<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>

<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glCopyBufferSubData">
    <info>
        <copyright>
            <year>2010-2014</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glCopyBufferSubData</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glCopyBufferSubData</refname>
        <refname>glCopyNamedBufferSubData</refname>
        <refpurpose>copy all or part of the data store of a buffer object to the data store of another buffer object</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glCopyBufferSubData</function></funcdef>
                <paramdef>GLenum <parameter>readTarget</parameter></paramdef>
                <paramdef>GLenum <parameter>writeTarget</parameter></paramdef>
                <paramdef>GLintptr <parameter>readOffset</parameter></paramdef>
                <paramdef>GLintptr <parameter>writeOffset</parameter></paramdef>
                <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
            </funcprototype>
            <funcprototype>
                <funcdef>void <function>glCopyNamedBufferSubData</function></funcdef>
                <paramdef>GLuint <parameter>readBuffer</parameter></paramdef>
                <paramdef>GLuint <parameter>writeBuffer</parameter></paramdef>
                <paramdef>GLintptr <parameter>readOffset</parameter></paramdef>
                <paramdef>GLintptr <parameter>writeOffset</parameter></paramdef>
                <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>readTarget</parameter></term>
            <listitem>
                <para>
                    Specifies the target to which the source buffer object
                    is bound for <function>glCopyBufferSubData</function>
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>writeTarget</parameter></term>
            <listitem>
                <para>
                    Specifies the target to which the destination buffer
                    object is bound for
                    <function>glCopyBufferSubData</function>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>readBuffer</parameter></term>
            <listitem>
                <para>
                    Specifies the name of the source buffer object for
                    <function>glCopyNamedBufferSubData</function>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>writeBuffer</parameter></term>
            <listitem>
                <para>
                    Specifies the name of the destination buffer object for
                    <function>glCopyNamedBufferSubData</function>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>readOffset</parameter></term>
            <listitem>
                <para>
                    Specifies the offset, in basic machine units, within the
                    data store of the source buffer object at which data
                    will be read.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>writeOffset</parameter></term>
            <listitem>
                <para>
                    Specifies the offset, in basic machine units, within the
                    data store of the destination buffer object at which
                    data will be written.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>size</parameter></term>
            <listitem>
                <para>
                    Specifies the size, in basic machine units, of the data
                    to be copied from the source buffer object to the
                    destination buffer object.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glCopyBufferSubData</function> and
            <function>glCopyNamedBufferSubData</function> copy part of the
            data store attached to a source buffer object to the data store
            attached to a destination buffer object. The number of basic
            machine units indicated by <parameter>size</parameter> is copied
            from the source at offset <parameter>readOffset</parameter> to
            the destination at <parameter>writeOffset</parameter>.
            <parameter>readOffset</parameter>,
            <parameter>writeOffset</parameter> and
            <parameter>size</parameter> are in terms of basic machine units.
        </para>
        <para>
            For <function>glCopyBufferSubData</function>,
            <parameter>readTarget</parameter> and
            <parameter>writeTarget</parameter> specify the targets to which
            the source and destination buffer objects are bound, and must
            each 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"/>
        <para>
            Any of these targets may be used, but the targets
            <constant>GL_COPY_READ_BUFFER</constant> and
            <constant>GL_COPY_WRITE_BUFFER</constant> are provided
            specifically to allow copies between buffers without disturbing
            other GL state.
        </para>
        <para>
            <parameter>readOffset</parameter>,
            <parameter>writeOffset</parameter> and
            <parameter>size</parameter> must all be greater than or equal to
            zero. Furthermore, $readOffset+size$ must not exceeed the size
            of the source buffer object, and $writeOffset+size$ must not
            exceeed the size of the buffer bound to
            <parameter>writeTarget</parameter>. If the source and
            destination are the same buffer object, then the source and
            destination ranges must not overlap.
        </para>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
        <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>glCopyBufferSubData</function> if
            <parameter>readTarget</parameter> or
            <parameter>writeTarget</parameter> is not one of the buffer
            binding targets listed above.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by
            <function>glCopyBufferSubData</function> if zero is bound to
            <parameter>readTarget</parameter> or
            <parameter>writeTarget</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by
            <function>glCopyNamedBufferSubData</function> if
            <parameter>readBuffer</parameter> or
            <parameter>writeBuffer</parameter> is not the name of an
            existing buffer object.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if any of
            <parameter>readOffset</parameter>,
            <parameter>writeOffset</parameter> or
            <parameter>size</parameter> is negative, if $readOffset + size$
            is greater than the size of the source buffer object (its value
            of <constant>GL_BUFFER_SIZE</constant>), or if $writeOffset +
            size$ is greater than the size of the destination buffer object.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if the source
            and destination are the same buffer object, and the ranges
            $[readOffset,readOffset+size)$ and
            $[writeOffset,writeOffset+size)$ overlap.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if either
            the source or destination buffer object is mapped with
            <citerefentry><refentrytitle>glMapBufferRange</refentrytitle></citerefentry>
            or
            <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
            unless they were mapped with the
            <constant>GL_MAP_PERSISTENT</constant> bit set in the
            <function>glMapBufferRange</function>
            <parameter>access</parameter> flags.
        </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>glCopyBufferSubData</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='31']/*)"/>
                    </row>
                    <row>
                        <entry><function>glCopyNamedBufferSubData</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>glGenBuffers</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBufferData</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBufferSubData</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetBufferSubData</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glMapBufferRange</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>
