Cadence: The timing of the character’s strides
Stride Length: The amount of ground covered by each pace
Stride Width: The span of the character’s pace, used for balance
Player Movement Speeds
Max Payne
5.5 m/s
Jak and Daxter
6.6 m/s
Halo
6.86 m/s
God of War
7.5 m/s
Normal walking stride lengths and cadences
Unreal Tournament ‘04
8.8 m/s
Quake Wars
8.94 m/s
Serious Sam
12.5 m/s
Quake 4
15.25 m/s
Part 5.2
Character Animation
Page 153

10. Facial Expressions
Tools to manipulate a character’s facial musculature can create various lower-face and upper-face poses;
by combining them, much
more elaborate poses
can be generated.
Part 5.2
Character Animation
Page 154

11. Lip Sync
One of the most difficult animation tasks, lip sync requires the coordination of the character’s mouth with the voice track that will accompany it.
The quality of the animation is improved even further when head and arm movement is added.
Notice how the eye movements tend to distract from the pedestrian lip sync.
Part 5.2
Character Animation
Page 155

12. Skin
Rendering a game character’s skin combines the physical problem of realistically depicting multiple layers of fat, blood, skin cells, and hair, each of which reacts differently to light, with the psychological problem of successfully portraying a surface with which players are extremely familiar.
Traditional skin lighting allows light to enter the skin and to be reflected from the epidermal melanin and the blood vessels in the dermis.
Subsurface scattering lets light bounce around within the skin, emerging far from the point of entry, more heavily tinted by blood and skin pigments.
Part 5.2
Character Animation
Page 156

13. Character Cloning
In order to provide players with a variety of non-player characters without breaking the bank on art direction, it’s a common practice to build characters with a library of swappable body parts and color-shifted textures for skin and clothing.
6 templates w/color variation only
2 templates w/variation in color, texture, accessories
Some body parts don’t need cloning since viewers rarely focus on them.
(blue = static, red = moving)
Certain variations decrease the likelihood that viewers will spot clones.
Part 5.2
Character Animation
Page 157