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><head><title>glReadBuffer</title><link rel="stylesheet" href="style.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.59.1"/><link rel="home" href="index.xml" title="PyOpenGL 2.0.1.07 Man Pages"/><link rel="up" href="reference-GL.xml" title="GL"/><link rel="previous" href="glRasterPos.3G.xml" title="glRasterPos"/><link rel="next" href="glReadPixels.3G.xml" title="glReadPixels"/></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">glReadBuffer</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="glRasterPos.3G.xml">Prev</a> </td><th width="60%" align="center">GL</th><td width="20%" align="right"> <a accesskey="n" href="glReadPixels.3G.xml">Next</a></td></tr></table><hr/></div><div class="refentry" lang="en"><a name="glReadBuffer.3G"/><div class="titlepage"/><div class="refnamediv"><a name="glReadBuffer.3G-name"/><h2>Name</h2><p>glReadBuffer &#8212; select a color buffer source for pixels</p></div><div class="refsynopsisdiv"><a name="glReadBuffer.3G-c_spec"/><h2>C Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code>void <tt>glReadBuffer</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLenum <i><tt>mode</tt></i>);</code></td></tr></table></div><div class="refsynopsisdiv"><a name="glReadBuffer.3G-python_spec"/><h2>Python Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code><tt>glReadBuffer</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>mode</tt></i>) &#8594; <tt>None</tt></code></td></tr></table></div><div class="refsect1" lang="en"><a name="glReadBuffer.3G-parameters"/><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><i><tt>mode</tt></i></span></dt><dd>
						Specifies a color buffer. Accepted values are <tt>GL_FRONT_LEFT</tt>,
						<tt>GL_FRONT_RIGHT</tt>, <tt>GL_BACK_LEFT</tt>, <tt>GL_BACK_RIGHT</tt>,
						<tt>GL_FRONT</tt>, <tt>GL_BACK</tt>, <tt>GL_LEFT</tt>,
						<tt>GL_RIGHT</tt>, and <tt>GL_AUX</tt><i><tt>i</tt></i>, where
						<i><tt>i</tt></i> is between 0 and <tt>GL_AUX_BUFFERS</tt> -1.
					</dd></dl></div></div><div class="refsect1" lang="en"><a name="glReadBuffer.3G-description"/><h2>Description</h2><p>
			<tt>glReadBuffer</tt> specifies a color buffer as the source for subsequent <a href="glReadPixels.3G.xml"><tt>glReadPixels</tt></a>, <a href="glCopyTexImage1D.3G.xml"><tt>glCopyTexImage1D</tt></a>, <a href="glCopyTexImage2D.3G.xml"><tt>glCopyTexImage2D</tt></a>, <a href="glCopyTexSubImage1D.3G.xml"><tt>glCopyTexSubImage1D</tt></a>,
			<a href="glCopyTexSubImage2D.3G.xml"><tt>glCopyTexSubImage2D</tt></a>, <a href="glCopyTexSubImage3D.3G.xml"><tt>glCopyTexSubImage3D</tt></a>, and <a href="glCopyPixels.3G.xml"><tt>glCopyPixels</tt></a> commands.
			<i><tt>mode</tt></i> accepts one of twelve or more predefined values. (<tt>GL_AUX0</tt> through
			<tt>GL_AUX3</tt> are always defined.) In a fully configured system, <tt>GL_FRONT</tt>,
			<tt>GL_LEFT</tt>, and <tt>GL_FRONT_LEFT</tt> all name the front left buffer,
			<tt>GL_FRONT_RIGHT</tt> and <tt>GL_RIGHT</tt> name the front right buffer, and
			<tt>GL_BACK_LEFT</tt> and <tt>GL_BACK</tt> name the back left buffer.
		</p><p>
			Nonstereo double-buffered configurations have only a front left and a back left buffer. Single-buffered configurations
			have a front left and a front right buffer if stereo, and only a front left buffer if nonstereo. It is an error to
			specify a nonexistent buffer to <tt>glReadBuffer</tt>.
		</p><p>
			<i><tt>mode</tt></i> is initially <tt>GL_FRONT</tt> in single-buffered configurations, and
			<tt>GL_BACK</tt> in double-buffered configurations.
		</p></div><div class="refsect1" lang="en"><a name="glReadBuffer.3G-errors"/><h2>Errors</h2><p>
			<tt>GL_INVALID_ENUM</tt> is generated if <i><tt>mode</tt></i> is not one of the twelve (or more)
			accepted values.
		</p><p>
			<tt>GL_INVALID_OPERATION</tt> is generated if <i><tt>mode</tt></i> specifies a buffer that does not
			exist.
		</p><p>
			<tt>GL_INVALID_OPERATION</tt> is generated if <tt>glReadBuffer</tt> is executed between the
			execution of <a href="glBegin.3G.xml"><tt>glBegin</tt></a> and the corresponding execution of <a href="glBegin.3G.xml"><tt>glEnd</tt></a>.
		</p></div><div class="refsect1" lang="en"><a name="glReadBuffer.3G-associated_gets"/><h2>Associated Gets</h2><p>
			<tt>glGet</tt> with argument <tt>GL_READ_BUFFER</tt>
		</p></div><div class="refsect1" lang="en"><a name="glReadBuffer.3G-see_also"/><h2>See Also</h2><p>
			<span class="simplelist"><a href="glCopyPixels.3G.xml">glCopyPixels</a>, <a href="glCopyTexImage1D.3G.xml">glCopyTexImage1D</a>, <a href="glCopyTexImage2D.3G.xml">glCopyTexImage2D</a>, <a href="glCopyTexSubImage1D.3G.xml">glCopyTexSubImage1D</a>, <a href="glCopyTexSubImage2D.3G.xml">glCopyTexSubImage2D</a>, <a href="glCopyTexSubImage3D.3G.xml">glCopyTexSubImage3D</a>, <a href="glDrawBuffer.3G.xml">glDrawBuffer</a>, <a href="glReadPixels.3G.xml">glReadPixels</a></span>
		</p></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="glRasterPos.3G.xml">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="reference-GL.xml">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="glReadPixels.3G.xml">Next</a></td></tr><tr><td width="40%" align="left" valign="top">glRasterPos </td><td width="20%" align="center"><a accesskey="h" href="index.xml">Home</a></td><td width="40%" align="right" valign="top"> glReadPixels</td></tr></table></div></body></html>
