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<refentry id="glVertexAttribPointer">
    <refmeta>
	<refentrytitle>glVertexAttribPointer</refentrytitle>
	<manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
	<refname>glVertexAttribPointer</refname>
	<refpurpose>define an array of generic vertex attribute data</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
	<funcsynopsis>
	    <funcprototype>
		<funcdef>void <function>glVertexAttribPointer</function></funcdef>
		<paramdef>GLuint <parameter>index</parameter></paramdef>
		<paramdef>GLint <parameter>size</parameter></paramdef>
		<paramdef>GLenum <parameter>type</parameter></paramdef>
		<paramdef>GLboolean <parameter>normalized</parameter></paramdef>
		<paramdef>GLsizei <parameter>stride</parameter></paramdef>
		<paramdef>const GLvoid * <parameter>pointer</parameter></paramdef>
	    </funcprototype>
	</funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
	<variablelist>
	    <varlistentry>
		<term><parameter>index</parameter></term>
		<listitem>
		    <para>Specifies the index of the generic vertex
		    attribute to be modified.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><parameter>size</parameter></term>
		<listitem>
		    <para>Specifies the number of components per
		    generic vertex attribute. Must
		    be 1, 2, 3, or 4. The initial value is 4.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><parameter>type</parameter></term>
		<listitem>
		    <para>Specifies the data type of each component in
		    the array. Symbolic constants
		    <constant>GL_BYTE</constant>,
		    <constant>GL_UNSIGNED_BYTE</constant>,
		    <constant>GL_SHORT</constant>,
		    <constant>GL_UNSIGNED_SHORT</constant>,
		    <constant>GL_INT</constant>,
		    <constant>GL_UNSIGNED_INT</constant>,
		    <constant>GL_FLOAT</constant>, or
		    <constant>GL_DOUBLE</constant> are
		    accepted. The initial value is <constant>GL_FLOAT</constant>.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><parameter>normalized</parameter></term>
		<listitem>
		    <para>Specifies whether fixed-point data values
		    should be normalized (<constant>GL_TRUE</constant>)
		    or converted directly as fixed-point values
		    (<constant>GL_FALSE</constant>) when they are
		    accessed.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><parameter>stride</parameter></term>
		<listitem>
		    <para>Specifies the byte offset between consecutive
		    generic vertex attributes. If <parameter>stride</parameter>
		    is 0, the generic vertex attributes 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 component of
		    the first generic vertex attribute in the array. The initial value is 0.</para>
		</listitem>
	    </varlistentry>
	</variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
	<para><function>glVertexAttribPointer</function> specifies the
	location and data format of the array of generic vertex attributes at index <parameter>index</parameter>
	to use when rendering. <parameter>size</parameter>
	specifies the number of components per attribute and must be 1,
	2, 3, or 4. <parameter>type</parameter> specifies the data type
	of each component, and <parameter>stride</parameter> specifies
	the byte stride from one attribute to the next, allowing vertices and
	attributes to be packed into a single array or
	stored in separate arrays. 
        If set to <constant>GL_TRUE</constant>,
	<parameter>normalized</parameter> indicates that values stored
	in an integer format are to be mapped to the range [-1,1] (for
	signed values) or [0,1] (for unsigned values) when they are
	accessed and converted to floating point. Otherwise, values will
	be converted to floats directly without normalization.</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 generic vertex attribute 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 generic vertex attribute array
        client-side state (<constant>GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING</constant>) for index <parameter>index</parameter>.</para>

	<para>When a generic vertex attribute array is specified,
	<parameter>size</parameter>, <parameter>type</parameter>,
	<parameter>normalized</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 a generic vertex attribute array,
	call
	<citerefentry><refentrytitle>glEnableVertexAttribArray</refentrytitle></citerefentry>
	and
	<citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>
	with <parameter>index</parameter>. If enabled, the generic
	vertex attribute array is used when
        <citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry>, 
        <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>, 
        <citerefentry><refentrytitle>glMultiDrawArrays</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>, 
        <citerefentry><refentrytitle>glMultiDrawElements</refentrytitle></citerefentry>, or 
        <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>
        is called.</para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
	<para><function>glVertexAttribPointer</function> is available
	only if the GL version is 2.0 or greater.</para>

	<para>Each generic vertex attribute 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>glVertexAttribPointer</function> is
	not allowed between the execution of
	<citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
	and the corresponding execution of
	<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>,
	but an error may or may not be generated. If no error is
	generated, the operation is undefined.</para>

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

	<para>Generic vertex attribute 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_VALUE</constant> is generated if
	<parameter>index</parameter> is greater than or equal to
	<constant>GL_MAX_VERTEX_ATTRIBS</constant>.</para>

	<para><constant>GL_INVALID_VALUE</constant> is generated if
	<parameter>size</parameter> is not 1, 2, 3, or 4.</para>

	<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>glGet</refentrytitle></citerefentry>
	with argument <constant>GL_MAX_VERTEX_ATTRIBS</constant></para>

	<para><citerefentry><refentrytitle>glGetVertexAttrib</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and <constant>GL_VERTEX_ATTRIB_ARRAY_ENABLED</constant></para>

	<para><citerefentry><refentrytitle>glGetVertexAttrib</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and <constant>GL_VERTEX_ATTRIB_ARRAY_SIZE</constant></para>

	<para><citerefentry><refentrytitle>glGetVertexAttrib</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and <constant>GL_VERTEX_ATTRIB_ARRAY_TYPE</constant></para>

	<para><citerefentry><refentrytitle>glGetVertexAttrib</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and <constant>GL_VERTEX_ATTRIB_ARRAY_NORMALIZED</constant></para>

	<para><citerefentry><refentrytitle>glGetVertexAttrib</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and <constant>GL_VERTEX_ATTRIB_ARRAY_STRIDE</constant></para>

	<para><citerefentry><refentrytitle>glGetVertexAttrib</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and <constant>GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING</constant></para>

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

	<para><citerefentry><refentrytitle>glGetVertexAttribPointerv</refentrytitle></citerefentry>
	with arguments <parameter>index</parameter> and
	<constant>GL_VERTEX_ATTRIB_ARRAY_POINTER</constant></para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
	<para><citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glColorPointer</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glEnableVertexAttribArray</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glEdgeFlagPointer</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>glNormalPointer</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glPopClientAttrib</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glPushClientAttrib</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glSecondaryColorPointer</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glTexCoordPointer</refentrytitle></citerefentry>,
	<citerefentry><refentrytitle>glVertexAttrib</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glVertexPointer</refentrytitle></citerefentry>
	</para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 2003-2005 3Dlabs Inc. Ltd. 
            This material may be distributed subject to the terms and conditions set forth in 
            the Open Publication License, v 1.0, 8 June 1999.
            <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
        </para>
    </refsect1>
</refentry>
