115 lines
5.1 KiB
XML
115 lines
5.1 KiB
XML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="glGetAttribLocation">
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<refmeta>
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<refentrytitle>glGetAttribLocation</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glGetAttribLocation</refname>
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<refpurpose>Returns the location of an attribute variable</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>GLint <function>glGetAttribLocation</function></funcdef>
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<paramdef>GLuint <parameter>program</parameter></paramdef>
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<paramdef>const GLchar *<parameter>name</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>program</parameter></term>
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<listitem>
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<para>Specifies the program object to be
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queried.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>name</parameter></term>
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<listitem>
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<para>Points to a null terminated string containing
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the name of the attribute variable whose location is
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to be queried.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para><function>glGetAttribLocation</function> queries the
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previously linked program object specified by
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<parameter>program</parameter> for the attribute variable
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specified by <parameter>name</parameter> and returns the index
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of the generic vertex attribute that is bound to that attribute
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variable. If <parameter>name</parameter> is a matrix attribute
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variable, the index of the first column of the matrix is
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returned. If the named attribute variable is not an active
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attribute in the specified program object or if
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<parameter>name</parameter> starts with the reserved prefix
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"gl_", a value of -1 is returned.</para>
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<para>The association between an attribute variable name and a
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generic attribute index can be specified at any time by calling
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<citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>.
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Attribute bindings do not go into effect until
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<citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>
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is called. After a program object has been linked successfully,
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the index values for attribute variables remain fixed until the
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next link command occurs. The attribute values can only be
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queried after a link if the link was successful.
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<function>glGetAttribLocation</function> returns the binding
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that actually went into effect the last time
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<citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>
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was called for the specified program object. Attribute bindings
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that have been specified since the last link operation are not
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returned by <function>glGetAttribLocation</function>.</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para><function>glGetAttribLocation</function> is available only
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if the GL version is 2.0 or greater.</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<parameter>program</parameter> is not a value generated by
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OpenGL.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<parameter>program</parameter> is not a program object.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<parameter>program</parameter> has not been successfully
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linked.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<function>glGetAttribLocation</function> is executed between the
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execution of
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<citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
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and the corresponding execution of
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<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>
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with argument <parameter>program</parameter> and the index of an
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active attribute</para>
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<para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry></para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para><citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexAttrib</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexAttribPointer</refentrytitle></citerefentry></para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 2003-2005 3Dlabs Inc. Ltd.
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This material may be distributed subject to the terms and conditions set forth in
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the Open Publication License, v 1.0, 8 June 1999.
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<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
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</para>
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</refsect1>
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</refentry>
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