---
title: WebGL2RenderingContext.beginTransformFeedback()
slug: Web/API/WebGL2RenderingContext/beginTransformFeedback
tags:
  - API
  - WebGL
  - WebGL2
  - 参考
  - 实验性
  - 方法
translation_of: Web/API/WebGL2RenderingContext/beginTransformFeedback
---
<div>{{APIRef("WebGL")}} {{SeeCompatTable}}</div>

<p><a href="/en-US/docs/Web/API/WebGL_API">WebGL 2 API</a> 的 <strong><code>WebGL2RenderingContext.beginTransformFeedback()</code></strong> 方法开始一个变换回传（Transform Feedback）操作。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">void <var>gl</var>.beginTransformFeedback(<var>primitiveMode</var>);
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>primitiveMode</code></dt>
 <dd>A {{domxref("GLenum")}} specifying the output type of the primitives that will be recorded into the buffer objects that are bound for transform feedback. 可能的值：
 <ul>
  <li><code>gl.POINTS</code></li>
  <li><code>gl.LINES</code></li>
  <li><code>gl.TRIANGLES</code></li>
 </ul>
 </dd>
</dl>

<h3 id="返回值">返回值</h3>

<p>无。</p>

<h2 id="示例">示例</h2>

<pre class="brush: js">var transformFeedback = gl.createTransformFeedback();
gl.bindTransformFeedback(gl.TRANSFORM_FEEDBACK, transformFeedback);
gl.beginTransformFeedback(gl.TRIANGLES);
gl.drawArrays(gl.TRIANGLES, 0, 3);
</pre>

<h2 id="规范">规范</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', "#3.7.15", "beginTransformFeedback")}}</td>
   <td>{{Spec2('WebGL2')}}</td>
   <td>WebGL中初次定义。</td>
  </tr>
  <tr>
   <td>{{SpecName('OpenGL ES 3.0', "glBeginTransformFeedback.xhtml", "glBeginTransformFeedback")}}</td>
   <td>{{Spec2('OpenGL ES 3.0')}}</td>
   <td>OpenGL API 页面。</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{Compat("api.WebGL2RenderingContext.beginTransformFeedback")}}</p>

<h2 id="相关链接">相关链接</h2>

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