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1 | <?xml version="1.0" encoding="UTF-8"?> |
2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> | |
4 | <refentry id="glTransformFeedbackVaryings"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>2010</year> | |
9 | <holder>Khronos Group</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glTransformFeedbackVaryings</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glTransformFeedbackVaryings</refname> | |
17 | <refpurpose>specify values to record in transform feedback buffers</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glTransformFeedbackVaryings</function></funcdef> | |
23 | <paramdef>GLuint<parameter>program</parameter></paramdef> | |
24 | <paramdef>GLsizei<parameter>count</parameter></paramdef> | |
25 | <paramdef>const char **<parameter>varyings</parameter></paramdef> | |
26 | <paramdef>GLenum<parameter>bufferMode</parameter></paramdef> | |
27 | </funcprototype> | |
28 | </funcsynopsis> | |
29 | </refsynopsisdiv> | |
30 | <refsect1 id="parameters"><title>Parameters</title> | |
31 | <variablelist> | |
32 | <varlistentry> | |
33 | <term><parameter>program</parameter></term> | |
34 | <listitem> | |
35 | <para> | |
36 | The name of the target program object. | |
37 | </para> | |
38 | </listitem> | |
39 | </varlistentry> | |
40 | <varlistentry> | |
41 | <term><parameter>count</parameter></term> | |
42 | <listitem> | |
43 | <para> | |
44 | The number of varying variables used for transform feedback. | |
45 | </para> | |
46 | </listitem> | |
47 | </varlistentry> | |
48 | <varlistentry> | |
49 | <term><parameter>varyings</parameter></term> | |
50 | <listitem> | |
51 | <para> | |
52 | An array of <parameter>count</parameter> zero-terminated strings specifying the | |
53 | names of the varying variables to use for transform feedback. | |
54 | </para> | |
55 | </listitem> | |
56 | </varlistentry> | |
57 | <varlistentry> | |
58 | <term><parameter>bufferMode</parameter></term> | |
59 | <listitem> | |
60 | <para> | |
61 | Identifies the mode used to capture the varying variables when transform feedback is active. | |
62 | <parameter>bufferMode</parameter> must be <constant>GL_INTERLEAVED_ATTRIBS</constant> or <constant>GL_SEPARATE_ATTRIBS</constant>. | |
63 | </para> | |
64 | </listitem> | |
65 | </varlistentry> | |
66 | </variablelist> | |
67 | </refsect1> | |
68 | <refsect1 id="description"><title>Description</title> | |
69 | <para> | |
70 | The names of the vertex or geometry shader outputs to be recorded in transform feedback mode | |
71 | are specified using <function>glTransformFeedbackVaryings</function>. When a geometry shader | |
72 | is active, transform feedback records the values of selected geometry shader output variables | |
73 | from the emitted vertices. Otherwise, the values of the selected vertex shader outputs are | |
74 | recorded. | |
75 | </para> | |
76 | <para> | |
77 | The state set by <function>glTranformFeedbackVaryings</function> is stored and takes effect | |
78 | next time <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry> is called | |
79 | on <parameter>program</parameter>. When <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry> | |
80 | is called, <parameter>program</parameter> is linked so that the values of the specified varying variables | |
81 | for the vertices of each primitive generated by the GL are written to a single buffer | |
82 | object if <parameter>bufferMode</parameter> is <constant>GL_INTERLEAVED_ATTRIBS</constant> or multiple | |
83 | buffer objects if <parameter>bufferMode</parameter> is <constant>GL_SEPARATE_ATTRIBS</constant>. | |
84 | </para> | |
85 | <para> | |
86 | In addition to the errors generated by <function>glTransformFeedbackVaryings</function>, the | |
87 | program <parameter>program</parameter> will fail to link if: | |
88 | <itemizedlist> | |
89 | <listitem> | |
90 | <para> | |
91 | The count specified by <function>glTransformFeedbackVaryings</function> is non-zero, but the | |
92 | program object has no vertex or geometry shader. | |
93 | </para> | |
94 | </listitem> | |
95 | <listitem> | |
96 | <para> | |
97 | Any variable name specified in the <parameter>varyings</parameter> array is not declared as an output | |
98 | in the vertex shader (or the geometry shader, if active). | |
99 | </para> | |
100 | </listitem> | |
101 | <listitem> | |
102 | <para> | |
103 | Any two entries in the <parameter>varyings</parameter> array specify the same varying variable. | |
104 | </para> | |
105 | </listitem> | |
106 | <listitem> | |
107 | <para> | |
108 | The total number of components to capture in any varying variable in <parameter>varyings</parameter> | |
109 | is greater than the constant <constant>GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS</constant> | |
110 | and the buffer mode is <constant>GL_SEPARATE_ATTRIBS</constant>. | |
111 | </para> | |
112 | </listitem> | |
113 | <listitem> | |
114 | <para> | |
115 | The total number of components to capture is greater than the constant | |
116 | <constant>GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS</constant> and the buffer | |
117 | mode is <constant>GL_INTERLEAVED_ATTRIBS</constant>. | |
118 | </para> | |
119 | </listitem> | |
120 | </itemizedlist> | |
121 | </para> | |
122 | </refsect1> | |
123 | <refsect1 id="notes"><title>Notes</title> | |
124 | <para> | |
125 | <function>glGetTransformFeedbackVarying</function> is available only if the GL version is 3.0 or greater. | |
126 | </para> | |
127 | </refsect1> | |
128 | <refsect1 id="errors"><title>Errors</title> | |
129 | <para> | |
130 | <constant>GL_INVALID_VALUE</constant> is generated if <parameter>program</parameter> is not | |
131 | the name of a program object. | |
132 | </para> | |
133 | <para> | |
134 | <constant>GL_INVALID_VALUE</constant> is generated if <parameter>bufferMode</parameter> is <constant>GL_SEPARATE_ATTRIBS</constant> | |
135 | and <parameter>count</parameter> is greater than the implementation-dependent limit <constant>GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS</constant>. | |
136 | </para> | |
137 | </refsect1> | |
138 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
139 | <para> | |
140 | <citerefentry><refentrytitle>glGetTransformFeedbackVarying</refentrytitle></citerefentry> | |
141 | </para> | |
142 | </refsect1> | |
143 | <refsect1 id="seealso"><title>See Also</title> | |
144 | <para> | |
145 | <citerefentry><refentrytitle>glBeginTransformFeedback</refentrytitle></citerefentry>, | |
146 | <citerefentry><refentrytitle>glEndTransformFeedback</refentrytitle></citerefentry>, | |
147 | <citerefentry><refentrytitle>glGetTransformFeedbackVarying</refentrytitle></citerefentry> | |
148 | </para> | |
149 | </refsect1> <refsect1 id="Copyright"><title>Copyright</title> | |
150 | <para> | |
151 | Copyright <trademark class="copyright"></trademark> 2010 Khronos Group. | |
152 | This material may be distributed subject to the terms and conditions set forth in | |
153 | the Open Publication License, v 1.0, 8 June 1999. | |
154 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>. | |
155 | </para> | |
156 | </refsect1> | |
157 | </refentry> |