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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="glReadBuffer"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glReadBuffer</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glReadBuffer</refname> | |
17 | <refpurpose>select a color buffer source for pixels</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glReadBuffer</function></funcdef> | |
23 | <paramdef>GLenum <parameter>mode</parameter></paramdef> | |
24 | </funcprototype> | |
25 | </funcsynopsis> | |
26 | </refsynopsisdiv> | |
27 | <refsect1 id="parameters"><title>Parameters</title> | |
28 | <variablelist> | |
29 | <varlistentry> | |
30 | <term><parameter>mode</parameter></term> | |
31 | <listitem> | |
32 | <para> | |
33 | Specifies a color buffer. | |
34 | Accepted values are | |
35 | <constant>GL_FRONT_LEFT</constant>, | |
36 | <constant>GL_FRONT_RIGHT</constant>, | |
37 | <constant>GL_BACK_LEFT</constant>, | |
38 | <constant>GL_BACK_RIGHT</constant>, | |
39 | <constant>GL_FRONT</constant>, | |
40 | <constant>GL_BACK</constant>, | |
41 | <constant>GL_LEFT</constant>, and the constants | |
42 | <constant>GL_COLOR_ATTACHMENT<emphasis>i</emphasis></constant>. | |
43 | </para> | |
44 | </listitem> | |
45 | </varlistentry> | |
46 | </variablelist> | |
47 | </refsect1> | |
48 | <refsect1 id="description"><title>Description</title> | |
49 | <para> | |
50 | <function>glReadBuffer</function> specifies a color buffer as the source for subsequent | |
51 | <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>, | |
52 | <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>, and | |
53 | <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry> commands. | |
54 | <parameter>mode</parameter> accepts one of twelve or more predefined values. | |
55 | In a fully configured system, | |
56 | <constant>GL_FRONT</constant>, | |
57 | <constant>GL_LEFT</constant>, and | |
58 | <constant>GL_FRONT_LEFT</constant> all name the front left buffer, | |
59 | <constant>GL_FRONT_RIGHT</constant> and | |
60 | <constant>GL_RIGHT</constant> name the front right buffer, and | |
61 | <constant>GL_BACK_LEFT</constant> and | |
62 | <constant>GL_BACK</constant> name the back left buffer. | |
63 | Furthermore, the constants <constant>GL_COLOR_ATTACHMENT<emphasis>i</emphasis></constant> may be used to indicate the | |
64 | <emphasis>i</emphasis><superscript>th</superscript> color attachment where <emphasis>i</emphasis> ranges from zero to the | |
65 | value of <constant>GL_MAX_COLOR_ATTACHMENTS</constant> minus one. | |
66 | </para> | |
67 | <para> | |
68 | Nonstereo double-buffered configurations have only a front left and a | |
69 | back left buffer. | |
70 | Single-buffered configurations have a front left and a front right | |
71 | buffer if stereo, and only a front left buffer if nonstereo. | |
72 | It is an error to specify a nonexistent buffer to <function>glReadBuffer</function>. | |
73 | </para> | |
74 | <para> | |
75 | <parameter>mode</parameter> is initially <constant>GL_FRONT</constant> in single-buffered configurations | |
76 | and <constant>GL_BACK</constant> in double-buffered configurations. | |
77 | </para> | |
78 | </refsect1> | |
79 | <refsect1 id="errors"><title>Errors</title> | |
80 | <para> | |
81 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of the twelve | |
82 | (or more) accepted values. | |
83 | </para> | |
84 | <para> | |
85 | <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>mode</parameter> specifies a buffer | |
86 | that does not exist. | |
87 | </para> | |
88 | </refsect1> | |
89 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
90 | <para> | |
91 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_READ_BUFFER</constant> | |
92 | </para> | |
93 | </refsect1> | |
94 | <refsect1 id="seealso"><title>See Also</title> | |
95 | <para> | |
96 | <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, | |
97 | <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>, | |
98 | <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>, | |
99 | <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>, | |
100 | <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>, | |
101 | <citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>, | |
102 | <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry> | |
103 | </para> | |
104 | </refsect1> | |
105 | <refsect1 id="Copyright"><title>Copyright</title> | |
106 | <para> | |
107 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
108 | Silicon Graphics, Inc. This document is licensed under the SGI | |
109 | Free Software B License. For details, see | |
110 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
111 | </para> | |
112 | </refsect1> | |
113 | </refentry> |