332
Video Game Design Composition
a straight line, the result will look unnatural. Mechanical items may move in
straight lines, such as a window opening or closing, but natural objects, such as
characters and trees, move in arcs.
As discussed earlier in the chapter, arcs define the natural movement of an
articulated rotating joint. When you throw a ball, the ball does not move in a
straight line. As you rotate your arm to throw the ball, the ball moves in an arc
while it is in your hand. Also, once you release the ball, the ball curves toward
the ground as gravity pulls it downward.
Follow-Through and Overlapping Action
The principle of follow-through and overlapping come at the end of an
animated action.
Follow-through
is a continuation of movement beyond the
main event. When a baseball player swings a bat, the bat does not stop moving
when it hits the ball. The
momentum
of the bat causes follow-through. The
movement of the bat continues to follow the motion through the entire swing.
In another example, when a
character quickly turns his or
her head, hair, jewelry, and other
items the character is wearing
briefly continue moving after the
head stops. Animations should
incorporate the concept of follow-
through for realistic movement.
Overlapping
describes more than one motion occurring at the same time. It
is unusual to have one motion completed before the next motion starts. Think
about raising a glass to take a drink of water. As you raise the glass, your lips
begin to open and your head tips down before your arm completely raises the
glass to your lips. Now, try it the opposite way. Move the glass completely
to your lips before tipping your head down, and wait until your head is fully
tipped down before opening your lips. This feels unnatural. If you watch
somebody performing this activity, it looks unnatural, too.
Figure 11-10.
The principle of squash
and stretch can be seen in
the bouncing of a rubber
ball.
Goodheart-Willcox Publisher
CHEAT CODE: MOMENTUM
Momentum is a quantity of motion,
defined by mass × velocity. All
moving objects have momentum.