Communication game system, game control program and memory medium

Abstract

When players play car race by means of game machines, for example, a first machine game operates the object by an accelerator, brake, steering wheel and shift lever, calculates a prediction position the object reaches after a predetermined time from the current time, and transmits the prediction position to a second game machine as a position information. The time td is a time for transferring information through the network from the first game machine to the second game machine, that is, a delay time due to the communication. Similarly, other game machines can transmit the position information. Therefore, low process speed of a game is prevented due to communication load, with maintaining game quality.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a communication game system, a game control program and a memory medium.

2. Prior Art

In a communication game system having a plurality of game machines and a network for connecting the game machines to a server, on which a plurality of players-operate objects in real time, it is necessary that the server provides each game machine information concerning objects of other players. The more the players join the game, the heavier the communication load becomes. Then, the game processing speed decreases, the operational performance and the reality of the game are deteriorated.

Hitherto, data volume in each packet is decreased so that the problem of low process speed of the game is prevented.

The conventional technologies are known for adjusting the communication load of the Patent Publication 2001-044922 (patent document 1), Patent Publication 2000-331187 (patent document 2) and Patent Publication 2003-090728 (patent document 3).

In the patent document 1, a vehicles communication system is disclosed that communication interval is expanded as vehicles such as transportation trucks are farther remote from a base station. Then, the communication load is adjusted to be suitable for the communication necessity.

In the patent document 2, a moving picture generating method is disclosed, concerning a moving picture display of computer graphics, that a display area is divided into a plurality of areas and renewal of physical parameters is reduced.

In the patent document 3, a map display apparatus is disclosed, concerning a map data obtaining through wireless communication, that frequency of obtaining the map data is adjusted according to distance from the current place to the destination.

SUMMARY OF THE INVENTION

In the conventional communication game system, even if the data volume is decreased for each packet, the minimum information volume is not so small and the communication load cannot be sufficiently improved.

The present invention is invented to solve the conventional problems and has an object to prevent low process speed of a game due to communication load with maintaining game quality.

The present invention is a communication game system comprising a plurality of game machines and a network for connecting said game machines with one another, each said game machine (one game machine, hereafter) comprising a virtual space generating means for generating a virtual space in which a plurality of objects exist, an input means for inputting movement input information which causes movement of said object (corresponding object, hereafter) corresponding to said one game machine in said virtual space, a position information obtaining means for obtaining position information of other objects (opponent objects, hereafter) corresponding to other game machines (opponents' game machines) than said game machine, from said opponents game machines, a position information calculation means for calculating a position information of said corresponding object according to said movement input information, a position information transmission means for transmitting said position information to said opponent game machines, a distance calculation means for calculating distances between said corresponding object and opponent objects, according to said position information of said corresponding object and position information of said opponent objects, and an information volume calculation means for calculating necessary information volume of said position information of corresponding object to be transmitted to each said opponent game machine, according to distances between said opponent object and opponents objects, wherein said position information transmission means transmits said position information by said necessary information volume to said opponent game machines.

Therefore, low process speed of a game is prevented due to communication load, with maintaining game quality.

A communication game system according to the present invention may further comprises a position prediction calculation means for calculating a predicted position of said corresponding object at a time after a current time by a transfer time through said network, according to said position information of said corresponding object, and said position information transmission means may transmit said predicted position of said corresponding object as said position information to said opponent game machines.

Therefore, an error due to communication delay time is minimized concerning positional relationship between the corresponding object and the opponent objects.

A communication game system according to the present invention may further comprises a server which comprises a position information receiving means connected to said network for receiving said position information from said game machines, and a position information transmission means for transmitting said position information of each said game machine to opponent game machines.

In this case, each said game machine may further comprises a communication speed comparison means for comparing communication transfer time of a communication channel through said server and a communication channel not through said server, and a communication channel selecting means for selecting communication channel of higher communication speed, from said communication channels through and not through said server.

Therefore, the communication channel is optimized.

In a communication game system according the present invention, each said game machine may further comprises a reference communication speed comparison means for comparing communication transfer time of a predetermined reference transfer time with said transfer time of said communication channel through said server and not through said server, and an additional game machine comparison means for comparing communication transfer time of one of said opponent game machines of a communication channel through said server and not through said server, with said predetermined reference transfer time.

Therefore, playing condition of games is improved.

In a communication game system according to the present invention, said virtual space generating means generates further a moving path through which said corresponding object moves in said virtual space, and said distance calculation means calculates said distance along said moving path.

Therefore, information volume is suitably set for game of car race etc. in which objects run on a moving path with giving good game impression.

In certain communication game systems according to the invention, said distance between said objects is one-line (Euclid) distance.

Therefore, information volume is suitably set for fighting game etc. according to feeling of distance between objects.

In a communication game system according to the present invention, wherein said position information transmission means adjusts said information volume by communication frequency.

Therefore, communication load is decreased with maintaining the information volume of each communication. So, low process speed of a game is prevented due to communication load, with maintaining game quality.

Or, in a communication game system according to the present invention, positions on said moving path are included in said position information, and further widthwise positions when said information volume is a lot.

Therefore, not so important information of widthwise position can be omitted of remote object in a game of car race etc. in which objects run on a moving path.

In a communication game system according to the present invention, said information volume calculation means may adjust said information volume, further according to positional relationship between said corresponding object and said opponent objects.

The objects adjacent to each other but on independent moving paths from each other after branch off are handled similarly to remote objects. The information volume is further decreased.

The present invention is a game control program executed on a game machine for a communication game system which comprises a plurality of game machines and a network for connecting said game machines with one another, comprising: a virtual space generating step for generating a virtual space in which a plurality of objects exist, an input step for inputting movement input information which causes movement of said object (corresponding object, hereafter) corresponding to said one game machine in said virtual space, a position information obtaining step for obtaining position information of other objects (opponent objects, hereafter) corresponding to other game machines (opponents' game machines) than said game machine, from said opponents game machines, a position information calculation step for calculating a position information of said corresponding object according to said movement input information, a position information transmission step for transmitting said position information to said opponent game machines, a distance calculation step for calculating distances between said corresponding object and opponent objects, according to said position information of said corresponding object and position information of said opponent objects, and an information volume calculation step for calculating necessary information volume of said position information of corresponding object to be transmitted to each said opponent game machine, according to distances between said opponent object and opponents objects, wherein said position information transmission step transmits said position information by said necessary information volume to said opponent game machines.

Therefore, low process speed of a game is prevented due to communication load, with maintaining game quality.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an embodiment of communication game system according to the present invention.

FIG. 2 is a elevation view showing a game machine in FIG. 1.

FIG. 3 is a block diagram of a control unit of the game machine in FIG. 2.

FIG. 4 is a figure showing a moving path in a game executed by the communication game system in FIG. 1.

FIG. 5 is a figure of a display image showing a relationship between two objects in the game executed by the communication game system in FIG. 1.

FIG. 6 is a figure of a display image showing another relationship between two objects in the game executed by the communication game system in FIG. 1.

FIG. 7 is a figure of a display image showing further another relationship between two objects in the game executed by the communication game system in FIG. 1.

FIG. 8 is a graph showing communication frequency of position information in a game executed by the communication game system in FIG. 1.

FIG. 9 is a flowchart showing a processing executed by the embodiment of the communication game system according to the present invention.

FIG. 10 is a partially enlarged figure of the moving path in FIG. 4.

FIG. 11 is a flowchart showing a communication channel selection processing.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment

Hereafter, preferable embodiments of the communication game system and game control program according to the present invention are described with reference to the drawings.

[Communication Game System]

FIG. 1 is a block diagram showing an embodiment of communication game system according to the present invention, FIG. 2 is a elevation view showing a game machine in FIG. 1, and FIG. 3 is a block diagram of a control unit of the game machine in FIG. 2.

In FIG. 1, a plurality of game machines GM1, GM2, . . . , GMn are connected to a network NW. A server SV, one or more personal computers PC, communication terminals such as a portable game machine HGM, mobile phone HP and so forth are connected to the network NW. The network NW may be a computer network constructed by a LAN, a wide area network through internet etc.

The server SV executes information communication with the game machines GM1 to GMn and controls the game machines when necessary. Players (not shown) of the game machines GM1 to GMn execute operational input by control units 100 included within the game machines GM1 to GMn so that communication is executed among the game machines GM1 to GMn and a game such as car race is executed.

The server SV has a position information receiving means and position information transmission means for receiving and transmitting position information mentioned below. The position information receiving means and position information transmission means are constructed by various calculation means and communication means which are known.

The control unit 100 is connected with a cash box CB so as to detect insertion of charge (coin) coin into the cash box CB for the game execution. The control unit 100 is connected with a card reader CD for reading cards such as item card etc.

On the personal computer PC, the portable game machine HGM and other communication terminals, the game or its tiny version can be executed, similar to the game executed on the game machines GM1 to GMn. Statistic of game result, ranking of players, various events and other information on games can be obtained on the communication terminals.

In FIG. 2, the game machine GM1 is representatively explained. The game machine GM1 is modeled on a cockpit of a car. A sheet 106 is provided. And an accelerator 101, a brake 102, a steering wheel 103 and a shift lever 104 connected with the control unit 100 are provided, which cooperatively function as input means for the position information input, mentioned below.

A CRT 312 is provided at a position of a front window in front of the sheet 106, for displaying information of car race. As car race information, traveling situation of a car (corresponding object) operated by the game machine GM1 and a car (opponent object) operated by the opponent game machine (opponent game machine GM2, for example). A radar image RD is further displayed for indicating a positional relationship between both cars on a driving lane.

In FIG. 3, the control unit 100 includes a CPU 301 for controlling the total components, a boot ROM 304 starting the control 100 unit up, and a system memory 302 for storing programs and data executed by the CPU 301.

The control unit is provided with a rendering processor 307 for generating and controlling images to be displayed, and a graphic memory 308 for storing images to be generated and sources of the images. The rendering processor displays the generated images.

The control unit is provided with a sound processor 309 for generating sound and a sound memory 310 for storing sound data to be generated. The sound processor 309 generates a digital signal of a sound according to the stored data in the sound memory 310 and outputs the sound from a speaker 313 and head phone (not shown).

The control unit 100 is provided with a memory device or memory medium 303 for programs and data. The program and data stored in the memory medium 303 are read into the system memory 302, graphic memory 308 and sound memory 310.

Information concerning game are included in the data stored in the memory medium 303.

The control unit 100 is provided with a communication interface 311 and a MODEM 314 though which a network IN is connected.

The components of the control unit 100 above are connected to a bus arbiter 306 which arbitrates communication among the components.

The game machine GM1 to GMn generate virtual spaces in which corresponding and opponent objects are included. As for generating the virtual space, the CPU 301, rendering processor 307, graphic memory 308 cooperatively function as a virtual space generating means.

FIG. 4 shows an example of a traveling (moving) path on which objects (C1, C2, C3 and C4, for example). The moving path extends from a start point ST, through a path S1, branched paths S2 and S3, branched paths S4 and S5, a path S6, branched paths S7, S8 and S9, and a path S10 to a goal point GL. The object C1 is on the path S4, object C2 on the path S5, objects C3 and C4 on the path S6.

FIGS. 5 and 6 show display image on the CRT 312 for indicating a relationship between the object C3 (corresponding object) corresponding to the game machine GM1 and the object C4 on the same path S6.

In FIG. 5, the object C3 and the object C4 traveling just in front of the object C3 are shown in the display image. In the radar image RD, the path of an area adjacent to the object C3 is shown. Indicators CI3 and CI4 indicating the objects C3 and C4, respectively, are shown on the path.

In FIG. 6, the object C3 and the object C4 traveling far in front of the object C3 are shown in the display image. In the radar image RD, the path of an area adjacent to the object C3 is shown. Indicators CI3 and CI4 indicating the objects C3 and C4, respectively, are shown on the path in the radar image.

In FIG. 7, only the object C3 is shown because the object C4 is sufficiently remote from the object C3. Only the indicator C13 indicating the object C3 is shown on the path of the radar image RD.

When players play car race by means of the game machines GM1 and GM2, for example, the game machine GM1 operates the object C3 by the accelerator 101, brake 102, steering wheel 103 and shift lever 104, calculates a prediction position the object C3 reaches after a predetermined time td from the current time, and transmits the prediction position to the game machine GM2 as a position information P11. The time td is a time for transferring information through the network from the game machine GM1 to the game machine GM2, that is, a delay time due to the communication.

The prediction position is calculated by various method. For example, a position advanced by a distance of a multiplication of the current velocity V1 and the time td from the current position of the object C3, that is,
(V1×td)  formula (1)

The game machine GM1 receives similar position information P12 from the game machine GM2. When PI1 is calculated, the game machine GM1 predicts a position of the object C4 and a distance D3,4 between the objects C3 and C4, also. The distance D3,4 is a distance along the moving path, for example.

The distance D3,4 is indicators of collision risk of objects C3 and C4 and of competition tension against the opponent (enemy) object. When the distance D3,4 is long, the necessity of the mutual position information PI1 and PI2 is low. Then, the game machines GM1 decreases the information volume to be transferred by decreasing transmission frequency of the position information PI1. The communication load of the game machine GM1 is lightened, and low game processing speed due to communication is prevented.

FIG. 8 is a graph showing a relationship between the distance between objects and the communication frequency. The communication frequency is declined as the distance increase, for example, by 4 steps (F1>F2>F3>F4). The communication frequency is set to be 60 times/sec at the maximum and 1 time/sec at the minimum. The lowest frequency is set to be a frequency for judging whether the communication is maintained or not, preferably.

It is also possible to execute a car race of objects C1 to C4 corresponding to more game machines GM1 to GM4, for example. In this case, information volume is adjusted according to distances between each object and other objects. If the distances from the object C1 to the object C2 is the distance of the maximum frequency F1, to the object C3 is the distance of the frequency F2 and to object C2 is the distance of the minimum frequency F4, the game machine GM1 transmits the predicted position information at the frequency of F1, F2 and F3 to the game machines GM2, Gm3 and GM4, respectively.

The position information may includes not only the position along the moving direction on the moving path but also widthwise position of the moving path, posture relative to the direction of the moving path and moving velocity of the object. The information volume may be adjusted by omitting these information.

In the game machine, as for obtaining the position information of opponent objects from the opponent game machines, the MODEM 314, communication I/F 311, CPU 301 and system memory 302 cooperatively function as a position information obtaining means.

In the game machine, as for calculating the position of the corresponding object (position information of corresponding object), the CPU 301 and system memory 302 cooperatively function as a position information calculation means.

In the game machine, as for calculating the predicted position information of the position advanced by the delay time from the current position, the CPU 301 and system memory 302 cooperatively function as a predicted position information calculation means.

In the game machine, as for transmitting the predicted position information to the opponent game machines, the CPU 301, system memory 302, communication I/F 311 and MODEM 314 cooperatively function as a position information transmission means.

In the game machine, as for calculating the distance between the objects, the CPU 301 and system memory 302 cooperatively function as a distance calculation means.

In the game machine, as for calculating the information volume of the position information to be transmitted to the opponent game machines, the CPU 301 and system memory 302 cooperatively function as an information volume calculation means.

The distance D1,2 may be a two dimensional or tree dimensional one-line distance between objects C1 and C2, in a game in which no moving path is defined, such as in a fighting game.

As shown in the enlarged moving path in FIG. 10, the distance between objects C1 and C2 on branched path S4 and S5, respectively, cannot be defined along the moving path. An summation of a distance d1,5 from the object C1 to the branch point J4,5 of the paths S4 and S5 and a distance d2,4 from the object C2 to the branch point J4,5 may be deemed as a distance D1,2, for example.
(d1,5+d2,4)  formula (2)

The communication frequency may be set according to the velocity of the object. If the velocity of the objects C3 and C4 are V3 and V4, respectively, the communication frequency is set according to the time up to a collision of the objects with each other, that is,
{D3,4/(V3−V4)}  formula (4)

In this case, if the velocity of the objects C1 and C2 are V1 and V2, respectively, a time calculated by division of a distance at the branch point J4,5 between the objects by the velocity deference of the objects may be similarly applicable.

Namely, α=constant is defined, and

(a) The time up to the collision is,
{d2,4−(d1,5/V1)×V2}/(V2−V1)  formula (5)
when (d1,5/V1)+α<(d2,4/V2).  (formula (4))
(b) The time up to the collision is,
{d1,5−(d2,4/V2)×V1}/(V1−V2)  formula (7)
when (d1,5/V)>(d2,4/V2)+α.  (formula (6))
(c) The communication frequency is made maximum due to high possibility of collision,
when (d1,5/V1)−(d2,4/V2)=<α.  (formula (8))

The processing of the game control of the game machine (GM1, for example) is executed, for each frame of the image displayed on the CRT 312, by the following steps.

Step S901: First, a time of next display timing of the game machine GM1 is obtained.

Step S902: Following to the step S901, it is judged whether the position information is received of the opponent objects C2 to C4 from the opponent game machines (GM2 to GM4, for example). When the position information reaches, the processing is advanced to the step S903, otherwise to the step S904.

Step S903: The function for predicting the positions of the opponent objects C2 to C4 is renewed. The function means, for example, a calculation that the current velocity V2 to V4 of the objects C2 to C4 are multiplied by a time (ta−t), from the current time t to a time ta, that is,
V2×(ta−t).  formula (9)

Position information newly received renews the velocity V2 to V4 according to the position of the last time. The position information may includes the velocity V2 to V4.

Step S904: Following to the step S903, the positions of the opponent objects C2 to C4 at the time ta is predicted according to the position information and the formula (9).

Step S905: Following to the step S904, the position and posture of the corresponding object C1 at the time ta is predicted according to the function of the formula (9) with the velocity V1 and so forth.

Step S906: The differences between the traveling distances of the corresponding object C1 and opponent objects C2 to C4 at the time ta are calculated.

Step S907: Following to the step S906, an image of one frame is displayed on the CRT 312. Then, the processing is advanced to the step S908.

Step S908: The position (display position) at the time ta is stored in a area of position history buffer in the system memory. Then, the processing is advanced to the step S909.

Step S909: It is judged whether the position information is to be transmitted at presence or not. When the position information is to be transmitted, the processing is advanced to the step S910, otherwise, to the step S911.

Step S910: According to the distance between the objects mentioned above and the processing based on FIG. 8, the position information transmission frequency is calculated. The time ta for position prediction at the next time and the prediction function are generated. Then, the processing is advanced to the step S911.

Step S911: The position information of the corresponding object C1 is transmitted to the opponent game machines GM1 to GM4. Then the processing is terminated.

As mentioned above, the communication load is lightened by adjusting the information volume according to the present invention. The communication load is further lightened by optimizing the communication channel according to evaluation of communication speed between the game machine (GM1, for example) and the opponent game machines (GM2 to GM4, for example).

In the game machine GM1, the communication channel i optimized by the steps in FIG. 11.

Step S1101: First, the opponent objects C1 to Cn selectable are shown on the CRT 312 of the game machine GM1, for player's selection.

Step S1102: Waiting for the player's selection, the processing is advanced to the step S1103 when the selection is finished.

Step S1103: The communication with the opponent game machines (GM2 to GM4) corresponding to the selected opponent objects (C2 to C4 for example) is executed directly, without through the server SV. The delay times td1 are obtained.

Step S1104: The communication with the opponent game machines (GM2 to GM4) corresponding to the selected opponent objects (C2 to C4, for example) is executed through the server SV. The delay times td1 are obtained.

Step S1105: The smaller Min(td1, td2) of td1 and td2 for the opponent game machines GM2 to GM4 are compared with a predetermined reference delay time td0 (reference communication time). When Min (td1, td2)>td0, the processing is advanced to the step S1106, otherwise, to the step S1107.

Step S1106: The objects not selected are shown. Then, the processing is returned to the step S1102.

Step S1107: The times td1 and td2 are compared for each game machine GM2 to GM4. When td1<td2, the processing is advanced to the step S1109, otherwise, to the step S1108.

Step S1108: The communication channel through the server is selected for the game machine is selected. Then, the processing is terminated.

Step S1109: The communication channel without through the server is selected for the game machine is selected. Then, the processing is terminated.

As for the communication channel selection, as for the communication speed comparison of the communication through and without through the server SV in the step S1107, the CPU 301, system memory 302, communication I/F 311 and MODEM 314 cooperatively function as a communication speed comparison means.

As for the communication speed comparison of the communication through and without through the server SV with the reference communication speed in S1105, the CPU 301, system memory 302, communication I/F 311 and MODEM 314 cooperatively function as a reference communication speed comparison means.

As for the selection of other objects in the steps S1106, S1101 and S1102, he CPU 301, system memory 302, rendering processor 307, graphic memory 308 and CRT 312 cooperatively function as an additional game machine comparison means.

The embodiment above is described concerning car race, however, the present invention is applicable to role playing game and other various games. As the distance between objects, various suitable distances may be applied for characteristics of the games, such as Euclid distance, Hamming distance etc.

According to the present invention, low process speed of a game is prevented due to communication load, with maintaining game quality.

Claims

1. A communication game system comprising a plurality of game machines and a network for connecting said game machines with one another, each said game machine (one game machine, hereafter) comprising:

a virtual space generating means for generating a virtual space in which a plurality of objects exist,

an input means for inputting movement input information which causes movement of said object (corresponding object, hereafter) corresponding to said one game machine in said virtual space,

a position information obtaining means for obtaining position information of other objects (opponent objects, hereafter) corresponding to other game machines (opponents' game machines) than said game machine, from said opponents game machines,

a position information calculation means for calculating a position information of said corresponding object according to said movement input information,

a position information transmission means for transmitting said position information of said corresponding object to said opponent game machines,

a distance calculation means for calculating distances between said corresponding object and opponent objects, according to said position information of said corresponding object and position information of said opponent objects, and

an information volume calculation means for calculating necessary information volume of said position information of corresponding object to be transmitted to each said opponent game machine, according to distances between said opponent object and opponents objects,

wherein said position information transmission means transmits said position information by said necessary information volume to said opponent game machines.

2. A communication game system according to claim 1, further comprising a position prediction calculation means for calculating a predicted position of said corresponding object at a time after a current time by a transfer time through said network, according to said position information of said corresponding object, wherein said position information transmission means transmits said predicted position of said corresponding object as said position information to said opponent game machines.

3. A communication game system according to claim 1, further comprising a server which comprises,

a position information receiving means connected to said network for receiving said position information from said game machines, and

a position information transmission means for transmitting said position information of each said game machine to opponent game machines.

4. A communication game system according to claim 2, each said game machine further comprising,

a communication speed comparison means for comparing communication transfer time of a communication channel through said server and a communication channel not through said server, and

a communication channel selecting means for selecting communication channel of higher communication speed, from said communication channels through and not through said server.

5. A communication game system according to claim 3, each said game machine further comprising,

a reference communication speed comparison means for comparing communication transfer time of a predetermined reference transfer time with said transfer time of said communication channel through said server and not through said server, and

an additional game machine comparison means for comparing communication transfer time of one of said opponent game machines of a communication channel through said server and not through said server, with said predetermined reference transfer time.

6. A communication game system according to claim 1, wherein said virtual space generating means generates further a moving path through which said corresponding object moves in said virtual space, and said distance calculation means calculates said distance along said moving path.

7. A communication game system according to claim 1, wherein said distance between said objects is one-line distance.

8. A communication game system according to claim 1, wherein said position information transmission means adjusts said information volume by communication frequency.

9. A communication game system according to claim 1, wherein positions on said moving path are included in said position information, and further widthwise positions when said information volume is a lot.

10. A communication game system according to claim 1, wherein said information volume calculation means adjusts said information volume, further according to positional relationship between said corresponding object and said opponent objects.

11. A game control program executed on a game machine for a communication game system which comprises a plurality of game machines and a network for connecting said game machines with one another, comprising:

a virtual space generating step for generating a virtual space in which a plurality of objects exist,

an input step for inputting movement input information which causes movement of said object (corresponding object, hereafter) corresponding to said one game machine in said virtual space,

a position information obtaining step for obtaining position information of other objects (opponent objects, hereafter) corresponding to other game machines (opponents' game machines) than said game machine, from said opponents game machines,

a position information calculation step for calculating a position information of said corresponding object according to said movement input information,

a position information transmission step for transmitting said position information to said opponent game machines,

a distance calculation step for calculating distances between said corresponding object and opponent objects, according to said position information of said corresponding object and position information of said opponent objects, and

an information volume calculation step for calculating necessary information volume of said position information of corresponding object to be transmitted to each said opponent game machine, according to distances between said opponent object and opponents objects,

wherein said position information transmission step transmits said position information by said necessary information volume to said opponent game machines.

12. A memory medium readable by a computer in which program code executable by said computer of said game control program according to claim 11.