
<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>
