161 lines
8.5 KiB
XML
161 lines
8.5 KiB
XML
<?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>
|