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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
+ "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
+<refentry id="glGetTransformFeedbackVarying">
+ <refmeta>
+ <refmetainfo>
+ <copyright>
+ <year>2010</year>
+ <holder>Khronos Group</holder>
+ </copyright>
+ </refmetainfo>
+ <refentrytitle>glGetTransformFeedbackVarying</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>glGetTransformFeedbackVarying</refname>
+ <refpurpose>retrieve information about varying variables selected for transform feedback</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>glGetTransformFeedbackVarying</function></funcdef>
+ <paramdef>GLuint<parameter>program</parameter></paramdef>
+ <paramdef>GLuint<parameter>index</parameter></paramdef>
+ <paramdef>GLsizei<parameter>bufSize</parameter></paramdef>
+ <paramdef>GLsizei *<parameter>length</parameter></paramdef>
+ <paramdef>GLsizei<parameter>size</parameter></paramdef>
+ <paramdef>GLenum *<parameter>type</parameter></paramdef>
+ <paramdef>char *<parameter>name</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <refsect1 id="parameters"><title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>program</parameter></term>
+ <listitem>
+ <para>
+ The name of the target program object.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>index</parameter></term>
+ <listitem>
+ <para>
+ The index of the varying variable whose information to retrieve.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>bufSize</parameter></term>
+ <listitem>
+ <para>
+ The maximum number of characters, including the null terminator, that may be written into <parameter>name</parameter>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>length</parameter></term>
+ <listitem>
+ <para>
+ The address of a variable which will receive the number of characters written into <parameter>name</parameter>,
+ excluding the null-terminator. If <parameter>length</parameter> is <constant>NULL</constant> no length is returned.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>size</parameter></term>
+ <listitem>
+ <para>
+ The address of a variable that will receive the size of the varying.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>
+ The address of a variable that will recieve the type of the varying.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>
+ The address of a buffer into which will be written the name of the varying.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para>
+ Information about the set of varying variables in a linked program that will be captured
+ during transform feedback may be retrieved by calling <function>glGetTransformFeedbackVarying</function>.
+ <function>glGetTransformFeedbackVarying</function> provides information about the varying
+ variable selected by <parameter>index</parameter>. An <parameter>index</parameter> of 0 selects
+ the first varying variable specified in the <parameter>varyings</parameter> array passed
+ to <citerefentry><refentrytitle>glTransformFeedbackVaryings</refentrytitle></citerefentry>, and
+ an <parameter>index</parameter> of <constant>GL_TRANSFORM_FEEDBACK_VARYINGS-1</constant> selects
+ the last such variable.
+ </para>
+ <para>
+ The name of the selected varying is returned as a null-terminated string in
+ <parameter>name</parameter>. The actual number of characters written into <parameter>name</parameter>,
+ excluding the null terminator, is returned in <parameter>length</parameter>. If <parameter>length</parameter>
+ is NULL, no length is returned. The maximum number of characters that may be written into <parameter>name</parameter>,
+ including the null terminator, is specified by <parameter>bufSize</parameter>.
+ </para>
+ <para>
+ The length of the longest varying name in program is given by <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>,
+ which can be queried with <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>.
+ </para>
+ <para>
+ For the selected varying variable, its type is returned into <parameter>type</parameter>. The size of
+ the varying is returned into <parameter>size</parameter>. The value in <parameter>size</parameter> is
+ in units of the type returned in <parameter>type</parameter>. The type returned can be any of the
+ scalar, vector, or matrix attribute types returned by <citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>.
+ If an error occurred, the return parameters <parameter>length</parameter>, <parameter>size</parameter>,
+ <parameter>type</parameter> and <parameter>name</parameter> will be unmodified. This command will return as much
+ information about the varying variables as possible. If no information is available, <parameter>length</parameter>
+ will be set to zero and <parameter>name</parameter> will be an empty string. This situation could
+ arise if <function>glGetTransformFeedbackVarying</function> is called after a failed link.
+ </para>
+ </refsect1>
+ <refsect1 id="errors"><title>Errors</title>
+ <para>
+ <constant>GL_INVALID_VALUE</constant> is generated if <parameter>program</parameter> is not
+ the name of a program object.
+ </para>
+ <para>
+ <constant>GL_INVALID_VALUE</constant> is generated if <parameter>index</parameter> is greater or equal to
+ the value of <constant>GL_TRANSFORM_FEEDBACK_VARYINGS</constant>.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is generated <parameter>program</parameter> has not been linked.
+ </para>
+ </refsect1>
+ <refsect1 id="associatedgets"><title>Associated Gets</title>
+ <para>
+ <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry> with argument <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>.
+ </para>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>glBeginTransformFeedback</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glEndTransformFeedback</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glTransformFeedbackVaryings</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>
+ </para>
+ </refsect1> <refsect1 id="Copyright"><title>Copyright</title>
+ <para>
+ Copyright <trademark class="copyright"></trademark> 2010 Khronos Group.
+ This material may be distributed subject to the terms and conditions set forth in
+ the Open Publication License, v 1.0, 8 June 1999.
+ <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
+ </para>
+ </refsect1>
+</refentry>
HCoop / clinton / guile-figl.git / blobdiff