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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glBufferSubData">
    <info>
        <copyright>
            <year>2005</year>
            <holder>Sams Publishing</holder>
        </copyright>
        <copyright>
            <year>2010-2014</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glBufferSubData</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glBufferSubData</refname>
        <refname>glNamedBufferSubData</refname>
        <refpurpose>updates a subset of a buffer object's data store</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glBufferSubData</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLintptr <parameter>offset</parameter></paramdef>
                <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
                <paramdef>const GLvoid * <parameter>data</parameter></paramdef>
            </funcprototype>
            <funcprototype>
                <funcdef>void <function>glNamedBufferSubData</function></funcdef>
                <paramdef>GLuint <parameter>buffer</parameter></paramdef>
                <paramdef>GLintptr <parameter>offset</parameter></paramdef>
                <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
                <paramdef>const void *<parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Specifies the target to which the buffer object is bound
                    for <function>glBufferSubData</function>, which must be
                    one of the buffer binding targets in the following
                    table:
                </para>
                <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="bufferbindings.xml"/>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>buffer</parameter></term>
            <listitem>
                <para>
                    Specifies the name of the buffer object
                    for <function>glNamedBufferSubData</function>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>offset</parameter></term>
            <listitem>
                <para>
                    Specifies the offset into the buffer object's data store
                    where data replacement will begin, measured in bytes.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>size</parameter></term>
            <listitem>
                <para>
                    Specifies the size in bytes of the data store region
                    being replaced.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Specifies a pointer to the new data that will be copied
                    into the data store.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glBufferSubData</function> and
            <function>glNamedBufferSubData</function> redefine some or all
            of the data store for the specified buffer object. Data starting
            at byte offset <parameter>offset</parameter> and extending for
            <parameter>size</parameter> bytes is copied to the data store
            from the memory pointed to by <parameter>data</parameter>.
            <parameter>offset</parameter> and <parameter>size</parameter>
            must define a range lying entirely within the buffer object's
            data store.
        </para>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
        <para>
            When replacing the entire data store, consider using
            <function>glBufferSubData</function> rather than completely
            recreating the data store with
            <function>glBufferData</function>. This avoids the cost of
            reallocating the data store.
        </para>
        <para>
            Consider using multiple buffer objects to avoid stalling the
            rendering pipeline during data store updates. If any rendering
            in the pipeline makes reference to data in the buffer object
            being updated by <function>glBufferSubData</function>,
            especially from the specific region being updated, that
            rendering must drain from the pipeline before the data store can
            be updated.
        </para>
        <para>
            Clients must align data elements consistent with the
            requirements of the client platform, with an additional
            base-level requirement that an offset within a buffer to a datum
            comprising $N$ bytes be a multiple of $N$.
        </para>
        <para>
            The <constant>GL_ATOMIC_COUNTER_BUFFER</constant> target is
            available only if the GL version is 4.2 or greater.
        </para>
        <para> 
            The <constant>GL_DISPATCH_INDIRECT_BUFFER</constant> and
            <constant>GL_SHADER_STORAGE_BUFFER</constant> targets are
            available only if the GL version is 4.3 or greater.
        </para>
        <para>
            The <constant>GL_QUERY_BUFFER</constant> target is available
            only if the GL version is 4.4 or greater.
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated by
            <function>glBufferSubData</function> if
            <parameter>target</parameter> is not one of the accepted buffer
            targets.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by
            <function>glBufferSubData</function> if zero is bound to
            <parameter>target</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by
            <function>glNamedBufferSubData</function> if
            <parameter>buffer</parameter> is not the name of an existing
            buffer object.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if
            <parameter>offset</parameter> or <parameter>size</parameter> is
            negative, or if $offset + size$ is greater than the value of
            <constant>GL_BUFFER_SIZE</constant> for the specified buffer
            object.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if any
            part of the specified range of the buffer object is mapped with
            <citerefentry><refentrytitle>glMapBufferRange</refentrytitle></citerefentry>
            or
            <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
            unless it was mapped with the
            <constant>GL_MAP_PERSISTENT_BIT</constant> bit set in the
            <function>glMapBufferRange</function>
            <parameter>access</parameter> flags.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if the
            value of the <constant>GL_BUFFER_IMMUTABLE_STORAGE</constant>
            flag of the buffer object is <constant>GL_TRUE</constant> and
            the value of <constant>GL_BUFFER_STORAGE_FLAGS</constant> for
            the buffer object does not have the
            <constant>GL_DYNAMIC_STORAGE_BIT</constant> bit set.
        </para>
    </refsect1>
    <refsect1 xml:id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetBufferSubData</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="versions"><title>Version Support</title>
        <informaltable>
            <tgroup cols="13" align="left">
                <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
                <tbody>
                    <row>
                        <entry><function>glBufferSubData</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='20']/*)"/>
                    </row>
                    <row>
                        <entry><function>glNamedBufferSubData</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='45']/*)"/>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBufferData</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glMapBufferRange</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glUnmapBuffer</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2005 Addison-Wesley.
            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>
