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<refentry id="glGetBufferSubData">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2005</year>
                <holder>Sams Publishing</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetBufferSubData</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetBufferSubData</refname>
        <refpurpose>returns a subset of a buffer object's data store</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetBufferSubData</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLintptr <parameter>offset</parameter></paramdef>
                <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
                <paramdef>GLvoid * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <!-- eqn: ignoring delim $$ -->
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Specifies the target buffer object.
                    The symbolic constant must be
                    <constant>GL_ARRAY_BUFFER</constant>,
                    <constant>GL_ATOMIC_COUNTER_BUFFER</constant>,
                    <constant>GL_COPY_READ_BUFFER</constant>,
                    <constant>GL_COPY_WRITE_BUFFER</constant>,
                    <constant>GL_DRAW_INDIRECT_BUFFER</constant>,
                    <constant>GL_DISPATCH_INDIRECT_BUFFER</constant>,
                    <constant>GL_ELEMENT_ARRAY_BUFFER</constant>,
                    <constant>GL_PIXEL_PACK_BUFFER</constant>,
                    <constant>GL_PIXEL_UNPACK_BUFFER</constant>,
                    <constant>GL_QUERY_RESULT_BUFFER</constant>,
                    <constant>GL_TEXTURE_BUFFER</constant>,
                    <constant>GL_TRANSFORM_FEEDBACK_BUFFER</constant>, or
                    <constant>GL_UNIFORM_BUFFER</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>offset</parameter></term>
            <listitem>
                <para>
                    Specifies the offset into the buffer object's data store from which data will be returned,
                    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 returned.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Specifies a pointer to the location where buffer object data is returned.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glGetBufferSubData</function> returns some or all of the data from the buffer object currently 
            bound to <parameter>target</parameter>. Data starting at byte offset <parameter>offset</parameter> and
            extending for <parameter>size</parameter> bytes is copied from the data store to the memory pointed to by
            <parameter>data</parameter>. An error is thrown if the buffer object is currently mapped, or if
            <parameter>offset</parameter> and <parameter>size</parameter> together define a range beyond the bounds 
            of the buffer object's data store.
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            If an error is generated,
            no change is made to the contents of <parameter>data</parameter>.
        </para>
        <para>
            The <constant>GL_ATOMIC_COUNTER_BUFER</constant> target is available only if the GL version is 4.2 or greater.
        </para>
        <para>
            The <constant>GL_DISPATCH_INDIRECT_BUFFER</constant> target is available only if the GL version is 4.3 or greater.
        </para>
        <para>
            The <constant>GL_QUERY_RESULT_BUFFER</constant> target is available only if the GL version is 4.4 or greater.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not 
            <constant>GL_ARRAY_BUFFER</constant>, <constant>GL_ELEMENT_ARRAY_BUFFER</constant>, 
            <constant>GL_PIXEL_PACK_BUFFER</constant>, or <constant>GL_PIXEL_UNPACK_BUFFER</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>offset</parameter> or 
            <parameter>size</parameter> is negative, or if together they define a region of memory
            that extends beyond the buffer object's allocated data store.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if the reserved buffer object name 0 is bound to <parameter>target</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if the buffer object being queried is mapped.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBufferData</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBufferSubData</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glUnmapBuffer</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 2005 Addison-Wesley. 
            Copyright <trademark class="copyright"></trademark> 2011-2013 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.
            <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
        </para>
    </refsect1>
</refentry>
