Revision 1031652 of WebGLQuery

<div>{{APIRef("WebGL")}} {{SeeCompatTable}}</div>

<p>The <strong><code>WebGLQuery</code></strong> interface is part of the <a href="/en-US/docs/Web/API/WebGL_API">WebGL 2</a> API and provides ways to asynchronously query for information. By default, occlusion queries and primitive queries are available.</p>

<p>Another kind of queries are disjoint timer queries, which allow you to measure performance and profiling of your GPU. Disjoint timer queries are available with the {{domxref("EXT_disjoint_timer_query")}} extension only.</p>

<p>When working with <code>WebGLQuery</code> objects, the following methods of the {{domxref("WebGL2RenderingContext")}} are useful:</p>

<ul>
 <li>{{domxref("WebGL2RenderingContext.createQuery()")}}</li>
 <li>{{domxref("WebGL2RenderingContext.deleteQuery()")}}</li>
 <li>{{domxref("WebGL2RenderingContext.isQuery()")}}</li>
 <li>{{domxref("WebGL2RenderingContext.beginQuery()")}}</li>
 <li>{{domxref("WebGL2RenderingContext.endQuery()")}}</li>
 <li>{{domxref("WebGL2RenderingContext.getQuery()")}}</li>
 <li>{{domxref("WebGL2RenderingContext.getQueryParameter()")}}</li>
</ul>

<h2 id="Examples">Examples</h2>

<h3>Creating a <code>WebGLQuery</code> object</h3>

<p>in this example, <code>gl</code> must be a {{domxref("WebGL2RenderingContext")}}. <code>WebGLQuery</code> objects are not available in WebGL 1.</p>

<pre class="brush: js">
var query = gl.createQuery();
</pre>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('WebGL2', "#3.2", "WebGLQuery")}}</td>
   <td>{{Spec2('WebGL2')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}} [2]</td>
   <td>{{CompatNightly}} [1]</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1] WebGL 2 is enabled by default in Firefox Nightly. To enable it in a release version of Firefox, set the preference <code>webgl.enable-prototype-webgl2</code> to <code>true</code> in about:config.</p>

<p>[2] To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag <code>--enable-unsafe-es3-apis</code>.</p>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{domxref("EXT_disjoint_timer_query")}}</li>
</ul>