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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
<refentry id="glGetHistogramParameter">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glGetHistogramParameter</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glGetHistogramParameter</refname>
<refpurpose>get histogram parameters</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetHistogramParameterfv</function></funcdef>
<paramdef>GLenum <parameter>target</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLfloat * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetHistogramParameteriv</function></funcdef>
<paramdef>GLenum <parameter>target</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLint * <parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>target</parameter></term>
<listitem>
<para>
Must be one of
<constant>GL_HISTOGRAM</constant> or
<constant>GL_PROXY_HISTOGRAM</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>pname</parameter></term>
<listitem>
<para>
The name of the parameter to be retrieved.
Must be one of
<constant>GL_HISTOGRAM_WIDTH</constant>,
<constant>GL_HISTOGRAM_FORMAT</constant>,
<constant>GL_HISTOGRAM_RED_SIZE</constant>,
<constant>GL_HISTOGRAM_GREEN_SIZE</constant>,
<constant>GL_HISTOGRAM_BLUE_SIZE</constant>,
<constant>GL_HISTOGRAM_ALPHA_SIZE</constant>,
<constant>GL_HISTOGRAM_LUMINANCE_SIZE</constant>, or
<constant>GL_HISTOGRAM_SINK</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>params</parameter></term>
<listitem>
<para>
Pointer to storage for the returned values.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>glGetHistogramParameter</function> is used to query parameter values for the current histogram or for
a proxy. The histogram state information may be queried by calling
<function>glGetHistogramParameter</function> with a <parameter>target</parameter> of <constant>GL_HISTOGRAM</constant> (to
obtain information for the current histogram table) or
<constant>GL_PROXY_HISTOGRAM</constant> (to obtain information from the most recent
proxy request) and one of the following values for the <parameter>pname</parameter> argument:
</para>
<para>
</para>
<informaltable frame="topbot">
<tgroup cols="2" align="left">
<colspec/>
<colspec/>
<thead>
<row>
<entry rowsep="1" align="left"><emphasis role="bold">
Parameter
</emphasis></entry>
<entry rowsep="1" align="left"><emphasis role="bold">
Description
</emphasis></entry>
</row>
</thead>
<tbody>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_WIDTH</constant>
</entry>
<entry align="left">
Histogram table width
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_FORMAT</constant>
</entry>
<entry align="left">
Internal format
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_RED_SIZE</constant>
</entry>
<entry align="left">
Red component counter size, in bits
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_GREEN_SIZE</constant>
</entry>
<entry align="left">
Green component counter size, in bits
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_BLUE_SIZE</constant>
</entry>
<entry align="left">
Blue component counter size, in bits
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_ALPHA_SIZE</constant>
</entry>
<entry align="left">
Alpha component counter size, in bits
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_LUMINANCE_SIZE</constant>
</entry>
<entry align="left">
Luminance component counter size, in bits
</entry>
</row>
<row>
<entry align="left">
<constant>GL_HISTOGRAM_SINK</constant>
</entry>
<entry align="left">
Value of the <emphasis>sink</emphasis> parameter
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
<function>glGetHistogramParameter</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
is called with an argument of <constant>GL_EXTENSIONS</constant>.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not one of the allowable
values.
</para>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is not one of the allowable
values.
</para>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetHistogramParameter</function> is executed
between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glGetHistogram</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glHistogram</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 1991-2006
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
</para>
</refsect1>
</refentry>