
<refentry id="glGetBufferParameteriv">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2005</year>
                <holder>Sams Publishing</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetBufferParameteriv</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetBufferParameteriv</refname>
        <refpurpose>return parameters of a buffer object</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetBufferParameteriv</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLenum <parameter>value</parameter></paramdef>
                <paramdef>GLint * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <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_ELEMENT_ARRAY_BUFFER</constant>,
                    <constant>GL_PIXEL_PACK_BUFFER</constant>, or
                    <constant>GL_PIXEL_UNPACK_BUFFER</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>value</parameter></term>
            <listitem>
                <para>
                    Specifies the symbolic name of a buffer object parameter.
                    Accepted values are <constant>GL_BUFFER_ACCESS</constant>, <constant>GL_BUFFER_MAPPED</constant>, 
                    <constant>GL_BUFFER_SIZE</constant>, or <constant>GL_BUFFER_USAGE</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Returns the requested parameter.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glGetBufferParameteriv</function> returns in <parameter>data</parameter> a selected parameter of the buffer object
            specified by <parameter>target</parameter>.
        </para>
        <para>
            <parameter>value</parameter> names a specific buffer object parameter, as follows:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_BUFFER_ACCESS</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the access policy set while mapping the buffer object.  
                        The initial value is <constant>GL_READ_WRITE</constant>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BUFFER_MAPPED</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns a flag indicating whether the buffer object is currently 
                        mapped. The initial value is <constant>GL_FALSE</constant>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BUFFER_SIZE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the size of the buffer object, measured in bytes.  
                        The initial value is 0.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BUFFER_USAGE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the buffer object's usage pattern.  The initial value is
                        <constant>GL_STATIC_DRAW</constant>.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </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>
            <function>glGetBufferParameteriv</function> is available only if the GL version is 1.5 or greater.
        </para>
        <para>
            Targets <constant>GL_PIXEL_PACK_BUFFER</constant> and <constant>GL_PIXEL_UNPACK_BUFFER</constant> are available 
            only if the GL version is 2.1 or greater.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> or <parameter>value</parameter> is not an
            accepted value.
        </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 <function>glGetBufferParameteriv</function>
            is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
            and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBufferData</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. 
            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>
