Tutorial reversi

Check out an update version of the Reversi Tutorial which uses the BGA Type Safe Template.

Game File Reference

Overview

• dbmodel.sql - database model
• gameinfos.inc.php - meta-information
• gameoptions.json - game options & user preferences
• img/ - game art
• Game Metadata Manager - tags and metadata media
• material.inc.php - static data
• misc/ - studio-only storage
• modules/ - additional game code
• states.inc.php - state machine
• stats.json - statistics
• X.action.php - player actions
• X.css - interface stylesheet
• Game.php - main logic
• X.js - interface logic
• X.view.php - dynamic game layout
• X_X.tpl - static game layout

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Useful Components

Official

• Deck: a PHP component to manage cards (deck, hands, picking cards, moving cards, shuffle deck, ...).
• Draggable: a JS component to manage drag'n'drop actions.
• Counter: a JS component to manage a counter that can increase/decrease (ex: player's score).
• ExpandableSection: a JS component to manage a rectangular block of HTML than can be displayed/hidden.
• Scrollmap: a JS component to manage a scrollable game area (useful when the game area can be infinite. Examples: Saboteur or Takenoko games).
• Stock: a JS component to manage and display a set of game elements displayed at a position.
• Zone: a JS component to manage a zone of the board where several game elements can come and leave, but should be well displayed together (See for example: token's places at Can't Stop).

Undocumented component (if somebody knows please help with docs)

• Wrapper: a JS component to wrap a <div> element around its child, even if these elements are absolute positioned.

Unofficial

• BGA Code Sharing - Shared resources, projects on git hub, common code, other links
• BGA Studio Cookbook - Tips and instructions on using API's, libraries and frameworks
• Common board game elements image resources

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Game Development Process

• First steps with BGA Studio
• Create a game in BGA Studio: Complete Walkthrough
• Tutorial reversi
• Tutorial gomoku
• Tutorial hearts
• BGA Studio Guidelines
• BGA game Lifecycle
• Pre-release checklist
• Post-release phase
• Player Resources - add player help/rules to your game page

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Guides for Common Topics

• Translations - make your game translatable
• Game Replay
• Mobile Users
• 3D
• Compatibility

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Miscellaneous Resources

• Studio FAQ
• Tools and tips of BGA Studio - Tips and instructions on setting up development environment
• Studio logs - Instructions for log access
• Practical debugging - Tips focused on debugging
• Troubleshooting - Most common "I am really stuck" situations
• Studio Bugs - Reports against Studio itself (not BGA!)

Introduction

Using this tutorial, you can build a complete working game on the BGA environment: Reversi.

Before you read this tutorial, you must:

• Read the overall presentations of the BGA Framework (see here).
• Know the rules of Reversi.
• Know the languages used on BGA: PHP, SQL, HTML, CSS, Javascript
• Setup your development environment First Steps with BGA Studio

Create your first game

Note: you should already have created a project following instructions in Create a new game project. While you will find a reversi directory in your SFTP folder, do not use it for this tutorial. Instead, use the project you have created as an (empty) starting point.

With the initial skeleton of code provided in your project, you can already start a game from the BGA Studio:

• Go to your studio Control panel, then Manage games and select your initial project. Note: there are warnings displayed about a missing BGG_ID and presentation text. You can ignore that for now.
• Click the Play link next to your project name. This will open the Play page and offer to create a new table for your project. Optional: click the Heart icon to add your project to your favorite games list.
• On the Play page, on the top of the page, make sure that your settings are "Simple game", "Real time" and "Manual".
• Click "Create table" to create a table of your project.
• For now, we are going to work with one player only, so use the (-) button to set the number of players to 1. Most of the time it is simpler to proceed with only one player during the early phase of development of your game, as it's easy and fast to start/stop games. If you choose to start with 2 players, you should see two names on the right: testdude0 and testdude1. To switch between them, press the red arrow button near their names; it will open another tab. This way you don't need to login and logout from multiple accounts.)
• Reminder: Always use the "Express Start" button to start the game.

Thus, you can start a "Reversi" game, and arrive on a void, empty game. Yeah.

End the game by clicking on the game options icon on the top right, and then on "Express Stop".

Editing the game information (Optional)

This step is optional and will fix the warnings on the project page (missing BGG_ID and presentation).

Edits to fix Errors

• Edit your local copy of the gameinfos.inc.php file:
  • Change the bgg_id value from 0 to 2389 - that's around line 37.
  • Add 1, to the players array - that's around line 41.
  • Change the presentation array content - that's around line 134. Uncomment one line and change the text. Remove the final comma if you keep only one line!
• Upload the gameinfos.inc.php file to the SFTP server (see Connect to your SFTP folder).

Test your Edits

• Go back to your project page, and in the "Game Information" section, click "Reload game informations".
• Finally, refresh the project page in your browser (usually CTRL-F5).

Not working?

Some changes will require bypassing the cache. It is often worth doing a hard refresh to make sure the

Sometimes the cache will keep your changes from showing. Since this is a possibility, it will be useful to know how to bypass the cache. To do so you may manually clear cache or use a shortcut to refresh and ignore the cached version of the page. Here's how

Windows

Chrome, Firefox, or Edge: Press Ctrl+F5 or Shift+F5 or Ctrl+Shift+R

Mac

Chrome or Firefox: Press Shift+Command+R

Safari for Mac: Press Command+Option+E to empty the cache, then hold down Shift and click Reload in the toolbar

Make it look like Reversi

Let's start with the board. This will give you a good idea of how things will look and where tokens should go.

Be careful designing the layout of your game: you must always keep in mind that players with a 1024px screen width must be able to play. Usually, it means that the width of the play area can be 750px (in the worst case).

For Reversi, it's useless to have a 750x750px board - much too big, so we chose this one which fit perfectly (536x528):

Note that we are using a jpg file. Jpg filesare lighter than png, so they are faster to load. Later, we are going to use PNGs for tokens because they allow for transparency.

Add the board

use lowercase file names

• upload board.jpg in your img/ directory.
• edit reversi_reversi.tpl to add a div for your board.

Note: If you are building this game by following the tutorial, you will have a different project name than reversi (i.e. mygame_mygame.tpl). The file names in your project will be different than shown in this tutorial, replacing reversi with your project name. Be sure that any code (other than comments) that references reversi is changed to your actual project name.

<div id="board">
</div>

• edit your reversi.css file to transform it into a visible board:

#board {
   width: 536px;
   height: 528px;
   background-image: url('img/board.jpg');
}

Important: refresh your page. Here's your board:

If the board does not appear, refresh the page (always do this when you update the CSS file), and check the image filename. Remember file names are case sensitive!

Code the Grid

Now, we need to create some invisible HTML elements where squares are. These elements will be used as position references for the white and black tokens.

Make a Square Template

The board is 8 squares by 8 squares. This means we need 64 squares. To avoid writing 64 individual div elements on our template, we are going to use the "block" feature.

Let's modify our template (the .tpl file) like this:

 <div id="board">
    <!-- BEGIN square -->
        <div id="square_{X}_{Y}" class="square" style="left: {LEFT}px; top: {TOP}px;"></div>
    <!-- END square -->
 </div>

As you can see, we created a "square" block, with 4 variable elements: X, Y, LEFT, and TOP. We are going to use this block 64 times during page load.

Use Square Template to Build Grid

Let's do it in our reversi.view.php file, inside the build_page function:

Note that "reversi_reversi" is the name of the game and if you named your differently you will have to change that when you copy and paste. Example "testreversi_testreversi".

        $this->page->begin_block( "reversi_reversi", "square" );
        
        $hor_scale = 64.8;
        $ver_scale = 64.4;
        for( $x=1; $x<=8; $x++ )
        {
            for( $y=1; $y<=8; $y++ )
            {
                $this->page->insert_block( "square", array(
                    'X' => $x,
                    'Y' => $y,
                    'LEFT' => round( ($x-1)*$hor_scale+10 ),
                    'TOP' => round( ($y-1)*$ver_scale+7 )
                ) );
            }        
        }

Note: as you can see, squares in our board.jpg files do not have an exact width/height in pixels, and that's the reason we are using floating point numbers here.

Style Those Squares

Now, to finish our work and check if everything works fine, we are going to style our square a little bit in our CSS stylesheet:

#board {
    width: 536px;
    height: 528px;
    background-image: url('img/board.jpg');
    position: relative;
}

.square {
    width: 62px;
    height: 62px;
    position: absolute;
    background-color: red;
}

Explanations:

• With "position: relative" on board, we ensure square elements are positioned relatively to board.
• background-color: red; is used for testing. This allows us to see the invisible elements. (You could instead do something like border: 1px solid orange;. have fun and be creative)

Let's refresh and check our (beautiful) squares:

Now that you know the squares are there, you can remove the test line background-color: red; from your .square class in the CSS stylesheet.

Not Working?

If the styled squares do not appear, inspect and check your css (Chrome DevTools: Application > Frames > top > Stylesheets > reversi.css).

If your changes are not there try clearing your cache. Remember, you can bybass cache

The Tokens

Now, our board is ready for some tokens!

[Note: Throughout this tutorial, sometimes "tokens" is used, and sometimes "discs" is used. They are often swapped if you're looking at code in the reversi example project.]

Build the Token

There are quite a few steps before the tokens will appear. You may be used to testing after every change, but that won't work well here. The token will not show until you have add a div to the tpl, styles to the css, js template to the tpl, utility method in the js, adjusted the php file, and added the token to the board in the js file.

HTML in the .tpl file

At first, we introduce a new 'div' element as a child of "board" to host all these tokens (in our template):

    <!-- END square -->
    
    <div id="tokens">
    </div>
</div>

Note: tokens is plural. This div will be used to hold the token divs. Shortly, we will use javascript to add individual tokens to the board.

Add Token to img directory

Here's a new piece of art with the tokens. We need transparency here so we are using a png file:

Upload this image file tokens.png in your img/ directory.

Important Fun Fact: we are using ONE file for both tokens. It is really important to use a minimum number of graphic files for your game. This is called the "CSS sprite" technique, because it makes the game load faster and more reliable. Read more about CSS sprites.

Style the Tokens in .css file

.token {
    width: 56px;
    height: 56px;
    position: absolute;
    background-image: url('img/tokens.png');
}
.tokencolor_ffffff { background-position: 0px 0px;   }
.tokencolor_000000 { background-position: -56px 0px;   }

With this CSS code, we could apply the classes "token" and "tokencolor_ffffff" to a div element and we'd got a white token.

Note the "position: absolute" which allows us to position tokens on the board and make them "slide" to their positions.

Build Token JS Template in .tpl file

Now, let's make the first token appear on our board. Tokens are not visible at the beginning of the game: they appear dynamically during the game. For this reason, we are going to make them appear from our Javascript code, with a BGA Framework technique called "JS template".

In our template file (reversi_reversi.tpl), let's create the piece of HTML needed to display our token:

<script type="text/javascript">

// Templates

var jstpl_token='<div class="token tokencolor_${color}" id="token_${x_y}"></div>';

</script>

Note: we already created the "templates" section for you in the game skeleton.

As you can see, we defined a JS template named jstpl_token with a piece of HTML and two variables: the color of the token and its x/y coordinates. Note that the syntax of the argument is different for template block variables (braces {}) and JS template variables (dollar and braces ${}).

Add Token Utility Method in .js file

Now, let's create a method in our Javascript code (in the reversi.js file) that will make a token appear on the board, using this template. Add under the section //// Utility methods:

        addTokenOnBoard: function( x, y, player )
        {
            dojo.place( this.format_block( 'jstpl_token', {
                x_y: x+'_'+y,
                color: this.gamedatas.players[ player ].color
            } ) , 'tokens' );
            
            this.placeOnObject( 'token_'+x+'_'+y, 'overall_player_board_'+player );
            this.slideToObject( 'token_'+x+'_'+y, 'square_'+x+'_'+y ).play();
        },

Utility Method Explanation

• with dojo.place and this.format_block methods, we create a HTML piece of code and insert it as a new child of tokens div element.
• with BGA this.placeOnObject method, we place this element over the panel of some player.
• Immediately after, using BGA this.slideToObject method, we make the token slide to the square element, its final destination.
• 'overall_player_board_'+player refers to the div element that contains each player's information and avatar. By initially placing the token here, it gives the effect that the player's avatar is throwing the token onto the board.

Note: don't forget to call the play(), otherwise the token will remain at its original location.

Note: during this process, the parent of the new token HTML element will stay tokens. placeOnObject and slideToObject methods are only moving the position of elements on screen, and they are not modifying the HTML tree.

Set Token Colors in setupNewGame in .game.php file

Before we can show a token, we need to set the player colors in the setupNewGame function in reversi.game.php:

Replace $default_colors = $gameinfos['player_colors']; with the following line:

        $default_colors = array( "ffffff", "000000" );

Note: A few lines below, you may have to remove the line self::reattributeColorsBasedOnPreferences( $players, $gameinfos['player_colors'] );

Test the Token

Now, to test if everything works fine

addTokenOnBoard() in .js file to Test

In reversi.js, in setup: function, under // TODO: Set up your game interface here add

this.addTokenOnBoard( 2, 2, this.player_id );

Now restart the game.

Note: if the page fails to load with a Javascript error: n is null message, make sure you have added the "tokens" div in your template as instructed above.

A token should appear and slide immediately to its position, like this:

The database

We did most of the client-side programming, so let's have a look on the other side now. To design the database model of our game, you will need to access the database. You won't need to do anything in database UI, yet.

Accessing the Database

To access the database, start a game, then click "Go to game database" link at the bottom of our game, to access the database directly with a PhpMyAdmin instance.

After the first time you've acess the database, you could skip opening a game and instead, go to https://studio.boardgamearena.com/db/ . Your PhpMyAdmin username/password is in your welcome email.

Note: do not remove existing tables

Create Table in .sql file

Now, you are able to create the table(s) you need for your game, and report every SQL command used in your dbmodel.sql file.

The database model of Reversi is short: just one table with the squares of the board.

CREATE TABLE IF NOT EXISTS `board` (
  `board_x` smallint(5) unsigned NOT NULL,
  `board_y` smallint(5) unsigned NOT NULL,
  `board_player` int(10) unsigned DEFAULT NULL,
  PRIMARY KEY (`board_x`,`board_y`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Add the above SQL to dbmodel.sql. Pay special attention to the backtick ` character vs. the single quote ' when working with SQL.

Test the Table

Now, a new database with a board table will be created each time we start a Reversi game. This is why after modifying our dbmodel.sql it's a good time to stop your current game & start a new game.

Start a new game and verify a table is created.

Setup the initial game position

Note: From now on, you must launch the game with two players to get two player_ids within the database. Otherwise, the game will crash.

The setupNewGame method of our reversi.game.php is called during initial setup. This initializes our data and places the starting tokens on the board. At the beginning of the game, there should be 4 tokens on the board.

Initialize the Board in .game.php file

Under // TODO: setup the initial game situation here, initialize the board

        // Init the board
        $sql = "INSERT INTO board (board_x,board_y,board_player) VALUES ";
        $sql_values = array();
        list( $blackplayer_id, $whiteplayer_id ) = array_keys( $players );
        for( $x=1; $x<=8; $x++ )
        {
            for( $y=1; $y<=8; $y++ )
            {
                $token_value = "NULL";
                if( ($x==4 && $y==4) || ($x==5 && $y==5) )  // Initial positions of white player
                    $token_value = "'$whiteplayer_id'";
                else if( ($x==4 && $y==5) || ($x==5 && $y==4) )  // Initial positions of black player
                    $token_value = "'$blackplayer_id'";
                    
                $sql_values[] = "('$x','$y',$token_value)";
            }
        }
        $sql .= implode( ',', $sql_values );
        self::DbQuery( $sql );

Board Initialization Explanation

• We create one table entry for each square, with a NULL value which means "empty square"
• On 4 of the squares, we place an initial token.

After this, we set activeNextPlayer to make the first player active at the beginning of the game (this line is already present in the default code template).

If you didn't do it earlier, you need to remove the call to self::reattributeColorsBasedOnPreferences() in SetupNewGame(). If you don't, player color preferences will try (and fail) to override the two colors supported here.

Show the Initial Token Setup

Now, we need to make these tokens appear on the client side. The first step is to return the token positions with our getAllDatas() PHP method. getAllDatas() is called during each page reload.

In the getAllDatas() method, after // TODO: Gather all information about current game situation (visible by player $current_player_id), add the following lines:

        // Get reversi board token
        $result['board'] = self::getObjectListFromDB( "SELECT board_x x, board_y y, board_player player
                                                       FROM board
                                                       WHERE board_player IS NOT NULL" );

Next, you may need to modify the query that gets player information to also get the player's colors. This is in the variable $sql, above the lines you just inserted in getAllDatas(). Below is what the line will look like. Notice how we've added player_color color to the sql query.

$sql = "SELECT player_id id, player_score score, player_color color FROM player ";

We are using the BGA framework's getObjectListFromDB() that formats the result of this SQL query in a PHP array with x, y and player attributes. We add it to the result associative array with the key board.

Last, we process this array client side. Let's place a token on the board for each array item. We'll do this in our Javascript setup method under // TODO: Set up your game interface here, according to "gamedatas".

This will result in a removal or edit of the previously added line this.addTokenOnBoard(2, 2, this.player_id);

            for( var i in gamedatas.board )
            {
                var square = gamedatas.board[i];
                
                if( square.player !== null )
                {
                    this.addTokenOnBoard( square.x, square.y, square.player );
                }
            }

The board entry created in getAllDatas() is used here as gamedatas.board

Test the Game Start

Reload... and here we are:

It starts to feel like Reversi here...

The game state machine

Stop your game, again. You're about to start the core game logic.

You already read Focus on BGA game state machine, so you know that this is the heart of your game logic. For reversi, it's relatively simple. Here's a diagram of our game state machine:

Build your States

And here's our states.inc.php, according to this diagram:

$machinestates = array(

    1 => array(
        "name" => "gameSetup",
        "description" => clienttranslate("Game setup"),
        "type" => "manager",
        "action" => "stGameSetup",
        "transitions" => array( "" => 10 )
    ),
    
    10 => array(
        "name" => "playerTurn",
		"description" => clienttranslate('${actplayer} must play a disc'),
		"descriptionmyturn" => clienttranslate('${you} must play a disc'),
        "type" => "activeplayer",
        "args" => "argPlayerTurn",
        "possibleactions" => array( 'playDisc' ),
        "transitions" => array( "playDisc" => 11, "zombiePass" => 11 )
    ),
    
    11 => array(
        "name" => "nextPlayer",
        "type" => "game",
        "action" => "stNextPlayer",
        "updateGameProgression" => true,        
        "transitions" => array( "nextTurn" => 10, "cantPlay" => 11, "endGame" => 99 )
    ),
   
    99 => array(
        "name" => "gameEnd",
        "description" => clienttranslate("End of game"),
        "type" => "manager",
        "action" => "stGameEnd",
        "args" => "argGameEnd"
    )

);

Now, in reversi.game.php let's create the methods that are declared in this game states description file:

• argPlayerTurn: referenced in the args property of the playerTurn state; this is the name of the method to call to retrieve arguments for this gamestate. Arguments are sent to the client side to be used on onEnteringState or to set arguments in the gamestate description.
• stNextPlayer: referenced in the action property of the nextPlayer state; this is the name of the method to call when this game state become the current game state.

Test Your States

... and start a new Reversi game.

As you can see on the screen capture below, the BGA framework makes the game jump to our first game state playerTurn right after the initial setup. That's why the status bar contains the description of playerTurn state ("XXXX must play a disc"):

The rules

We will use the getPossibleMoves PHP method to:

• Indicate to the current player where she is allowed to play by returning a list of coordinates
• Check if the player has the right to play in the spot they choose

Example of getPossibleMoves here https://gist.github.com/leocaseiro/a8bc2851bd0caddd06685b5035937d15

This is pure PHP programming here, and there are no special things from the BGA framework that can be used. This is why we won't go into details here. The overall idea is:

• Create a getTurnedOverDiscs(x,y) method that returns coordinates of discs that would be turned over if a token would be played at x,y.
• Loop through all free squares of the board and call the getTurnedOverDiscs method on each of them. If at least 1 token is turned over, this is a valid move.

IMPORTANT: Making a database query is slow! Please don't load the entire game board with a SQL query multiple times. In our implementation, we load the entire board once at the beginning of getPossibleMoves, and then pass the board as an argument to all methods.

If you want to look into details, please look at the "utility method" sections of reversi.game.php. If building the tutorial yourself, copy the functions under "Utility functions" comment from the Reversi tutorial.

Display allowed moves

Now we want to highlight the squares where the player can place a disc.

To do this, we add a argPlayerTurn method in reversi.game.php. This method is called on the server each time we enter into playerTurn game state, and its result is transferred automatically to the client-side:

    function argPlayerTurn()
    {
        return array(
            'possibleMoves' => self::getPossibleMoves( self::getActivePlayerId() )
        );
    }

We use the getPossibleMoves method we just developed.

Each time we enter into a new game state, we use the onEnteringState Javascript method (in the reversi.js file, under "Game & client states"). This lets us use the data returned by the method above on the client side.

        onEnteringState: function( stateName, args )
        {
           console.log( 'Entering state: '+stateName );
            
            switch( stateName )
            {
            case 'playerTurn':
                this.updatePossibleMoves( args.args.possibleMoves );
                break;
            }
        },

So, when we enter into playerTurn game state, we call our updatePossibleMoves method (under the "Utility methods" section). This method looks like this:

        updatePossibleMoves: function( possibleMoves )
        {
            // Remove current possible moves
            dojo.query( '.possibleMove' ).removeClass( 'possibleMove' );

            for( var x in possibleMoves )
            {
                for( var y in possibleMoves[ x ] )
                {
                    // x,y is a possible move
                    dojo.addClass( 'square_'+x+'_'+y, 'possibleMove' );
                }            
            }
                        
            this.addTooltipToClass( 'possibleMove', '', _('Place a disc here') );
        },

Here's what this does. At first, it removes all possibleMove classes currently applied with the very useful combination of dojo.query and removeClass method.

Then it loops through all possible moves our PHP updatePossibleMoves function created for us, and adds the possibleMove class to each corresponding square.

Finally, it uses the BGA framework addTooltipToClass method to associate a tooltip to all those highlighted squares so that players can understand their meaning.

To see the possible moves we need to create a CSS class (possibleMove) that can be applied to a square element to highlight it:

.possibleMove {
    background-color: white;
    opacity: 0.2;
    filter:alpha(opacity=20); /* For IE8 and earlier */  
    cursor: pointer;  
}

And here we are:

Let's play

From now, it's better to restart a game with 2 players, because we are going to implement a complete Reversi turn. The summary of what we are going to do is:

• When we click on a possibleMove square, send the move to the server.
• Server side, check the move is correct, apply Reversi rules and jump to next player.
• Client side, change the token position to reflect the move.

First we associate each click on a square to one of our methods using our Javascript setup method:

            dojo.query( '.square' ).connect( 'onclick', this, 'onPlayDisc' );

Note the use of the "dojo.query" method to get all HTML elements with "square" class in just one function call. Now, our "onPlayDisc" method is called each time someone clicks on a square.

Here's our "onPlayDisc" method below:

        onPlayDisc: function( evt )
        {
            // Stop this event propagation
            dojo.stopEvent( evt );

            // Get the clicked square x and y
            // Note: square id format is "square_X_Y"
            var coords = evt.currentTarget.id.split('_');
            var x = coords[1];
            var y = coords[2];

            if( ! dojo.hasClass( 'square_'+x+'_'+y, 'possibleMove' ) )
            {
                // This is not a possible move => the click does nothing
                return ;
            }
            
            if( this.checkAction( 'playDisc' ) )    // Check that this action is possible at this moment
            {            
                this.ajaxcall( "/reversi/reversi/playDisc.html", {
                    x:x,
                    y:y
                }, this, function( result ) {} );
            }            
        },

Warning: Make sure to replace reversi in line this.ajaxcall( "/reversi/reversi/playDisc.html", { with the name of your project. E.g. "/yourgamename/yourgamename/playDisc.html"

What we do here is:

• We stop the propagation of the Javascript onclick event. Otherwise, it can lead to random behavior so it's always a good idea.
• We get the x/y coordinates of the square by using evt.currentTarget.id
• We check that clicked square has the possibleMove class, otherwise we know for sure that we can't play there.
• We check that playDisc action is possible, according to current game state (see possibleactions entry in our playerTurn game state defined above). This check is important to avoid issues if a player double clicks on a square.
• Finally, we make a call to the server using BGA ajaxcall method with argument x and y.

Now, we have to manage this playDisc action on the server side. At first, we introduce a playDisc entry point in our reversi.action.php:

    public function playDisc()
    {
        self::setAjaxMode();     
        $x = self::getArg( "x", AT_posint, true );
        $y = self::getArg( "y", AT_posint, true );
        $result = $this->game->playDisc( $x, $y );
        self::ajaxResponse( );
    }

As you can see, we get the 2 arguments x and y from the javascript call, and call a corresponding playDisc method in our game logic (reversi.game.php).

Now, let's have a look of this playDisc method:

    function playDisc( $x, $y )
    {
        // Check that this player is active and that this action is possible at this moment
        self::checkAction( 'playDisc' );  

... at first, we check that this action is possible according to current game state (see "possible action"). We already did it on client side, but it's important to do it on server side too (otherwise it would be possible to cheat).

        // Now, check if this is a possible move
        $board = self::getBoard();
        $player_id = self::getActivePlayerId();
        $turnedOverDiscs = self::getTurnedOverDiscs( $x, $y, $player_id, $board );
        
        if( count( $turnedOverDiscs ) > 0 )
        {
            // This move is possible!

...now, we are using the getTurnedOverDiscs method again to check that this move is possible.

            // Let's place a disc at x,y and return all "$returned" discs to the active player
            
            $sql = "UPDATE board SET board_player='$player_id'
                    WHERE ( board_x, board_y) IN ( ";
            
            foreach( $turnedOverDiscs as $turnedOver )
            {
                $sql .= "('".$turnedOver['x']."','".$turnedOver['y']."'),";
            }
            $sql .= "('$x','$y') ) ";
                       
            self::DbQuery( $sql );

... we update the database to change the color of all turned over disc + the disc we just placed.

            // Update scores according to the number of disc on board
            $sql = "UPDATE player
                    SET player_score = (
                    SELECT COUNT( board_x ) FROM board WHERE board_player=player_id
                    )";
            self::DbQuery( $sql );
            
            // Statistics
            self::incStat( count( $turnedOverDiscs ), "turnedOver", $player_id );
            if( ($x==1 && $y==1) || ($x==8 && $y==1) || ($x==1 && $y==8) || ($x==8 && $y==8) )
                self::incStat( 1, 'discPlayedOnCorner', $player_id );
            else if( $x==1 || $x==8 || $y==1 || $y==8 )
                self::incStat( 1, 'discPlayedOnBorder', $player_id );
            else if( $x>=3 && $x<=6 && $y>=3 && $y<=6 )
                self::incStat( 1, 'discPlayedOnCenter', $player_id );

... now, we update both player score by counting all disc, and we manage game statistics.

            // Notify
            self::notifyAllPlayers( "playDisc", clienttranslate( '${player_name} plays a disc and turns over ${returned_nbr} disc(s)' ), array(
                'player_id' => $player_id,
                'player_name' => self::getActivePlayerName(),
                'returned_nbr' => count( $turnedOverDiscs ),
                'x' => $x,
                'y' => $y
            ) );

            self::notifyAllPlayers( "turnOverDiscs", '', array(
                'player_id' => $player_id,
                'turnedOver' => $turnedOverDiscs
            ) );
            
            $newScores = self::getCollectionFromDb( "SELECT player_id, player_score FROM player", true );
            self::notifyAllPlayers( "newScores", "", array(
                "scores" => $newScores
            ) );

... then we notify about all these changes. We are using for that 3 notifications (playDisc, turnOverDiscs and newScores that we are going to implement on client side later). Note that the description of the playDisc notification will be logged in the game log.

            // Then, go to the next state
            $this->gamestate->nextState( 'playDisc' );
        }
        else
            throw new BgaSystemException( "Impossible move" );
    }

... finally, we jump to the next game state if everything goes fine (playDisc is the name of a transition in the playerTurn game state description above which leads to state 11 which is nextPlayer).

To make the statistics work, we have to initialize them in stats.json:

{
  "player": {
    "discPlayedOnCorner": {
      "id": 10,
      "name": "Discs played on a corner",
      "type": "int"
    },
    "discPlayedOnBorder": {
      "id": 11,
      "name": "Discs played on a border",
      "type": "int"
    },
    "discPlayedOnCenter": {
      "id": 12,
      "name": "Discs played on board center part",
      "type": "int"
    },
    "turnedOver": {
      "id": 13,
      "name": "Number of discs turned over",
      "type": "int"
    }
  }
}

A last thing to do on the server side is to activate the next player when we enter the nextPlayer game state (in the reversi.game.php file, under "Game state reactions"):

    function stNextPlayer()
    {
        // Active next player
        $player_id = self::activeNextPlayer();

        // Check if both player has at least 1 discs, and if there are free squares to play
        $player_to_discs = self::getCollectionFromDb( "SELECT board_player, COUNT( board_x )
                                                       FROM board
                                                       GROUP BY board_player", true );

        if( ! isset( $player_to_discs[ null ] ) )
        {
            // Index 0 has not been set => there's no more free place on the board !
            // => end of the game
            $this->gamestate->nextState( 'endGame' );
            return ;
        }
        else if( ! isset( $player_to_discs[ $player_id ] ) )
        {
            // Active player has no more disc on the board => he looses immediately
            $this->gamestate->nextState( 'endGame' );
            return ;
        }
        
        // Can this player play?

        $possibleMoves = self::getPossibleMoves( $player_id );
        if( count( $possibleMoves ) == 0 )
        {

            // This player can't play
            // Can his opponent play ?
            $opponent_id = self::getUniqueValueFromDb( "SELECT player_id FROM player WHERE player_id!='$player_id' " );
            if( count( self::getPossibleMoves( $opponent_id ) ) == 0 )
            {
                // Nobody can move => end of the game
                $this->gamestate->nextState( 'endGame' );
            }
            else
            {            
                // => pass his turn
                $this->gamestate->nextState( 'cantPlay' );
            }
        }
        else
        {
            // This player can play. Give him some extra time
            self::giveExtraTime( $player_id );
            $this->gamestate->nextState( 'nextTurn' );
        }

    }

Now, when we play a token, the rules are checked and the token appears in the database.

Of course, as we don't manage notifications on client side, we need to press F5 after each move to see the changes on the board.

Make the move appear automatically

Now, what we have to do is process the notifications sent by the server and make the move appear on the interface.

In our setupNotifications method in reversi.js, we register 2 methods for the 2 notifications we created at the previous step (playDisc and turnOverDiscs):

            dojo.subscribe( 'playDisc', this, "notif_playDisc" );
            this.notifqueue.setSynchronous( 'playDisc', 500 );
            dojo.subscribe( 'turnOverDiscs', this, "notif_turnOverDiscs" );
            this.notifqueue.setSynchronous( 'turnOverDiscs', 1500 );
            dojo.subscribe( 'newScores', this, "notif_newScores" );
            this.notifqueue.setSynchronous( 'newScores', 500 );

As you can see, we associate each of our 3 notifications with a method prefixed with notif_. We also define these notifications as "synchronous", with a duration in millisecond. It tells the user interface to wait some time after executing the notification, to let the animation end before starting the next notification. In our specific case, the animation will be the following:

• Make a disc slide from the player panel to its place on the board
• (wait 500ms)
• Make all turned over discs blink (and of course turned them over)
• (wait 1500ms)
• Update the player scores
• (wait 500ms)

The 2nd parameter in dojo.subscribe call (this) is the context, and will be passed in as a parameter to the specified method.

Let's have a look now on the playDisc notification handler method:

        notif_playDisc: function( notif )
        {
            // Remove current possible moves (makes the board more clear)
            dojo.query( '.possibleMove' ).removeClass( 'possibleMove' );        
        
            this.addTokenOnBoard( notif.args.x, notif.args.y, notif.args.player_id );
        },

No surprise here, we re-used some existing stuff to:

• Remove the highlighted squares.
• Add a new disc on board, coming from player panel.

Now, here's the method that handles the turnOverDiscs notification:

        notif_turnOverDiscs: function( notif )
        {
            // Get the color of the player who is returning the discs
            var targetColor = this.gamedatas.players[ notif.args.player_id ].color;

            // Make these discs blink and set them to the specified color
            for( var i in notif.args.turnedOver )
            {
                var token = notif.args.turnedOver[ i ];
                
                // Make the token blink 2 times
                var anim = dojo.fx.chain( [
                    dojo.fadeOut( { node: 'token_'+token.x+'_'+token.y } ),
                    dojo.fadeIn( { node: 'token_'+token.x+'_'+token.y } ),
                    dojo.fadeOut( { 
                                    node: 'token_'+token.x+'_'+token.y,
                                    onEnd: function( node ) {

                                        // Remove any color class
                                        dojo.removeClass( node, [ 'tokencolor_000000', 'tokencolor_ffffff' ] );
                                        // ... and add the good one
                                        dojo.addClass( node, 'tokencolor_'+targetColor );
                                                             
                                    } 
                                  } ),
                    dojo.fadeIn( { node: 'token_'+token.x+'_'+token.y  } )
                                 
                ] ); // end of dojo.fx.chain

                // ... and launch the animation
                anim.play();                
            }
        },

The list of the discs to be turned over has been made available by our server side code in notif.args.turnedOver (see previous paragraph). We loop through all these discs, and create a complex animation using dojo.Animation for each of them. The complete documentation on dojo animations can be found here.

In few words: we create a chain of 4 animations to make the disc fade out, fade in, fade out again, and fade in again. At the end of the second fade out, we change the color of the disc. Finally, we launch the animation with play().

And Also the notification to update the scores:

notif_newScores: function( notif )
        {
            for( var player_id in notif.args.scores )
            {
                var newScore = notif.args.scores[ player_id ];
                this.scoreCtrl[ player_id ].toValue( newScore );
            }
        },