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<refentry id="glNormalPointer">

    <refmeta>

        <refmetainfo>

            <copyright>

                <year>1991-2006</year>

                <holder>Silicon Graphics, Inc.</holder>

            </copyright>

        </refmetainfo>

        <refentrytitle>glNormalPointer</refentrytitle>

        <manvolnum>3G</manvolnum>

    </refmeta>

    <refnamediv>

        <refname>glNormalPointer</refname>

        <refpurpose>define an array of normals</refpurpose>

    </refnamediv>

    <refsynopsisdiv><title>C Specification</title>

        <funcsynopsis>

            <funcprototype>

                <funcdef>void <function>glNormalPointer</function></funcdef>

                <paramdef>GLenum <parameter>type</parameter></paramdef>

                <paramdef>GLsizei <parameter>stride</parameter></paramdef>

                <paramdef>const GLvoid * <parameter>pointer</parameter></paramdef>

            </funcprototype>

        </funcsynopsis>

    </refsynopsisdiv>

    <!-- eqn: ignoring delim $$ -->

    <refsect1 id="parameters"><title>Parameters</title>

        <variablelist>

        <varlistentry>

            <term><parameter>type</parameter></term>

            <listitem>

                <para>

                    Specifies the data type of each coordinate in the array.

                    Symbolic constants

                    <constant>GL_BYTE</constant>,

                    <constant>GL_SHORT</constant>,

                    <constant>GL_INT</constant>,

                    <constant>GL_FLOAT</constant>, and

                    <constant>GL_DOUBLE</constant>

                    are accepted. The initial value is <constant>GL_FLOAT</constant>.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>stride</parameter></term>

            <listitem>

                <para>

                    Specifies the byte offset between consecutive normals. If <parameter>stride</parameter> is

                    0, the normals are understood to be tightly packed in

                    the array. The initial value is 0.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>pointer</parameter></term>

            <listitem>

                <para>

                    Specifies a pointer to the first coordinate of the first normal in the

                    array. The initial value is 0.

                </para>

            </listitem>

        </varlistentry>

        </variablelist>

    </refsect1>

    <refsect1 id="description"><title>Description</title>

        <para>

            <function>glNormalPointer</function> specifies the location and data format of an array of normals

            to use when rendering.

            <parameter>type</parameter> specifies the data type of each normal coordinate,

            and <parameter>stride</parameter> specifies the byte stride from one

            normal to the next, allowing vertices and attributes

            to be packed into a single array or stored in separate arrays.

            (Single-array storage may be more efficient on some implementations;

            see <citerefentry><refentrytitle>glInterleavedArrays</refentrytitle></citerefentry>.)

        </para>

        <para>

            If a non-zero named buffer object is bound to the <constant>GL_ARRAY_BUFFER</constant> target

            (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a normal array is

            specified, <parameter>pointer</parameter> is treated as a byte offset into the buffer object's data store.

            Also, the buffer object binding (<constant>GL_ARRAY_BUFFER_BINDING</constant>) is saved as normal vertex array

            client-side state (<constant>GL_NORMAL_ARRAY_BUFFER_BINDING</constant>).

        </para>

        <para>

            When a normal array is specified,

            <parameter>type</parameter>, <parameter>stride</parameter>, and <parameter>pointer</parameter> are saved as client-side

            state, in addition to the current vertex array buffer object binding.

        </para>

        <para>

            To enable and disable the normal array, call

            <citerefentry><refentrytitle>glEnableClientState</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glDisableClientState</refentrytitle></citerefentry> with the argument

            <constant>GL_NORMAL_ARRAY</constant>. If

            enabled, the normal array is used

            when <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glMultiDrawArrays</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glMultiDrawElements</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>, or

            <citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry> is called.

        </para>

    </refsect1>

    <refsect1 id="notes"><title>Notes</title>

        <para>

            <function>glNormalPointer</function> is available only if the GL version is 1.1 or greater.

        </para>

        <para>

            The normal array is initially disabled and isn't accessed when

            <citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glMultiDrawArrays</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glMultiDrawElements</refentrytitle></citerefentry>

            is called.

        </para>

        <para>

            Execution of <function>glNormalPointer</function> is not allowed between

            <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>,

            but an error may or may not be generated. If an error is not generated,

            the operation is undefined.

        </para>

        <para>

            <function>glNormalPointer</function> is typically implemented on the client side.

        </para>

        <para>

            Normal array parameters are client-side state and are therefore not

            saved or restored by <citerefentry><refentrytitle>glPushAttrib</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glPopAttrib</refentrytitle></citerefentry>.

            Use <citerefentry><refentrytitle>glPushClientAttrib</refentrytitle></citerefentry> and

            <citerefentry><refentrytitle>glPopClientAttrib</refentrytitle></citerefentry> instead.

        </para>

    </refsect1>

    <refsect1 id="errors"><title>Errors</title>

        <para>

            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not an accepted value.

        </para>

        <para>

            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>stride</parameter> is negative.

        </para>

    </refsect1>

    <refsect1 id="associatedgets"><title>Associated Gets</title>

        <para>

            <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_NORMAL_ARRAY</constant>

        </para>

        <para>

            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_NORMAL_ARRAY_TYPE</constant>

        </para>

        <para>

            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_NORMAL_ARRAY_STRIDE</constant>

        </para>

        <para>

            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_NORMAL_ARRAY_BUFFER_BINDING</constant>

        </para>

        <para>

            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_ARRAY_BUFFER_BINDING</constant>

        </para>

        <para>

            <citerefentry><refentrytitle>glGetPointerv</refentrytitle></citerefentry> with argument <constant>GL_NORMAL_ARRAY_POINTER</constant>

        </para>

    </refsect1>

    <refsect1 id="seealso"><title>See Also</title>

        <para>

            <citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glColorPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDisableClientState</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glEdgeFlagPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glEnableClientState</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glFogCoordPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glIndexPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glInterleavedArrays</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glMultiDrawArrays</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glMultiDrawElements</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glNormal</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glPopClientAttrib</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glPushClientAttrib</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glSecondaryColorPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glTexCoordPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glVertexAttribPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glVertexPointer</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>