kontra
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Kontra HTML5 game development library
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<title>Kontra.js – GameLoop</title>
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<span id="api" class="nav-api-heading">API</span>
<ul aria-labelledby="api">
<li><a href="api/animation" >Animation</a></li>
<li><a href="api/assets" >Assets</a></li>
<li><a href="api/core" >Core</a></li>
<li><a href="api/events" >Events</a></li>
<li><a href="api/gameLoop" aria-current="page">GameLoop</a></li>
<li><a href="api/keyboard" >Keyboard</a></li>
<li><a href="api/plugin" >Plugin</a></li>
<li><a href="api/pointer" >Pointer</a></li>
<li><a href="api/pool" >Pool</a></li>
<li><a href="api/quadtree" >Quadtree</a></li>
<li><a href="api/sprite" >Sprite</a></li>
<li><a href="api/spriteSheet" >SpriteSheet</a></li>
<li><a href="api/store" >Store</a></li>
<li><a href="api/tileEngine" >TileEngine</a></li>
<li><a href="api/vector" >Vector</a></li>
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<h1>GameLoop(​properties)
</h1>
<p>The game loop updates and renders the game every frame. The game loop is stopped by default and will not start until the loops <code>start()</code> function is called.</p>
<p>The game loop uses a time-based animation with a fixed <code>dt</code> to <a href="http://blog.sklambert.com/using-time-based-animation-implement/">avoid frame rate issues</a>. Each update call is guaranteed to equal 1/60 of a second.</p>
<p>This means that you can avoid having to do time based calculations in your update functions and instead do fixed updates.</p>
<div class="tablist">
<ul role="tablist">
<li role="presentation" data-tab="global">
<button role="tab" id="gameloop-global-tab">Global Object</button>
</li>
<li role="presentation" data-tab="es">
<button role="tab" id="gameloop-es-tab">ES Module Import</button>
</li>
<li role="presentation" data-tab="bundle">
<button role="tab" id="gameloop-bundle-tab">Module Bundler</button>
</li>
<li role="presentation"></li>
</ul>
<section role="tabpanel" aria-labelledby=gameloop-global-tab data-tabpanel="global"><pre><code class="language-js">let { Sprite, GameLoop } = kontra;
let sprite = Sprite({
x: 100,
y: 200,
width: 20,
height: 40,
color: 'red'
});
let loop = GameLoop({
update: function(dt) {
// no need to determine how many pixels you want to
// move every second and multiple by dt
// sprite.x += 180 * dt;
// instead just update by how many pixels you want
// to move every frame and the loop will ensure 60FPS
sprite.x += 3;
},
render: function() {
sprite.render();
}
});
loop.start();</code></pre></section>
<section role="tabpanel" aria-labelledby=gameloop-es-tab data-tabpanel="es"><pre><code class="language-js">import { Sprite, GameLoop } from 'path/to/kontra.mjs';
let sprite = Sprite({
x: 100,
y: 200,
width: 20,
height: 40,
color: 'red'
});
let loop = GameLoop({
update: function(dt) {
// no need to determine how many pixels you want to
// move every second and multiple by dt
// sprite.x += 180 * dt;
// instead just update by how many pixels you want
// to move every frame and the loop will ensure 60FPS
sprite.x += 3;
},
render: function() {
sprite.render();
}
});
loop.start();</code></pre></section>
<section role="tabpanel" aria-labelledby=gameloop-bundle-tab data-tabpanel="bundle"><pre><code class="language-js">import { Sprite, GameLoop } from 'kontra';
let sprite = Sprite({
x: 100,
y: 200,
width: 20,
height: 40,
color: 'red'
});
let loop = GameLoop({
update: function(dt) {
// no need to determine how many pixels you want to
// move every second and multiple by dt
// sprite.x += 180 * dt;
// instead just update by how many pixels you want
// to move every frame and the loop will ensure 60FPS
sprite.x += 3;
},
render: function() {
sprite.render();
}
});
loop.start();</code></pre></section>
</div>
<h3 id="title-GameLoop"><span class="visually-hidden">GameLoop</span> Parameters</span></h3>
<dl aria-labelledby="title-GameLoop">
<dt>
<code>properties</code>
</dt>
<dd><p>Object. Properties of the game loop.</p>
</dd>
<dt>
<code>properties.update</code>
</dt>
<dd><p>Function. Function called every frame to update the game. Is passed the fixed <code>dt</code> as a parameter.</p>
</dd>
<dt>
<code>properties.render</code>
</dt>
<dd><p>Function. Function called every frame to render the game.</p>
</dd>
<dt>
<code>properties.fps</code>
<span class="optional">Optional</span>
</dt>
<dd><p>Number. Desired frame rate. Defaults to <code>60</code>.</p>
</dd>
<dt>
<code>properties.clearCanvas</code>
<span class="optional">Optional</span>
</dt>
<dd><p>Boolean. Clear the canvas every frame before the <code>render()</code> function is called. Defaults to <code>true</code>.</p>
</dd>
</dl>
<section class="toc">
<h2 id="toc"><a href="#toc" class="section-link">Table of Contents<span aria-hidden="true">#</span></a></h2>
<ul aria-labelledby="toc">
<li>
<h3 id="properties">Properties</h3>
<ul aria-labelledby="properties">
<li>
<a href="api/gameLoop#isStopped">
<span>GameLoop​.isStopped</span>
</a>
</li>
</ul>
</li>
<li>
<h3 id="methods">Methods</h3>
<ul aria-labelledby="methods">
<li>
<a href="api/gameLoop#render">
<span>GameLoop​.render(​)</span>
</a>
</li>
<li>
<a href="api/gameLoop#start">
<span>GameLoop​.start(​)</span>
</a>
</li>
<li>
<a href="api/gameLoop#stop">
<span>GameLoop​.stop(​)</span>
</a>
</li>
<li>
<a href="api/gameLoop#update">
<span>GameLoop​.update(​dt)</span>
</a>
</li>
</ul>
</li>
</ul>
</section>
<section>
<h2 id="isStopped">
<a href="api/gameLoop#isStopped" class="section-link">
<span>GameLoop​.isStopped</span>
<span aria-hidden="true">#</span>
</a>
</h2>
<p>If the game loop is currently stopped.</p>
<div class="tablist">
<ul role="tablist">
<li role="presentation" data-tab="global">
<button role="tab" id="isstopped-global-tab">Global Object</button>
</li>
<li role="presentation" data-tab="es">
<button role="tab" id="isstopped-es-tab">ES Module Import</button>
</li>
<li role="presentation" data-tab="bundle">
<button role="tab" id="isstopped-bundle-tab">Module Bundler</button>
</li>
<li role="presentation"></li>
</ul>
<section role="tabpanel" aria-labelledby=isstopped-global-tab data-tabpanel="global"><pre><code class="language-js">let { GameLoop } = kontra;
let loop = GameLoop({
// ...
});
console.log(loop.isStopped); //=> true
loop.start();
console.log(loop.isStopped); //=> false
loop.stop();
console.log(loop.isStopped); //=> true</code></pre></section>
<section role="tabpanel" aria-labelledby=isstopped-es-tab data-tabpanel="es"><pre><code class="language-js">import { GameLoop } from 'path/to/kontra.mjs';
let loop = GameLoop({
// ...
});
console.log(loop.isStopped); //=> true
loop.start();
console.log(loop.isStopped); //=> false
loop.stop();
console.log(loop.isStopped); //=> true</code></pre></section>
<section role="tabpanel" aria-labelledby=isstopped-bundle-tab data-tabpanel="bundle"><pre><code class="language-js">import { GameLoop } from 'kontra';
let loop = GameLoop({
// ...
});
console.log(loop.isStopped); //=> true
loop.start();
console.log(loop.isStopped); //=> false
loop.stop();
console.log(loop.isStopped); //=> true</code></pre></section>
</div>
</section>
<section>
<h2 id="render">
<a href="api/gameLoop#render" class="section-link">
<span>GameLoop​.render(​)</span>
<span aria-hidden="true">#</span>
</a>
</h2>
<p>Called every frame to render the game. Put all of your games render logic here.</p>
</section>
<section>
<h2 id="start">
<a href="api/gameLoop#start" class="section-link">
<span>GameLoop​.start(​)</span>
<span aria-hidden="true">#</span>
</a>
</h2>
<p>Start the game loop.</p>
</section>
<section>
<h2 id="stop">
<a href="api/gameLoop#stop" class="section-link">
<span>GameLoop​.stop(​)</span>
<span aria-hidden="true">#</span>
</a>
</h2>
<p>Stop the game loop.</p>
</section>
<section>
<h2 id="update">
<a href="api/gameLoop#update" class="section-link">
<span>GameLoop​.update(​dt)</span>
<span aria-hidden="true">#</span>
</a>
</h2>
<p>Called every frame to update the game. Put all of your games update logic here.</p>
<h3 id="title-update"><span class="visually-hidden">update</span> Parameters</span></h3>
<dl aria-labelledby="title-update">
<dt>
<code>dt</code>
</dt>
<dd><p>Number. The fixed dt time of 1/60 of a frame.</p>
</dd>
</dl>
</section>
</div>
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