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<refentry id="glBufferStorage">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2013</year>
                <holder>Khronos Group</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glBufferStorage</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glBufferStorage</refname>
        <refpurpose>creates and initializes a buffer object's immutable data store</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glBufferStorage</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
                <paramdef>const GLvoid * <parameter>data</parameter></paramdef>
                <paramdef>GLbitfield <parameter>flags</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_BUFFER</constant>,
                    <constant>GL_SHADER_STORAGE_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>size</parameter></term>
            <listitem>
                <para>
                    Specifies the size in bytes of the buffer object's new data store.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Specifies a pointer to data that will be copied into the data store for initialization,
                    or <constant>NULL</constant> if no data is to be copied.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>flags</parameter></term>
            <listitem>
                <para>
                    Specifies the intended usage of the buffer's data store. Must be a bitwise combination
                    of the following flags. <constant>GL_DYNAMIC_STORAGE_BIT</constant>, <constant>GL_MAP_READ_BIT</constant>
                    <constant>GL_MAP_WRITE_BIT</constant>, <constant>GL_MAP_PERSISTENT_BIT</constant>, <constant>GL_MAP_COHERENT_BIT</constant>,
                    and <constant>GL_CLIENT_STORAGE_BIT</constant>.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glBufferStorage</function> creates a new immutable data store for the buffer object currently bound to
            <parameter>target</parameter>. The size of the data store is specified by <parameter>size</parameter>. If
            an initial data is available, its address may be supplied in <parameter>data</parameter>. Otherwise, to
            create an uninitialized data store, <parameter>data</parameter> should be <constant>NULL</constant>.
        </para>
        <para>
            The <parameter>flags</parameter> parameters specifies the intended usage of the buffer's data store.
            It must be a bitwise combination of a subset of the following flags:
            <variablelist>
                <varlistentry>
                    <term><constant>GL_DYNAMIC_STORAGE_BIT</constant></term>
                    <listitem>
                        <para>
                            The contents of the data store may be
                            updated after creation through calls to <citerefentry><refentrytitle>glBufferSubData</refentrytitle></citerefentry>.
                            If this bit is not set, the buffer content may not be directly updated by the client. The data argument
                            may be used to specify the initial content of the buffer's data store regardless of the presence of
                            the <constant>GL_DYNAMIC_STORAGE_BIT</constant>. Regardless of the presence of this bit,
                            buffers may always be updated with server-side calls such as
                            <citerefentry><refentrytitle>glCopyBufferSubData</refentrytitle></citerefentry> and
                            <citerefentry><refentrytitle>glClearBufferSubData</refentrytitle></citerefentry>.
                        </para>
                    </listitem>
                </varlistentry>
                <varlistentry>
                    <term><constant>GL_MAP_READ_BIT</constant></term>
                    <listitem>
                        <para>
                            The data store may be mapped by the client for
                            read access and a pointer in the client's address space obtained that may be read from.
                        </para>
                    </listitem>
                </varlistentry>
                <varlistentry>
                    <term><constant>GL_MAP_WRITE_BIT</constant></term>
                    <listitem>
                        <para>
                            The data store may be mapped by the client for
                            write access and a pointer in the client's address space obtained that may be written through.
                        </para>
                    </listitem>
                </varlistentry>
                <varlistentry>
                    <term><constant>GL_MAP_PERSISTENT_BIT</constant></term>
                    <listitem>
                        <para>
                            The client may request that the server read
                            from or write to the buffer while it is mapped. The client's pointer to the data store remains
                            valid so long as the data store is mapped, even during execution of drawing or dispatch commands.
                        </para>
                    </listitem>
                </varlistentry>
                <varlistentry>
                    <term><constant>GL_MAP_COHERENT_BIT</constant></term>
                    <listitem>
                        <para>
                            Shared access to buffers that are simultaneously
                            mapped for client access and are used by the server will be coherent, so long as that
                            mapping is performed using <citerefentry><refentrytitle>glMapBufferRange</refentrytitle></citerefentry>.
                            That is, data written to the store by either the client or server will be immediately visible to
                            the other with no further action taken by the application. In particular,
                        </para>
                    </listitem>
                    <itemizedlist>
                        <listitem>
                            <para>
                                If <constant>GL_MAP_COHERENT_BIT</constant> is not set and the client performs a write
                                followed by a call to the <citerefentry><refentrytitle>glMemoryBarrier</refentrytitle></citerefentry>
                                command with the <constant>GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT</constant> set, then in subsequent
                                commands the server will see the writes.
                            </para>
                        </listitem>
                        <listitem>
                            <para>
                                If <constant>GL_MAP_COHERENT_BIT</constant> is set and the client performs a write, then in
                                subsequent commands the server will see the writes.
                            </para>
                        </listitem>
                        <listitem>
                            <para>
                                If <constant>GL_MAP_COHERENT_BIT</constant> is not set and the server performs a write, the
                                application must call <citerefentry><refentrytitle>glMemoryBarrier</refentrytitle></citerefentry>
                                with the <constant>GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT</constant> set and then call
                                <citerefentry><refentrytitle>glFenceSync</refentrytitle></citerefentry> with
                                <constant>GL_SYNC_GPU_COMMANDS_COMPLETE</constant> (or <constant>glFinish</constant>).
                                Then the CPU will see the writes after the sync is complete.
                            </para>
                        </listitem>
                        <listitem>
                            <para>
                                If <constant>GL_MAP_COHERENT_BIT</constant> is set and the server does a write, the app must
                                call FenceSync with <constant>GL_SYNC_GPU_COMMANDS_COMPLETE</constant> (or <citerefentry><refentrytitle>glFinish</refentrytitle></citerefentry>).
                                Then the CPU will see the writes after the sync is complete.
                            </para>
                        </listitem>
                    </itemizedlist>
                </varlistentry>
                <varlistentry>
                    <term><constant>GL_CLIENT_STORAGE_BIT</constant></term> When all other criteria for the buffer storage allocation
                    are met, this bit may be used by an implementation to determine whether to use storage that is local to the
                    server or to the client to serve as the backing store for the buffer.
                </varlistentry>
            </variablelist>
        </para>
        <para>
            The allowed combinations of flags are subject to certain restrictions. They are as follows:
            <itemizedlist>
                <listitem>
                    <para>
                        If <parameter>flags</parameter> contains <constant>GL_MAP_PERSISTENT_BIT</constant>, it
                        must also contain at least one of <constant>GL_MAP_READ_BIT</constant> or <constant>GL_MAP_WRITE_BIT</constant>.
                    </para>
                </listitem>
                <listitem>
                    <para>
                        If <parameter>flags</parameter> contains <constant>GL_MAP_COHERENT_BIT</constant>, it must
                        also contain <constant>GL_MAP_PERSISTENT_BIT</constant>.
                    </para>
                </listitem>
            </itemizedlist>
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            <function>glBufferStorage</function> is available only if the GL version is 4.4 or greater.
        </para>
        <para>
            If <parameter>data</parameter> is <constant>NULL</constant>, a data store of the specified size is still created,
            but its contents remain uninitialized and thus undefined.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
            one of the accepted buffer targets.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>size</parameter> is less than or equal to zero.
        </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_OUT_OF_MEMORY</constant> is generated if the GL is unable to create a
            data store with the properties requested in <parameter>flags</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if flags has any bits set other than
            those defined above.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> error is generated if <parameter>flags</parameter> contains <constant>GL_MAP_PERSISTENT_BIT</constant>
            but does not contain at least one of <constant>GL_MAP_READ_BIT</constant> or <constant>GL_MAP_WRITE_BIT</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>flags</parameter> contains <constant>GL_MAP_COHERENT_BIT</constant>, but
            does not also contain <constant>GL_MAP_PERSISTENT_BIT</constant>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if the <constant>GL_BUFFER_IMMUTABLE_STORAGE</constant> flag of the buffer
            bound to <parameter>target</parameter> is <constant>GL_TRUE</constant>.
        </para>
    </refsect1>
    <refsect1 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetBufferSubData</refentrytitle></citerefentry>
        </para>
        <para>
            <citerefentry><refentrytitle>glGetBufferParameter</refentrytitle></citerefentry> with argument <constant>GL_BUFFER_SIZE</constant> or <constant>GL_BUFFER_USAGE</constant>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBindBuffer</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> 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>
