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26 Chapter 1: Introduction to Computer Graphics and 3D
SQUASH AND STRETCH
This technique makes a character, for example, respond to gravity, movement, and inertia
by literally squashing it down and stretching it up when it moves. For example, a cartoon
character will squeeze down when it’s about to jump up, stretch out a bit while it’s flying
in the air, and squash back down when it lands to make the character look as if it’s react-
ing to gravity.
EASEIN AND EASEOUT
Objects never really stop suddenly. Everything comes to rest in its own time, slowing
before coming to a complete stop in most cases. This is referred to as ease-out.
Just as objects don’t stop suddenly, they don’t immediately start moving. Most things
need to accelerate a bit before reaching full speed. This is referred to as ease-in. The
bouncing-ball tutorial in Chapter 8 illustrates ease-in and ease-out.
FOLLOWTHROUGH AND ANTICIPATION
Sometimes you have to exaggerate the weight of an object in animation, especially in
cartoons. You can exaggerate a character’s weight, for instance, by using well-designed
follow-through and anticipation.
You should create a bit of movement in your character or object before it moves.
Anticipation is a technique in which a character or object winds up before it moves, like a
spring that coils inward before it bounces.
Likewise, objects ending an action typically have a follow-through. Think about the
movement of gymnasts. When they land, they need to bend a bit at the knees and waist
to stabilize their landing. In the same way, a cape on a jumping character will continue to
move even after the character lands.
The axe tutorial in Chapter 8 will give you a chance to implement these two concepts.
Physics
In Chapter 12, “Maya Dynamics and Effects,” you’ll see that one of Maya’s most powerful
features is its ability to simulate the dynamics of moving objects. To use that capability
effectively, you need a general awareness of the properties of physics—how objects behave
in the physical world.
Newton’s Laws of Motion
You need to know three basic laws of motion. Sir Isaac Newton set forth these three laws,
summarized here. Everyone in animation needs to understand the first two laws, because
they play a large part in how animations should look. Coming to terms with the third is
an art:
An object in motion will remain in motion, and an object at rest will remain at rest •
unless an external force acts upon the object. This is called inertia, and understand-
ing it is critical to good animation. You’ll find more on this in Chapters 8 and 9.
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