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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glBufferStorage">
  <info>
    <copyright>
      <year>2014</year>

      <holder>Khronos Group</holder>
    </copyright>
  </info>

  <refmeta>
    <refentrytitle>glBufferStorage</refentrytitle>

    <manvolnum>3G</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>glBufferStorage</refname>

    <refname>glNamedBufferStorage</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>

      <funcprototype>
        <funcdef>void <function>glNamedBufferStorage</function></funcdef>

        <paramdef>GLuint <parameter>buffer</parameter></paramdef>

        <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>

        <paramdef>const void *<parameter>data</parameter></paramdef>

        <paramdef>GLbitfield <parameter>flags</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>glBufferStorage</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>glNamedBufferStorage</function> function.</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 xml:id="description">
    <title>Description</title>

    <para><function>glBufferStorage</function> and
    <function>glNamedBufferStorage</function> create a new immutable data
    store. For <function>glBufferStorage</function>, the buffer object
    currently bound to <parameter>target</parameter> will be initialized. For
    <function>glNamedBufferStorage</function>, <parameter>buffer</parameter>
    is the name of the buffer object that will be configured. 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>

            <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 <function>glFinish</function>). 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 <function>glFenceSync</function> 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>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>GL_CLIENT_STORAGE_BIT</constant></term>

          <listitem>
            <para>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.</para>
          </listitem>
        </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 xml:id="notes">
    <title>Notes</title>

    <para><function>glBufferStorage</function> is available only if the GL
    version is 4.4 or greater.</para>

    <para><function>glNamedBufferStorage</function> is available only if the
    GL version is 4.5 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 xml:id="errors">
    <title>Errors</title>

    <para><constant>GL_INVALID_ENUM</constant> is generated by
    <function>glBufferStorage</function> if <parameter>target</parameter> is
    not one of the accepted buffer targets.</para>

    <para><constant>GL_INVALID_OPERATION</constant> is generated by
    <function>glNamedBufferStorage</function> if buffer is not the name of an
    existing buffer object.</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 by
    <function>glBufferStorage</function> 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
    <parameter>flags</parameter> 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 by
    <function>glBufferStorage</function> 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 xml: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 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>glBufferStorage</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='44']/*)"/>
                    </row>
                    <row>
                        <entry><function>glNamedBufferStorage</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>glBufferSubData</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
        <citerefentry><refentrytitle>glUnmapBuffer</refentrytitle></citerefentry>
    </para>
  </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 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>
