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Chapter 11 Animation Composition
Articulation
Articulation
is the bending and positioning of movable parts, such as arms
and legs in synchronization with the translation of a walking character. The legs
articulate in a stepping motion as the character is translated to a new position.
If the legs are articulated without translating the character, the active animation
would look as if the character is running in place.
Articulation is plotted by mapping a point on an object and following it
through the motion path, or animation arc. An
animation arc
is the path an
articulated feature follows through the animation. This is shown in Figure 11-4.
Video game designers need to be aware of the animation arc. How many games
have you played where a character’s arm or leg moves through another object
when it is articulated? This is an error and reflects poorly on the game.
In video game design, an artist often must duplicate the articulation of real
objects or humans. A 3D modeling animator might use a motion-capture system
to record the actual articulation movements of a person. Motion capture is
discussed later in this chapter.
Morphing
Morphing
is a change in the physical shape of an object. Objects can be
squashed, stretched, exploded, joined, and more. Each time the size or shape of the
object changes, a morph occurs. Objects that collide impart energy to each other
when they hit. This energy causes waves or deformations. Additionally, objects can
change state. Water can boil into a gas and metal can be melted into a liquid.
The law of conservation of energy states that energy cannot be created or
destroyed, but can change state. Kinetic energy is the energy of movement.
The kinetic energy of two items colliding cannot be destroyed. Rather it is
transformed into heat, sound, and stored energy. Stored energy is potential
energy. Potential energy can exist as gravitational, elastic, chemical, electrical,
or magnetic energy, as described in Figure 11-5.
Figure 11-4.
The animation arc is
the path an object
follows through an
animation.
Goodheart-Willcox Publisher
Animation
arc