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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glPatchParameter">
    <info>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group.</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glPatchParameter</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glPatchParameter</refname>
        <refpurpose>specifies the parameters for patch primitives</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glPatchParameteri</function></funcdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLint <parameter>value</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glPatchParameterfv</function></funcdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>const GLfloat *<parameter>values</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>pname</parameter></term>
            <listitem>
                <para>
                    Specifies the name of the parameter to set. The symbolc constants <constant>GL_PATCH_VERTICES</constant>,
                    <constant>GL_PATCH_DEFAULT_OUTER_LEVEL</constant>, and <constant>GL_PATCH_DEFAULT_INNER_LEVEL</constant> are accepted.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>value</parameter></term>
            <listitem>
                <para>
                    Specifies the new value for the parameter given by <parameter>pname</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>values</parameter></term>
            <listitem>
                <para>
                    Specifies the address of an array containing the new values for the parameter given by <parameter>pname</parameter>.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glPatchParameter</function> specifies the parameters that will be used for patch primitives. <parameter>pname</parameter>
            specifies the parameter to modify and must be either <constant>GL_PATCH_VERTICES</constant>, <constant>GL_PATCH_DEFAULT_OUTER_LEVEL</constant>
            or <constant>GL_PATCH_DEFAULT_INNER_LEVEL</constant>. For <function>glPatchParameteri</function>, <parameter>value</parameter> specifies
            the new value for the parameter specified by <parameter>pname</parameter>. For <function>glPatchParameterfv</function>, <parameter>values</parameter>
            specifies the address of an array containing the new values for the parameter specified by <parameter>pname</parameter>.
        </para>
        <para>
            When <parameter>pname</parameter> is <constant>GL_PATCH_VERTICES</constant>, <parameter>value</parameter> specifies the number
            of vertices that will be used to make up a single patch primitive. Patch primitives are consumed by the tessellation control
            shader (if present) and subsequently used for tessellation. When primitives are specified using
            <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry> or a similar function, each patch will be made
            from <parameter>parameter</parameter> control points, each represented by a vertex taken from the enabeld vertex arrays.
            <parameter>parameter</parameter> must be greater than zero, and less than or equal to the value of <constant>GL_MAX_PATCH_VERTICES</constant>.
         </para>
         <para>
            When <parameter>pname</parameter> is <constant>GL_PATCH_DEFAULT_OUTER_LEVEL</constant> or <constant>GL_PATCH_DEFAULT_INNER_LEVEL</constant>,
            <parameter>values</parameter> contains the address of an array contiaining the default outer or inner tessellation levels, respectively,
            to be used when no tessellation control shader is present.
         </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is not an accepted value.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>pname</parameter> is <constant>GL_PATCH_VERTICES</constant>
            and <parameter>value</parameter> is less than or equal to zero, or greater than the value of <constant>GL_MAX_PATCH_VERTICES</constant>.
        </para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawArraysInstanced</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>,
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2010-2013 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
        </para>
    </refsect1>
</refentry>
