120 lines
6.2 KiB
XML
120 lines
6.2 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="glReadBuffer">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glReadBuffer</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glReadBuffer</refname>
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<refpurpose>select a color buffer source for pixels</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glReadBuffer</function></funcdef>
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<paramdef>GLenum <parameter>mode</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>mode</parameter></term>
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<listitem>
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<para>
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Specifies a color buffer.
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Accepted values are
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<constant>GL_FRONT_LEFT</constant>,
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<constant>GL_FRONT_RIGHT</constant>,
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<constant>GL_BACK_LEFT</constant>,
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<constant>GL_BACK_RIGHT</constant>,
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<constant>GL_FRONT</constant>,
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<constant>GL_BACK</constant>,
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<constant>GL_LEFT</constant>,
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<constant>GL_RIGHT</constant>, and
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<constant>GL_AUX</constant><emphasis>i</emphasis>,
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where <emphasis>i</emphasis> is between 0 and the value of <constant>GL_AUX_BUFFERS</constant> minus 1.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para>
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<function>glReadBuffer</function> specifies a color buffer as the source for subsequent
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<citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>, and
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<citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry> commands.
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<parameter>mode</parameter> accepts one of twelve or more predefined values.
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(<constant>GL_AUX0</constant> through <constant>GL_AUX3</constant> are always defined.)
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In a fully configured system,
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<constant>GL_FRONT</constant>,
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<constant>GL_LEFT</constant>, and
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<constant>GL_FRONT_LEFT</constant> all name the front left buffer,
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<constant>GL_FRONT_RIGHT</constant> and
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<constant>GL_RIGHT</constant> name the front right buffer, and
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<constant>GL_BACK_LEFT</constant> and
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<constant>GL_BACK</constant> name the back left buffer.
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</para>
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<para>
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Nonstereo double-buffered configurations have only a front left and a
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back left buffer.
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Single-buffered configurations have a front left and a front right
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buffer if stereo, and only a front left buffer if nonstereo.
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It is an error to specify a nonexistent buffer to <function>glReadBuffer</function>.
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</para>
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<para>
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<parameter>mode</parameter> is initially <constant>GL_FRONT</constant> in single-buffered configurations
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and <constant>GL_BACK</constant> in double-buffered configurations.
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</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para>
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<constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of the twelve
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(or more) accepted values.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>mode</parameter> specifies a buffer
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that does not exist.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glReadBuffer</function>
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is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
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and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
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</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_READ_BUFFER</constant>
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>
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</para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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