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<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glGetAttribLocation</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /></head><body><div class="refentry"><a id="glGetAttribLocation"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetAttribLocation — return the location of an attribute variable</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">GLint <strong class="fsfunc">glGetAttribLocation</strong>(</code></td><td>GLuint <var class="pdparam">program</var>, </td></tr><tr><td> </td><td>const GLchar *<var class="pdparam">name</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>program</code></em></span></dt><dd><p>Specifies the program object to be
		    queried.</p></dd><dt><span class="term"><em class="parameter"><code>name</code></em></span></dt><dd><p>Points to a null terminated string containing
		    the name of the attribute variable whose location is
		    to be queried.</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p><code class="function">glGetAttribLocation</code> queries the
	previously linked program object specified by
	<em class="parameter"><code>program</code></em> for the attribute variable
	specified by <em class="parameter"><code>name</code></em> and returns the index
	of the generic vertex attribute that is bound to that attribute
	variable. If <em class="parameter"><code>name</code></em> is a matrix attribute
	variable, the index of the first column of the matrix is
	returned. If the named attribute variable is not an active
	attribute in the specified program object or if
	<em class="parameter"><code>name</code></em> starts with the reserved prefix
	"gl_", a value of -1 is returned.</p><p>The association between an attribute variable name and a
	generic attribute index can be specified at any time by calling
	<a class="citerefentry" href="glBindAttribLocation.xml"><span class="citerefentry"><span class="refentrytitle">glBindAttribLocation</span></span></a>.
	Attribute bindings do not go into effect until
	<a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
	is called. After a program object has been linked successfully,
	the index values for attribute variables remain fixed until the
	next link command occurs. The attribute values can only be
	queried after a link if the link was successful.
	<code class="function">glGetAttribLocation</code> returns the binding
	that actually went into effect the last time
	<a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
	was called for the specified program object. Attribute bindings
	that have been specified since the last link operation are not
	returned by <code class="function">glGetAttribLocation</code>.</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
	<em class="parameter"><code>program</code></em> is not a value generated by
	OpenGL.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
	<em class="parameter"><code>program</code></em> is not a program object.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
	<em class="parameter"><code>program</code></em> has not been successfully
	linked.</p></div><div class="refsect1"><a id="associatedgets"></a><h2>Associated Gets</h2><p><a class="citerefentry" href="glGetActiveAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glGetActiveAttrib</span></span></a>
	with argument <em class="parameter"><code>program</code></em> and the index of an
	active attribute</p><p><a class="citerefentry" href="glIsProgram.xml"><span class="citerefentry"><span class="refentrytitle">glIsProgram</span></span></a></p></div><div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p><a class="citerefentry" href="glBindAttribLocation.xml"><span class="citerefentry"><span class="refentrytitle">glBindAttribLocation</span></span></a>,
	<a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>,
	<a class="citerefentry" href="glVertexAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glVertexAttrib</span></span></a>,
	<a class="citerefentry" href="glVertexAttribPointer.xml"><span class="citerefentry"><span class="refentrytitle">glVertexAttribPointer</span></span></a></p></div><div class="refsect1"><a id="copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 2003-2005 3Dlabs Inc. Ltd. 
            This material may be distributed subject to the terms and conditions set forth in 
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p></div></div></body></html>