Files
qt4-x11/doc/html/script-context2d-scripts-pong-js.html
2025-08-24 20:55:26 +08:00

436 lines
34 KiB
HTML

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en_US" lang="en_US">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Qt 4.8: pong.js Example File (script/context2d/scripts/pong.js)</title>
<link rel="stylesheet" type="text/css" href="style/style.css" />
<script src="scripts/jquery.js" type="text/javascript"></script>
<script src="scripts/functions.js" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="style/superfish.css" />
<link rel="stylesheet" type="text/css" href="style/narrow.css" />
<!--[if IE]>
<meta name="MSSmartTagsPreventParsing" content="true">
<meta http-equiv="imagetoolbar" content="no">
<![endif]-->
<!--[if lt IE 7]>
<link rel="stylesheet" type="text/css" href="style/style_ie6.css">
<![endif]-->
<!--[if IE 7]>
<link rel="stylesheet" type="text/css" href="style/style_ie7.css">
<![endif]-->
<!--[if IE 8]>
<link rel="stylesheet" type="text/css" href="style/style_ie8.css">
<![endif]-->
<script src="scripts/superfish.js" type="text/javascript"></script>
<script src="scripts/narrow.js" type="text/javascript"></script>
</head>
<body class="" onload="CheckEmptyAndLoadList();">
<div class="header" id="qtdocheader">
<div class="content">
<div id="nav-logo">
<a href="index.html">Home</a></div>
<a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
<div id="narrowsearch"></div>
<div id="nav-topright">
<ul>
<li class="nav-topright-home"><a href="http://qt.digia.com/">Qt HOME</a></li>
<li class="nav-topright-dev"><a href="http://qt-project.org/">DEV</a></li>
<li class="nav-topright-doc nav-topright-doc-active"><a href="http://qt-project.org/doc/">
DOC</a></li>
<li class="nav-topright-blog"><a href="http://blog.qt.digia.com/">BLOG</a></li>
</ul>
</div>
<div id="shortCut">
<ul>
<li class="shortCut-topleft-inactive"><span><a href="index.html">Qt 4.8</a></span></li>
<li class="shortCut-topleft-active"><a href="http://qt-project.org/doc/">ALL VERSIONS </a></li>
</ul>
</div>
<ul class="sf-menu" id="narrowmenu">
<li><a href="#">API Lookup</a>
<ul>
<li><a href="classes.html">Class index</a></li>
<li><a href="functions.html">Function index</a></li>
<li><a href="modules.html">Modules</a></li>
<li><a href="namespaces.html">Namespaces</a></li>
<li><a href="qtglobal.html">Global Declarations</a></li>
<li><a href="qdeclarativeelements.html">QML elements</a></li>
</ul>
</li>
<li><a href="#">Qt Topics</a>
<ul>
<li><a href="qt-basic-concepts.html">Programming with Qt</a></li>
<li><a href="qtquick.html">Device UIs &amp; Qt Quick</a></li>
<li><a href="qt-gui-concepts.html">UI Design with Qt</a></li>
<li><a href="supported-platforms.html">Supported Platforms</a></li>
<li><a href="technology-apis.html">Qt and Key Technologies</a></li>
<li><a href="best-practices.html">How-To's and Best Practices</a></li>
</ul>
</li>
<li><a href="#">Examples</a>
<ul>
<li><a href="all-examples.html">Examples</a></li>
<li><a href="tutorials.html">Tutorials</a></li>
<li><a href="demos.html">Demos</a></li>
<li><a href="qdeclarativeexamples.html">QML Examples</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div class="wrapper">
<div class="hd">
<span></span>
</div>
<div class="bd group">
<div class="sidebar">
<div class="searchlabel">
Search index:</div>
<div class="search" id="sidebarsearch">
<form id="qtdocsearch" action="" onsubmit="return false;">
<fieldset>
<input type="text" name="searchstring" id="pageType" value="" />
<div id="resultdialog">
<a href="#" id="resultclose">Close</a>
<p id="resultlinks" class="all"><a href="#" id="showallresults">All</a> | <a href="#" id="showapiresults">API</a> | <a href="#" id="showarticleresults">Articles</a> | <a href="#" id="showexampleresults">Examples</a></p>
<p id="searchcount" class="all"><span id="resultcount"></span><span id="apicount"></span><span id="articlecount"></span><span id="examplecount"></span>&nbsp;results:</p>
<ul id="resultlist" class="all">
</ul>
</div>
</fieldset>
</form>
</div>
<div class="box first bottombar" id="lookup">
<h2 title="API Lookup"><span></span>
API Lookup</h2>
<div id="list001" class="list">
<ul id="ul001" >
<li class="defaultLink"><a href="classes.html">Class index</a></li>
<li class="defaultLink"><a href="functions.html">Function index</a></li>
<li class="defaultLink"><a href="modules.html">Modules</a></li>
<li class="defaultLink"><a href="namespaces.html">Namespaces</a></li>
<li class="defaultLink"><a href="qtglobal.html">Global Declarations</a></li>
<li class="defaultLink"><a href="qdeclarativeelements.html">QML elements</a></li>
</ul>
</div>
</div>
<div class="box bottombar" id="topics">
<h2 title="Qt Topics"><span></span>
Qt Topics</h2>
<div id="list002" class="list">
<ul id="ul002" >
<li class="defaultLink"><a href="qt-basic-concepts.html">Programming with Qt</a></li>
<li class="defaultLink"><a href="qtquick.html">Device UIs &amp; Qt Quick</a></li>
<li class="defaultLink"><a href="qt-gui-concepts.html">UI Design with Qt</a></li>
<li class="defaultLink"><a href="supported-platforms.html">Supported Platforms</a></li>
<li class="defaultLink"><a href="technology-apis.html">Qt and Key Technologies</a></li>
<li class="defaultLink"><a href="best-practices.html">How-To's and Best Practices</a></li>
</ul>
</div>
</div>
<div class="box" id="examples">
<h2 title="Examples"><span></span>
Examples</h2>
<div id="list003" class="list">
<ul id="ul003">
<li class="defaultLink"><a href="all-examples.html">Examples</a></li>
<li class="defaultLink"><a href="tutorials.html">Tutorials</a></li>
<li class="defaultLink"><a href="demos.html">Demos</a></li>
<li class="defaultLink"><a href="qdeclarativeexamples.html">QML Examples</a></li>
</ul>
</div>
</div>
</div>
<div class="wrap">
<div class="toolbar">
<div class="breadcrumb toolblock">
<ul>
<li class="first"><a href="index.html">Home</a></li>
<!-- Breadcrumbs go here -->
</ul>
</div>
<div class="toolbuttons toolblock">
<ul>
<li id="smallA" class="t_button">A</li>
<li id="medA" class="t_button active">A</li>
<li id="bigA" class="t_button">A</li>
<li id="print" class="t_button"><a href="javascript:this.print();">
<span>Print</span></a></li>
</ul>
</div>
</div>
<div class="content mainContent">
<h1 class="title">pong.js Example File</h1>
<span class="small-subtitle">script/context2d/scripts/pong.js</span>
<!-- $$$script/context2d/scripts/pong.js-description -->
<div class="descr"> <a name="details"></a>
<pre class="js"> <span class="comment">// globals</span>
<span class="name">playarea_canvas</span> <span class="operator">=</span> <span class="name">document</span>.<span class="name">getElementById</span>(<span class="string">'tutorial'</span>);
<span class="name">playarea_canvas</span>.<span class="name">resize</span>(<span class="number">320</span>,<span class="number">200</span>);
<span class="name">playarea</span> <span class="operator">=</span> <span class="name">playarea_canvas</span>.<span class="name">getContext</span>(<span class="string">'2d'</span>);
<span class="comment">//p1_scr = document.getElementById('p1_scr');</span>
<span class="comment">//p2_scr = document.getElementById('p2_scr');</span>
<span class="comment">//status_msg = document.getElementById('status');</span>
<span class="comment">//debug = document.getElementById('debug');</span>
<span class="name">ball_direction</span> <span class="operator">=</span> <span class="number">0</span>;
<span class="name">up</span> <span class="operator">=</span> -<span class="number">1</span>;
<span class="name">down</span> <span class="operator">=</span> <span class="number">1</span>;
<span class="comment">//key codes</span>
<span class="name">key_up</span> <span class="operator">=</span> <span class="number">38</span>;
<span class="name">key_down</span> <span class="operator">=</span> <span class="number">40</span>;
<span class="name">key_W</span> <span class="operator">=</span> <span class="number">87</span>;
<span class="name">key_S</span> <span class="operator">=</span> <span class="number">83</span>;
<span class="name">key_pause</span> <span class="operator">=</span> <span class="number">32</span>;
<span class="name">speed</span> <span class="operator">=</span> <span class="number">2</span>; <span class="comment">//controls the speed of the ball</span>
<span class="name">paddle_inc</span> <span class="operator">=</span> <span class="number">10</span>; <span class="comment">//how many pixels paddle can move in either direction</span>
<span class="name">pause</span> <span class="operator">=</span> <span class="number">false</span>;
<span class="name">player_1</span> <span class="operator">=</span> <span class="number">0</span>; <span class="comment">//player IDs</span>
<span class="name">player_2</span> <span class="operator">=</span> <span class="number">1</span>;
<span class="name">player_1_scr</span> <span class="operator">=</span> <span class="number">0</span>; <span class="comment">//player scores</span>
<span class="name">player_2_scr</span> <span class="operator">=</span> <span class="number">0</span>;
<span class="name">player_1_direction</span> <span class="operator">=</span> <span class="number">null</span>; <span class="comment">//null = no movement whatsoever</span>
<span class="name">player_2_direction</span> <span class="operator">=</span> <span class="number">null</span>;
<span class="name">pa</span> <span class="operator">=</span> new <span class="name">Array</span>();
<span class="name">divider</span> <span class="operator">=</span> new <span class="name">Array</span>();
<span class="name">paddle_1</span> <span class="operator">=</span> new <span class="name">Array</span>();
<span class="name">paddle_2</span> <span class="operator">=</span> new <span class="name">Array</span>();
<span class="name">ball</span> <span class="operator">=</span> new <span class="name">Array</span>();
<span class="keyword">function</span> <span class="name">sleep</span>(<span class="name">numberMillis</span>)
{
var <span class="name">now</span> = new <span class="name">Date</span>();
var <span class="name">exitTime</span> = <span class="name">now</span>.<span class="name">getTime</span>() <span class="operator">+</span> <span class="name">numberMillis</span>;
<span class="keyword">while</span> (<span class="number">true</span>) {
<span class="name">now</span> <span class="operator">=</span> new <span class="name">Date</span>();
<span class="keyword">if</span> (<span class="name">now</span>.<span class="name">getTime</span>() <span class="operator">&gt;</span> <span class="name">exitTime</span>)
<span class="keyword">return</span>;
}
}
<span class="keyword">function</span> <span class="name">init</span>()
{
<span class="name">pa</span>[<span class="string">'width'</span>] <span class="operator">=</span> <span class="number">150</span>;
<span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">=</span> <span class="number">140</span>;
<span class="name">pa</span>[<span class="string">'player_margin'</span>] <span class="operator">=</span> <span class="number">10</span>; <span class="comment">//area behind player paddles</span>
<span class="name">pa</span>[<span class="string">'foreground'</span>] <span class="operator">=</span> <span class="string">&quot;#FFFFFF&quot;</span>;
<span class="name">pa</span>[<span class="string">'background'</span>] <span class="operator">=</span> <span class="string">&quot;#000000&quot;</span>;
<span class="name">divider</span>[<span class="string">'pos'</span>] <span class="operator">=</span> <span class="name">pa</span>[<span class="string">'width'</span>]<span class="operator">/</span><span class="number">2</span>;
<span class="name">divider</span>[<span class="string">'width'</span>] <span class="operator">=</span> <span class="number">4</span>;
<span class="name">paddle_1</span>[<span class="string">'width'</span>] <span class="operator">=</span> <span class="number">8</span>;
<span class="name">paddle_1</span>[<span class="string">'height'</span>] <span class="operator">=</span> <span class="number">64</span>;
<span class="name">paddle_1</span>[<span class="string">'x'</span>] <span class="operator">=</span> <span class="name">pa</span>[<span class="string">'player_margin'</span>];
<span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">=</span> (<span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">/</span><span class="number">2</span> ) <span class="operator">-</span> (<span class="name">paddle_1</span>[<span class="string">'height'</span>] <span class="operator">/</span> <span class="number">2</span>);
<span class="name">paddle_2</span>[<span class="string">'width'</span>] <span class="operator">=</span> <span class="number">8</span>;
<span class="name">paddle_2</span>[<span class="string">'height'</span>] <span class="operator">=</span> <span class="number">64</span>;
<span class="name">paddle_2</span>[<span class="string">'x'</span>] <span class="operator">=</span> (<span class="name">pa</span>[<span class="string">'width'</span>] <span class="operator">-</span> <span class="name">pa</span>[<span class="string">'player_margin'</span>] <span class="operator">-</span> <span class="name">paddle_2</span>[<span class="string">'width'</span>]);
<span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">=</span> (<span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">/</span><span class="number">2</span> ) <span class="operator">-</span> (<span class="name">paddle_2</span>[<span class="string">'height'</span>] <span class="operator">/</span> <span class="number">2</span>);
<span class="name">ball</span>[<span class="string">'width'</span>] <span class="operator">=</span> <span class="number">10</span>;
<span class="name">ball</span>[<span class="string">'height'</span>] <span class="operator">=</span> <span class="number">10</span>;
<span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">=</span> (<span class="name">pa</span>[<span class="string">'width'</span>]<span class="operator">/</span><span class="number">2</span>) <span class="operator">-</span> (<span class="name">ball</span>[<span class="string">'width'</span>] <span class="operator">/</span> <span class="number">2</span>);
<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">=</span> (<span class="name">pa</span>[<span class="string">'height'</span>]<span class="operator">/</span><span class="number">2</span>) <span class="operator">-</span> (<span class="name">ball</span>[<span class="string">'height'</span>] <span class="operator">/</span> <span class="number">2</span>);
<span class="name">ball_direction</span> <span class="operator">=</span> <span class="name">Math</span>.<span class="name">random</span>() <span class="operator">*</span> <span class="number">360</span>; <span class="comment">//initialize ball direction, which is determined by angle, at random</span>
<span class="name">speed</span> <span class="operator">=</span> <span class="number">2</span>;
}
<span class="keyword">function</span> <span class="name">renderPlayarea</span>()
{
<span class="name">playarea</span>.<span class="name">beginPath</span>();
<span class="name">playarea</span>.<span class="name">clearRect</span>(<span class="number">0</span>,<span class="number">0</span>,<span class="name">pa</span>[<span class="string">'width'</span>],<span class="name">pa</span>[<span class="string">'height'</span>]);
<span class="name">playarea</span>.<span class="name">fillStyle</span> <span class="operator">=</span> <span class="name">pa</span>[<span class="string">'background'</span>];
<span class="name">playarea</span>.<span class="name">strokeStyle</span> <span class="operator">=</span> <span class="name">pa</span>[<span class="string">'foreground'</span>];
<span class="name">playarea</span>.<span class="name">fillRect</span>(<span class="number">0</span>,<span class="number">0</span>, <span class="name">pa</span>[<span class="string">'width'</span>], <span class="name">pa</span>[<span class="string">'height'</span>]);
<span class="comment">//move paddles</span>
<span class="keyword">if</span>(<span class="name">player_1_direction</span> <span class="operator">!=</span> <span class="number">null</span>)
{
<span class="keyword">if</span>(<span class="name">player_1_direction</span> <span class="operator">==</span> <span class="name">up</span>)
<span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">=</span> <span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">-</span> <span class="name">paddle_inc</span>;
else
<span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">=</span> <span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">+</span> <span class="name">paddle_inc</span>;
}
<span class="keyword">if</span>(<span class="name">player_2_direction</span> <span class="operator">!=</span> <span class="number">null</span>)
{
<span class="keyword">if</span>(<span class="name">player_2_direction</span> <span class="operator">==</span> <span class="name">up</span>)
<span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">=</span> <span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">-</span> <span class="name">paddle_inc</span>;
else
<span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">=</span> <span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">+</span> <span class="name">paddle_inc</span>;
}
<span class="name">playarea</span>.<span class="name">rect</span>(<span class="name">paddle_1</span>[<span class="string">'x'</span>],<span class="name">paddle_1</span>[<span class="string">'y'</span>],<span class="name">paddle_1</span>[<span class="string">'width'</span>],<span class="name">paddle_1</span>[<span class="string">'height'</span>]);
<span class="name">playarea</span>.<span class="name">rect</span>(<span class="name">paddle_2</span>[<span class="string">'x'</span>],<span class="name">paddle_2</span>[<span class="string">'y'</span>],<span class="name">paddle_2</span>[<span class="string">'width'</span>],<span class="name">paddle_2</span>[<span class="string">'height'</span>]);
<span class="comment">//move ball</span>
<span class="name">playarea</span>.<span class="name">rect</span>(<span class="name">ball</span>[<span class="string">'x'</span>], <span class="name">ball</span>[<span class="string">'y'</span>], <span class="name">ball</span>[<span class="string">'width'</span>], <span class="name">ball</span>[<span class="string">'height'</span>]);
<span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">=</span> <span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">+</span> <span class="name">Math</span>.<span class="name">cos</span>((<span class="name">ball_direction</span>)<span class="operator">*</span><span class="name">Math</span>.<span class="name">PI</span><span class="operator">/</span><span class="number">180</span>) <span class="operator">*</span> <span class="name">speed</span>;
<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">=</span> <span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">+</span> <span class="name">Math</span>.<span class="name">sin</span>((<span class="name">ball_direction</span>)<span class="operator">*</span><span class="name">Math</span>.<span class="name">PI</span><span class="operator">/</span><span class="number">180</span>) <span class="operator">*</span> <span class="name">speed</span>;
<span class="name">playarea</span>.<span class="name">fillStyle</span> <span class="operator">=</span> <span class="name">pa</span>[<span class="string">'foreground'</span>];
<span class="name">playarea</span>.<span class="name">fill</span>();
<span class="name">playarea</span>.<span class="name">beginPath</span>();
<span class="comment">//redraw divider</span>
<span class="name">playarea</span>.<span class="name">lineWidth</span> <span class="operator">=</span> <span class="name">divider</span>[<span class="string">'width'</span>];
<span class="name">playarea</span>.<span class="name">lineTo</span>(<span class="name">divider</span>[<span class="string">'pos'</span>], <span class="number">0</span>);
<span class="name">playarea</span>.<span class="name">lineTo</span>(<span class="name">divider</span>[<span class="string">'pos'</span>], <span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">=</span> <span class="number">200</span>);
<span class="name">playarea</span>.<span class="name">lineWidth</span> <span class="operator">=</span> <span class="number">1</span>;
<span class="name">playarea</span>.<span class="name">stroke</span>();
<span class="name">playarea</span>.<span class="name">closePath</span>();
}
<span class="keyword">function</span> <span class="name">testCollisions</span>()
{
<span class="comment">//make sure paddles don't go beyond play area</span>
<span class="keyword">if</span>(((<span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">&lt;=</span> <span class="number">0</span>) <span class="operator">&amp;&amp;</span> (<span class="name">player_1_direction</span> <span class="operator">==</span> <span class="name">up</span>)) <span class="operator">||</span> ((<span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">&gt;=</span> (<span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">-</span> <span class="name">paddle_1</span>[<span class="string">'height'</span>])) <span class="operator">&amp;&amp;</span> (<span class="name">player_1_direction</span> <span class="operator">==</span> <span class="name">down</span>)))
<span class="name">player_1_direction</span> <span class="operator">=</span> <span class="number">null</span>;
<span class="keyword">if</span>(((<span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">&lt;=</span> <span class="number">0</span>) <span class="operator">&amp;&amp;</span> (<span class="name">player_2_direction</span> <span class="operator">==</span> <span class="name">up</span>)) <span class="operator">||</span> ((<span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">&gt;=</span> (<span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">-</span> <span class="name">paddle_2</span>[<span class="string">'height'</span>])) <span class="operator">&amp;&amp;</span> (<span class="name">player_2_direction</span> <span class="operator">==</span> <span class="name">down</span>)))
<span class="name">player_2_direction</span> <span class="operator">=</span> <span class="number">null</span>;
<span class="comment">//check to see if ball went beyond paddles, and if so, score accordingly and reset playarea</span>
<span class="keyword">if</span>(<span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">&lt;=</span> <span class="number">0</span>)
{
<span class="name">setScore</span>(<span class="name">player_2</span>);
<span class="name">init</span>()
<span class="name">sleep</span>(<span class="number">1000</span>);
}
<span class="keyword">if</span>(<span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">&gt;=</span> (<span class="name">pa</span>[<span class="string">'width'</span>] <span class="operator">-</span> <span class="name">ball</span>[<span class="string">'width'</span>]))
{
<span class="name">setScore</span>(<span class="name">player_1</span>);
<span class="name">init</span>();
<span class="name">sleep</span>(<span class="number">1000</span>);
}
<span class="comment">//check to see if ball hit top or bottom wall. if so, change direction</span>
<span class="keyword">if</span>((<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">&gt;=</span> (<span class="name">pa</span>[<span class="string">'height'</span>] <span class="operator">-</span> <span class="name">ball</span>[<span class="string">'height'</span>])) <span class="operator">||</span> <span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">&lt;=</span> <span class="number">0</span>)
<span class="name">ball_direction</span> <span class="operator">=</span> -<span class="name">ball_direction</span>;
<span class="comment">//check to see if the ball hit a paddle, and if so, change ball angle dependant on where it hit the paddle</span>
<span class="keyword">if</span>((<span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">&lt;=</span> (<span class="name">paddle_1</span>[<span class="string">'x'</span>] <span class="operator">+</span> <span class="name">paddle_1</span>[<span class="string">'width'</span>])) <span class="operator">&amp;&amp;</span> (<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">&gt;=</span> <span class="name">paddle_1</span>[<span class="string">'y'</span>]) <span class="operator">&amp;&amp;</span> (<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">&lt;=</span> (<span class="name">paddle_1</span>[<span class="string">'y'</span>] <span class="operator">+</span> <span class="name">paddle_1</span>[<span class="string">'height'</span>])))
{
<span class="name">ball_direction</span> <span class="operator">=</span> -<span class="name">ball_direction</span><span class="operator">/</span><span class="number">2</span>;
<span class="name">speed</span> <span class="operator">+=</span> <span class="number">.5</span>;
}
<span class="keyword">if</span>(((<span class="name">ball</span>[<span class="string">'x'</span>] <span class="operator">+</span> <span class="name">ball</span>[<span class="string">'width'</span>]) <span class="operator">&gt;=</span> <span class="name">paddle_2</span>[<span class="string">'x'</span>]) <span class="operator">&amp;&amp;</span> (<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">&gt;=</span> <span class="name">paddle_2</span>[<span class="string">'y'</span>]) <span class="operator">&amp;&amp;</span> (<span class="name">ball</span>[<span class="string">'y'</span>] <span class="operator">&lt;=</span> (<span class="name">paddle_2</span>[<span class="string">'y'</span>] <span class="operator">+</span> <span class="name">paddle_2</span>[<span class="string">'height'</span>])))
{
<span class="name">ball_direction</span> <span class="operator">=</span> (<span class="number">180</span><span class="operator">+</span><span class="name">ball_direction</span>)<span class="operator">/</span><span class="number">2</span>;
<span class="name">speed</span> <span class="operator">+=</span> <span class="number">.5</span>;
}
}
<span class="keyword">function</span> <span class="name">setScore</span>(<span class="name">p</span>)
{
<span class="keyword">if</span>(<span class="name">p</span> <span class="operator">==</span> <span class="name">player_1</span>)
{
player_1_scr++;
<span class="comment">//p1_scr.firstChild.nodeValue = player_1_scr;</span>
}
<span class="keyword">if</span>(<span class="name">p</span> <span class="operator">==</span> <span class="name">player_2</span>)
{
player_2_scr++;
<span class="comment">//p2_scr.firstChild.nodeValue = player_2_scr;</span>
}
}
<span class="comment">//handle input</span>
<span class="name">document</span>.<span class="name">onkeydown</span> <span class="operator">=</span> <span class="keyword">function</span>(<span class="name">ev</span>)
{
<span class="keyword">switch</span>(<span class="name">ev</span>.<span class="name">keyCode</span>)
{
<span class="keyword">case</span> <span class="name">key_W</span>:
<span class="name">player_1_direction</span> <span class="operator">=</span> <span class="name">up</span>;
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="name">key_S</span>:
<span class="name">player_1_direction</span> <span class="operator">=</span> <span class="name">down</span>;
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="name">key_up</span>:
<span class="name">player_2_direction</span> <span class="operator">=</span> <span class="name">up</span>;
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="name">key_down</span>:
<span class="name">player_2_direction</span> <span class="operator">=</span> <span class="name">down</span>;
<span class="keyword">break</span>;
}
}
<span class="name">document</span>.<span class="name">onkeyup</span> <span class="operator">=</span> <span class="keyword">function</span>(<span class="name">ev</span>)
{
<span class="keyword">switch</span>(<span class="name">ev</span>.<span class="name">keyCode</span>)
{
<span class="keyword">case</span> <span class="name">key_W</span>:
<span class="keyword">case</span> <span class="name">key_S</span>:
<span class="name">player_1_direction</span> <span class="operator">=</span> <span class="number">null</span>;
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="name">key_up</span>:
<span class="keyword">case</span> <span class="name">key_down</span>:
<span class="name">player_2_direction</span> <span class="operator">=</span> <span class="number">null</span>;
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="name">key_pause</span>:
<span class="keyword">if</span>(<span class="name">pause</span> <span class="operator">==</span> <span class="number">false</span>)
{
<span class="name">clearInterval</span>(<span class="name">game</span>);
<span class="comment">//status_msg.style.visibility = &quot;visible&quot;;</span>
<span class="name">pause</span> <span class="operator">=</span> <span class="number">true</span>;
}
else
{
<span class="name">game</span> <span class="operator">=</span> <span class="name">setInterval</span>(<span class="name">main</span>, <span class="number">25</span>);
<span class="comment">//status_msg.style.visibility = &quot;hidden&quot;;</span>
<span class="name">pause</span> <span class="operator">=</span> <span class="number">false</span>;
}
<span class="keyword">break</span>;
}
}
<span class="keyword">function</span> <span class="name">main</span>()
{
<span class="name">testCollisions</span>();
<span class="name">renderPlayarea</span>();
}
<span class="name">init</span>();
<span class="name">game</span> <span class="operator">=</span> <span class="name">setInterval</span>(<span class="name">main</span>, <span class="number">25</span>);</pre>
</div>
<!-- @@@script/context2d/scripts/pong.js -->
</div>
</div>
</div>
<div class="ft">
<span></span>
</div>
</div>
<div class="footer">
<p>
<acronym title="Copyright">&copy;</acronym> 2015 The Qt Company Ltd.
Documentation contributions included herein are the copyrights of
their respective owners.</p>
<br />
<p>
The documentation provided herein is licensed under the terms of the
<a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation
License version 1.3</a> as published by the Free Software Foundation.</p>
<p>
Documentation sources may be obtained from <a href="http://www.qt-project.org">
www.qt-project.org</a>.</p>
<br />
<p>
Qt and respective logos are trademarks of The Qt Company Ltd
in Finland and/or other countries worldwide. All other trademarks are property
of their respective owners. <a title="Privacy Policy"
href="http://en.gitorious.org/privacy_policy/">Privacy Policy</a></p>
</div>
<script src="scripts/functions.js" type="text/javascript"></script>
</body>
</html>