cpp
/
crown-engine
miroir de https://github.com/crownengine/crown.git


			
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228
							<!DOCTYPE html>
<html class="writer-html5" lang="en" >
<head>
  <meta charset="utf-8" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" />

    <meta property="article:modified_time" content="2025-10-16T08:33:32+00:00" /><meta property="og:title" content="Scripting in Lua" />
<meta property="og:type" content="website" />
<meta property="og:url" content="https://docs.crownengine.org/html/latest/gameplay/lua_scripting.html" />
<meta property="og:site_name" content="Crown 0.60.0 Manual" />
<meta property="og:description" content="All gameplay code in Crown is written in Lua. This section will give you a basic understanding of how Lua is used and can be used in Crown. What is Lua: Lua is a simple, fast and lightweight scripting language which is easy to learn and supports all features needed to write an..." />
<meta name="description" content="All gameplay code in Crown is written in Lua. This section will give you a basic understanding of how Lua is used and can be used in Crown. What is Lua: Lua is a simple, fast and lightweight scripting language which is easy to learn and supports all features needed to write an..." />

  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Scripting in Lua &mdash; Crown 0.60.0 Manual 0.61.0 documentation</title>
      <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
      <link rel="stylesheet" href="../_static/css/theme.css" type="text/css" />
      <link rel="stylesheet" href="../_static/css/custom.css" type="text/css" />
    <link rel="shortcut icon" href="../_static/org.crownengine.Crown.svg"/>
    <link rel="canonical" href="https://docs.crownengine.org/html/latest/gameplay/lua_scripting.html" />
  <!--[if lt IE 9]>
    <script src="../_static/js/html5shiv.min.js"></script>
  <![endif]-->
  
        <script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script>
        <script src="../_static/jquery.js"></script>
        <script src="../_static/underscore.js"></script>
        <script src="../_static/doctools.js"></script>
    <script src="../_static/js/theme.js"></script>
    <link rel="index" title="Index" href="../genindex.html" />
    <link rel="search" title="Search" href="../search.html" />
    <link rel="copyright" title="Copyright" href="../copyright.html" />
    <link rel="next" title="Objects binding and lifetime" href="objects_binding.html" />
    <link rel="prev" title="Writing Gameplay" href="index.html" /> 
</head>

<body class="wy-body-for-nav"> 
  <div class="wy-grid-for-nav">
    <nav data-toggle="wy-nav-shift" class="wy-nav-side">
      <div class="wy-side-scroll">
        <div class="wy-side-nav-search" >
            <a href="../index.html">
            <img src="../_static/org.crownengine.Crown.svg" class="logo" alt="Logo"/>
          </a>
              <div class="version">
                Crown 0.60.0 Manual
              </div>
<div role="search">
  <form id="rtd-search-form" class="wy-form" action="../search.html" method="get">
    <input type="text" name="q" placeholder="Search docs" />
    <input type="hidden" name="check_keywords" value="yes" />
    <input type="hidden" name="area" value="default" />
  </form>
</div>
        </div><div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="Navigation menu">
              <ul class="current">
<li class="toctree-l1"><a class="reference internal" href="../changelog.html">Changelog</a></li>
<li class="toctree-l1"><a class="reference internal" href="../introduction.html">Introduction</a></li>
<li class="toctree-l1"><a class="reference internal" href="../installing_crown/index.html">Installing Crown</a></li>
<li class="toctree-l1"><a class="reference internal" href="../getting_started/index.html">Getting Started</a></li>
<li class="toctree-l1"><a class="reference internal" href="../level_editor/index.html">The Level Editor</a></li>
<li class="toctree-l1"><a class="reference internal" href="../importing_resources/index.html">Importing Resources</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="index.html">Writing Gameplay</a><ul class="current">
<li class="toctree-l2 current"><a class="current reference internal" href="#">Scripting in Lua</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#what-is-lua">What is Lua</a></li>
<li class="toctree-l3"><a class="reference internal" href="#runtime-entry-points">Runtime entry points</a></li>
<li class="toctree-l3"><a class="reference internal" href="#the-boot-script">The boot script</a></li>
<li class="toctree-l3"><a class="reference internal" href="#the-gamebase-framework">The GameBase framework</a></li>
<li class="toctree-l3"><a class="reference internal" href="#hot-reloading">Hot reloading</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="objects_binding.html">Objects binding and lifetime</a></li>
<li class="toctree-l2"><a class="reference internal" href="unit_interaction.html">Interacting with Units</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../deploying/index.html">Deploying</a></li>
<li class="toctree-l1"><a class="reference internal" href="../reference/index.html">Reference</a></li>
<li class="toctree-l1"><a class="reference internal" href="../lua_api.html">Lua API reference</a></li>
<li class="toctree-l1"><a class="reference internal" href="../glossary.html">Glossary</a></li>
<li class="toctree-l1"><a class="reference internal" href="../copyright.html">License</a></li>
<li class="toctree-l1"><a class="reference internal" href="../hackers/index.html">Hackers</a></li>
</ul>

        </div>
      </div>
    </nav>

    <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"><nav class="wy-nav-top" aria-label="Mobile navigation menu" >
          <i data-toggle="wy-nav-top" class="fa fa-bars"></i>
          <a href="../index.html">Crown 0.60.0 Manual</a>
      </nav>

      <div class="wy-nav-content">
        <div class="rst-content">
          <div role="navigation" aria-label="Page navigation">
  <ul class="wy-breadcrumbs">
      <li><a href="../index.html" class="icon icon-home"></a> &raquo;</li>
          <li><a href="index.html">Writing Gameplay</a> &raquo;</li>
      <li>Scripting in Lua</li>
      <li class="wy-breadcrumbs-aside">
            <a href="../_sources/gameplay/lua_scripting.rst.txt" rel="nofollow"> View page source</a>
      </li>
  </ul>
  <hr/>
</div>
          <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
           <div itemprop="articleBody">
             
  <section id="scripting-in-lua">
<h1>Scripting in Lua<a class="headerlink" href="#scripting-in-lua" title="Permalink to this headline">¶</a></h1>
<p>All gameplay code in Crown is written in Lua. This section will give you a basic
understanding of how Lua is used and can be used in Crown.</p>
<section id="what-is-lua">
<h2>What is Lua<a class="headerlink" href="#what-is-lua" title="Permalink to this headline">¶</a></h2>
<p>Lua is a simple, fast and lightweight scripting language which is easy to learn
and supports all features needed to write any type of game.</p>
<p>Lua is widely known in the games industry and has been used for decades to write
many successful commercial games.</p>
</section>
<section id="runtime-entry-points">
<h2>Runtime entry points<a class="headerlink" href="#runtime-entry-points" title="Permalink to this headline">¶</a></h2>
<p>When Crown runs, it calls a small set of predefined global functions at
specific times:</p>
<blockquote>
<div><ul class="simple">
<li><p>init()</p></li>
<li><p>shutdown()</p></li>
<li><p>update(dt)</p></li>
<li><p>render(dt)</p></li>
</ul>
</div></blockquote>
<p>The init() function is called right after the runtime starts. It can be used to
initialize global state etc. while shutdown() is called just before the runtime
exits.</p>
<p>update(dt) and render(dt) are called periodically as part of the game loop. You
can use them to implement any gameplay logic, input handling and other per-frame
updates your game may need.</p>
</section>
<section id="the-boot-script">
<h2>The boot script<a class="headerlink" href="#the-boot-script" title="Permalink to this headline">¶</a></h2>
<p>The boot script is the first Lua script that is executed when Crown starts.</p>
<p>In the boot script you will typically define the <a class="reference internal" href="#runtime-entry-points">runtime entry points</a> and
possibly require() additional lua scripts, like you would do in regular Lua
programs. One difference is that Crown expects the .lua extension to be omitted
(i.e. require(“foo/bar”) instead of “foo/bar.lua”). This is for consistency with
how resources are referenced elsewhere.</p>
<p>Projects may contain multiple boot scripts for different purposes (for example,
separate boot scripts for the editors and the game). You can specify which boot
script to use in the <a class="reference internal" href="../reference/boot_config.html"><span class="doc">Boot Config</span></a> file.</p>
</section>
<section id="the-gamebase-framework">
<h2>The GameBase framework<a class="headerlink" href="#the-gamebase-framework" title="Permalink to this headline">¶</a></h2>
<p>Crown automatically generates a <code class="docutils literal notranslate"><span class="pre">main.lua</span></code> script in the root folder of
<a class="reference internal" href="../getting_started/create_new_project.html"><span class="doc">new projects</span></a>.</p>
<p>You may notice that it contains some strangely named
Game.init()/Game.update()/etc. functions, as well as other utility functions.</p>
<p>Those functions are part of the GameBase framework, which is a tiny layer built
on top of the fundamental <a class="reference internal" href="#runtime-entry-points">runtime entry points</a>.</p>
<p>The GameBase layer allows for integration with the editors and adds support to
common functionalities such as loading levels, creating a default camera etc.</p>
<p>Expert users can avoid the GameBase althogheter by defining plain
init/update/shutdown but we recommend to stick with it if you plan to use our
tools.</p>
</section>
<section id="hot-reloading">
<h2>Hot reloading<a class="headerlink" href="#hot-reloading" title="Permalink to this headline">¶</a></h2>
<p>Crown fully supports reloading of gameplay code while the game is running.</p>
<p>Hot reloading is achieved by re-executing modified Lua files. This method works
well in general, but needs some care in specific occasions. Consider the
following script:</p>
<div class="highlight-lua notranslate"><div class="highlight"><pre><span></span><span class="n">Foo</span> <span class="o">=</span> <span class="p">{}</span>
</pre></div>
</div>
<p>Every time Crown reloads such file, a new table will be created and its
reference will be stored in the variable Foo, making the previous state
unreachable.</p>
<p>To make it hot-reload safe you could check whether the Foo objects exists
already, and skip its creation if that is the case:</p>
<div class="highlight-lua notranslate"><div class="highlight"><pre><span></span><span class="n">Foo</span> <span class="o">=</span> <span class="n">Foo</span> <span class="ow">or</span> <span class="p">{}</span>
</pre></div>
</div>
</section>
</section>


           </div>
          </div>
          <footer><div class="rst-footer-buttons" role="navigation" aria-label="Footer">
        <a href="index.html" class="btn btn-neutral float-left" title="Writing Gameplay" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a>
        <a href="objects_binding.html" class="btn btn-neutral float-right" title="Objects binding and lifetime" accesskey="n" rel="next">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
    </div>

  <hr/>

  <div role="contentinfo">
    <p>&#169; <a href="../copyright.html">Copyright</a> Except where otherwise noted, content on this page is licensed under a CC-BY-SA 4.0 Int. License.
      <span class="lastupdated">Last updated on Oct 16, 2025.
      </span></p>
  </div>

  Built with <a href="https://www.sphinx-doc.org/">Sphinx</a> using a
    <a href="https://github.com/readthedocs/sphinx_rtd_theme">theme</a>
    provided by <a href="https://readthedocs.org">Read the Docs</a>.
   

</footer>
        </div>
      </div>
    </section>
  </div>
  <script>
      jQuery(function () {
          SphinxRtdTheme.Navigation.enable(true);
      });
  </script>
    <!-- Theme Analytics -->
    <script async src="https://www.googletagmanager.com/gtag/js?id=G-XNVGCMNDZH"></script>
    <script>
      window.dataLayer = window.dataLayer || [];
      function gtag(){dataLayer.push(arguments);}
      gtag('js', new Date());

      gtag('config', 'G-XNVGCMNDZH', {
          'anonymize_ip': true,
      });
    </script> 

</body>
</html>