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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glDrawElementsInstanced">
    <info>
        <copyright>
            <year>2010-2014</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glDrawElementsInstanced</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glDrawElementsInstanced</refname>
        <refpurpose>draw multiple instances of a set of elements</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glDrawElementsInstanced</function></funcdef>
                <paramdef>GLenum <parameter>mode</parameter></paramdef>
                <paramdef>GLsizei <parameter>count</parameter></paramdef>
                <paramdef>GLenum <parameter>type</parameter></paramdef>
                <paramdef>const void * <parameter>indices</parameter></paramdef>
                <paramdef>GLsizei <parameter>primcount</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>mode</parameter></term>
            <listitem>
                <para>
                    Specifies what kind of primitives to render.
                    Symbolic constants
                    <constant>GL_POINTS</constant>,
                    <constant>GL_LINE_STRIP</constant>,
                    <constant>GL_LINE_LOOP</constant>,
                    <constant>GL_LINES</constant>,
                    <constant>GL_TRIANGLE_STRIP</constant>,
                    <constant>GL_TRIANGLE_FAN</constant> and
                    <constant>GL_TRIANGLES</constant>
                    are accepted.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>count</parameter></term>
            <listitem>
                <para>
                    Specifies the number of elements to be rendered.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>type</parameter></term>
            <listitem>
                <para>
                    Specifies the type of the values in <parameter>indices</parameter>. Must be one of <constant>GL_UNSIGNED_BYTE</constant>,
                    <constant>GL_UNSIGNED_SHORT</constant>, or <constant>GL_UNSIGNED_INT</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>indices</parameter></term>
            <listitem>
                <para>
                    Specifies a pointer to the location where the indices are stored.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>primcount</parameter></term>
            <listitem>
                <para>
                    Specifies the number of instances of the specified range of indices to be rendered.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glDrawElementsInstanced</function> behaves identically to <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>
            except that <parameter>primcount</parameter> instances of the set of elements are executed. Those attributes
                        that have divisor N where N is other than zero
                        (as specified by <citerefentry><refentrytitle>glVertexAttribDivisor</refentrytitle></citerefentry>)
                        advance once every N instances. Thus, the element transferred from instanced
                        vertex attributes is given by:
            <informalequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <!-- eqn: instance over divisor:-->
                <mml:mrow>
                                        <mml:mfrac>
                                                <mml:mi mathvariant="italic">instance</mml:mi>
                                                <mml:mn>divisor</mml:mn>
                                        </mml:mfrac>
                </mml:mrow>
            </mml:math></informalequation>

                        The value of <parameter>instance</parameter> may be read by a vertex shader as <constant>gl_InstanceID</constant>.
        </para>
        <para>
                        To enable and disable a generic vertex attribute array, call
                        <citerefentry><refentrytitle>glEnableVertexAttribArray</refentrytitle></citerefentry> and
                        <citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>.
        </para>
        <para>
                        If an array corresponding to a generic attribute required by a vertex shader
                        is not enabled, then the corresponding element is taken from the current generic
                        attribute state.
        </para>

    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of <constant>GL_POINTS</constant>,
            <constant>GL_LINE_STRIP</constant>, <constant>GL_LINE_LOOP</constant>, <constant>GL_LINES</constant>,
            <constant>GL_TRIANGLE_STRIP</constant>, <constant>GL_TRIANGLE_FAN</constant>, or <constant>GL_TRIANGLES</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> or <parameter>primcount</parameter> are negative.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
            enabled array and the buffer object's data store is currently mapped.
        </para>
        <para>
                        <constant>GL_INVALID_FRAMEBUFFER_OPERATION</constant> is generated if the currently bound framebuffer is not
                        framebuffer complete (i.e. the return value from
                        <citerefentry><refentrytitle>glCheckFramebufferStatus</refentrytitle></citerefentry> is not <constant>GL_FRAMEBUFFER_COMPLETE</constant>).
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if transform feedback is active and not paused.
        </para>
    </refsect1>
    <refsect1 xml:id="versions">
        <title>API Version Support</title>
        <informaltable>
            <tgroup cols="3" align="left">
                <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
                <tbody>
                    <row>
                        <entry>glDrawElementsInstanced</entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='es30']/*)"/>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glCheckFramebufferStatus</refentrytitle></citerefentry>,
                        <citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawArraysInstanced</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>,
                        <citerefentry><refentrytitle>glEnableVertexAttribArray</refentrytitle></citerefentry>,
                        <citerefentry><refentrytitle>glVertexAttribDivisor</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2010-2014 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>
