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"stylesheet" type=
"text/css" href=
"opengl-man.css" /><title>glGetTransformFeedbackVarying
</title><meta name=
"generator" content=
"DocBook XSL Stylesheets V1.69.1" /></head><body><div class=
"refentry" lang=
"en" xml:
lang=
"en"><a id=
"glGetTransformFeedbackVarying"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>glGetTransformFeedbackVarying — retrieve information about varying variables selected for transform feedback
</p></div><div class=
"refsynopsisdiv"><h2>C Specification
</h2><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glGetTransformFeedbackVarying
</b>(
</code></td><td>GLuint
</td><td><var class=
"pdparam">program
</var>,
</td></tr><tr><td> </td><td>GLuint
</td><td><var class=
"pdparam">index
</var>,
</td></tr><tr><td> </td><td>GLsizei
</td><td><var class=
"pdparam">bufSize
</var>,
</td></tr><tr><td> </td><td>GLsizei *
</td><td><var class=
"pdparam">length
</var>,
</td></tr><tr><td> </td><td>GLsizei
</td><td><var class=
"pdparam">size
</var>,
</td></tr><tr><td> </td><td>GLenum *
</td><td><var class=
"pdparam">type
</var>,
</td></tr><tr><td> </td><td>char *
</td><td><var class=
"pdparam">name
</var><code>)
</code>;
</td></tr></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"parameters"></a><h2>Parameters
</h2><div class=
"variablelist"><dl><dt><span class=
"term"><em class=
"parameter"><code>program
</code></em></span></dt><dd><p>
5 The name of the target program object.
6 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>index
</code></em></span></dt><dd><p>
7 The index of the varying variable whose information to retrieve.
8 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>bufSize
</code></em></span></dt><dd><p>
9 The maximum number of characters, including the null terminator, that may be written into
<em class=
"parameter"><code>name
</code></em>.
10 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>length
</code></em></span></dt><dd><p>
11 The address of a variable which will receive the number of characters written into
<em class=
"parameter"><code>name
</code></em>,
12 excluding the null-terminator. If
<em class=
"parameter"><code>length
</code></em> is
<code class=
"constant">NULL
</code> no length is returned.
13 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>size
</code></em></span></dt><dd><p>
14 The address of a variable that will receive the size of the varying.
15 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>type
</code></em></span></dt><dd><p>
16 The address of a variable that will recieve the type of the varying.
17 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>name
</code></em></span></dt><dd><p>
18 The address of a buffer into which will be written the name of the varying.
19 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
20 Information about the set of varying variables in a linked program that will be captured
21 during transform feedback may be retrieved by calling
<code class=
"function">glGetTransformFeedbackVarying
</code>.
22 <code class=
"function">glGetTransformFeedbackVarying
</code> provides information about the varying
23 variable selected by
<em class=
"parameter"><code>index
</code></em>. An
<em class=
"parameter"><code>index
</code></em> of
0 selects
24 the first varying variable specified in the
<em class=
"parameter"><code>varyings
</code></em> array passed
25 to
<a href=
"glTransformFeedbackVaryings.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glTransformFeedbackVaryings
</span></span></a>, and
26 an
<em class=
"parameter"><code>index
</code></em> of
<code class=
"constant">GL_TRANSFORM_FEEDBACK_VARYINGS-
1</code> selects
27 the last such variable.
29 The name of the selected varying is returned as a null-terminated string in
30 <em class=
"parameter"><code>name
</code></em>. The actual number of characters written into
<em class=
"parameter"><code>name
</code></em>,
31 excluding the null terminator, is returned in
<em class=
"parameter"><code>length
</code></em>. If
<em class=
"parameter"><code>length
</code></em>
32 is NULL, no length is returned. The maximum number of characters that may be written into
<em class=
"parameter"><code>name
</code></em>,
33 including the null terminator, is specified by
<em class=
"parameter"><code>bufSize
</code></em>.
35 The length of the longest varying name in program is given by
<code class=
"constant">GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH
</code>,
36 which can be queried with
<a href=
"glGetProgram.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGetProgram
</span></span></a>.
38 For the selected varying variable, its type is returned into
<em class=
"parameter"><code>type
</code></em>. The size of
39 the varying is returned into
<em class=
"parameter"><code>size
</code></em>. The value in
<em class=
"parameter"><code>size
</code></em> is
40 in units of the type returned in
<em class=
"parameter"><code>type
</code></em>. The type returned can be any of the
41 scalar, vector, or matrix attribute types returned by
<a href=
"glGetActiveAttrib.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGetActiveAttrib
</span></span></a>.
42 If an error occurred, the return parameters
<em class=
"parameter"><code>length
</code></em>,
<em class=
"parameter"><code>size
</code></em>,
43 <em class=
"parameter"><code>type
</code></em> and
<em class=
"parameter"><code>name
</code></em> will be unmodified. This command will return as much
44 information about the varying variables as possible. If no information is available,
<em class=
"parameter"><code>length
</code></em>
45 will be set to zero and
<em class=
"parameter"><code>name
</code></em> will be an empty string. This situation could
46 arise if
<code class=
"function">glGetTransformFeedbackVarying
</code> is called after a failed link.
47 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"errors"></a><h2>Errors
</h2><p>
48 <code class=
"constant">GL_INVALID_VALUE
</code> is generated if
<em class=
"parameter"><code>program
</code></em> is not
49 the name of a program object.
51 <code class=
"constant">GL_INVALID_VALUE
</code> is generated if
<em class=
"parameter"><code>index
</code></em> is greater or equal to
52 the value of
<code class=
"constant">GL_TRANSFORM_FEEDBACK_VARYINGS
</code>.
54 <code class=
"constant">GL_INVALID_OPERATION
</code> is generated
<em class=
"parameter"><code>program
</code></em> has not been linked.
55 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"associatedgets"></a><h2>Associated Gets
</h2><p>
56 <a href=
"glGetProgram.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGetProgram
</span></span></a> with argument
<code class=
"constant">GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH
</code>.
57 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"seealso"></a><h2>See Also
</h2><p>
58 <a href=
"glBeginTransformFeedback.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glBeginTransformFeedback
</span></span></a>,
59 <a href=
"glEndTransformFeedback.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glEndTransformFeedback
</span></span></a>,
60 <a href=
"glTransformFeedbackVaryings.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glTransformFeedbackVaryings
</span></span></a>,
61 <a href=
"glGetProgram.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGetProgram
</span></span></a>
62 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
63 Copyright
<span class=
"trademark"></span>©
2010 Khronos Group.
64 This material may be distributed subject to the terms and conditions set forth in
65 the Open Publication License, v
1.0,
8 June
1999.
66 <a href=
"http://opencontent.org/openpub/" target=
"_top">http://opencontent.org/openpub/
</a>.
67 </p></div></div></body></html>
HCoop / clinton / guile-figl.git / blob