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---
title: WebGLRenderingContext.blendEquationSeparate()
slug: Web/API/WebGLRenderingContext/blendEquationSeparate
translation_of: Web/API/WebGLRenderingContext/blendEquationSeparate
---
<div>{{APIRef("WebGL")}}</div>
<p>The <strong><code>WebGLRenderingContext.blendEquationSeparate()</code></strong> method of the <a href="/en-US/docs/Web/API/WebGL_API">WebGL API</a> is used to set the RGB blend equation and alpha blend equation separately.</p>
<p>The blend equation determines how a new pixel is combined with a pixel already in the {{domxref("WebGLFramebuffer")}}.</p>
<h2 id="Syntax">Syntax</h2>
<pre class="syntaxbox">void <var>gl</var>.blendEquationSeparate(<var>modeRGB, modeAlpha</var>);
</pre>
<h3 id="Parameters">Parameters</h3>
<dl>
<dt><code>modeRGB</code></dt>
<dd>A {{domxref("GLenum")}} specifying how the red, green and blue components of source and destination colors are combined. Must be either:
<ul>
<li><code>gl.FUNC_ADD</code>: source + destination (default value),</li>
<li><code>gl.FUNC_SUBTRACT</code>: source - destination,</li>
<li><code>gl.FUNC_REVERSE_SUBTRACT</code>: destination - source,</li>
<li>When using the {{domxref("EXT_blend_minmax")}} extension:
<ul>
<li><code>ext.MIN_EXT</code>: Minimum of source and destination,</li>
<li><code>ext.MAX_EXT</code>: Maximum of source and destination.</li>
</ul>
</li>
<li>When using a {{domxref("WebGL2RenderingContext", "WebGL 2 context", "", 1)}}, the following values are available additionally:
<ul>
<li><code>gl.MIN</code>: Minimum of source and destination,</li>
<li><code>gl.MAX</code>: Maximum of source and destination.</li>
</ul>
</li>
</ul>
</dd>
<dt><code>modeAlpha</code></dt>
<dd>A {{domxref("GLenum")}} specifying how the alpha component (transparency) of source and destination colors are combined. Must be either:
<ul>
<li><code>gl.FUNC_ADD</code>: source + destination (default value),</li>
<li><code>gl.FUNC_SUBTRACT</code>: source - destination,</li>
<li><code>gl.FUNC_REVERSE_SUBTRACT</code>: destination - source,</li>
<li>When using the {{domxref("EXT_blend_minmax")}} extension:
<ul>
<li><code>ext.MIN_EXT</code>: Minimum of source and destination,</li>
<li><code>ext.MAX_EXT</code>: Maximum of source and destination.</li>
</ul>
</li>
<li>When using a {{domxref("WebGL2RenderingContext", "WebGL 2 context", "", 1)}}, the following values are available additionally:
<ul>
<li><code>gl.MIN</code>: Minimum of source and destination,</li>
<li><code>gl.MAX</code>: Maximum of source and destination.</li>
</ul>
</li>
</ul>
</dd>
</dl>
<h3 id="Return_value">Return value</h3>
<p>None.</p>
<h3 id="Exceptions">Exceptions</h3>
<p>If <em>mode</em> is not one of the three possible values, a <code>gl.INVALID_ENUM</code> error is thrown.</p>
<h2 id="Examples">Examples</h2>
<p>To set the blend equations, use:</p>
<pre class="brush: js">gl.blendEquationSeparate(gl.FUNC_ADD, gl.FUNC_SUBTRACT);
</pre>
<p>To get the current blend equations, query the <code>BLEND_EQUATION</code>, <code>BLEND_EQUATION_RGB</code> and <code>BLEND_EQUATION_ALPHA</code> constants which return <code>gl.FUNC_ADD</code>, <code>gl.FUNC_SUBTRACT</code>, <code>gl.FUNC_REVERSE_SUBTRACT</code>, or if the {{domxref("EXT_blend_minmax")}} is enabled: <code>ext.MIN_EXT</code> or <code>ext.MAX_EXT</code>.</p>
<pre class="brush: js">gl.getParameter(gl.BLEND_EQUATION_RGB) === gl.FUNC_ADD;
// true
gl.getParameter(gl.BLEND_EQUATION_ALPHA) === gl.FUNC_ADD;
// true
</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", "blendEquationSeparate")}}</td>
<td>{{Spec2('WebGL')}}</td>
<td>Initial definition for WebGL.</td>
</tr>
<tr>
<td>{{SpecName('OpenGL ES 2.0', "glBlendEquationSeparate.xml", "glBlendEquationSeparate")}}</td>
<td>{{Spec2('OpenGL ES 2.0')}}</td>
<td>Man page of the OpenGL ES 2.0 API.</td>
</tr>
<tr>
<td>{{SpecName('OpenGL ES 3.0', "glBlendEquationSeparate.xhtml", "glBlendEquationSeparate")}}</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>{{Compat("api.WebGLRenderingContext.blendEquationSeparate")}}</p>
<h2 id="See_also">See also</h2>
<ul>
<li>{{domxref("WebGLRenderingContext.blendEquation()")}}</li>
<li>{{domxref("WebGLRenderingContext.blendColor()")}}</li>
<li>{{domxref("WebGLRenderingContext.blendFunc()")}}</li>
<li>{{domxref("EXT_blend_minmax")}}</li>
</ul>
|
