Game Development Reference
In-Depth Information
eventually turn into computer programs. You will need to have at least a nodding
acquaintance with how programmers think about data and the relationships
between different items of data, ideas that crop up in this discussion.
Resources
The term
resource
refers to types of objects or materials the game can move or
exchange, which the game handles as numeric quantities, performing arithmetic
operations on the values. Resource does not refer to specific instances of these types
of objects but the type itself in an abstract sense. Marbles constitute a resource in
your game if your player can pick up marbles, trade them, and put them down
again, but the word
resource
doesn't describe a specific marble in your player's
pocket or even a specific collection of marbles; it describes marbles generally.
Marbles are a resource, but
the 15 marbles in the player's pocket
are an
instance
of a
resource: a particular collection of marbles.
NOTE
Purely cos-
metic items are not a
resource. If you build
a level full of flowers
but the player can't
do anything with
them and nothing
ever happens to them,
then flowers are not a
resource. The flowers
set the stage and con-
tribute aesthetically,
but the core mechanics
will not need to take
flowers into account.
The core mechanics define the processes by which the game creates, uses, trades,
and destroys resources; that is, the rules by which specific instances of resources—
one lump of gold, the marbles in the player's pocket, the ammo in her inventory,
the water in her reservoir—can legally be moved from place to place or from owner
to owner, or can come into or go out of the game.
A resource may be of a type that can be handled as individual items, such as mar-
bles, or of a type that cannot be divided into individual items, such as water
(although water may be measured in volumetric units).
Games often treat nonphysical concepts such as
popularity
or vague concepts such
as
resistance to poison
as resources, even though we don't ordinarily think of these
as quantities that can be measured and even bought and sold. Part of a game
designer's job involves quantifying the unquantifiable—turning such abstract
qualities as
charisma
or
pugnacity
into numbers that a program can manipulate.
Entities
An
entity
is a particular instance of a resource or the state of some element of the
game world. (A light may be
on
or
off,
for instance.) A building, a character, or an
animal can be an entity, but perhaps less obviously a pile of gold or a vessel of
water can be an entity. The state of a traffic light that at any given time might be
red, green, or yellow can also be an entity.
Be sure you understand the difference between resources and entities. Remember
that a resource is only a type of thing, not the thing itself. A specific airplane is an
entity, but if your game includes a factory that manufactures airplanes, such that
management of the supply of airplanes makes up part of the gameplay, then air-
planes, as a commodity, constitute a resource even though each individual airplane
remains an entity. Earlier, we noted that marbles can be a resource but a marble in
