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Claims  |
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What is claimed is:
1. Interactive, electronic game apparatus for playing a game in which game
characters appearing on a display are responsive to inputs from a game
user, said apparatus comprising:
a visual display presenting an observable state of said game and of said
game characters to said game user in response to a display signal,
an input device for interactively entering user input signals
representative of user interaction with game characters, and
processing means receiving said user input signals from said input device
and generating said display signal and outputting said display signal to
said visual display, said processing means including
an extensible plurality of independent character behavior controllers for
determining the behavior of respective said game characters, each said
character behavior controller containing independent behavior logic to
determine states and state transistions of its respective game character
as represented to said user by said display means, said character behavior
controllers being responsive to said user input signals and to game
control signals for adjusting the behavior of said respective game
characters,
a game controller for coordinating the behavior of said game characters,
the game controller containing logic to determine consistent game states
for said game and said characters, and communicating said game control
signals to said character behavior controllers so that the state of said
game and of said game characters is a consistent game state,
an operating system for operation of said character behavior controllers
and said game controller on said processing means,
each said character behavior controller including an independent
application process as defined by said operating system of said processing
means,
said game controller including logic to add new character behavior
controllers to said game.
2. The apparatus of claim 1 wherein said game controller receives character
state signals from said character behavior controllers, said character
state signals describing the observable state of characters controlled by
said character behavior controllers.
3. The apparatus of claim 1 wherein said game control signals include a
global game state signal, describing the observable states of said
characters controlled by said character behavior controllers.
4. The apparatus of claim 3 further comprising plural said global game
state signals, and wherein one said global game state signal is accessible
to one but not another of said character behavior controllers.
5. The apparatus of claim 1 wherein said processing means includes a
memory, and said game controller communicates with said character behavior
controllers using shared space of said memory.
6. The apparatus of claim 1 wherein said game controller communicates with
said character behavior controllers by message passing.
7. The apparatus of claim 1 wherein at least one of said character behavior
controllers generates an interaction with a character defined by another
said character behavior controller, said interaction requiring resolution
to determine subsequent behavior of a character controlled by said
character behavior controller, and wherein said game controller determines
the resolution of said interaction.
8. The apparatus of claim 1 wherein said game controller includes an
instance manager function which directs the creation and deletion of
characters controlled by said character behavior controllers.
9. The apparatus of claim 1 wherein said input device comprises a mouse or
keyboard, and wherein said game controller means performs a user interface
function that accepts said user input signals provided by said input
device for control of said game.
10. The apparatus of claim 9 wherein said user interface function only
selects and initializes said characters.
11. The apparatus of claim 9 wherein said user interface function
communicates some of said user input signals to said character behavior
controllers.
12. The apparatus of claim 1 wherein said character behavior controllers
accept some of said user input signals provided by said input device for
control of said game.
13. The apparatus of claim 1 wherein said game controller additionally
performs a user display function, so that said game controller provides
display signals to said visual display.
14. The apparatus of claim 13 wherein character display signals
representing displays for said characters are provided to said visual
display by said game controller.
15. The apparatus of claim 1 wherein character display signals representing
displays for said characters are provided to said visual display by said
character behavior controllers.
16. The apparatus of claim 15 wherein said game controller resolves
contention for display resources between said character display signals
from different said character behavior controllers.
17. The apparatus of claim 1 wherein said game controller and said
character behavior controllers are operated on a single computer.
18. The apparatus of claim 1 wherein said game controller and said
character behavior controllers are operated on multiple computers
communicating over a network.
19. The apparatus of claim 1 further comprising an audio output device for
producing sounds in response to audio output signals generated by said
processing means.
20. The method of claim 1 wherein said game controller includes an
independent application process as defined by said operating system of
said processing means.
21. Interactive, electronic game apparatus for playing a game with
replaceable game controller logic for game characters appearing on a
display and responsive to inputs from a game user, said apparatus
comprising:
a visual display presenting an observable state of said game and of said
game characters to said game user in response to a display signal,
an input device for interactively entering user input signals
representative of user interaction with game characters, and
processing means receiving said user input signals from said input device
and generating said display signal and outputting said display signal to
said visual display, said processing means including
one or more character behavior controllers for determining the behavior of
respective said game characters, each said character behavior controller
containing independent behavior logic to determine states and state
transistions of its respective game character or characters as presented
to said user by said display means, said character behavior controllers
being responsive to said user input signals and to game control signals
for adjusting the behavior of said respective game characters,
a game controller for coordinating the behavior of said game characters,
said game controller containing logic to determine consistent game states
for said game and said characters, and communicating said game control
signals to said character behavior controller of controllers so that the
state of said game and of said game characters is a consistent game state,
an operating system for operation of said character behavior controller or
controllers and said game controller on said processing means,
said game controller and said character behavior controller or controllers
comprising distinct processes as defined by said operating system of said
processing means,
whereby said game controller can be used with one or more different
character behavior controllers, and said one or more character behavior
controllers can be used with a different game controller.
22. The apparatus of claim 21 wherein said game controller receives
character state signals from one said character behavior controller, said
character state signals describing states and state transistors of a
character controlled by said character behavior controller.
23. The apparatus of claim 21 wherein at least one of said character
behavior controllers generates a character action causing an interaction
with another character requiring resolution to determine subsequent
behavior of a character controlled by said one character behavior
controller, and said interaction is resolved by an interaction manager
function provided in said game controller.
24. The apparatus of claim 21 wherein said game controller includes an
instance manager function which directs the creation and deletion of
characters controlled by said character behavior controller or
controllers.
25. A method to coordinate the actions of a plurality of characters
appearing on a visual display in an interactive computer or video game,
said method comprising:
presenting the observable state of said game and of said game characters to
said game user in response to a display signal,
providing an input device for interactively entering user input signals
representative of user interaction with game characters,
receiving said user input signals from said input device and generating
said display signal and outputting said display signal to said visual
display at a processing means,
executing control logic for said characters and said game by an operating
system at said processing means,
controlling the behavior of said plural characters by character behavior
controllers determining states and state transitions for respective
characters and each including an independent application process as
defined by said operating system of said processing means,
coordinating the behavior of said game characters by a game controller
executing as part of said control logic for said game,
for said game controller, determining consistent game states for said game
and said characters, and
communicating game control signals to said character behavior controllers
so that the state of said game and of said game characters is a consistent
game state,
for each said character behavior controller, responding to said user input
signals and said game control signals by responsively determining a
current state of its respective game character for representation to said
user by said display means,
adding a new character to said game by adding a new character behavior
controller.
26. The method of claim 25 further comprising communicating character state
signals from said character behavior controllers to said game controller,
whereby said game controller is informed of states and state transitions
of characters controlled by said character behavior controllers.
27. The method of claim 25 further comprising communicating an interaction
signal from one said character behavior controller to said game
controller, whereby said game controller is required to respond to
determine subsequent behavior of a character controlled by said one
character behavior controller.
28. The method of claim 25 further comprising communicating creation or
deletion signals from said game controller to said character behavior
controllers for creating and deleting characters controlled by said
character behavior controllers.
29. Electronic display apparatus for multiple independent display
characters, said apparatus comprising:
a visual display presenting an observable state of said display characters
in response to a display signal,
processing means generating said display signal and outputting said display
signal to said visual display, said processing means including
a plurality of character behavior controllers for determining the behavior
of respective said display characters, each said character behavior
controller containing independent behavior logic to determine states and
state transitions of its respective display character as represented to
said user by said display means, said character behavior controller being
responsive to display control signals for adjusting the behavior of said
respective display characters,
a display controller for coordinating the behavior of said display
characters, said display controller containing logic to determine
consistent display states for said display and said characters, and
communicating said display control signals to said character behavior
controllers so that the state of said display and of said display
characters is a consistent display state,
an operating system for operation of said character behavior controllers
and said display controller on said processing means,
each said character behavior controller including an independent
application process as defined by said operating system of said processing
means,
said display controller including logic to add new character behavior
controllers to said visual display.
30. A method for adding character behavior control logic to an interactive,
electronic game with game characters appearing on a display and responsive
to inputs from a game user, said method comprising:
presenting the observable state of said game and of said game characters to
said game user at a visual display in response to a display signal,
providing an input device for interactively entering user input signals
representative of user interaction with game characters,
receiving said user input signals from said input device and generating
said display signal and outputting said display signal to said visual
display at a processing means that operates in one of two character
behavioral control configurations,
executing control logic for said characters and said game at said
processing means,
controlling the behavior of said characters by independent character
behavior controllers determining states and state transitions for
respective characters and executing as part of said control logic for said
characters,
coordinating the behavior of said game characters by a game controller
executing as part of said control logic for said game,
for said game controller, determining consistent game states for said game
and said characters and communicating game control signals to said
character behavior controllers so that the state of said game and of said
game characters is a consistent game state,
for said character behavior controllers, responding to said user input
signals and to said game control signals by responsively determining a
current state for its respective game character as represented to said
user by said visual display, and
modifying said character control logic at said processing means from a
first character behavior control configuration including a first but not a
second of two distinct character behavior controllers to a second
character behavior control configuration including both said first and
said second character behavior controllers.
31. The method of claim 30 wherein said modifying includes altering
character registration information provided at said processing means. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates to interactive computer and video games and to
screen savers.
In interactive computer and video games, the user employs various input
devices to control animated characters on a video screen, to influence
their behavior, and to attempt to achieve the objectives posed by the
game. There are many examples and forms of such games, which are
distributed either as software permitting playing of the game on a
personal computer or as combined software/hardware video game devices.
These include arcade and Nintendo-style games, combat and flight
simulation games, adventure games, sports strategy games, and others.
The characters in these games are specified at the time the game is
developed. A single application program is used to define each game, which
can include the option for playing the game with single or multiple
characters controlled by one or more users. Some games allow new visual
elements or game scenarios to be added to a preexisting game. This is the
case with SimCity (which adds new cities and graphics) or with Microsoft
Flight Simulator (which adds new airplanes and terrains). These additions
are implemented by adding new data that are then acted upon by the
preexisting program logic of the game.
In a somewhat related area, some screen savers, which provide a changing
display for an inactive computer screen, permit user interaction to select
combinations of display items to be presented whenever the screen saver is
invoked.
SUMMARY OF THE INVENTION
This invention features a computer or video game in which new characters
can be added to the game and still participate fully in interactions with
prior characters and with the game environment. This is achieved by
providing independent control logic for each character in the form of a
character behavior controller. A game controller coordinates the various
character behavior controllers, mediates their actions, and assures that
the resulting visual display appears consistent to the game user. The
invention drastically alters the relation that computer and video games
can have with their users. Instead of merely following preset rules of a
game, a user can employ the game as a framework to assemble his or her own
fictional world. New characters can vary enormously in their appearance,
patterns of behavior, and user control modes, so long as they subscribe to
the paradigms established for interaction with the other entities in the
game. These characters may be highly interactive, or merely configurable
as in a screen saver display.
The invention allows computer games to assume characteristics that have
until now been restricted to other kinds of toys. Play sets and
construction toys, such as Playmobile and Lego, have always been
extensible, and various kinds of dolls (particularly based upon movies and
television programs) have been offered as an expanding family of related
toys. This is a particularly appealing paradigm for computer games,
because the characters can actually move, interact, and evolve following
the behavioral logic embodied by the characters and the modes of
interaction set by the game. Multiple instances of the same character can
easily be created, and the same characters can be used with different game
controllers.
A character can be a person or animal with its own behavioral
characteristics: it knows how to move, how to change its appearance, and
how to react to other characters in the same game. A character can also be
an inanimate object that changes state and participates in interactions,
e.g., thrown balls, walls placed as barriers, etc. A character can even be
an active background, i.e., a screen area (e.g. falling rain) that changes
state based upon game conditions and influences other characters
accordingly. Any type of character can be added independently according to
the capabilities of this invention.
Preferably the game controller executes four basic game control functions:
1. Providing the user interface to play the game. This provides the user
the ability to set up and manage the game as a whole, as well as an
ability to interact as necessary with the individual applications that
control the characters.
2. Managing the creation and deletion of character instances. Creation and
deletion may be caused either through the user interface (as during the
initial setup of the game) or by interactions of characters during the
game.
3. Resolving the interactions of the characters (e.g. collisions, battles,
etc.).
4. Maintaining a consistent global state for the game. This also includes
disseminating the global state to all of the characters and to the user
interface entity of the game controller.
For each particular game, the interactions of the characters with the game
control are reflected in the specifics of the interfaces between them, as
described below.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Drawings
FIG. 1 is a block diagram showing elements of an interactive electronic
game according to the invention.
FIG. 2 is a block diagram showing the components of the game controller of
the FIG. 1 game.
FIG. 3 is an example of a screen display of the FIG. 1 game illustrating
the user interface to the game controller.
FIG. 4 is an example of a screen display of the FIG. 1 game illustrating
the instance manager of the game controller during the startup of the game
and indicates how the user can invoke multiple instances of the
characters.
FIG. 5 shows examples of screen displays of the FIG. 1 game illustrating
the function of the interaction manager of the game controller.
FIG. 6 shows examples of screen displays of the FIG. 1 game illustrating
the function of the global state manager of the game controller.
FIG. 7 is a block diagram showing the components of the FIG. 1 game
involved in display of a game character.
FIG. 8 is a flow chart describing the communication between the game
controller and the character behavior controllers at startup.
FIG. 9 is a representation of the global data accessed by each of the
character behavior controllers in determining its behavior.
FIG. 10 is a diagram illustrating the communication between the game
controller and the character behavior controllers during the game.
FIG. 11 is a table showing the global state data for an example
implementation of the invention.
FIGS.12A-12D are screen displays showing the sequence of screens for
initialization of characters in the example implementation.
FIGS. 13A-13D are screen displays showing the sequence of screens for
interaction of characters in the example implementation.
FIG. 14 shows implementation options for communication between the game
controller and the character behavior controllers.
Structure
Referring to FIGS. 1 and 2, an electronic interactive game according to the
invention employs the components shown on FIGS. 1 and 2. These figures
show a single game controller 101 and two character behavior controllers
102, with interactions indicated by arrows 110/111 and 112/113. Game
controller 101 and character behavior controllers 102 are implemented as
independent processes on a computer system having a visual display, a user
interaction device (e.g. a keyboard and mouse), and a central processing
unit and operating system.
The electronic game according to the invention achieves its objective of
extensibility by allowing multiple characters controlled by multiple
character behavior controllers 102 to participate in the game. These
character behavior controllers 102 are independently executing programs,
i.e. independent processes as defined by the operating system. For Windows
3.1 and Windows NT, independent processes have separate entries in the
Task List display; for Unix they are separately listed by the ps command
(with -e flag). For Unix and Windows NT, independent processes also have
independent address spaces (see Maurice J. Bach, The Design of the Unix
Operating System, p. 10 and Helen Custer, Inside Windows NT, p. 84).
Character behavior controllers 102 provide the independent behavioral logic
for the characters, whereas game controller 101 coordinates the activities
of the characters. Game controller 101 interacts with the character
behavior controllers 102 through global state data 103 or through direct
interactions 110/111 and 112/113.
The first kind of interaction is through the global state data 103. As
shown by arrow 110, the global state data are written by the game
controller 101. From there, information is extracted by the individual
character behavior controllers (arrows 111) as a basis for their behavior.
In the preferred embodiment, the global state data are represented as a
shared-memory object that can be accessed by each of the character
behavior controllers. Each character behavior controller can thus
independently check the contents of the global state data to know the
externally-observable state information about all other objects in the
game. Further in the preferred embodiment, the game controller assigns a
character type identifier to each character behavior controller, so that
it can recognize its own characters in the global state data. The content
of the global state data is described in FIG. 9 and discussed in detail
below.
The other kind of interaction with the character behavior controllers is
via action messages (arrows 112-113). Action messages from the character
behavior controllers to the game controller (arrows 112) communicate
changes in character states and motions, and initiate interactions with
other characters. Action messages from the game controller to the
character behavior controllers (arrows 113) cause the characters to change
state or motion (including possibly to enter a pause state awaiting
resolution of interactions) and present interaction results. The role of
game controller 101 is to maintain a consistent global state for the game
by resolving all inputs (e.g. arrows 112), updating the global state data
103 (arrow 110), and communicating with each of the character behavior
controllers 102 to force state changes where necessary (arrows 113).
FIG. 2 shows how this is done. This figure gives the internal structure of
game controller 101. There are four components reflecting four functions
of game controller 101: the user interface 201, the instance manager 202,
the interaction manager 203, and the global state manager 204.
The user interface 201 manages the interactions of the game as a whole with
the user and provides a mechanism to pass user control actions for
individual characters. Game-level interactions start and stop the game,
introduce new characters, and change overall game characteristics (e.g.
speed). In this function the user interface interacts with all of the
other game controller components: it initiates and reflects instance
creation (arrow 210), it modifies and reflects the global state (arrow
212), and it may initiate or provide for resolution of character
interactions (arrow 211).
User control of individual characters is achieved either by direct
interaction with the character behavior controllers or by messaging
between the game controller and the character behavior controller. The
result, as seen by the user, is shown in FIG. 3. The user is presented
with multiple characters images 301-303 on the screen. In the preferred
embodiment, the user will click on characters and then use mouse and
keyboard actions to control an individual character according to that
character's character behavior controller logic. This is achieved, for
example, by allowing the selected character behavior controller to present
a pop-up window which offers control options to the user. (Other methods
for user control of characters are described in the example game
implementation presented below.) Game controller actions may be performed
by the screen menus 304, 305 or by user interaction with other
game-control objects 306 on the user screen.
Returning to FIG.2, the instance manager 202 manages the creation and
deletion of instances of characters through interaction with the
appropriate character behavior controllers. At creation, each character
instance is assigned a unique identifier which is communicated to the
character behavior controller, so that it can recognize that character in
the global state data. Instances of characters may be created at startup
as well as in the course of the game. For example, instances of game
characters may be created or destroyed as a result of interactions between
characters (e.g. a collision may cause an object to be destroyed) or as a
result of decision logic in an individual character (e.g. a character may
spontaneously replicate itself). Consequently, as noted above, the
instance manager has a two-way interaction the user interface (arrow 210).
It also provides output to the global state manager and receives instance
management input as a result of global state resolution (arrow 213).
Depending upon the specifics of particular games, the instance manager may
also initiate and terminate execution of character behavior controllers as
they are or are not required for control of active characters. Also, one
instance of a character behavior controller may manage multiple character
instances, or additional instances of the character behavior controller
may be created.
FIG. 4 shows an example of how the services of the instance manager could
be used at the start of a game. At the upper left of the screen is a
selection box 401 showing the names of character types available to the
user. The user clicks on an character type name and then clicks on another
location on the screen. In response, the instance manager causes a
character instance for the appropriate character behavior controller to be
associated with a display object in that location. The figure shows three
different character instances 405-407 of the character type represented by
name 403. The individual character instances can then evolve according to
the logic of the character behavior controller for that character type.
Again returning to FIG. 2, the interaction manager 203 resolves all
character conflicts as needed to maintain a consistent global state for
the game. Interactions may be initiated by individual characters (as an
action message--arrow 215) or by the global state manager in the course of
attempting to maintain global state. For example, characters may touch,
speak to, or attack other characters, causing character-to-character
interactions to be passed by the global state manager (arrow 214) to the
interaction manager 203. A character behavior controller may also request
the creation of another instance of a character, or may simply request a
change of state which causes an inconsistency trapped by the global state
manager. The logic of the interaction manager may use specific
interaction-control data (described as an interaction table) and well as
any other game controller data to resolve interactions for consistent
global state. Execution of the outcome of an interaction is handled
through the global state manager (arrow 214).
FIG. 5 gives an example of an action taken by the interaction manager. In
this case the interaction 501 is a collision of objects. There are three
possible results 502-504. The first is an elastic collision with new
motions for each of the objects. The second is a collision in which one of
the objects is destroyed (causing an input to the instance manager). The
third is a collision in which one of the objects splits into two smaller
ones. This causes a new object to be created and one of the original
objects to change form. The interaction manager determines which of the
possible results actually occurs (in this case 503), and communicates that
result to the global state manager.
The final component in FIG. 2 is the global state manager 204. This
component has the responsibility to maintain a consistent global state for
the game. As inputs it takes the current states and motions, as well as
any changes initiated by the character behavior controllers (arrow 216) or
the other game controller elements (arrows 212-214). It then attempts to
represent a global state according to the underlying principles of the
game. For example, it takes the current positions and motions of the
characters and attempts to describe their new positions. It contains logic
to identify inconsistencies and generates inputs to the interaction
manager where they occur. These inconsistencies are resolved by the
interaction manager (arrow 214) before it accepts other inputs, so as to
quickly determine a consistent state. This requires that the global state
manager and interaction manager be designed to avoid excessive iterations
to reach a consistent global state. The global state is then expressed
(arrow 217) in the global state data 103. It is also communicated to the
user interface (arrow 212) as necessary.
FIG. 6 shows an example. In this case the global state manager is
responsible for the motions of all the characters on the screen. It
recognizes a collision 601, which is resolved by the interaction manager
(event 602). It then updates the state of the single remaining character
(event 603), calls the instance manager to delete the other character
(event 604), and updates the position and motion information in the global
state data (event 605). This completes the discussion of structure for the
game controller.
FIG. 7 describes the structure of a character behavior controller. There
are again four components: the user interface 701, the internal state
manager 702, the interaction handler 703, and the game state manager 704.
The user interface 701 reacts to user control actions performed on a
character instance (e.g. by mouse and keyboard) and provides user feedback
on the state of the character instance (e.g. through visual image or
sound). As noted earlier, it is a responsibility of the game controller
user interface to perform whatever functions (if any) are necessary to see
that user interface actions can be passed through. User interface actions
provide inputs to the internal state manager 702, as well as the displays
associated with the internal state (bidirectional arrow 710). In the
preferred embodiment, the user interface 701 is responsible for
positioning the character's image on the screen based upon the character's
motion and state as influenced by the game controller.
The internal state manager 702 controls the state of the character as
embodied in the character behavior controller. A character's internal
state is reflected through the user interface 701 to the user and through
the game state manager 704 to the rest of the game. Changes in state
initiated by the game (e.g. through action messages 216) will be
communicated through the game state manager as indicated by arrow 711.
(Note that since the game state involves both character states and global
states, "saving" a game for subsequent play means saving not only the
global state data, but also a representation of the internal states for
all characters.)
The game state manager 704 is responsible for input/output functions for
participation in the game. It reads the global state data 103 (arrow 715),
it sends and receives action messages associated with character states and
motions (arrows 215 and 216), and it directs (arrow 712) interaction
handler 703 to initiate interactions with the game controller 101. The
game state manager retains the identity of the character instance as
assigned by the instance manager 202. Typically, the game state manager's
internal logic would include a timing mechanism that would determine when
the global state must be checked. Like the user interface, game state
manager 704 provides input to the internal state manager (arrow 711) and
reflects an externally visible substate--in this case the substate
relevant to the rest of the game.
Finally, the interaction handler 703 is the local counterpart of the
interaction manager 203 in the game controller 101. It receives
interaction requests (arrow 712) from game state manager 704, generates
interactions to be passed through to interaction manager 203, and receives
interaction results (passed through from an action message 216) to be
presented to the game state manager for further influence on the
character's state.
Operation
To initiate the game, the user interface of the game controller provides
the means to establish an initial game configuration. This includes
creating instances of all of the selected characters, assigning an initial
state to each, and propagating an initial version of the global state
data.
The process of game initialization is depicted in FIG. 8. In the first step
801, the game user invokes user interface 201 of game controller 101 to
create instances of the desired character types. This involves interaction
of user interface 201 with the instance manager 202, as described above in
the discussion of FIG. 2.
In the next step 802, the user initializes each character instance. This
may be trivial if the character has a well-defined initial state.
Otherwise, this relies upon the ability of user interface 201 to pass
through user control actions to the character behavior controller, as
described in the discussion of user interfaces 201 and 701.
Subsequently in step 803, each character behavior controller sends an
action message with initial motion and state data. The action message
reflects the character's initial state as embodied in the internal state
manager 702 and translated to the game substate in game state manager 704.
The message is sent by game state manager 704.
Finally in step 804, the global state manager 204 receives all action
messages and defines an initial global state. Any interactions at this
stage are resolved through the interaction manager 203. The initial global
state is then written as global state data 104 and the character behavior
controllers can draw and position each character's image accordingly. At
this point the initial local and global state data are complete, and the
game can proceed.
Note that additional instances of character types can be added to a game in
progress by the same initialization process. The new instance is
positioned and initialized by user interface 201 (step 801) and then by
interaction with the character's character behavior controller (step 802).
When the character's character behavior controller initiates execution, it
sends an action message with motion and state information to the game
controller (step 803), and its presence is then reflected in the global
state data (step 804).
Following initialization, the game controller 101 and the character
behavior controllers 102 interact via independently-dispatched messages
and the global state data 103. In the preferred embodiment, each character
behavior controller and the game controller will have a defined update
interval. At the expiration of this interval, a timer will cause an update
to each of the control components based upon the elapsed time, the global
state data, and the messages received.
For the game controller, the sequence of actions follows the information
flows in FIG. 2:
1. Motion and state action messages are processed by global state manager
204. Global state interactions are identified and communicated to the
interaction manager 203.
2. Interaction manager 203 resolves interactions from the character
behavior controllers as well as interactions received from global state
manager 204.
3. Through communication with the interaction manager 203, the global state
manager establishes a new global system state. The new state is propagated
in the form of an update to the global state data 103.
4. All game objects are brought into consistency with the new global system
state. This may include creation or deletion of character instances by the
instance manager 202, as well as changes to the user interface 201. It may
also include adjustment to the individual character motions and states. In
the preferred embodiment, such adjustments to the character objects are
achieved by action messages sent from the game controller 101 to the
individual character behavior controllers 102. The character behavior
controller reacts to these action messages according to its own logic to
complete the update sequence.
For the character behavior controllers the actions follow the information
flow described in FIG. 7. The sequence is as follows:
1. The game state manager 704 reads the global state data 103 and processes
any outstanding action messages from game controller 101. Each character's
image is presented on the screen based the character's game state as
corrected by any action messages.
2. Changes in game state are provided by game state manager 704 as an input
to the internal state manager 702. The character's internal state is
synchronized with the global state data and any other game input or user
interface actions. The internal state is updated for the next time
interval.
3. The new internal character state is communicated to the game state
manager 704.
4. Game state manager 704 generates action messages reflecting the change
of character state. State and motion action messages are sent directly
from game state manager 704 to game controller 101; interactions are
communicated via interaction handler 703. Since the character instance
controls its own internal state, it may choose to make some state and
motion transitions dependent upon acknowledgment from the game controller
101 so as to avoid race conditions. This acknowledgment may be received
either via action message or by inspection of the global state data 103.
FIG. 9 gives a representation of the global state data 103 in the preferred
embodiment. In the figure the global state data has three parts: global
data 902, state and motion data 903, and derived data 904. The global data
are descriptive of the game as a whole; in the figure it is the number of
initialized characters. The state and motion data 903 are in the form of a
matrix with a row for each character instance in the game. The data in
each row are divided into three sections. The first of the sections
contains identity information for the object, namely its instance and
character behavior controller identities, as assigned by the instance
manager 202. The second section is descriptive of the motion of the
object, including as examples the components of position, velocity, and
acceleration for the object in question. The third section describes the
characteristics and externally-observable state of the object. The
specifics of the observable state will depend upon the special features of
individual games. As examples, the observable state may indicate the
fearsomeness of a monster or the military value of a soldier. The number
of components of this third section will depend upon the specifics of the
game.
Derived data 904 refers to data that can be calculated from the state and
motion data 903, but is included for efficiency because it would need to
be recalculated by each character behavior controller individually. The
example in FIG. 9 is the matrix of distances between character instances.
This can be derived from the motion data, but in some cases it will be
more efficient for the global state manager 204 to calculate it once and
for all, and distribute it with the global state data 103.
FIG. 10 describes the action messages sent between the character behavior
controllers 102 and the game controller 101 in the preferred embodiment.
Messages from the character behavior controllers to the game controller
(FIG. 10A) include the character-initiated changes in state or motion.
These are of the same type as the state and motion data in the global
state data 103, but they have not yet been resolved for possible conflicts
between characters. In addition the character behavior controllers may
user action messages to communicate interactions. These may be of two
types:
1. Character-to-character interactions, such as an attraction or an attack,
are communicated by identifying the other character or characters and the
interaction type.
2. Character-to-game controller interactions can include, for example,
spawning of additional characters or deletion of the character itself.
Messages from the game controller to the character behavior controllers
(FIG. 10B) represent fewer types and result from resolved interactions. As
noted above, the resolution of an interaction may result in changes to a
character's state, motion, or both. The interaction result message allows
a character to react directly to the result of an action it initiates.
It should be noted that for any particular game, the specific realization
of the global state data of FIG. 9 and the action messages of FIG. 10
determine the interface between the character behavior controllers and the
game controller. Hence, given that a character behavior controller
supports the basic communications paradigms of a given game, the
requirements for compatibility are
ability to interpret and react to action messages
ability to read and understand global state data
understanding of character states, motions, characteristics, and
interactions
Any character behavior controller that meets these requirements, regardless
of its other behavioral logic or screen appearance, can participate in the
game. Thus once the interface characteristics are set, new characters can
be conceived and implemented by any developer. Similarly, new game
controllers can be implemented to work with existing characters.
Example Game Implementation
This section illustrates the operation of the invention by concentrating on
a particular example game implemented using Microsoft Visual Basic Version
3.0. A complete program listing is attached as an Appendix. While the
listing is self-contained, this section describes the operation of the
game and indicates how the implementation realizes the structures of the
invention. To simplify implementation, these structures are not always
broken out as independent modules of the code. For example, user interface
actions are frequently invoked where they arise, rather than being
collected into a separate code module. This example game has been
demonstrated on a Gateway 2000 PC, model 4DX-33V, with DOS version 6,
Microsoft Windows 3.1, and the Visual Basic runtime libraries.
The example game includes a game controller 101 and two character behavior
controllers 102, for an elephant and a mouse. To the user, the game
controller 101 appears as the background of the game with a menu bar
allowing the user to introduce new characters and to exit the game. For
this sample application, the behavior of the characters is quite simple:
both characters move so as to stay within the frame area defined by the
client display, and the elephant is afraid of mice. Specifically, if the
mouse gets too close to the elephant, then the elephant attacks it. The
attack is resolved by the game controller so that the mouse either escapes
or is deleted. If the mouse escapes, then the elephant retreats; the mouse
retreats whenever under attack. The character behavior controllers have
been designed so that multiple instances of each character can be created
through the client user interface and managed independently by the
character behavior controllers. In this example game it is simple to
verify that the game controller and the character behavior controllers are
independent processes: they all appear as independent items in the Windows
3.1 Task List.
The underlying communication between character behavior controllers and
game controller is based upon Microsoft Windows Dynamic Data Exchange
(DDE). This is a facility of Microsoft Windows 3.1 which is designed
specifically for application-to-application messaging. It is described,
for example, in the Microsoft Visual Basic Programmer's Guide (Version
3.0), Chapter 21. The game controller 101 is implemented as a DDE
destination application, which accesses the services provided by the
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