Game Development Reference
In-Depth Information
even if the temperature outside the refrigerator changes. The point at which
the system stabilizes is called the
equilibrium
.
Figure 4.5
displays the effects of
negative feedback.
FIGURe 4.5
The effect of negative
feedback
The simplest shape of the equilibrium is a straight horizontal line, but some systems
might have different equilibriums. An equilibrium might change steadily over time
or be periodical (
Figure 4.6
). Changing equilibriums requires a dynamic factor that
changes more or less independently of the negative feedback mechanism. The out-
side temperature throughout the year is an example of a periodical equilibrium that
is caused by the periodic waxing and waning of the available hours of daylight and
the relative strength of the sun.
FIGURe 4.6
negative feedback on
changing equilibriums.
On the left, a rising
equilibrium; on the
right, a periodically
changing equilibrium.
POsiTive FeedBacK creaTes an arms race
Positive feedback creates an exponential curve (
Figure 4.7
). Collecting interest on
your savings account is a classic example of such a curve. If the interest is the only
source of money going into your savings account, the money will spiral upward,
gaining speed as the accumulated sum creates more and more interest over time.
In games, this type of positive feedback is often used to create an arms race between
multiple players. A good example is the harvesting of raw materials in
StarCraft
(or
similar constructions in many other RTS games). In
StarCraft
, you can spend 50
