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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="glGetAttribLocation"> | |
5 | <refmeta> | |
6 | <refentrytitle>glGetAttribLocation</refentrytitle> | |
7 | <manvolnum>3G</manvolnum> | |
8 | </refmeta> | |
9 | <refnamediv> | |
10 | <refname>glGetAttribLocation</refname> | |
11 | <refpurpose>Returns the location of an attribute variable</refpurpose> | |
12 | </refnamediv> | |
13 | <refsynopsisdiv><title>C Specification</title> | |
14 | <funcsynopsis> | |
15 | <funcprototype> | |
16 | <funcdef>GLint <function>glGetAttribLocation</function></funcdef> | |
17 | <paramdef>GLuint <parameter>program</parameter></paramdef> | |
18 | <paramdef>const GLchar *<parameter>name</parameter></paramdef> | |
19 | </funcprototype> | |
20 | </funcsynopsis> | |
21 | </refsynopsisdiv> | |
22 | <refsect1 id="parameters"><title>Parameters</title> | |
23 | <variablelist> | |
24 | <varlistentry> | |
25 | <term><parameter>program</parameter></term> | |
26 | <listitem> | |
27 | <para>Specifies the program object to be | |
28 | queried.</para> | |
29 | </listitem> | |
30 | </varlistentry> | |
31 | <varlistentry> | |
32 | <term><parameter>name</parameter></term> | |
33 | <listitem> | |
34 | <para>Points to a null terminated string containing | |
35 | the name of the attribute variable whose location is | |
36 | to be queried.</para> | |
37 | </listitem> | |
38 | </varlistentry> | |
39 | </variablelist> | |
40 | </refsect1> | |
41 | <refsect1 id="description"><title>Description</title> | |
42 | <para><function>glGetAttribLocation</function> queries the | |
43 | previously linked program object specified by | |
44 | <parameter>program</parameter> for the attribute variable | |
45 | specified by <parameter>name</parameter> and returns the index | |
46 | of the generic vertex attribute that is bound to that attribute | |
47 | variable. If <parameter>name</parameter> is a matrix attribute | |
48 | variable, the index of the first column of the matrix is | |
49 | returned. If the named attribute variable is not an active | |
50 | attribute in the specified program object or if | |
51 | <parameter>name</parameter> starts with the reserved prefix | |
52 | "gl_", a value of -1 is returned.</para> | |
53 | ||
54 | <para>The association between an attribute variable name and a | |
55 | generic attribute index can be specified at any time by calling | |
56 | <citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>. | |
57 | Attribute bindings do not go into effect until | |
58 | <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry> | |
59 | is called. After a program object has been linked successfully, | |
60 | the index values for attribute variables remain fixed until the | |
61 | next link command occurs. The attribute values can only be | |
62 | queried after a link if the link was successful. | |
63 | <function>glGetAttribLocation</function> returns the binding | |
64 | that actually went into effect the last time | |
65 | <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry> | |
66 | was called for the specified program object. Attribute bindings | |
67 | that have been specified since the last link operation are not | |
68 | returned by <function>glGetAttribLocation</function>.</para> | |
69 | </refsect1> | |
70 | <refsect1 id="notes"><title>Notes</title> | |
71 | <para><function>glGetAttribLocation</function> is available only | |
72 | if the GL version is 2.0 or greater.</para> | |
73 | </refsect1> | |
74 | <refsect1 id="errors"><title>Errors</title> | |
75 | <para><constant>GL_INVALID_OPERATION</constant> is generated if | |
76 | <parameter>program</parameter> is not a value generated by | |
77 | OpenGL.</para> | |
78 | ||
79 | <para><constant>GL_INVALID_OPERATION</constant> is generated if | |
80 | <parameter>program</parameter> is not a program object.</para> | |
81 | ||
82 | <para><constant>GL_INVALID_OPERATION</constant> is generated if | |
83 | <parameter>program</parameter> has not been successfully | |
84 | linked.</para> | |
85 | ||
86 | <para><constant>GL_INVALID_OPERATION</constant> is generated if | |
87 | <function>glGetAttribLocation</function> is executed between the | |
88 | execution of | |
89 | <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
90 | and the corresponding execution of | |
91 | <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.</para> | |
92 | </refsect1> | |
93 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
94 | <para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry> | |
95 | with argument <parameter>program</parameter> and the index of an | |
96 | active attribute</para> | |
97 | ||
98 | <para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry></para> | |
99 | </refsect1> | |
100 | <refsect1 id="seealso"><title>See Also</title> | |
101 | <para><citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>, | |
102 | <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>, | |
103 | <citerefentry><refentrytitle>glVertexAttrib</refentrytitle></citerefentry>, | |
104 | <citerefentry><refentrytitle>glVertexAttribPointer</refentrytitle></citerefentry></para> | |
105 | </refsect1> | |
106 | <refsect1 id="Copyright"><title>Copyright</title> | |
107 | <para> | |
108 | Copyright <trademark class="copyright"></trademark> 2003-2005 3Dlabs Inc. Ltd. | |
109 | This material may be distributed subject to the terms and conditions set forth in | |
110 | the Open Publication License, v 1.0, 8 June 1999. | |
111 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>. | |
112 | </para> | |
113 | </refsect1> | |
114 | </refentry> |