Building Browsergames » buildingbrowsergames http://buildingbrowsergames.com Ever wanted to build a browsergame? Mon, 29 Mar 2010 14:00:39 +0000 http://wordpress.org/?v=2.8.5 en hourly 1 We’re Finished! http://buildingbrowsergames.com/2009/02/19/were-finished/ http://buildingbrowsergames.com/2009/02/19/were-finished/#comments Thu, 19 Feb 2009 14:00:05 +0000 Luke http://buildingbrowsergames.com/?p=775 It’s been just about 10 months since we first began our tutorial, by designing the database for our game. Over the months, our game has grown and evolved – and for the most part, we have fulfilled our original goal: to build a basic browsergame.

Over the course of our tutorial, we’ve:

  • Built a basic authentication system
  • Added some simple stat storage and retrieval for every entity in our game
  • Created an items system
  • Created a basic combat system
  • Built armor and weapons into our combat system
  • Fleshed out our exploration system to support multiple areas

While that might not seem like much, what’s important here is that we’ve laid the groundwork for something bigger – and if you were thinking of building your own game and not sure where to start, now you’ve got your starting point.

Not sure what to do next? How about:

  • Building quests
  • Player vs. Player combat
  • More shops
  • More items
  • Player rankings

With the code that we’ve written for our tutorial(which you can get from the Google Code project), you’ve got a decent starting point for your own game.

With that being said, we’re finished! The first tutorial is complete – now go out and make something with it!

What do you want to see in the next tutorial? What could have been better about this one? Send your thoughts and suggestions to buildingbrowsergames@gmail.com.

]]> http://buildingbrowsergames.com/2009/02/19/were-finished/feed/ 10 Implementing Multiple Areas (Perl) http://buildingbrowsergames.com/2009/01/19/implementing-multiple-areas-perl/ http://buildingbrowsergames.com/2009/01/19/implementing-multiple-areas-perl/#comments Mon, 19 Jan 2009 14:00:58 +0000 Luke http://buildingbrowsergames.com/?p=689 Now that our database is prepared for multiple areas, we are going to build multiple areas into our exploration/combat system.

To start off, check out version 47 of our code from the Google Code Project:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/php/pbbg tutorial -r 47

With a fresh checkout of the code, we can get started. The first thing we will do is copy the code from forest.cgi over to explore.cgi, which is where we will now be storing our exploration code. Once that’s done, we will need to change the way that our script retrieves the current monster for a player to fight:

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my $area_id = $query->url_param('area');
$sth = $dbh->prepare("SELECT monster FROM area_monsters WHERE area = ? ORDER BY RAND() LIMIT 1");
$sth->execute($area_id);
my $monster_id;
$sth->bind_columns(\$monster_id);
$sth->fetch;
$sth = $dbh->prepare("SELECT name FROM monsters WHERE id = ?");
$sth->execute($monster_id);
$sth->bind_columns(\$parameters{monster});
$sth->fetch;

Because we will be intermingling arguments passed through both GET and POST for our code, we have to use the url_param method – we will also need to make a slight change to how we determine whether we’re being POST’d to or not:

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if($query->request_method() eq 'POST') {

With our code changes made, we need to put areas and monsters in areas into our database for our code to retrieve:

INSERT INTO areas(name) VALUES ('Forest');
INSERT INTO areas(name) VALUES ('Woods');
INSERT INTO area_monsters(area,monster) VALUES (1,1);
INSERT INTO area_monsters(area,monster) VALUES (1,2);
INSERT INTO area_monsters(area,monster) VALUES (2,3);

Once the data is inserted, our changes are (mostly) complete. Try visiting explore.cgi?area=1, and refreshing a few times – you should only ever see monsters appearing that belong in the area with the ID of 1.

While you are testing that, you may have noticed that the title tag for our page still says ‘The Forest’ – we should probably modify our code to also retrieve the name of the area we’re visiting:

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my $area_id = $arguments{'area'};
$sth = $dbh->prepare("SELECT name FROM areas WHERE id = ?");
$sth->execute($area_id);
$sth->bind_columns(\$parameters{area_name});
$sth->fetch;
 
my $template = HTML::Template->new(
		filename	=>	'explore.tmpl',

With that code added, it’s easy enough to tweak our template(renamed from forest.tmpl to explore.tmpl) to display the current area in it’s <title> tag, in addition to changing where our combat form POSTs to:

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    	<title>The <!--tmpl_var name='area_name'--></title>
    </head>
    <body>
    	<tmpl_unless name='combat'>
    		<p>You've encountered a <!--tmpl_var name='monster'-->!</p>
    		<form action='explore.cgi?area=<!--tmpl_var name='area'-->' method='post'>
    			<input type='submit' name='action' value='Attack' /> or 
    			<input type='submit' name='action' value='Run Away' />
    			<input type='hidden' name='monster' value='<!--tmpl_var name='monster'-->' />
    		</form>
    	<tmpl_else>
    		<ul>
    		<tmpl_loop name='combat'>
    			<li><strong><!--tmpl_var name='attacker'--></strong> attacks <!--tmpl_var name='defender'--> for <!--tmpl_var name='damage'--> damage!</li>
    		</tmpl_loop>
    		</ul>
    		<tmpl_if name='won'>
    			<p>You killed <strong><!--tmpl_var name='monster'--></strong>! You gained <strong><!--tmpl_var name='gold'--></strong> gold, and <strong><!--tmpl_var name='exp'--></strong> experience.</p>
    			<tmpl_if name='level_up'>
        			<p><strong>You gained a level!</strong></p>
    			</tmpl_if>
    			<p>You found a <strong><!--tmpl_var name='item'--></strong>!</p>
    			<p><a href='explore.cgi?area=<!--tmpl_var name='area'-->'>Explore Again</a></p>

With our template changes finished, we’re done! Your game can now support multiple different areas that players can encounter enemies in – all you have to do is link them to explore.cgi?area=<area_id>, where <area_id> is an ID for an area in the database. Here’s what our new code looks like:

explore.cgi:

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#!/usr/bin/perl -w
 
use strict;
use CGI qw(:cgi);
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
use Data::Dumper;
use HTML::Template;
use DBI;
use config;
use weaponstats;
 
my $query = new CGI;
my %arguments = $query->Vars;
 
my $dbh = DBI->connect("DBI:mysql:$config{dbName}:$config{dbHost}",$config{dbUser},$config{dbPass},{RaiseError => 1});
my $sth;
my %parameters;
 
if($query->request_method() eq 'POST') {
	if($arguments{action} eq 'Attack') {
		# fighting the monster	
		use stats;
		use monsterstats;
		my $cookie = $query->cookie('username+password'); 
		my ($username) = split(/\+/,$cookie);
		$sth = $dbh->prepare("SELECT id FROM users WHERE UPPER(username) = UPPER(?)");
		$sth->execute($username);
		my $userID;
		$sth->bind_columns(\$userID);
		$sth->fetch;
		my %player = (
			name		=>	$username,
			attack		=>	stats::getStat('atk',$userID),
			defence		=>	stats::getStat('def',$userID),
			curhp		=>	stats::getStat('curhp',$userID)
		);
		my $phand = stats::getStat('phand',$userID);
		$player{attack} += weaponstats::getWeaponStat('atk',$phand);
		use armorstats;
		my @armor = qw(atorso ahead alegs aright aleft);
		foreach my $key(@armor) {
			my $id = stats::getStat($key,$userID);
			my $defence = armorstats::getArmorStat('defence',$id);
			$player{defence} += $defence;
		}		
		$sth = $dbh->prepare("SELECT id FROM monsters WHERE name = ?");
		$sth->execute($arguments{monster});
		my $monsterID;
		$sth->bind_columns(\$monsterID);
		$sth->fetch;
		my %monster = (
			name		=>	$arguments{monster},
			attack		=>	monsterstats::getMonsterStat('atk',$monsterID),
			defence		=>	monsterstats::getMonsterStat('def',$monsterID),
			curhp		=>	monsterstats::getMonsterStat('maxhp',$monsterID)
		);
		my @combat;
		my $turns = 0;
		my ($attacker,$defender);
		while($player{curhp} > 0 && $monster{curhp} > 0) {
			my %attack;
			if($turns % 2 != 0) {
				$attacker = \%monster;
				$defender = \%player;
			} else {
				$attacker = \%player;
				$defender = \%monster;
			}
			my $damage = 0;
			if($attacker->{attack} > $defender->{defence}) {
				$damage = $attacker->{attack} - $defender->{defence};	
			}
			my %attack = (
				attacker => $attacker->{name},
				defender => $defender->{name},
				damage => $damage
			);
			$defender->{curhp} -= $damage;
			push @combat, \%attack;
			$turns++;
		}
		stats::setStat('curhp',$userID,$player{curhp});
		if($player{curhp} > 0) {
			# player won
			stats::setStat('gc',$userID,stats::getStat('gc',$userID) + monsterstats::getMonsterStat('gc',$monsterID));
			$parameters{won} = 1;
			$parameters{gold} = monsterstats::getMonsterStat('gc',$monsterID);
			my $rand = int(rand(99))+1;
			$sth = $dbh->prepare("SELECT item_id FROM monster_items WHERE monster_id = ? AND rarity >= ? ORDER BY RAND() LIMIT 1");
			$sth->execute($monsterID,$rand);
			my $itemID;
			$sth->bind_columns(\$itemID);
			$sth->fetch;
			$sth = $dbh->prepare("SELECT count(id) FROM user_items WHERE user_id = ? AND item_id = ?");
			$sth->execute($userID,$itemID);
			my $count;
			$sth->bind_columns(\$count);
			$sth->fetch;
			if($count > 0) {
				# already has one of the item
				$sth = $dbh->prepare("UPDATE user_items SET quantity = quantity + 1 WHERE user_id = ? AND item_id = ?");
			} else {
				# has none of the item - new row
				$sth = $dbh->prepare("INSERT INTO user_items(quantity,user_id,item_id) VALUES (1,?,?)");
			}
			$sth->execute($userID,$itemID);
			$sth = $dbh->prepare("SELECT name FROM items WHERE id = ?");
			$sth->execute($itemID);
			$sth->bind_columns(\$parameters{item});
			$sth->fetch;
 
            my $monster_exp = monsterstats::getMonsterStat('exp',$monsterID);
            $parameters{exp} = $monster_exp;
            my $exp_rem = stats::getStat('exp_rem',$userID);
            $exp_rem -= $monster_exp;
            if($exp_rem <= 0) {
                $exp_rem = 100;
                $parameters{level_up} = 1;
            }
            stats::setStat('exp_rem',$userID,$exp_rem);   		
		} else {
			# monster won	
			$parameters{lost} = 1;
		}
		$parameters{combat} = \@combat;
	} else {
		# running away - back to the index page!
		print $query->redirect('index.cgi');
	}	
} else {
    my $area_id = $arguments{'area'};
    $sth = $dbh->prepare("SELECT monster FROM area_monsters WHERE area = ? ORDER BY RAND() LIMIT 1");
    $sth->execute($area_id);
    my $monster_id;
    $sth->bind_columns(\$monster_id);
    $sth->fetch;
    $sth = $dbh->prepare("SELECT name FROM monsters WHERE id = ?");
    $sth->execute($monster_id);
    $sth->bind_columns(\$parameters{monster});
    $sth->fetch;
}
 
my $area_id = $query->url_param('area');
$sth = $dbh->prepare("SELECT name FROM areas WHERE id = ?");
$sth->execute($area_id);
$sth->bind_columns(\$parameters{area_name});
$sth->fetch;
 
my $template = HTML::Template->new(
		filename	=>	'explore.tmpl',
		associate	=>	$query,
	);
$template->param(%parameters);
print $query->header(), $template->output;

explore.tmpl:

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<html>
<head>
	<title>The <!--tmpl_var name='area_name'--></title>
</head>
<body>
	<tmpl_unless name='combat'>
		<p>You've encountered a <!--tmpl_var name='monster'-->!</p>
		<form action='explore.cgi?area=<!--tmpl_var name='area'-->' method='post'>
			<input type='submit' name='action' value='Attack' /> or 
			<input type='submit' name='action' value='Run Away' />
			<input type='hidden' name='monster' value='<!--tmpl_var name='monster'-->' />
		</form>
	<tmpl_else>
		<ul>
		<tmpl_loop name='combat'>
			<li><strong><!--tmpl_var name='attacker'--></strong> attacks <!--tmpl_var name='defender'--> for <!--tmpl_var name='damage'--> damage!</li>
		</tmpl_loop>
		</ul>
		<tmpl_if name='won'>
			<p>You killed <strong><!--tmpl_var name='monster'--></strong>! You gained <strong><!--tmpl_var name='gold'--></strong> gold, and <strong><!--tmpl_var name='exp'--></strong> experience.</p>
			<tmpl_if name='level_up'>
    			<p><strong>You gained a level!</strong></p>
			</tmpl_if>
			<p>You found a <strong><!--tmpl_var name='item'--></strong>!</p>
			<p><a href='explore.cgi?area=<!--tmpl_var name='area'-->'>Explore Again</a></p>
		</tmpl_if>
		<tmpl_if name='lost'>
			<p>You were killed by <strong><!--tmpl_var name='monster'--></strong>.</p>
		</tmpl_if>
		<p><a href='index.cgi'>Back to main</a></p>
	</tmpl_unless>
</body>
</html>

Extra Credit

  • Make the explore page verify that the area ID passed to explore.cgi actaully exists within the database(hint: SELECT COUNT).
]]> http://buildingbrowsergames.com/2009/01/19/implementing-multiple-areas-perl/feed/ 0 Implementing Multiple Areas (PHP) http://buildingbrowsergames.com/2009/01/15/implementing-multiple-areas-php/ http://buildingbrowsergames.com/2009/01/15/implementing-multiple-areas-php/#comments Thu, 15 Jan 2009 14:00:11 +0000 Luke http://buildingbrowsergames.com/?p=686 Now that we’ve prepared our database for multiple areas, it’s time to build multiple area support into our exploration/combat system.

To begin with, check out version 46 from the Google Code Project:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/php/pbbg tutorial -r 46

With that done, we can get down to business. Start by copying all of forest.php’s code over to explore.php, which is going to be the new location of our exploration code. Once that’s done, we need to change the way that our script retrieves the current monster for a player to fight:

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$area_id = $_GET['area'];
$query = sprintf("SELECT monster FROM area_monsters WHERE area = %s ORDER BY RAND() LIMIT 1",
    mysql_real_escape_string($area_id));
$result = mysql_query($query);
list($monster_id) = mysql_fetch_row($result);
$query = sprintf("SELECT name FROM monsters WHERE id = %s",
    mysql_real_escape_string($monster_id));
$result = mysql_query($query);
list($monster) = mysql_fetch_row($result);
$smarty->assign('monster',$monster);

Note: this code should overwrite your old code, starting at line 129. We are modifying the way that monster retrieval works.

With the code changes made, we should set up areas and monsters in areas for our code to retrieve:

INSERT INTO areas(name) VALUES ('Forest');
INSERT INTO areas(name) VALUES ('Woods');
INSERT INTO area_monsters(area,monster) VALUES (1,1);
INSERT INTO area_monsters(area,monster) VALUES (1,2);
INSERT INTO area_monsters(area,monster) VALUES (2,3);

With the new data inserted, try visiting explore.php?area=1, and see what happens – you should only ever see monsters that belong in the area with the ID of 1.

While you’re testing, you might notice that the title tag of our page still says ‘The Forest’ – while we’re at it, we may as well modify our code to also retrieve the name of the area we are currently visiting:

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$query = sprintf("SELECT name FROM areas WHERE id = %s",
    mysql_real_escape_string($_GET['area']));
$result = mysql_query($query);
list($area_name) = mysql_fetch_row($result);
$smarty->assign('area',$area_name);
$smarty->assign('area_id',$_GET['area']);
 
$smarty->display('explore.tpl');

That code should be outside any of the code responding to whether our page is being POST’d to or not; we need to set the page title properly whether we’re just encountering something, or completing a fight. You’ll notice that we have also set the area_id – this is because we will need to tweak where the form in our template goes, in addition to renaming it from forest.tpl to explore.tpl:

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	<title>The {$area}</title>
</head>
<body>
	{if $combat eq ''}
		<p>You've encountered a {$monster}!</p>
		<form action='explore.php?area={$area_id}' method='post'>
			<input type='submit' name='action' value='Attack' /> or 
			<input type='submit' name='action' value='Run Away' />
			<input type='hidden' name='monster' value='{$monster}' />
		</form>
	{else}
		<ul>
		{foreach from=$combat key=id item=i}
			<li><strong>{$i.attacker}</strong> attacks {$i.defender} for {$i.damage} damage!</li>
		{/foreach}
		</ul>
		{if $won eq 1}
			<p>You killed <strong>{$smarty.post.monster}</strong>! You gained <strong>{$gold}</strong> gold, and {$exp} experience.</p>
			{if $level_up eq 1}
			    <p><strong>You gained a level!</strong></p>
			{/if}
			<p>You found a <strong>{$item}</strong>!</p>
			<p><a href='explore.php?area={$area_id}'>Explore Again</a></p>

With those changes made, we’re finished! Your game can now support multiple different areas where players can encounter enemies – just link them to explore.php?area=1 for area 1, explore.php?area=2 for area 2, and so on. Here’s what our new code files look like:

explore.php:

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<?php
 
require_once 'smarty.php';
require_once 'weapon-stats.php';
require_once 'login-check.php';
 
session_start();
 
require_once 'config.php';		// our database settings
$conn = mysql_connect($dbhost,$dbuser,$dbpass)
	or die('Error connecting to mysql');
mysql_select_db($dbname);
 
if($_POST) {
	if($_POST['action'] == 'Attack') {
		require_once 'stats.php';			// player stats
		require_once 'monster-stats.php';	// monster stats
		// to begin with, we'll retrieve our player and our monster stats 
		$query = sprintf("SELECT id FROM users WHERE UPPER(username) = UPPER('%s')",
					mysql_real_escape_string($_SESSION['username']));
		$result = mysql_query($query);
		list($userID) = mysql_fetch_row($result);
		$player = array (
			name		=>	$_SESSION['username'],
			attack 		=>	getStat('atk',$userID),
			defence		=>	getStat('def',$userID),
			curhp		=>	getStat('curhp',$userID)
		);
		$phand = getStat('phand',$userID);
		$atk = getWeaponStat('atk',$phand);
		$player['attack'] += $atk;
		require_once 'armor-stats.php';		// armor stats
		$armor = array('atorso','ahead','alegs','aright','aleft');
		foreach ($armor as $key) {
			$id = getStat($key,$userID);
			$defence = getArmorStat('defence',$id);
			$player['defence'] += $defence;
		}		
 
		$query = sprintf("SELECT id FROM monsters WHERE name = '%s'",
					mysql_real_escape_string($_POST['monster']));
		$result = mysql_query($query);
		list($monsterID) = mysql_fetch_row($result);
		$monster = array (
			name		=>	$_POST['monster'],
			attack		=>	getMonsterStat('atk',$monsterID),
			defence		=>	getMonsterStat('def',$monsterID),
			curhp		=>	getMonsterStat('maxhp',$monsterID)
		);
		$combat = array();
		$turns = 0;		
		while($player['curhp'] > 0 && $monster['curhp'] > 0 && $turns <= 100) {
			if($turns % 2 != 0) {
				$attacker = &$monster;
				$defender = &$player;	
			} else {
				$attacker = &$player;
				$defender = &$monster;
			}
			$damage = 0;
			if($attacker['attack'] > $defender['defence']) {
				$damage = $attacker['attack'] - $defender['defence'];	
			}
			$defender['curhp'] -= $damage;
			$combat[$turns] = array(
				attacker	=>	$attacker['name'],
				defender	=>	$defender['name'],
				damage		=>	$damage
			);
			$turns++;
		}
		setStat('curhp',$userID,$player['curhp']);
		if($player['curhp'] > 0) {
			// player won
			setStat('gc',$userID,getStat('gc',$userID)+getMonsterStat('gc',$monsterID));	
			$smarty->assign('won',1);
			$smarty->assign('gold',getMonsterStat('gc',$monsterID));
			$rand = rand(0,100);
			$query = sprintf("SELECT item_id FROM monster_items WHERE monster_id = %s AND rarity >= %s ORDER BY RAND() LIMIT 1",
				mysql_real_escape_string($monsterID),
				mysql_real_escape_string($rand));
			$result = mysql_query($query);
			list($itemID) = mysql_fetch_row($result);
			$query = sprintf("SELECT count(id) FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
				mysql_real_escape_string($userID),mysql_real_escape_string($itemID));
			$result = mysql_query($query);
			list($count) = mysql_fetch_row($result);
			if ($count > 0) {
				# already has one of the item
				$query = sprintf("UPDATE user_items SET quantity = quantity + 1 WHERE user_id = '%s' AND item_id = '%s'",
					mysql_real_escape_string($userID),
					mysql_real_escape_string($itemID));
			} else {
				# has none - new row
				$query = sprintf("INSERT INTO user_items(quantity,user_id,item_id) VALUES (1,'%s','%s')",
					mysql_real_escape_string($userID),
					mysql_real_escape_string($itemID));
			}
			mysql_query($query);
			# retrieve the item name, so that we can display it
			$query = sprintf("SELECT name FROM items WHERE id = %s",
				mysql_real_escape_string($itemID));
			$result = mysql_query($query);
			list($itemName) = mysql_fetch_row($result);
			$smarty->assign('item',$itemName);
 
			$monster_exp = getMonsterStat('exp',$monsterID);
			$smarty->assign('exp',$monster_exp);
			$exp_rem = getStat('exp_rem',$userID);
			$exp_rem -= $monster_exp;
			$level_up = 0;
			if($exp_rem <= 0) {
			    // level up!
			    $exp_rem = 100;
			    $level_up = 1;
			}
		    $smarty->assign('level_up',$level_up);
			setStat('exp_rem',$userID,$exp_rem);
		} else {
			// monster won
			$smarty->assign('lost',1);	
		}
		$smarty->assign('combat',$combat);
	} else {
		// Running away! Send them back to the main page
		header('Location: index.php');	
	}
} else {
    $area_id = $_GET['area'];
    $query = sprintf("SELECT monster FROM area_monsters WHERE area = %s ORDER BY RAND() LIMIT 1",
        mysql_real_escape_string($area_id));
    $result = mysql_query($query);
    list($monster_id) = mysql_fetch_row($result);
    $query = sprintf("SELECT name FROM monsters WHERE id = %s",
        mysql_real_escape_string($monster_id));
    $result = mysql_query($query);
    list($monster) = mysql_fetch_row($result);
    $smarty->assign('monster',$monster);
}
 
$query = sprintf("SELECT name FROM areas WHERE id = %s",
    mysql_real_escape_string($_GET['area']));
$result = mysql_query($query);
list($area_name) = mysql_fetch_row($result);
$smarty->assign('area',$area_name);
$smarty->assign('area_id',$_GET['area']);
 
$smarty->display('explore.tpl');
 
?>

explore.tpl:

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<html>
<head>
	<title>The {$area}</title>
</head>
<body>
	{if $combat eq ''}
		<p>You've encountered a {$monster}!</p>
		<form action='explore.php?area={$area_id}' method='post'>
			<input type='submit' name='action' value='Attack' /> or 
			<input type='submit' name='action' value='Run Away' />
			<input type='hidden' name='monster' value='{$monster}' />
		</form>
	{else}
		<ul>
		{foreach from=$combat key=id item=i}
			<li><strong>{$i.attacker}</strong> attacks {$i.defender} for {$i.damage} damage!</li>
		{/foreach}
		</ul>
		{if $won eq 1}
			<p>You killed <strong>{$smarty.post.monster}</strong>! You gained <strong>{$gold}</strong> gold, and {$exp} experience.</p>
			{if $level_up eq 1}
			    <p><strong>You gained a level!</strong></p>
			{/if}
			<p>You found a <strong>{$item}</strong>!</p>
			<p><a href='explore.php?area={$area_id}'>Explore Again</a></p>
		{/if}
		{if $lost eq 1}
			<p>You were killed by <strong>{$smarty.post.monster}</strong>.</p>
		{/if}		
			<p><a href='index.php'>Back to main</a></p>
	{/if}
</body>
</html>

Extra Credit

  • Make it so that when the user visits explore.php without passing in an area to visit, a random area is selected for them to explore.
]]> http://buildingbrowsergames.com/2009/01/15/implementing-multiple-areas-php/feed/ 0 Adding Experience to our Combat System(Perl) http://buildingbrowsergames.com/2009/01/08/adding-experience-to-our-combat-systemperl/ http://buildingbrowsergames.com/2009/01/08/adding-experience-to-our-combat-systemperl/#comments Thu, 08 Jan 2009 14:00:38 +0000 Luke http://buildingbrowsergames.com/?p=673 I was recently e-mailed by Building Browsergames reader Mehmet Simsek – who noticed something that I completely missed: our combat system doesn’t have any experience or levelling built into it!

When a player kills a monster in the forest using our current codebase, they get gold and an item – but they don’t actually gain any experience(or levels) for killing the monster. Luckily for us, adding experience to our combat system is a quick (and fairly painless) task: we’ll start off by adding a few more stats to the database:

INSERT INTO stats(display_name, short_name) VALUES
    ('Experience','exp'),
    ('Experience Remaining', 'exp_rem');

We will use these two stats to keep track of the experience a player still needs for their next level, and the experience that a monster gives after it has been killed. Exactly what happens when a player levels up is up to you, the game developer.

We will also need to insert the values for the experience stat for our monsters into our database:

INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='exp'),(SELECT id FROM monsters WHERE name='Crazy Eric'),5,'Monster');
INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='exp'),(SELECT id FROM monsters WHERE name='Lazy Russell'),10,'Monster');
INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='exp'),(SELECT id FROM monsters WHERE name='Hard Hitting Louis'),15,'Monster');

As you can see, we are inserting rows into our entity_stats table, so that each of the monsters in our game will give different amounts of experience. With these database changes made, it’s just a matter of opening up forest.cgi and making some changes:

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my $monster_exp = monsterstats::getMonsterStat('exp',$monsterID);
$parameters{exp} = $monster_exp;
my $exp_rem = stats::getStat('exp_rem',$userID);
$exp_rem -= $monster_exp;
if($exp_rem <= 0) {
    $exp_rem = 100;
    $parameters{level_up} = 1;
}
stats::setStat('exp_rem',$userID,$exp_rem);

You may have noticed that we’re setting some new variables for our template – so we’ll need to modify forest.tmpl as well:

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<p>You killed <strong><!--tmpl_var name='monster'--></strong>! You gained <strong><!--tmpl_var name='gold'--></strong> gold, and <strong><!--tmpl_var name='exp'--></strong> experience.</p>
<tmpl_if name='level_up'>
	<p><strong>You gained a level!</strong></p>
</tmpl_if>

With all your changes made, try playing your game – you should notice the message “You gained a level!” appearing whenever your character levels up.

Extra Credit

  • Change the forest template so that in the post-combat summary, the player will also be told how much experience remains before their next level.
  • Modify the code given so that your game will track the total experience a player has collected – and also display it on the main page.
]]> http://buildingbrowsergames.com/2009/01/08/adding-experience-to-our-combat-systemperl/feed/ 0 Adding Experience to our Combat System(PHP) http://buildingbrowsergames.com/2009/01/05/adding-experience-to-our-combat-systemphp/ http://buildingbrowsergames.com/2009/01/05/adding-experience-to-our-combat-systemphp/#comments Mon, 05 Jan 2009 14:00:28 +0000 Luke http://buildingbrowsergames.com/?p=671 Building Browsergames reader Mehmet Simsek recently e-mailed me to point out something that I can’t believe I missed: our combat system doesn’t have any experience or levelling built into it!

Right now, when a player kills a monster in the forest, they get gold and an item – but they don’t get any experience. Thankfully, adding experience to our combat system is a fairly simple task: to begin with, we’ll add a few more stats to the database:

INSERT INTO stats(display_name, short_name) VALUES
    ('Experience','exp'),
    ('Experience Remaining', 'exp_rem');

These two stats will let us keep track of the player’s current experience, and the experience that a monster gives after it has been killed. We will be using both to determine when the player has levelled up – although what happens after they level up is up to you.

We will also need to insert some starter values for our monsters:

INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='exp'),(SELECT id FROM monsters WHERE name='Crazy Eric'),5,'Monster');
INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='exp'),(SELECT id FROM monsters WHERE name='Lazy Russell'),10,'Monster');
INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='exp'),(SELECT id FROM monsters WHERE name='Hard Hitting Louis'),15,'Monster');

As you can see, we have inserted rows into the entity_stats table that will make it so that the Crazy Eric monster gives 5 experience, Lazy Russell gives 10, and Hard Hitting Louis gives 15 experience.

With the neccessary database changes made, it’s just a matter of opening up forest.php and making some changes:

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$monster_exp = getMonsterStat('exp',$monsterID);
$smarty->assign('exp',$monster_exp);
$exp_rem = getStat('exp_rem',$userID);
$exp_rem -= $monster_exp;
$level_up = 0;
if($exp_rem <= 0) {
    // level up!
    $exp_rem = 100;
    $level_up = 1;
}
$smarty->assign('level_up',$level_up);
setStat('exp_rem',$userID,$exp_rem);

As you can see, we are also setting some new variables in our Smarty template – so we will need to modify that as well:

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{if $won eq 1}
	<p>You killed <strong>{$smarty.post.monster}</strong>! You gained <strong>{$gold}</strong> gold, and {$exp} experience.</p>
	{if $level_up eq 1}
	    <p><strong>You gained a level!</strong></p>
	{/if}

With those changes made, test out your game – you should notice that the message “You gained a level!” will appear occasionally while you fight monsters in the forest.

Extra Credit

  • Right now, a player will level up on their first fight, and then start levelling normally. Make it so that the first level up does not happen.
  • Modify the code given so that when a player levels up, the value of their magic, defence, or attack stat gets raised by one – randomly.
  • Modify the code given so that when a player levels up, they are allowed to choose which attribute to increase.
  • Modify the code given so that when the player levels up, a special ‘level’ stat is modified – which is then displayed on the main page.
]]> http://buildingbrowsergames.com/2009/01/05/adding-experience-to-our-combat-systemphp/feed/ 2 Our current database structure http://buildingbrowsergames.com/2008/11/13/our-current-database-structure/ http://buildingbrowsergames.com/2008/11/13/our-current-database-structure/#comments Thu, 13 Nov 2008 14:00:22 +0000 Luke http://buildingbrowsergames.com/?p=546 As we’ve been working through our tutorial, our database has undergone a lot of different changes. Sometimes columns were added to tables to accommodate new features, and sometimes tables were removed entirely. At any rate, it is clear to see that as our game has grown more complex, so has our database structure.

For someone who has been following along since the beginning, this isn’t quite as much of an issue: your database will have changed along each step of the tutorial. But for someone who has been using Google Code checkouts, you don’t necessarily know how the database has changed – which makes it a bit of work to re-create.

With that said, here is a dump of our entire database currently – which you can import with phpmyadmin or the MySQL command-line client, to build a copy of our current (working) database:

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-- phpMyAdmin SQL Dump
-- version 2.10.3deb1ubuntu0.2
-- http://www.phpmyadmin.net
 
SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
 
-- 
-- Table structure for table `entity_stats`
-- 
 
DROP TABLE IF EXISTS `entity_stats`;
CREATE TABLE IF NOT EXISTS `entity_stats` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `stat_id` int(11) DEFAULT NULL,
  `entity_id` int(11) DEFAULT NULL,
  `value` text,
  `entity_type` enum('User','Monster','Item') DEFAULT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=30 ;
 
-- 
-- Dumping data for table `entity_stats`
-- 
 
INSERT INTO `entity_stats` (`id`, `stat_id`, `entity_id`, `value`, `entity_type`) VALUES 
(1, 2, 1, '2', 'Monster'),
(2, 3, 1, '2', 'Monster'),
(3, 5, 1, '8', 'Monster'),
(4, 2, 2, '1', 'Monster'),
(5, 3, 2, '0', 'Monster'),
(6, 5, 2, '4', 'Monster'),
(7, 2, 3, '4', 'Monster'),
(8, 3, 3, '3', 'Monster'),
(9, 5, 3, '10', 'Monster'),
(10, 4, 1, '5', 'Monster'),
(11, 4, 2, '20', 'Monster'),
(12, 4, 3, '5', 'Monster'),
(13, 2, 1, '2', 'Item'),
(14, 17, 13, 'ahead', 'Item'),
(15, 17, 14, 'atorso', 'Item'),
(16, 17, 15, 'alegs', 'Item'),
(17, 17, 16, 'aright', 'Item'),
(18, 17, 17, 'aleft', 'Item'),
(19, 17, 0, '0', 'Item'),
(20, 2, 7, '0', 'Item'),
(21, 2, 0, '0', 'Item'),
(22, 18, 20, 'potion', 'Item'),
(23, 18, 21, 'crystal_ball', 'Item'),
(24, 3, 0, '0', 'Item'),
(25, 18, 4, '0', 'Item'),
(26, 18, 2, '0', 'Item'),
(27, 2, 4, '0', 'Item'),
(28, 2, 2, '0', 'Item'),
(29, 2, 5, '0', 'Item');
 
-- --------------------------------------------------------
 
-- 
-- Table structure for table `items`
-- 
 
DROP TABLE IF EXISTS `items`;
CREATE TABLE IF NOT EXISTS `items` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` text,
  `type` enum('Weapon','Armor','Usable','Foo') DEFAULT NULL,
  `price` int(11) NOT NULL DEFAULT '10',
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=21 ;
 
-- 
-- Dumping data for table `items`
-- 
 
INSERT INTO `items` (`id`, `name`, `type`, `price`) VALUES 
(1, 'Wooden Sword', 'Weapon', 10),
(2, 'Flail', 'Weapon', 15),
(3, 'Mace', 'Weapon', 10),
(4, 'Pizza Slicer', 'Weapon', 10),
(5, 'Bow and Arrows', 'Weapon', 10),
(6, 'Rolling Pin', 'Weapon', 10),
(7, 'Dagger', 'Weapon', 10),
(16, 'Sample Right Arm', 'Armor', 10),
(15, 'Sample Legs', 'Armor', 10),
(14, 'Sample Torso', 'Armor', 10),
(13, 'Sample Helmet', 'Armor', 10),
(17, 'Sample Left Arm', 'Armor', 10),
(21, 'Crystal Ball', 'Usable', 10),
(20, 'Red Potion', 'Usable', 10);
 
-- --------------------------------------------------------
 
-- 
-- Table structure for table `monsters`
-- 
 
DROP TABLE IF EXISTS `monsters`;
CREATE TABLE IF NOT EXISTS `monsters` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` text,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ;
 
-- 
-- Dumping data for table `monsters`
-- 
 
INSERT INTO `monsters` (`id`, `name`) VALUES 
(1, 'Crazy Eric'),
(2, 'Lazy Russell'),
(3, 'Hard Hitting Louis');
 
-- --------------------------------------------------------
 
-- 
-- Table structure for table `monster_items`
-- 
 
DROP TABLE IF EXISTS `monster_items`;
CREATE TABLE IF NOT EXISTS `monster_items` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `monster_id` int(11) DEFAULT NULL,
  `item_id` int(11) DEFAULT NULL,
  `rarity` int(11) DEFAULT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;
 
-- 
-- Dumping data for table `monster_items`
-- 
 
INSERT INTO `monster_items` (`id`, `monster_id`, `item_id`, `rarity`) VALUES 
(1, 1, 1, 100),
(2, 2, 2, 100),
(3, 3, 4, 100),
(4, 4, 5, 100);
 
-- --------------------------------------------------------
 
-- 
-- Table structure for table `stats`
-- 
 
DROP TABLE IF EXISTS `stats`;
CREATE TABLE IF NOT EXISTS `stats` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `display_name` text,
  `short_name` varchar(10) DEFAULT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=19 ;
 
-- 
-- Dumping data for table `stats`
-- 
 
INSERT INTO `stats` (`id`, `display_name`, `short_name`) VALUES 
(1, 'Magic', 'mag'),
(2, 'Attack', 'atk'),
(3, 'Defence', 'def'),
(4, 'Gold', 'gc'),
(5, 'Maximum HP', 'maxhp'),
(6, 'Current HP', 'curhp'),
(7, 'Set Default HP Values', 'sethp'),
(8, 'Gold In Bank', 'bankgc'),
(9, 'Password Reset - hash vulnerability', 'pwrd'),
(10, 'Primary Hand Weapon', 'phand'),
(11, 'Secondary Hand Weapon', 'shand'),
(12, 'Armor - Head', 'ahead'),
(13, 'Armor - Torso', 'atorso'),
(14, 'Armor - Legs', 'alegs'),
(15, 'Armor - Right Arm', 'aright'),
(16, 'Armor - Left Arm', 'aleft'),
(17, 'Item Armor Slot', 'aslot'),
(18, 'Item Use Token', 'token');
 
-- --------------------------------------------------------
 
-- 
-- Table structure for table `users`
-- 
 
DROP TABLE IF EXISTS `users`;
CREATE TABLE IF NOT EXISTS `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(250) DEFAULT NULL,
  `password` varchar(50) DEFAULT NULL,
  `is_admin` tinyint(1) NOT NULL DEFAULT '0',
  `last_login` timestamp NULL DEFAULT NULL,
  `email` text NOT NULL,
  `confirmed` tinyint(1) NOT NULL DEFAULT '0',
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
 
 
-- --------------------------------------------------------
 
-- 
-- Table structure for table `user_items`
-- 
 
DROP TABLE IF EXISTS `user_items`;
CREATE TABLE IF NOT EXISTS `user_items` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `item_id` int(11) NOT NULL,
  `quantity` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

While this dump is relatively useless for people working with a framework like Rails or Django, it will help those of you who are using Perl or PHP to build a game – and therefore don’t have your database generated for you by your framework.

One of the benefits of this dump is that it’s pristine – there are no user accounts or user inventories being stored. It also includes all of the ‘DROP TABLE’ statements at the beginning – so if you want to ‘reset’ your game, you can easily do so by just re-running this SQL.

]]> http://buildingbrowsergames.com/2008/11/13/our-current-database-structure/feed/ 3 Dropping Items (Perl) http://buildingbrowsergames.com/2008/10/23/dropping-items-perl/ http://buildingbrowsergames.com/2008/10/23/dropping-items-perl/#comments Thu, 23 Oct 2008 14:00:29 +0000 Luke http://buildingbrowsergames.com/?p=520 Now that we’ve built a way for users to buy items, we need a way for users to get items – by killing monsters. Today, we’ll be adding drops to our combat system.

To begin with, check out a recent copy of the source code for our tutorial:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/perl/pbbg tutorial -r 42

In order to keep track of the items that our monsters drop, we need to add another table to our database:

CREATE TABLE monster_items (
	id int NOT NULL AUTO_INCREMENT,
	monster_id int,
	item_id int,
	rarity int,
	PRIMARY KEY(id)
);

The monster_items table will be what we use to keep track of the items that monsters can drop after users kill them. Most of this table explains itself – but you might be wondering about what the ‘rarity’ column is there for. Essentially, the ‘rarity’ column is there for exactly what it says it’s there for; defining the rarity of a drop! We will use the value in the column to randomly determine which items drop from a monster – allowing us to have item A at 10% rarity, and item B at 90% rarity from the same monster.

With our table created, let’s move on to writing some code. We’ll get the ball rolling with a slight tweak to forest.tmpl:

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<p>You found a <strong><!--tmpl_var name='item'--></strong>!</p>

We will be using that extra piece of code in our template to display the item that the user gains after killing the monster.

With our template tweaked, we can move on to writing some actual code inside forest.cgi:

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my $rand = int(rand(100));
$sth = $dbh->prepare("SELECT item_id FROM monster_items WHERE monster_id = ? AND rarity >= ? ORDER BY RAND() LIMIT 1");
$sth->execute($monsterID,$rand);
my $itemID;
$sth->bind_columns(\$itemID);
$sth->fetch;
$sth = $dbh->prepare("SELECT count(id) FROM user_items WHERE user_id = ? AND item_id = ?");
$sth->execute($userID,$itemID);
my $count;
$sth->bind_columns(\$count);
$sth->fetch;
if($count > 0) {
	# already has one of the item
	$sth = $dbh->prepare("UPDATE user_items SET quantity = quantity + 1 WHERE user_id = ? AND item_id = ?");
} else {
	# has none of the item - new row
	$sth = $dbh->prepare("INSERT INTO user_items(quantity,user_id,item_id) VALUES (1,?,?)");
}
$sth->execute($userID,$itemID);
$sth = $dbh->prepare("SELECT name FROM items WHERE id = ?");
$sth->execute($itemID);
$sth->bind_columns(\$parameters{item});
$sth->fetch;

If you’ve been paying attention, you might have noticed that this code is (for the most part), an exact copy of the code from our items shop from earlier. The only ‘new’ part of this code is the first 5 lines or so; it is there that we retrieve the new loot for the user. To begin with, we generate a random number between 0, and 100. While we don’t really need to pass the value through int(), it makes the number a lot simpler to work with(as it’s now 20, instead of 20.020859). Next, we use a single line of SQL to retrieve a random item for the player that is A) dropped by the monster, and B) has a rarity greater than or equal to the value that we randomly generated earlier. We use the ORDER BY RAND() clause to randomize within our results, and finally add LIMIT 1 to make sure that we only get one back. Once we’ve retrieved the random item to add to the player’s inventory, we’re finished – users can now received random items from the monsters that they kill in combat.

Here’s the updated forest.cgi:

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#!/usr/bin/perl -w
 
use strict;
use CGI qw(:cgi);
use HTML::Template;
use DBI;
use config;
 
my $query = new CGI;
my %arguments = $query->Vars;
 
my $dbh = DBI->connect("DBI:mysql:$config{dbName}:$config{dbHost}",$config{dbUser},$config{dbPass},{RaiseError => 1});
my $sth;
my %parameters;
 
if(%arguments) {
	if($arguments{action} eq 'Attack') {
		# fighting the monster	
		use stats;
		use monsterstats;
		my $cookie = $query->cookie('username+password'); 
		my ($username) = split(/\+/,$cookie);
		$sth = $dbh->prepare("SELECT id FROM users WHERE UPPER(username) = UPPER(?)");
		$sth->execute($username);
		my $userID;
		$sth->bind_columns(\$userID);
		$sth->fetch;
		my %player = (
			name		=>	$username,
			attack		=>	stats::getStat('atk',$userID),
			defence		=>	stats::getStat('def',$userID),
			curhp		=>	stats::getStat('curhp',$userID)
		);
		my $phand = stats::getStat('phand',$userID);
		$player{attack} += weaponstats::getWeaponStat('atk',$phand);
		use armorstats;
		my @armor = qw(atorso ahead alegs aright aleft);
		foreach my $key(@armor) {
			my $id = stats::getStat($key,$userID);
			my $defence = armorstats::getArmorStat('defence',$id);
			$player{defence} += $defence;
		}		
		$sth = $dbh->prepare("SELECT id FROM monsters WHERE name = ?");
		$sth->execute($arguments{monster});
		my $monsterID;
		$sth->bind_columns(\$monsterID);
		$sth->fetch;
		my %monster = (
			name		=>	$arguments{monster},
			attack		=>	monsterstats::getMonsterStat('atk',$monsterID),
			defence		=>	monsterstats::getMonsterStat('def',$monsterID),
			curhp		=>	monsterstats::getMonsterStat('maxhp',$monsterID)
		);
		my @combat;
		my $turns = 0;
		my ($attacker,$defender);
		while($player{curhp} > 0 && $monster{curhp} > 0) {
			my %attack;
			if($turns % 2 != 0) {
				$attacker = \%monster;
				$defender = \%player;
			} else {
				$attacker = \%player;
				$defender = \%monster;
			}
			my $damage = 0;
			if($attacker->{attack} > $defender->{defence}) {
				$damage = $attacker->{attack} - $defender->{defence};	
			}
			my %attack = (
				attacker => $attacker->{name},
				defender => $defender->{name},
				damage => $damage
			);
			$defender->{curhp} -= $damage;
			push @combat, \%attack;
			$turns++;
		}
		stats::setStat('curhp',$userID,$player{curhp});
		if($player{curhp} > 0) {
			# player won
			stats::setStat('gc',$userID,stats::getStat('gc',$userID) + monsterstats::getMonsterStat('gc',$monsterID));
			$parameters{won} = 1;
			$parameters{gold} = monsterstats::getMonsterStat('gc',$monsterID);
			my $rand = int(rand(99))+1;
			$sth = $dbh->prepare("SELECT item_id FROM monster_items WHERE monster_id = ? AND rarity >= ? ORDER BY RAND() LIMIT 1");
			$sth->execute($monsterID,$rand);
			my $itemID;
			$sth->bind_columns(\$itemID);
			$sth->fetch;
			$sth = $dbh->prepare("SELECT count(id) FROM user_items WHERE user_id = ? AND item_id = ?");
			$sth->execute($userID,$itemID);
			my $count;
			$sth->bind_columns(\$count);
			$sth->fetch;
			if($count > 0) {
				# already has one of the item
				$sth = $dbh->prepare("UPDATE user_items SET quantity = quantity + 1 WHERE user_id = ? AND item_id = ?");
			} else {
				# has none of the item - new row
				$sth = $dbh->prepare("INSERT INTO user_items(quantity,user_id,item_id) VALUES (1,?,?)");
			}
			$sth->execute($userID,$itemID);
			$sth = $dbh->prepare("SELECT name FROM items WHERE id = ?");
			$sth->execute($itemID);
			$sth->bind_columns(\$parameters{item});
			$sth->fetch;
		} else {
			# monster won	
			$parameters{lost} = 1;
		}
		$parameters{combat} = \@combat;
	} else {
		# running away - back to the index page!
		print $query->redirect('index.cgi');
	}	
} else {
	$sth = $dbh->prepare("SELECT name FROM monsters ORDER BY RAND() LIMIT 1");
	$sth->execute();
	my $monster;
	$sth->bind_columns(\$monster);
	$sth->fetch;
	$parameters{monster} = $monster;
}
 
 
my $template = HTML::Template->new(
		filename	=>	'forest.tmpl',
		associate	=>	$query,
	);
$template->param(%parameters);
print $query->header(), $template->output;

Extra Credit

  • Change the ‘you found an item’ message to also display the total quantity of the item that is in the user’s inventory.
]]> http://buildingbrowsergames.com/2008/10/23/dropping-items-perl/feed/ 0 Dropping Items (PHP) http://buildingbrowsergames.com/2008/10/22/dropping-items-php/ http://buildingbrowsergames.com/2008/10/22/dropping-items-php/#comments Wed, 22 Oct 2008 14:00:33 +0000 Luke http://buildingbrowsergames.com/?p=514 Now that we’ve created a way for users to buy items, we need to create a way for users to get items without buying them – like from monsters they kill in combat. Today, we will be adding item drops to our combat system.

To start off, check out a recent copy of our code:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/php/pbbg tutorial -r 42

First things first, we need to add a table to our database:

CREATE TABLE monster_items (
	id int NOT NULL AUTO_INCREMENT,
	monster_id int,
	item_id int,
	rarity int,
	PRIMARY KEY(id)
);

We will be using this monster_items table to keep track of the items that users can gain after combat. The monster_id and item_id columns are fairly self-explanatory; the one column that might need some explaining is the rarity column. We will be using this column to determine how frequently different items drop from our monsters – for example, if we put a Sword into our monster_items table, with a rarity of 10, it would have a 10% chance of dropping any time that the monster it was linked to was killed. As you can see, we will be using the rarity column to define the chance of an item dropping.

With our database preparations made, let’s move on to writing some code. First, open up forest.tpl:

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<p>You found a <strong>{$item}</strong>!</p>

We will be using that brief addition to display to the user the new item that they just found. Now that we’ve modified our template, let’s make some changes to what happens when a player wins a fight:

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$rand = rand(0,100);
$query = sprintf("SELECT item_id FROM monster_items WHERE monster_id = %s AND rarity >= %s ORDER BY RAND() LIMIT 1",
	mysql_real_escape_string($monsterID),
	mysql_real_escape_string($rand));
$result = mysql_query($query);
list($itemID) = mysql_fetch_row($result);
$query = sprintf("SELECT count(id) FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
	mysql_real_escape_string($userID),mysql_real_escape_string($itemID));
$result = mysql_query($query);
list($count) = mysql_fetch_row($result);
if ($count > 0) {
	# already has one of the item
	$query = sprintf("UPDATE user_items SET quantity = quantity + 1 WHERE user_id = '%s' AND item_id = '%s'",
		mysql_real_escape_string($userID),
		mysql_real_escape_string($itemID));
} else {
	# has none - new row
	$query = sprintf("INSERT INTO user_items(quantity,user_id,item_id) VALUES (1,'%s','%s')",
		mysql_real_escape_string($userID),
		mysql_real_escape_string($itemID));
}
mysql_query($query);
# retrieve the item name, so that we can display it
$query = sprintf("SELECT name FROM items WHERE id = %s",
	mysql_real_escape_string($itemID));
$result = mysql_query($query);
list($itemName) = mysql_fetch_row($result);
$smarty->assign('item',$itemName);

Most of this code is the same code as we used to add items to the player’s inventory in our item shop from earlier. However, the first 5 lines are what we’re really interested in: they are how we retrieve the random item that the player should receive. First, we generate a value between 0 and 100 – this will be the ‘rarity barrier’. We use the number that we generated to choose items from the monster’s drop table, which have a rarity greater than or equal to our random number. For example, if we were to generate the number 20, any items with a rarity of 20 or greater would be available for the player to win as a result of their combat. Once we’ve retrieved a random item for the player, we add it to their inventory – and that’s that. You’ve seen everything else we do in this code before.

Here’s the new forest.php:

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<?php
 
require_once 'smarty.php';
require_once 'weapon-stats.php';
require_once 'login-check.php';
 
session_start();
 
require_once 'config.php';		// our database settings
$conn = mysql_connect($dbhost,$dbuser,$dbpass)
	or die('Error connecting to mysql');
mysql_select_db($dbname);
 
if($_POST) {
	if($_POST['action'] == 'Attack') {
		require_once 'stats.php';			// player stats
		require_once 'monster-stats.php';	// monster stats
		// to begin with, we'll retrieve our player and our monster stats 
		$query = sprintf("SELECT id FROM users WHERE UPPER(username) = UPPER('%s')",
					mysql_real_escape_string($_SESSION['username']));
		$result = mysql_query($query);
		list($userID) = mysql_fetch_row($result);
		$player = array (
			name		=>	$_SESSION['username'],
			attack 		=>	getStat('atk',$userID),
			defence		=>	getStat('def',$userID),
			curhp		=>	getStat('curhp',$userID)
		);
		$phand = getStat('phand',$userID);
		$atk = getWeaponStat('atk',$phand);
		$player['attack'] += $atk;
		require_once 'armor-stats.php';		// armor stats
		$armor = array('atorso','ahead','alegs','aright','aleft');
		foreach ($armor as $key) {
			$id = getStat($key,$userID);
			$defence = getArmorStat('defence',$id);
			$player['defence'] += $defence;
		}		
 
		$query = sprintf("SELECT id FROM monsters WHERE name = '%s'",
					mysql_real_escape_string($_POST['monster']));
		$result = mysql_query($query);
		list($monsterID) = mysql_fetch_row($result);
		$monster = array (
			name		=>	$_POST['monster'],
			attack		=>	getMonsterStat('atk',$monsterID),
			defence		=>	getMonsterStat('def',$monsterID),
			curhp		=>	getMonsterStat('maxhp',$monsterID)
		);
		$combat = array();
		$turns = 0;		
		while($player['curhp'] > 0 && $monster['curhp'] > 0 && $turns <= 100) {
			if($turns % 2 != 0) {
				$attacker = &$monster;
				$defender = &$player;	
			} else {
				$attacker = &$player;
				$defender = &$monster;
			}
			$damage = 0;
			if($attacker['attack'] > $defender['defence']) {
				$damage = $attacker['attack'] - $defender['defence'];	
			}
			$defender['curhp'] -= $damage;
			$combat[$turns] = array(
				attacker	=>	$attacker['name'],
				defender	=>	$defender['name'],
				damage		=>	$damage
			);
			$turns++;
		}
		setStat('curhp',$userID,$player['curhp']);
		if($player['curhp'] > 0) {
			// player won
			setStat('gc',$userID,getStat('gc',$userID)+getMonsterStat('gc',$monsterID));	
			$smarty->assign('won',1);
			$smarty->assign('gold',getMonsterStat('gc',$monsterID));
			$rand = rand(0,100);
			$query = sprintf("SELECT item_id FROM monster_items WHERE monster_id = %s AND rarity >= %s ORDER BY RAND() LIMIT 1",
				mysql_real_escape_string($monsterID),
				mysql_real_escape_string($rand));
			$result = mysql_query($query);
			list($itemID) = mysql_fetch_row($result);
			$query = sprintf("SELECT count(id) FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
				mysql_real_escape_string($userID),mysql_real_escape_string($itemID));
			$result = mysql_query($query);
			list($count) = mysql_fetch_row($result);
			if ($count > 0) {
				# already has one of the item
				$query = sprintf("UPDATE user_items SET quantity = quantity + 1 WHERE user_id = '%s' AND item_id = '%s'",
					mysql_real_escape_string($userID),
					mysql_real_escape_string($itemID));
			} else {
				# has none - new row
				$query = sprintf("INSERT INTO user_items(quantity,user_id,item_id) VALUES (1,'%s','%s')",
					mysql_real_escape_string($userID),
					mysql_real_escape_string($itemID));
			}
			mysql_query($query);
			# retrieve the item name, so that we can display it
			$query = sprintf("SELECT name FROM items WHERE id = %s",
				mysql_real_escape_string($itemID));
			$result = mysql_query($query);
			list($itemName) = mysql_fetch_row($result);
			$smarty->assign('item',$itemName);				
		} else {
			// monster won
			$smarty->assign('lost',1);	
		}
		$smarty->assign('combat',$combat);
	} else {
		// Running away! Send them back to the main page
		header('Location: index.php');	
	}
} else {
	$query = sprintf("SELECT name FROM monsters ORDER BY RAND() LIMIT 1");
	$result = mysql_query($query);
	list($monster) = mysql_fetch_row($result);
	$smarty->assign('monster',$monster);
}
 
$smarty->display('forest.tpl');
 
?>

Extra Credit

  • As I mentioned, we’re duplicating code here – which is bad. Can you DRY out the code to add an item to a player’s inventory?
]]> http://buildingbrowsergames.com/2008/10/22/dropping-items-php/feed/ 0 Using Items (Perl) http://buildingbrowsergames.com/2008/10/17/using-items-perl/ http://buildingbrowsergames.com/2008/10/17/using-items-perl/#comments Fri, 17 Oct 2008 14:00:31 +0000 Luke http://buildingbrowsergames.com/?p=491 Our game is still missing something really important: items that users can actually use!

Today, we’ll be writing the code that allows our users to use the items in their inventory. To start off, check out a copy of the code for our project:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/perl/pbbg tutorial -r 38

And then we’re ready to go!

To start off, we’ll build a basic template for our inventory page, and put it inside inventory.tmpl:

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<html>
<head>
	<title>Your Inventory</title>
</head>
<body>
	<p>This is your inventory. Check out all the stuff you've got!</p>
	<tmpl_if name='message'>
		<p><!--tmpl_var name='message'--></p>
	</tmpl_if>
	<ul>
		<tmpl_loop name='inventory'>
		<li>
			<strong><!--tmpl_var name='name'--> x <!--tmpl_var name='quantity'--></strong>
			<form action='inventory.cgi' method='post'>
				<input type='hidden' name='item-id' value='<!--tmpl_var name="id"-->' />
				<input type='submit' value='Use' />
			</form>
		</li>
		</tmpl_loop>
	</ul>
</body>
</html>

With our template built, we can start writing the code inside inventory.cgi:

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#!/usr/bin/perl -w
 
use strict;
use CGI qw(:cgi);
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
use HTML::Template;
use DBI;
use config;
 
my $query = new CGI;
my %arguments = $query->Vars;
 
my $dbh = DBI->connect("DBI:mysql:$config{dbName}:$config{dbHost}",$config{dbUser},$config{dbPass},{RaiseError => 1});
my $sth;
my %parameters;
 
use stats;
 
my $cookie = $query->cookie('username+password');
my ($username) = split(/\+/,$cookie);
$sth = $dbh->prepare("SELECT id FROM users WHERE UPPER(username) = UPPER(?)");
$sth->execute($username);
my $userID;
$sth->bind_columns(\$userID);
$sth->fetch;
 
$sth = $dbh->prepare("SELECT item_id, quantity FROM user_items WHERE user_id = ?");
$sth->execute($userID);
my @inventory = ();
while(my $row = $sth->fetchrow_hashref) {
	my $sth2 = $dbh->prepare("SELECT name FROM items WHERE id = ?");
	$sth2->execute($row->{item_id});
	$sth2->bind_columns(\$row->{name});
	$sth2->fetch;
	push @inventory, $row;
}
 
$parameters{inventory} = \@inventory;
 
my $template = HTML::Template->new(
		filename	=>	'inventory.tmpl',
		associate	=>	$query,
		die_on_bad_params => 0,
	);
$template->param(%parameters);
print $query->header(), $template->output;

This code is almost entirely from our item shop code – so there isn’t really anything you haven’t seen before. The one new piece is the die_on_bad_params parameter that we are passing to HTML::Template->new() – we do this so that it won’t complain about the fact that our @inventory variable has the value ‘item_id’ inside of it, but the template doesn’t.

Our code is still missing something, however: the ability to actually use items!

If you remember the initial database preparations that we did earlier, you’ll remember that we created a new stat called ‘Item Use Token’ – and now we’ll be putting that stat to use. We will be using the ‘Item Use Token’ stat in conjunction with what’s known as a Dispatch Table to easily write the code that will run when our items are used.

For now, we’ll insert a single item with the token ‘potion’:

INSERT INTO items(name,type,price) VALUES ('Red Potion','Usable',10);
	INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='token'),(SELECT id FROM items WHERE name='Red Potion'),'potion','Item');

With that stat set up, we can buckle down and start on our dispatch table.

Dispatch tables are one of the more useful tools available to you as a programmer; they allow you to create a hash of functions(instead of values), and then call functions by key. This makes them perfect for our items system, because using dispatch tables will allow us to easily add new code for items in the most efficient manner possible. Let’s write some code to define and interact with a dispatch table:

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my %actions = (
	'potion' => \&use_potion,
);
 
sub use_potion {
	$parameters{message} = 'This is code that would run if the user used a potion.';
}
 
if(%arguments) {
	if($arguments{'item-id'}) {
		use items;
		$sth = $dbh->prepare("SELECT item_id FROM user_items WHERE user_id = ? AND id = ?");
		$sth->execute($userID,$arguments{'item-id'});
		my $itemID;
		$sth->bind_columns(\$itemID);
		$sth->fetch;
		my $token = items::getStat('token',$itemID);
		$actions{$token}->();
	}
}

If you visit your inventory page and click on ‘Use’ underneath the item in your character’s inventory, you should be treated to the simple message ‘This is code that would run when the user used a potion’. Neat, eh?

While we’ve built the functionality for a single item, that’s not really our use-case – we need to see how useful this system will be if we want to add another item without writing too much extra code. Ideally, we would only need to write the code that makes this item special – and thankfully, dispatch tables let us do just that. First, we’ll add another item, with the token ‘crystal_ball’:

INSERT INTO items(name,type,price) VALUES ('Crystal Ball','Usable',10);
	INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='token'),(SELECT id FROM items WHERE name='Crystal Ball'),'crystal_ball','Item');

And now that we’ve added the item, we’ll add the code to run when an item with that token gets used:

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my %actions = (
	'potion' => \&use_potion,
	'crystal_ball'	=>	\&use_crystal_ball,
);
 
sub use_crystal_ball {
	$parameters{message} = 'This is code that would run if the user used a crystal ball.';
}

And if you use the crystal ball now that we’ve written that code, you’ll see the message ‘This is code that would run if the user used a crystal ball.’.

The ability to keep our code organized in this way is what makes dispatch tables so useful – it doesn’t take us long at all to write more code to support any new items we want to add, and it’s as simple as just adding a new token(which serves as a key in the dispatch table), and then writing the function that will be called(you could even map multiple tokens to the same function, if you wanted to – although in that situation you should just have two items with the same token).

And with that, our inventory page is complete! Users can now use any items that you have defined tokens and written the code for – and you can run any code that should be executed no matter what the item’s token is by adding it just after the line that says:

$actions{$token}->();

Here’s the (slightly re-organized) code for inventory.cgi:

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#!/usr/bin/perl -w
 
use strict;
use CGI qw(:cgi);
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
use HTML::Template;
use DBI;
use config;
 
my $query = new CGI;
my %arguments = $query->Vars;
 
my $dbh = DBI->connect("DBI:mysql:$config{dbName}:$config{dbHost}",$config{dbUser},$config{dbPass},{RaiseError => 1});
my $sth;
my %parameters;
 
use stats;
 
my $cookie = $query->cookie('username+password');
my ($username) = split(/\+/,$cookie);
$sth = $dbh->prepare("SELECT id FROM users WHERE UPPER(username) = UPPER(?)");
$sth->execute($username);
my $userID;
$sth->bind_columns(\$userID);
$sth->fetch;
 
my %actions = (
	'potion' => \&use_potion,
	'crystal_ball'	=>	\&use_crystal_ball,
);
 
sub use_crystal_ball {
	$parameters{message} = 'This is code that would run if the user used a crystal ball.';
}
 
sub use_potion {
	$parameters{message} = 'This is code that would run if the user used a potion.';
}
 
if(%arguments) {
	if($arguments{'item-id'}) {
		use items;
		$sth = $dbh->prepare("SELECT item_id FROM user_items WHERE user_id = ? AND id = ?");
		$sth->execute($userID,$arguments{'item-id'});
		my $itemID;
		$sth->bind_columns(\$itemID);
		$sth->fetch;
		my $token = items::getStat('token',$itemID);
		$actions{$token}->();
	}
}
 
$sth = $dbh->prepare("SELECT id, item_id, quantity FROM user_items WHERE user_id = ?");
$sth->execute($userID);
my @inventory = ();
while(my $row = $sth->fetchrow_hashref) {
	my $sth2 = $dbh->prepare("SELECT name FROM items WHERE id = ?");
	$sth2->execute($row->{item_id});
	$sth2->bind_columns(\$row->{name});
	$sth2->fetch;
	push @inventory, $row;
}
 
$parameters{inventory} = \@inventory;
 
my $template = HTML::Template->new(
		filename	=>	'inventory.tmpl',
		associate	=>	$query,
		die_on_bad_params => 0,
	);
$template->param(%parameters);
print $query->header(), $template->output;

And here’s inventory.tmpl:

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<html>
<head>
	<title>Your Inventory</title>
</head>
<body>
	<p>This is your inventory. Check out all the stuff you've got!</p>
	<tmpl_if name='message'>
		<p><!--tmpl_var name='message'--></p>
	</tmpl_if>
	<ul>
		<tmpl_loop name='inventory'>
		<li>
			<strong><!--tmpl_var name='name'--> x <!--tmpl_var name='quantity'--></strong>
			<form action='inventory.cgi' method='post'>
				<input type='hidden' name='item-id' value='<!--tmpl_var name="id"-->' />
				<input type='submit' value='Use' />
			</form>
		</li>
		</tmpl_loop>
	</ul>
</body>
</html>

Extra Credit

  • Re-factor the weapons and armor systems, so that they are all sold from the item-shop – and when you use them from your inventory, the items are equipped.
]]> http://buildingbrowsergames.com/2008/10/17/using-items-perl/feed/ 0 Using Items (PHP) http://buildingbrowsergames.com/2008/10/16/using-items-php/ http://buildingbrowsergames.com/2008/10/16/using-items-php/#comments Thu, 16 Oct 2008 14:00:17 +0000 Luke http://buildingbrowsergames.com/?p=488 What game is complete without usable items? Not ours, that’s for sure!

With that in mind, today we are going to write the code that makes items usable. To start off, check out a copy of the code for our project:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/php/pbbg tutorial -r 37

And then we’re ready to go!

To start off, we’ll build a basic template for our inventory page, and put it inside inventory.tpl:

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<html>
<head>
	<title>Your Inventory</title>
</head>
<body>
	<p>This is your inventory. Check out all the stuff you've got!</p>
	<ul>
		{foreach from=$inventory key=id item=i}
		<li>
			<strong>{$i.name} x {$i.quantity}</strong>
			<form action='inventory.php' method='post'>
				<input type='hidden' name='item-id' value='{$i.id}' />
				<input type='submit' value='Use' />
			</form>
		</li>
		{/foreach}
	</ul>
</body>
</html>

With the template built, we can get started on the code for inventory.php:

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<?php
 
require_once 'smarty.php';
 
session_start();
 
require_once 'config.php';		// our database settings
$conn = mysql_connect($dbhost,$dbuser,$dbpass)
	or die('Error connecting to mysql');
mysql_select_db($dbname);
// retrieve player's ID
$query = sprintf("SELECT id FROM users WHERE UPPER(username) = UPPER('%s')",
			mysql_real_escape_string($_SESSION['username']));
$result = mysql_query($query);
list($userID) = mysql_fetch_row($result);
 
$inventory = array();
$query = sprintf("SELECT id, item_id, quantity FROM user_items WHERE user_id = '%s'",
		mysql_real_escape_string($userID));
$result = mysql_query($query);
while($row = mysql_fetch_assoc($result)) {
	 $item_query = sprintf("SELECT name FROM items WHERE id = '%s'",
		mysql_real_escape_string($row['item_id']));
	$item_result = mysql_query($item_query);
	list($row['name']) = mysql_fetch_row($item_result);
	array_push($inventory,$row);
}
$smarty->assign('inventory',$inventory);
$smarty->display('inventory.tpl');
 
?>

This code is essentially taken straight from our item shop code – but it’s missing one key thing: the ability to actually use items!

If you remember our initial database preparations, you’ll remember that we inserted a new stat called ‘Item Use Token’ – and this is where that stat will come into play. We will be using the ‘Item Use Token’ stat and something known as a Dispatch Table to easily write arbitrary code that can be run whenever our items are used.

For now, we’ll insert a single item with the use token of ‘potion’:

INSERT INTO items(name,type,price) VALUES ('Red Potion','Usable',10);
	INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='token'),(SELECT id FROM items WHERE name='Red Potion'),'potion','Item');

With that token in place, we will be able to start writing our dispatch table.

Dispatch Tables are a bit of a strange beast; essentially, what you end up doing when you create a dispatch table is creating an associative array, filled with function definitions(instead of values). Then, you use a certain key value to retrieve the function you are supposed to call. This is actually perfect for items system, because it will allow us to easily add new and different types of items anytime we want or need to(by simply adding another token, and then writing the code to handle it). Let’s get started on our dispatch table:

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function use_potion() {
	echo 'This is code that would run when the user used a potion.';
}
$actions = array('potion' => 'use_potion');
 
if($_POST) {
	if($_POST['item-id']) {
		$query = sprintf("SELECT item_id FROM user_items WHERE user_id = '%s' AND id = '%s'",
			mysql_real_escape_string($userID),
			mysql_real_escape_string($_POST['item-id']));
		$result = mysql_query($query);
		list($itemID) = mysql_fetch_row($result);
		require_once 'items.php';
		$token = getItemStat('token',$itemID);
		call_user_func($actions[$token]);
	}
}

And if you visit your inventory page and click ‘Use’ on the item in your character’s inventory, you should be treated to the simple message ‘This is code that would run when the user used a potion.’. Neat, eh?

While this shows you how to build this functionality for a single item, single items aren’t really what this code is geared towards. So let’s add another item and type:

INSERT INTO items(name,type,price) VALUES ('Crystal Ball','Usable',10);
	INSERT INTO entity_stats(stat_id,entity_id,value,entity_type) VALUES ((SELECT id FROM stats WHERE short_name='token'),(SELECT id FROM items WHERE name='Crystal Ball'),'crystal_ball','Item');

Now that we’ve added another item token to handle, we’ll write the code that gets run when an item with that token gets used:

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	function use_crystal_ball() {
		echo 'This is code that would run when the user used a crystal ball.';
	}
	$actions = array('potion' => 'use_potion','crystal_ball' => 'use_crystal_ball');

And now if you use a crystal ball, you will get the message ‘This is code that would run when the user used a crystal ball.’.

This is why dispatch tables are so useful – it doesn’t take us long at all to write more code to support more items anytime we need to.

With that, our inventory page is essentially finished! You can run any code that should run after any item is used by running it just after the call to call_user_func(), and you can run any code specific to that item token by defining it within the $actions array. Handy!

Here’s the (slightly re-organized) code for inventory.php:

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<?php
 
require_once 'smarty.php';
 
session_start();
 
require_once 'config.php';		// our database settings
$conn = mysql_connect($dbhost,$dbuser,$dbpass)
	or die('Error connecting to mysql');
mysql_select_db($dbname);
// retrieve player's ID
$query = sprintf("SELECT id FROM users WHERE UPPER(username) = UPPER('%s')",
			mysql_real_escape_string($_SESSION['username']));
$result = mysql_query($query);
list($userID) = mysql_fetch_row($result);
 
$actions = array('potion' => 'use_potion','crystal_ball' => 'use_crystal_ball');
 
if($_POST) {
	if($_POST['item-id']) {
		$query = sprintf("SELECT item_id FROM user_items WHERE user_id = '%s' AND id = '%s'",
			mysql_real_escape_string($userID),
			mysql_real_escape_string($_POST['item-id']));
		$result = mysql_query($query);
		list($itemID) = mysql_fetch_row($result);
		require_once 'items.php';
		$token = getItemStat('token',$itemID);
		call_user_func($actions[$token]);
	}
}
 
$inventory = array();
$query = sprintf("SELECT id, item_id, quantity FROM user_items WHERE user_id = '%s'",
		mysql_real_escape_string($userID));
$result = mysql_query($query);
while($row = mysql_fetch_assoc($result)) {
	 $item_query = sprintf("SELECT name FROM items WHERE id = '%s'",
		mysql_real_escape_string($row['item_id']));
	$item_result = mysql_query($item_query);
	list($row['name']) = mysql_fetch_row($item_result);
	array_push($inventory,$row);
}
$smarty->assign('inventory',$inventory);
$smarty->display('inventory.tpl');
 
function use_potion() {
	echo 'This is code that would run when the user used a potion.';
}
function use_crystal_ball() {
	echo 'This is code that would run when the user used a crystal ball.';
}
?>

And here’s the template(inventory.tpl):

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<html>
<head>
	<title>Your Inventory</title>
</head>
<body>
	<p>This is your inventory. Check out all the stuff you've got!</p>
	<ul>
		{foreach from=$inventory key=id item=i}
		<li>
			<strong>{$i.name} x {$i.quantity}</strong>
			<form action='inventory.php' method='post'>
				<input type='hidden' name='item-id' value='{$i.id}' />
				<input type='submit' value='Use' />
			</form>
		</li>
		{/foreach}
	</ul>
</body>
</html>

Extra Credit

  • Build healing potions that heal the player for 10, 20, or 30 HP (you may need to add another stat to the item to do this).
]]> http://buildingbrowsergames.com/2008/10/16/using-items-php/feed/ 8