Game Development Reference
In-Depth Information
it hold? Suddenly in the corner of your vision, you spot a bird made of skulls and swing your
eyes quickly after
it.
The mouse offers many more degrees of movement than, say, a keyboard key that is simply in a
pressed
position. But binary keys have their moments, too. Take a game like
Tetris
(1986). The goal of
Tetris
or
not pressed
is to position shapes, each made of four square blocks, such that they
fill the horizontal space of the playing area with no holes. As such, movement in this game—
the player moves one piece at a time—is in the length of a single block. Movement happens
on a grid. If it didn't, it would be hard to fit new pieces into the holes between
existing pieces.
Binary keys make sense here: one tap of a key can correspond to one block of movement.
You could design a way to control
Tetris
with a mouse—maybe the shape would always snap to
the closest grid position to the player's horizontal mouse position. But what about the mouse's
vertical axis? In this example, it has nothing to do (see Figure
2.10
).
Tetris
wasn't designed with a
mouse in mind.
Figure 2.10
Grid-based movement in
Tetris
, with keyboard keys and with a mouse.
A game that was designed for a mouse instead of grafted to one might look very different from
a grid-based game like
Tetris
. As an example, take Christophe Andreani's 1987 Atari ST game
Bubble Ghost
. Andreani made the protagonist of his game a ghost—insubstantial, it can travel
anywhere a mouse cursor can without worry of colliding with walls or obstacles. However, the
ghost is trying to maneuver a fragile bubble (by blowing on it) through a mansion full of things
that, while harmless to the ghost, will pop the bubble on contact. So you can see that this game
was
designed with the mouse foremost in mind.
