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diff --git a/libkdegames/kgame/libkdegames.html b/libkdegames/kgame/libkdegames.html new file mode 100644 index 00000000..66206c47 --- /dev/null +++ b/libkdegames/kgame/libkdegames.html @@ -0,0 +1,187 @@ +<html> + <head> + <title>Documentation for libkdegames</title> + <meta content=""> + <style></style> + </head> + <body> + <H1>Documentation for the classes in libkdegames</H1> +<!--------------------------------------------------------------------------------> + <H3>Design Principles</H3> + The library <em>kdegames</em> contains a collection of classes that can be used + to develop games using the KDE environment very easily. There are a few + principles that were used when developing the library:<P> + + <UL> + <LI><b>usable for a big variety of games</b><br> + The class <em>KGame</em> provides many features that are needed in many games. + It can be used for board games, card games, maze games, simulation games, strategy games and + many more.<br> + It does not (yet) include special features for realtime games, but can be used there, too. + <LI><b>features one-player and multi-player games</b></br> + A game developed with this library can easily support any number of simultaneous players. + So use it for one-player games (like Tetris or KSame), for two-player games (like TicTacToe + or chess) or for games with an arbitrary number of players. + <LI><b>computer players can easily be developed</b><br> + The class <em>KPlayer</em> represents an abstract player in a game. This can be a + human player that gets the input from the mouse or the keyboard. Or it can be a computer + player that makes moves by random or with artificial intelligence. All this can be achieved + subclassing KPlayer. + <LI><b>support for network games transparently</b><br> + The class <em>KGame</em> contains lots of features for network game support. Developing + a network game using a TCP/IP connection is very easy this way. But the default + case is still the local game. So the user should not need to connect to the internet + or to select a game server to play a game. + <LI><b>support for turn based and for asynchronous games</b><br> + You can use this library for turn based games, when only one player can make a move at a time + (like most bord games or card games), but also for asynchronous games, when every player can + make a move any time (like many action games). + </UL> +<!--------------------------------------------------------------------------------> + <H3>The central game class: <em>KGame</em></H3> + + When you want to develop your own KDE game using the KDE games library, you most likely want + to use the <em>KGame</em> class. There are two possible ways to extend it to your own needs: + Create a subclass and overwrite the virtual methods, or simply create an instance of KGame + and connect to the appropriate signals.<P> + + <<more code about KGame, an easy example>> + +<!--------------------------------------------------------------------------------> + <H3>Network games and related classes</H3> + + One of the main principles in the design of <em>KGame</em> was to make network games possible + with a minimum of effort for the game developer.<P> + + A network game is a game with usually several players, that are on different computers. These + computers are usually connected to the internet, and all the moves a player does are exchanged + over this network.<P> + + The exchange of moves and other information is done using the class <em>KMessageServer</em>. + An object of this class is a server that waits for connections. Someone who wants to take part + in the game has to connect to this server - usually using an internet socket connection. He does + this by creating a <em>KMessageClient</em> object. This object connects to the message server.<P> + + The transfer of data is realised by subclasses of the abstract class <em>KMessageIO</em>. One object + of this class is created on the client side, one on the server side. Different types of networks can + be supported by creating new subclasses of KMessageIO. There are already two subclasses of KMessageIO: + <em>KMessageSocket</em> uses a internet socket connection to transfer the data from the message client + to the message server or vice versa. <em>KMessageDirect</em> can be used if both the message server and + the message client are within the same process. The data blocks are copied directly to the other side, + so the transfer is faster and needs no network bandwidth.<P> + + A typical network game situation could look like this:<P> + + <IMG SRC="kmessageserver.png"><P> + + Here, three KGame object (called message clients) are connected to the KMessageServer object. One + is in the same process, so it uses KMessageDirect. The other two use KMessageSocket, so an internet + socket connection is used. KGame doesn't talk directly to the message server, but uses a KMessageClient + object instead. One of the KMessageClient objects is the admin of the message server. This client has some + priviledges. It may e.g. kill the connection to other message clients, or limit the number of clients + that may connect.<P> + + The KGame objects are by default all equal. So the usual approach will be that every KGame object will + store the complete status of the game, and any change or move will be broadcasted to the other KGame + objects, so that they all change the status in identical ways. Sometimes it may be necessary (or just + easier to implement) that one KGame object is a <em>game server</em> (i.e. he is repsonsible for everything, + he coordinates the complete game and stores the game status), whereas the other KGame objects are + only dumb stubs that are used to contact the <em>game server</em>. You can implement both approaches + using the message server structure. If you need to elect the KGame object that shall be + the game server, you may e.g. use the one that has the KMessageClient that is the admin of the message + server. (Of course this is only a suggestion, you can use other approaches.)<P> + + The main principle when developing the message server/client structure was, that the message server + doesn't have <em>any</em> idea of the game and its rules that is played. The message server only forwards + messages from one message client to the others without interpreting or manipulating the data. So always + keep in mind that the message server is <em>not</em> a game server! It does not store any data about + the game status. It is only a server for network connections and message broadcasting, <em>not</em> + for game purposes. The reason for this principle is, that <em>any</em> game can be played using a + KMessageServer on any computer. The computer being the message server doesn't need to know anything + about the game that is played on it. So you don't have to install new versions of the game there. Only + the clients need to be game specific.<P> + + Usually you don't need to create <em>KMessageServer</em> or <em>KMessageClient</em> objects in your game, + since <em>KGame</em> does this for you. There are three different scenarios fo network games that are + all supported in <em>KGame</em>:<P> + + <b>Scenario 1: local game</b><P> + + The local game should always be the default state a game should be in. To avoid having this scenario + as a special case, <em>KGame</em> automatically creates a KMessageServer object and a KMessageClient + object. So every change and every move is sent to the message server and is returned to the KGame + object before it is processed. Since the connection between the message client and the message server + uses KMessageDirect the data transfer is very fast and wont hurt in most cases.<P> + + <IMG SRC="scenario0.png"><P> + + This is the default situation right after creating the <em>KGame</em> object.<P> + + <b>Scenario 2: network game, started by one player</b><P> + + If one user is bored of playing alone, he can open his game for connections from the outside world. + He listens to a TCP/IP socket port (i.e. a number between 0 and 65535). Other players can create + KGame objects of their own and connect to this port. They need to know the IP address of that computer + and the port number. This situation will have this structure: + + <IMG SRC="scenario1.png"><P> + + The first player has to do something like:<P> + + <PRE> + KGame *myGame = new KGame (); + // wait for connections on port 12345 + myGame->offerConnections (12345); + </PRE> + + And the other players have to do something like:<P> + + <PRE> + KGame *myGame = new KGame (); + // connect to the message server + myGame->connectToServer ("theServer.theDomain.com", 12345); + </PRE> + + This automatically removes the message server in these KGame objects and connects to the given + one instead.<P> + + <b>Scenario 3: network game, using a stand alone message server</b><P> + + Sometimes it is not possible to let the message server run on one of the players computer. If e.g. all + the players have their computer in a local network that uses masquerading to contact the internet, + other computers cannot connect to them since the computer doesn't have a IP address to the outside + world. Then the only way to play a network game is to have a standalone KMessageServer object on + another server computer (somthing like "games.kde.org" e.g.). Since the KMessageServer isn't game + specific at all, every game can be played using it. There doesn't have to be any special software + installed on that server computer, only the program creating a KMessageServer object.<P> + + This scenario has some more advantages: The message server can be a well known meeting point to + start a game. This way one could play games against other players you never knew before. Furthermore + the game is stopped brutally when the program that contains the message server in scenario 2 is + quitted. (Migration of message servers is not yet implemented, but may be in the future.) Using a + stand alone message server, the players may enter and leave the game as they want. + + <IMG SRC="scenario2.png"><P> + + To create this scenario, a special KMessageServer program has to be started on the computer + that shall be the stand alone message server:<P> + + <PRE> + % kmessageserver -port=12345 + </PRE> + + The other games that want to connect have to do this (supposed the stand alone message server + has the IP address "games.kde.org"):<P> + + <PRE> + KGame *myGame = new KGame (); + // connect to the message server + myGame->connectToServer ("games.kde.org", 12345); + </PRE> + + + + +<!--------------------------------------------------------------------------------> + </body> +</html>
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