272 lines
12 KiB
XML
272 lines
12 KiB
XML
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<?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="glGetHistogram">
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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>glGetHistogram</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glGetHistogram</refname>
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<refpurpose>get histogram table</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>glGetHistogram</function></funcdef>
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<paramdef>GLenum <parameter>target</parameter></paramdef>
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<paramdef>GLboolean <parameter>reset</parameter></paramdef>
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<paramdef>GLenum <parameter>format</parameter></paramdef>
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<paramdef>GLenum <parameter>type</parameter></paramdef>
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<paramdef>GLvoid * <parameter>values</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>target</parameter></term>
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<listitem>
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<para>
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Must be
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<constant>GL_HISTOGRAM</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>reset</parameter></term>
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<listitem>
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<para>
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If <constant>GL_TRUE</constant>, each component counter that is actually returned
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is reset to zero. (Other counters are unaffected.)
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If <constant>GL_FALSE</constant>, none of the counters in the histogram table is modified.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>format</parameter></term>
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<listitem>
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<para>
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The format of values to be returned in <parameter>values</parameter>.
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Must be one of
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<constant>GL_RED</constant>,
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<constant>GL_GREEN</constant>,
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<constant>GL_BLUE</constant>,
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<constant>GL_ALPHA</constant>,
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<constant>GL_RGB</constant>,
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<constant>GL_BGR</constant>,
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<constant>GL_RGBA</constant>,
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<constant>GL_BGRA</constant>,
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<constant>GL_LUMINANCE</constant>, or
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<constant>GL_LUMINANCE_ALPHA</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>type</parameter></term>
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<listitem>
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<para>
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The type of values to be returned in <parameter>values</parameter>.
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Symbolic constants
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<constant>GL_UNSIGNED_BYTE</constant>,
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<constant>GL_BYTE</constant>,
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<constant>GL_BITMAP</constant>,
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<constant>GL_UNSIGNED_SHORT</constant>,
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<constant>GL_SHORT</constant>,
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<constant>GL_UNSIGNED_INT</constant>,
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<constant>GL_INT</constant>,
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<constant>GL_FLOAT</constant>,
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<constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
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<constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
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<constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
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<constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
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<constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
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<constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
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<constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
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<constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
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<constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
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<constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
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<constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and
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<constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
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are accepted.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>values</parameter></term>
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<listitem>
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<para>
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A pointer to storage for the returned histogram table.
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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>glGetHistogram</function> returns the current histogram table as a one-dimensional image
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with the same width as the histogram.
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No pixel transfer operations are performed on this image, but pixel storage
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modes that are applicable to 1D images are honored.
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</para>
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<para>
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If a non-zero named buffer object is bound to the <constant>GL_PIXEL_PACK_BUFFER</constant> target
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(see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a histogram table is
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requested, <parameter>values</parameter> is treated as a byte offset into the buffer object's data store.
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</para>
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<para>
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Color components that are requested in the specified <parameter>format</parameter>, but which
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are not included in the internal format of the histogram, are returned as
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zero.
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The assignments of internal color components to the components
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requested by <parameter>format</parameter> are:
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</para>
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<informaltable frame="topbot">
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<tgroup cols="2" align="left">
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<colspec/>
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<colspec/>
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<thead>
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<row>
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<entry rowsep="1" align="left"><emphasis role="bold">
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Internal Component
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</emphasis></entry>
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<entry rowsep="1" align="left"><emphasis role="bold">
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Resulting Component
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</emphasis></entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry align="left">
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Red
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</entry>
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<entry align="left">
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Red
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</entry>
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</row>
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<row>
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<entry align="left">
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Green
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</entry>
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<entry align="left">
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Green
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</entry>
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</row>
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<row>
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<entry align="left">
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Blue
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</entry>
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<entry align="left">
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Blue
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</entry>
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</row>
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<row>
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<entry align="left">
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Alpha
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</entry>
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<entry align="left">
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Alpha
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</entry>
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</row>
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<row>
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<entry align="left">
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Luminance
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</entry>
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<entry align="left">
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Red
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>
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</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para>
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<function>glGetHistogram</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
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is called with an argument of <constant>GL_EXTENSIONS</constant>.
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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>target</parameter> is not <constant>GL_HISTOGRAM</constant>.
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</para>
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<para>
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<constant>GL_INVALID_ENUM</constant> is generated if <parameter>format</parameter> is not one of the allowable
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values.
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</para>
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<para>
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<constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not one of the allowable
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values.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>type</parameter> is one of
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<constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
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<constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
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<constant>GL_UNSIGNED_SHORT_5_6_5</constant>, or
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<constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>
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and <parameter>format</parameter> is not <constant>GL_RGB</constant>.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>type</parameter> is one of
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<constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
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<constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
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<constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
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<constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
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<constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
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<constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
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<constant>GL_UNSIGNED_INT_10_10_10_2</constant>, or
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<constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
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and <parameter>format</parameter> is neither <constant>GL_RGBA</constant> nor <constant>GL_BGRA</constant>.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
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<constant>GL_PIXEL_PACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
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<constant>GL_PIXEL_PACK_BUFFER</constant> target and the data would be packed to the buffer
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object such that the memory writes required would exceed the data store size.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
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<constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>values</parameter> is not evenly divisible
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into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetHistogram</function> is executed
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between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
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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>glGetHistogramParameter</refentrytitle></citerefentry>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_PACK_BUFFER_BINDING</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>glHistogram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glResetHistogram</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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