Opentk/Source/Bind/Specifications/Docs/GL/glGetQueryObject.xml

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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetQueryObject">
    <info>
        <copyright>
            <year>2005</year>
            <holder>Sams Publishing</holder>
        </copyright>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glGetQueryObject</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetQueryObject</refname>
        <refpurpose>return parameters of a query object</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetQueryObjectiv</function></funcdef>
                <paramdef>GLuint <parameter>id</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLint * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetQueryObjectuiv</function></funcdef>
                <paramdef>GLuint <parameter>id</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLuint * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetQueryObjecti64v</function></funcdef>
                <paramdef>GLuint <parameter>id</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLint64 * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetQueryObjectui64v</function></funcdef>
                <paramdef>GLuint <parameter>id</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLuint64 * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>id</parameter></term>
            <listitem>
                <para>
                    Specifies the name of a query object.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>pname</parameter></term>
            <listitem>
                <para>
                    Specifies the symbolic name of a query object parameter.
                    Accepted values are <constant>GL_QUERY_RESULT</constant> or <constant>GL_QUERY_RESULT_AVAILABLE</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>params</parameter></term>
            <listitem>
                <para>
                    If a buffer is bound to the <constant>GL_QUERY_RESULT_BUFFER</constant> target, then <parameter>params</parameter>
                    is treated as an offset to a location within that buffer's data store to receive the result of the query. If
                    no buffer is bound to <constant>GL_QUERY_RESULT_BUFFER</constant>, then <parameter>params</parameter> is
                    treated as an address in client memory of a variable to receive the resulting data.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glGetQueryObject</function> returns in <parameter>params</parameter> a selected parameter of the query object
            specified by <parameter>id</parameter>.
        </para>
        <para>
            <parameter>pname</parameter> names a specific query object parameter.  <parameter>pname</parameter> can be as follows:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_QUERY_RESULT</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the value of the query object's passed samples counter.
                        The initial value is 0.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_QUERY_RESULT_NO_WAIT</constant></term>
                <listitem>
                    <para>
                        If the result of the query is available (that is, a query of <constant>GL_QUERY_RESULT_AVAILABLE</constant> would
                        return non-zero), then <parameter>params</parameter> returns the value of the query object's passed samples counter,
                        otherwise, the data referred to by <parameter>params</parameter> is not modified.
                        The initial value is 0.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_QUERY_RESULT_AVAILABLE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns whether the passed samples counter is immediately available.
                        If a delay would occur waiting for the query result, <constant>GL_FALSE</constant> is returned.
                        Otherwise, <constant>GL_TRUE</constant> is returned, which also indicates that the results of all
                        previous queries are available as well.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
        <para>
            If an error is generated,
            no change is made to the contents of <parameter>params</parameter>.
        </para>
        <para>
            <function>glGetQueryObject</function> implicitly flushes the GL pipeline so that any incomplete rendering
            delimited by the occlusion query completes in finite time.
        </para>
        <para>
            If multiple queries are issued using the same query object <parameter>id</parameter> before calling
            <function>glGetQueryObject</function>, the results of the most recent query will be returned.  In this case,
            when issuing a new query, the results of the previous query are discarded.
        </para>
        <para>
            <function>glGetQueryObjecti64v</function> and <function>glGetQueryObjectui64v</function> are available only
            if the GL version is 3.3 or greater.
        </para>
        <para>
            <constant>GL_QUERY_RESULT_NO_WAIT</constant> is accepted for <parameter>pname</parameter> only if the
            GL version is 4.4 or greater.
        </para>
        <para>
            The <constant>GL_QUERY_RESULT_BUFFER</constant> target is available only if the GL version is 4.4 or higher.
            On earlier versions of the GL, <parameter>params</parameter> is always an address in client memory.
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is not an accepted value.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>id</parameter> is not the name of a query object.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>id</parameter> is the name of a currently active
            query object.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if a buffer is currently bound to the
            <constant>GL_QUERY_RESULT_BUFFER</constant> target and the command would cause data to be written beyond the bounds
            of that buffer's data store.
        </para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBeginQuery</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glEndQuery</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetQueryiv</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glIsQuery</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glQueryCounter</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2005 Addison-Wesley.
            Copyright <trademark class="copyright"/> 2010-2013 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.
            <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
        </para>
    </refsect1>
</refentry>