Ultimate Game Design : Building game worlds

Building Game Worlds
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U L T I M A T E G A M E D E S I G N
Here’s a script sample to make the enemies cower in fear and then flee once they
have tripped the “fearthis” trigger:
Line of Sight
Crowd
// JavaScript sample of "fearthis" trigger support
if(monster.inside(fearThisTrigger.getBoundary())) {
monster.playAnimation(fearAnim);
monster.reverseDirection();
}
Line of sight has a couple of different uses and meanings in game terminology.
Usually, it refers to what is visible to an actor. It could refer to what is visible to the
particular actor representing the player in the game. Normally, it refers to whether or
not an actor can see a particular object or another actor. Line of sight can be calculated
in several ways, and doesn’t always mean that something is physically viewable from
a character’s perspective. Enough semantics.
A line of sight trigger launches its event when a player breaks the line of sight radius;
in other words, when the player gets physically close enough on the grid to the line of
sight trigger. This can be used to start a giant boulder rolling perilously into motion
(think of Raiders of the Lost Ark/Indiana Jones). When a character breaks the line of
sight trigger, the boulder-rolling animation is launched on a motion path (in other
words, where the boulder starts rolling from, what path it follows, and where it is
destroyed or terminates).
Notice that many triggers rely on a radius. Much of tuning the right “feel” for the
interaction between events comes down to tuning radii.
If the boulder is visible to a player, here’s a script that starts the boulder rolling and
focuses a camera on the action:
// JavaScript sample of "line of sight" trigger support
if(objectVisible(player.currentPosition(), boulder)) {
boulder.startRolling();
playSound(boulderSound);
camera.focus(boulder);
}
A crowd trigger, when tripped, gives animation behavior information to a crowd of
actors. For instance, you might have entered a tribal village with several warriors
lined up at the village gateway to meet you. By picking up or attempting to steal
something from the village, you might trip a crowd trigger. This might cause all of