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---
title: WebGLRenderingContext.pixelStorei()
slug: Web/API/WebGLRenderingContext/pixelStorei
translation_of: Web/API/WebGLRenderingContext/pixelStorei
---
<div>{{APIRef("WebGL")}}</div>
<p><strong><code>WebGLRenderingContext.pixelStorei()</code></strong> 是 <a href="/en-US/docs/Web/API/WebGL_API">WebGL API</a> 中用于图像预处理的函数。</p>
<h2 id="语法">语法</h2>
<pre class="syntaxbox">void <var>gl</var>.pixelStorei(<var>pname</var>, <var>param</var>);
</pre>
<h3 id="参数">参数</h3>
<dl>
<dt>pname</dt>
<dd> {{domxref("Glenum")}} 类型 ，表示处理的方式。关于该参数可选值，请见下面表格。</dd>
<dt>param</dt>
<dd> {{domxref("GLint")}} 类型，表示 pname 处理方式的参数。关于该参数可选值，请见下面表格。</dd>
</dl>
<h3 id="返回值">返回值</h3>
<p>None.</p>
<h2 id="像素存储参数">像素存储参数</h2>
<table class="standard-table">
<thead>
<tr>
<th scope="col">模式名称 (<code>pname</code>)</th>
<th scope="col">描述</th>
<th scope="col">类型</th>
<th scope="col">默认值</th>
<th scope="col"> param 的可选值</th>
<th scope="col">Specified in</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>gl.PACK_ALIGNMENT</code></td>
<td>Packing of pixel data into memory</td>
<td>{{domxref("GLint")}}</td>
<td>4</td>
<td>1, 2, 4, 8</td>
<td>OpenGL ES 2.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_ALIGNMENT</code></td>
<td>Unpacking of pixel data from memory.</td>
<td>{{domxref("GLint")}}</td>
<td>4</td>
<td>1, 2, 4, 8</td>
<td>OpenGL ES 2.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_FLIP_Y_WEBGL</code></td>
<td>
<p dir="ltr" id="tw-target-text">如果为true，则把图片上下对称翻转坐标轴(图片本身不变)。</p>
</td>
<td>{{domxref("GLboolean")}}</td>
<td>false</td>
<td>true, false</td>
<td>WebGL</td>
</tr>
<tr>
<td><code>gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL</code></td>
<td>Multiplies the alpha channel into the other color channels</td>
<td>{{domxref("GLboolean")}}</td>
<td>false</td>
<td>true, false</td>
<td>WebGL</td>
</tr>
<tr>
<td><code>gl.UNPACK_COLORSPACE_CONVERSION_WEBGL</code></td>
<td>Default color space conversion or no color space conversion.</td>
<td>{{domxref("GLenum")}}</td>
<td><code>gl.BROWSER_DEFAULT_WEBGL</code></td>
<td><code>gl.BROWSER_DEFAULT_WEBGL</code>, <code>gl.NONE</code></td>
<td>WebGL</td>
</tr>
</tbody>
</table>
<p>When using a {{domxref("WebGL2RenderingContext", "WebGL 2 context", "", 1)}}, the following values are available additionally:</p>
<table class="standard-table">
<thead>
<tr>
<th scope="col">Constant</th>
<th scope="col">Description</th>
<th scope="col">Type</th>
<th scope="col">Default value</th>
<th scope="col">Allowed values (for <code>param</code>)</th>
<th scope="col">Specified in</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>gl.PACK_ROW_LENGTH</code></td>
<td>Number of pixels in a row.</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.PACK_SKIP_PIXELS</code></td>
<td>Number of pixel locations skipped before the first pixel is written into memory.</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.PACK_SKIP_ROWS</code></td>
<td>Number of rows of pixel locations skipped before the first pixel is written into memory</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_ROW_LENGTH</code></td>
<td>Number of pixels in a row.</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_IMAGE_HEIGHT</code></td>
<td>Image height used for reading pixel data from memory</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_SKIP_PIXELS</code></td>
<td>Number of pixel images skipped before the first pixel is read from memory</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_SKIP_ROWS</code></td>
<td>Number of rows of pixel locations skipped before the first pixel is read from memory</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
<tr>
<td><code>gl.UNPACK_SKIP_IMAGES</code></td>
<td>Number of pixel images skipped before the first pixel is read from memory</td>
<td>{{domxref("GLint")}}</td>
<td>0</td>
<td>0 to <code>Infinity</code></td>
<td>OpenGL ES 3.0</td>
</tr>
</tbody>
</table>
<h2 id="Examples">Examples</h2>
<p>Setting the pixel storage mode affects the {{domxref("WebGLRenderingContext.readPixels()")}} operations, as well as unpacking of textures with the {{domxref("WebGLRenderingContext.texImage2D()")}} and {{domxref("WebGLRenderingContext.texSubImage2D()")}} methods.<br>
</p>
<pre class="brush: js">var tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, tex);
gl.pixelStorei(gl.PACK_ALIGNMENT, 4);
</pre>
<p>To check the values for packing and unpacking of pixel data, you can query the same pixel storage parameters with {{domxref("WebGLRenderingContext.getParameter()")}}.</p>
<pre class="brush: js">gl.getParameter(gl.PACK_ALIGNMENT);
gl.getParameter(gl.UNPACK_ALIGNMENT);
</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('WebGL', "#5.14.3", "pixelStorei")}}</td>
<td>{{Spec2('WebGL')}}</td>
<td>Initial definition for WebGL.</td>
</tr>
<tr>
<td>{{SpecName('WebGL', "#PIXEL_STORAGE_PARAMETERS", "Pixel Storage Parameters")}}</td>
<td>{{Spec2('WebGL')}}</td>
<td>Additional pixel storage parameters that aren't specified in OpenGL.</td>
</tr>
<tr>
<td>{{SpecName('OpenGL ES 2.0', "glPixelStorei.xml", "glPixelStorei")}}</td>
<td>{{Spec2('OpenGL ES 2.0')}}</td>
<td>Man page of the OpenGL ES 2.0 API.</td>
</tr>
<tr>
<td>{{SpecName('WebGL2', "#3.7.2", "pixelStorei")}}</td>
<td>{{Spec2('WebGL2')}}</td>
<td>Updated definition for WebGL 2.</td>
</tr>
<tr>
<td>{{SpecName('OpenGL ES 3.0', "glPixelStorei.xhtml", "glPixelStorei")}}</td>
<td>{{Spec2('OpenGL ES 3.0')}}</td>
<td>Man page of the OpenGL ES 3.0 API.</td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
<p class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p>
<p>{{Compat("api/WebGLRenderingContext", "WebGLRenderingContext.pixelStorei")}}</p>
<h2 id="See_also">See also</h2>
<ul>
<li>{{domxref("WebGLRenderingContext.readPixels()")}}</li>
<li>{{domxref("WebGLRenderingContext.texImage2D()")}}</li>
<li>{{domxref("WebGLRenderingContext.texSubImage2D()")}}</li>
</ul>
|
