Building Browsergames » php 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 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(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 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 (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 Buying Items (PHP) http://buildingbrowsergames.com/2008/10/13/buying-items/ http://buildingbrowsergames.com/2008/10/13/buying-items/#comments Mon, 13 Oct 2008 14:00:17 +0000 Luke http://buildingbrowsergames.com/?p=480 Today, we’re going to build the items shop for our game. We’ve already run the initial database code to get everything prepared, and now it’s just a matter of writing the code to interact with it.

To begin with, check out a copy of our code from the Google Code Project:

svn checkout http://building-browsergames-tutorial.googlecode.com/svn/trunk/php/pbbg tutorial -r 36

And now we’re ready to get started on building our items system!

The first thing that we will need to build is our items shop. We’ll start off with the same template as our armor and weapons shops, but put this one inside item-shop.tpl:

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	<html>
	<head>
		<title>The Item Shop</title>
	</head>
	<body>
		<p>Welcome to the Item Shop.</p>
		<p><a href='index.php'>Back to main</a></p>
		<h3>Current Inventory:</h3>
		<ul>
			{foreach from=$inventory key=item_id item=i}
			<li>
				{$i.name} x {$i.quantity}
				<form action='item-shop.php' method='post'>
					<input type='hidden' name='sell-id' value='{$i.item_id}' />
					<input type='submit' value='Sell' />
				</form>
			</li>
			{/foreach}
		</ul>
		<p>You may purchase any of the items listed below.</p>
		{if $error ne ''}
			<p style='color:red'>{$error}</p>
		{/if}
		{if $message ne ''}
			<p style='color:green'>{$message}</p>
		{/if}
		<ul>
			{foreach from=$items key=id item=i}
				<li>
					<strong>{$i.name}</strong> - <em>{$i.price} gold coins</em>
					<form action='item-shop.php' method='post'>
						<input type='hidden' name='item-id' value='{$i.id}' />
						<input type='submit' value='Buy' />
					</form>
			{/foreach}
		</ul>
	</body>
	</html>

As you can see, this is largely the same template as with our other shops – with the one difference being the ‘Current Inventory’ display(as opposed to current weapons/armor in the other shops). When the user visits this shop, we will retrieve and display the contents of their inventory as well. With that being said, let’s start writing the code for the item shop inside item-shop.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);
require_once 'stats.php';	// player stats
$query = "SELECT DISTINCT(id), name, price FROM items WHERE type = 'Usable' ORDER BY RAND() LIMIT 5;";
$result = mysql_query($query);
$items = array();
while($row = mysql_fetch_assoc($result)) {
	array_push($items,$row);
}
$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);
$smarty->assign('items',$items);
$smarty->display('item-shop.tpl');
 
?>

For the most part, this is all review – the only interesting and new code that we’ve written is the code appearing between lines 23 and 33 – our inventory retrieval code. We retrieve all rows from our user_items table that are linked to the User ID of the player who is currently logged in, and then just loop through them and put them into our $inventory array – but not before also retrieving the name of the item(so that we can display it a little nicer).

Now that we’ve got displaying items down, we’ll want to write some code so that users can actually buy them:

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if($_POST) {
	if($_POST['item-id']) {
		$itemID = $_POST['item-id'];
		$query = sprintf("SELECT price FROM items WHERE id = '%s'",mysql_real_escape_string($itemID));
		$result = mysql_query($query);
		list($cost) = mysql_fetch_row($result);
		$gold = getStat('gc',$userID);
		if($gold >= $cost) {
			setStat('gc',$userID,($gold - $cost));
			$query = sprintf("SELECT count(id) FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
				mysql_real_escape_string($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);
			$smarty->assign('message','You purchased the item.');
		} else {
			$smarty->assign('error','You cannot afford that item!');
		}
	}
}

While that’s definitely a lot more code than we wrote to purchase weapons or armor, it’s still pretty simple once you take a look at it – essentially, once we get past the generic ‘do you have enough gold for this?’ check, we add the item to the user’s inventory. Because usable items can stack, we need to check if there is already a row in place for them or not. If there is no row in place, we insert a new one with the proper values(user ID, itemID, and quantity of 1). Otherwise, we just run an UPDATE statement on our table, to increment the quantity of the item for the player by 1.

Now that that’s finished, we only have one more thing to add to our item shop – the ability to sell items! We’ll quickly add that code to item-shop.php:

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} else if($_POST['sell-id']) {
	$itemID = $_POST['sell-id'];
	$query = sprintf("SELECT price FROM items WHERE id = '%s'",mysql_real_escape_string($itemID));
	$result = mysql_query($query);
	list($cost) = mysql_fetch_row($result);
	$gold = getStat('gc',$userID);
	setStat('gc',$userID,($gold + $cost));		
	$query = sprintf("SELECT quantity FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
		mysql_real_escape_string($userID),mysql_real_escape_string($itemID));
	$result = mysql_query($query);
	list($quantity) = mysql_fetch_row($result);
	if ($quantity > 1) {
		$query = sprintf("UPDATE user_items SET quantity = quantity - 1 WHERE user_id = '%s' AND item_id = '%s'",
			mysql_real_escape_string($userID),
			mysql_real_escape_string($itemID));
	} else {
		$query = sprintf("DELETE FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
			mysql_real_escape_string($userID),
			mysql_real_escape_string($itemID));
	}
	mysql_query($query);		
	$smarty->assign('message','You sold the item.');
}

This code is almost the exact same as the ‘buy item’ code, except for some small differences:

  • First, we are selecting quantity instead of COUNT(id) from user_items. Selecting the COUNT will tell us if a row exists or not – but it won’t tell us how many of the item the player has. user_items.quantity will.
  • Based on how many of the item the user has left, we perform one of two different queries: either an UPDATE query to decrement the quantiy of the item by 1, or a DELETE query – to remove the row from the user_items table if it will no longer be needed.

With all that code written, we’re finished! We now have a working item shop, and the beginnings of our inventory system up and running. Don’t forget to add a link to the item shop from the main page:

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<p><a href='item-shop.php'>The Item Shop</a></p>

And that’s it! Here’s the code for item-shop.tpl:

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<html>
<head>
	<title>The Item Shop</title>
</head>
<body>
	<p>Welcome to the Item Shop.</p>
	<p><a href='index.php'>Back to main</a></p>
	<h3>Current Inventory:</h3>
	<ul>
		{foreach from=$inventory key=item_id item=i}
		<li>
			{$i.name} x {$i.quantity}
			<form action='item-shop.php' method='post'>
				<input type='hidden' name='sell-id' value='{$i.item_id}' />
				<input type='submit' value='Sell' />
			</form>
		</li>
		{/foreach}
	</ul>
	<p>You may purchase any of the items listed below.</p>
	{if $error ne ''}
		<p style='color:red'>{$error}</p>
	{/if}
	{if $message ne ''}
		<p style='color:green'>{$message}</p>
	{/if}
	<ul>
		{foreach from=$items key=id item=i}
			<li>
				<strong>{$i.name}</strong> - <em>{$i.price} gold coins</em>
				<form action='item-shop.php' method='post'>
					<input type='hidden' name='item-id' value='{$i.id}' />
					<input type='submit' value='Buy' />
				</form>
		{/foreach}
	</ul>
</body>
</html>

And item-shop.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);
require_once 'stats.php';	// player stats
if($_POST) {
	if($_POST['item-id']) {
		$itemID = $_POST['item-id'];
		$query = sprintf("SELECT price FROM items WHERE id = '%s'",mysql_real_escape_string($itemID));
		$result = mysql_query($query);
		list($cost) = mysql_fetch_row($result);
		$gold = getStat('gc',$userID);
		if($gold >= $cost) {
			setStat('gc',$userID,($gold - $cost));
			$query = sprintf("SELECT count(id) FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
				mysql_real_escape_string($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);
			$smarty->assign('message','You purchased the item.');
		} else {
			$smarty->assign('error','You cannot afford that weapon!');
		}
	} else if($_POST['sell-id']) {
		$itemID = $_POST['sell-id'];
		$query = sprintf("SELECT price FROM items WHERE id = '%s'",mysql_real_escape_string($itemID));
		$result = mysql_query($query);
		list($cost) = mysql_fetch_row($result);
		$gold = getStat('gc',$userID);
		setStat('gc',$userID,($gold + $cost));		
		$query = sprintf("SELECT quantity FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
			mysql_real_escape_string($userID),mysql_real_escape_string($itemID));
		$result = mysql_query($query);
		list($quantity) = mysql_fetch_row($result);
		if ($quantity > 1) {
			$query = sprintf("UPDATE user_items SET quantity = quantity - 1 WHERE user_id = '%s' AND item_id = '%s'",
				mysql_real_escape_string($userID),
				mysql_real_escape_string($itemID));
		} else {
			$query = sprintf("DELETE FROM user_items WHERE user_id = '%s' AND item_id = '%s'",
				mysql_real_escape_string($userID),
				mysql_real_escape_string($itemID));
		}
		mysql_query($query);		
		$smarty->assign('message','You sold the item.');
	}
}
$query = "SELECT DISTINCT(id), name, price FROM items WHERE type = 'Usable' ORDER BY RAND() LIMIT 5;";
$result = mysql_query($query);
$items = array();
while($row = mysql_fetch_assoc($result)) {
	array_push($items,$row);
}
$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);
$smarty->assign('items',$items);
$smarty->display('item-shop.tpl');
 
?>

Extra Credit

  • Right now, we’re just displaying generic messages when a user buys an item. Change the messages so that they also tell the user what item they bought.
  • Add a box to the shop page that lets the user enter the quantity of the item they want to buy – so that users can buy 1 or more of any item.
  • Right now, our ’sell’ code is not very secured – a malicious user could simply pass in the ID of any item they wanted to sell that was in our game(whether it was in their inventory or not). Modify the item selling code so that it uses the ID of the row in user_items instead.
]]> http://buildingbrowsergames.com/2008/10/13/buying-items/feed/ 0 Integrating Armor into our combat system (PHP) http://buildingbrowsergames.com/2008/09/29/integrating-armor-into-our-combat-system-php/ http://buildingbrowsergames.com/2008/09/29/integrating-armor-into-our-combat-system-php/#comments Mon, 29 Sep 2008 14:00:50 +0000 Luke http://buildingbrowsergames.com/?p=426 We just added a way for our users to buy armor, but we still need to make it so that a user’s armor actually affects the our combat system. Today, we will integrate armor into our combat system, so that a user’s equipment can affect the results of the combat.

This is a lot easier than it sounds. We retrieve the armor’s ‘defense’ stat, and take it off of the damage that the player is going to receive. It’s a simple formula, but it works – and you’re free to tweak it as much as you’d like for your own game.

All we have to do is open up forest.php, and add our code just after we retrieve the player’s weapon and modify their attack:

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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;
}

And that’s the only change we need to make! We just loop through all the available armor slots, and then add their defense values to the player’s defense before we get to the main combat code. It’s just that simple!

Extra Credit

  • Make the combat system also display the different defence modifiers for the player – e.g. – “1 defence from torso armor, 2 defence from legs armor”.
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