Game Development Reference
In-Depth Information
A navigation mechanism establishes a relationship between the way the player
moves the controls and the way the avatar responds on the screen. The player learns
this relationship and uses it until it becomes automatic. When a player gives move-
ment commands, the avatar must respond in a consistent and predictable way.
Anything that disrupts the player's understanding of the control relationship, such
as a sudden change of camera angles, may cause the player to make a steering error.
This section assumes that players steer using a joystick except where otherwise
indicated; for most purposes, you may consider a joystick interchangeable with a
D-pad but offering finer control. Joystick directions are referred to as up (forward or
away from the player), down (towards the player), left, and right. Steering wheels
for cars or control yokes for aircraft aren't covered here because they should be
self-explanatory.
If the player designates a point in the landscape and the character or vehicle moves
to that target without further player control, the game uses
point-and-click navigation
.
Screen-Oriented Steering
In screen-oriented steering, when the player moves the joystick up, the avatar
moves toward the top of the screen. Implementation details vary somewhat
depending on the camera model. This section documents several major variants.
TOP-DOWN AND ISOMETRIC PERSPECTIVES
In a top-down or isometric perspective in which the player sees the avatar from
above, moving the joystick up, down, left, or right causes the avatar to instantly
turn and face the corresponding edge of the screen, and then move in that direc-
tion. Classic arcade games that used a top-down perspective, such as
Gauntlet
, use
this simplest of all steering methods.
2D SIDE-SCROLLING GAMES
In traditional side-scrollers, the joystick controls left and right movement as it does
for the top-down perspective. The player controls the avatar's vertical jumps to
platforms using a separate controller button. Moving the joystick up can augment
the effect of the jump button; moving the joystick down may be left undefined;
and because the game world is 2D, the avatar cannot move away from or toward
the player.
3D GAMES
Three-dimensional games usually use avatar-oriented rather than screen-oriented
steering to provide a consistent set of controls regardless of camera angle, but rare
exceptions do exist.
Crash Bandicoot
provides the best-known example. When the
player pushes the joystick up, the avatar moves toward the top of the screen, which
