sdk/1.1/docs/man/clEnqueueAcquireGLObjects.xml

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<refentry>
    <refentryinfo>
        <keywordset>
            <keyword>clEnqueueAcquireGLObjects</keyword>
        </keywordset>
    </refentryinfo>

    <refmeta>                                    
        <refentrytitle>clEnqueueAcquireGLObjects</refentrytitle>

        <refmiscinfo>
            <copyright>
                <year>2007-2010</year>
                <holder>The Khronos Group Inc. 
 Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included
in all copies or substantial portions of the Materials.</holder>
            </copyright>
        </refmiscinfo>
        <manvolnum>3</manvolnum>
    </refmeta>

<!-- ================================ SYNOPSIS -->

    <refnamediv id="clEnqueueAcquireGLObjects">             
        <refname>clEnqueueAcquireGLObjects</refname>

        <refpurpose>
            Acquire OpenCL memory objects that have been created from OpenGL objects.
        </refpurpose>
    </refnamediv>


    <refsynopsisdiv xmlns:xlink="http://www.w3.org/1999/xlink"><title></title>
        <funcsynopsis>
            <funcprototype>
                <funcdef><link xlink:href="scalarDataTypes.html">cl_int</link>

                    <function>                   
                        clEnqueueAcquireGLObjects
                    </function>
                </funcdef>

                <paramdef><link xlink:href="abstractDataTypes.html">cl_command_queue</link><parameter>command_queue</parameter></paramdef>
                <paramdef><link xlink:href="scalarDataTypes.html">cl_uint</link><parameter>num_objects</parameter></paramdef>
                <paramdef>const <link xlink:href="abstractDataTypes.html">cl_mem</link><parameter>*mem_objects</parameter></paramdef>
                <paramdef><link xlink:href="scalarDataTypes.html">cl_uint</link><parameter>num_events_in_wait_list</parameter></paramdef>
                <paramdef>const <link xlink:href="abstractDataTypes.html">cl_event</link><parameter>*event_wait_list</parameter></paramdef>
                <paramdef><link xlink:href="abstractDataTypes.html">cl_event</link><parameter>*event</parameter></paramdef>

            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>


<!-- ================================ PARAMETERS -->


    <refsect1 id="parameters">
        <title>Parameters</title>
        <variablelist>


            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        command_queue
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
A valid command-queue. All devices used to create the OpenCL context
associated with <varname>command_queue</varname> must support acquiring shared CL/GL objects.
This constraint is enforced at context creation time.
                    </para>
               </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        num_objects
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
The number of memory objects to be acquired in <varname>mem_objects</varname>.
                    </para>
                </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        mem_objects
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
A pointer to a list of CL memory objects that correspond to GL objects.
                    </para>
                </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        event_wait_list
                    </varname>
                </term>
and
                <term>
                    <varname> <!-- parameter name -->
                        num_events_in_wait_list
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
Specify events that need to complete before this
particular command can be executed. If <varname>event_wait_list</varname> is NULL, then this particular command
does not wait on any event to complete. If <varname>event_wait_list</varname> is NULL,
<varname>num_events_in_wait_list</varname>
must be 0. If <varname>event_wait_list</varname> is not NULL,
the list of events pointed to by <varname>event_wait_list</varname> must
be valid and <varname>num_events_in_wait_list</varname> must be greater than 0.
The events specified in
<varname>event_wait_list</varname> act as synchronization points.
                    </para>
                </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        event
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        Returns an event object that identifies this command and can be used to query or queue a 
                        wait for the command to complete. <varname>event</varname> can be NULL in which
                        case it will not be possible for the application to query the status of this command or queue 
                        a wait for this command to complete.
                    </para>
                    <para>
                        When the <citerefentry href="gl_event"><refentrytitle>cl_khr_gl_event</refentrytitle></citerefentry>
                        extension is enabled,   
                        If an OpenGL context is bound to the current thread, then any OpenGL commands which:
                    </para>
                    <itemizedlist mark="disc">
                        <listitem>
                            affect or access the contents of a memory object listed in the <varname>mem_objects</varname> list, and 
                        </listitem>
                        <listitem>
                            were issued on that OpenGL context prior to the call to 
                            <citerefentry><refentrytitle>clEnqueueAcquireGLObjects</refentrytitle></citerefentry> 
                        </listitem>
                    </itemizedlist>
                    <para>
                        will complete before execution of any OpenCL commands following the
                        <citerefentry><refentrytitle>clEnqueueAcquireGLObjects</refentrytitle></citerefentry>  
                        which affect or access any of those memory objects. If a non-NULL <varname>event</varname> object is 
                        returned, it will report completion only after completion of such OpenGL commands.
                    </para>
                </listitem>
            </varlistentry>

        </variablelist>
    </refsect1>


<!-- ================================ DESCRIPTION  -->

    <refsect1 id="description"><title>Description</title>
        <para>
These
objects need to be acquired before they can be used by any OpenCL commands queued to a
command-queue. The OpenGL objects are acquired by the OpenCL context associated with
<varname>command_queue</varname> and can therefore be used by all command-queues associated with the OpenCL
context.
        </para>

    </refsect1>


<!-- ================================ NOTES  -->


    <refsect1 id="notes"><title>Notes</title>
        <para>
            In order to ensure data integrity, the application is responsible for synchronizing access to shared
CL/GL objects by their respective APIs. Failure to provide such synchronization may result in
race conditions and other undefined behavior including non-portability between
implementations.
        </para>
        <para>
            Prior to calling <function>clEnqueueAcquireGLObjects</function>, the application 
            must ensure that any pending GL operations which access the objects specified in 
             <varname>mem_objects</varname> have completed. This may be accomplished portably 
             by issuing and waiting for completion of a 
             <citerefentry><refentrytitle>glFinish</refentrytitle></citerefentry> command on 
             all GL contexts with pending references to these objects. Implementations may 
             offer more efficient synchronization methods; for example on some platforms 
             calling <citerefentry><refentrytitle>glFlush</refentrytitle></citerefentry>  
             may be sufficient, or synchronization may be implicit within a thread, or 
             there may be vendor-specific extensions that enable placing a fence in the 
             GL command stream and waiting for completion of that fence in the 
             CL command queue. Note that no synchronization methods other than 
              <citerefentry><refentrytitle>glFinish</refentrytitle></citerefentry> are 
              portable between OpenGL implementations at this time.
        </para>
        <para>
            Similarly, after calling <function>clEnqueueReleaseGLObjects</function>, 
            the application is responsible for ensuring that any pending OpenCL operations 
            which access the objects specified in <varname>mem_objects</varname> have
completed prior to executing subsequent GL commands which reference these objects. This
may be accomplished portably by calling <citerefentry><refentrytitle>clWaitForEvents</refentrytitle></citerefentry> with the event object returned by
<function>clEnqueueReleaseGLObjects</function>, or by calling <citerefentry><refentrytitle>glFinish</refentrytitle></citerefentry>. As above, some implementations may
offer more efficient methods.
        </para>
        <para>
The application is responsible for maintaining the proper order of operations if the CL and GL
contexts are in separate threads.
        </para>
        <para>
If a GL context is bound to a thread other than the one in which <function>clEnqueueReleaseGLObjects</function>
is called, changes to any of the objects in <varname>mem_objects</varname> may not be visible to that context without
additional steps being taken by the application. For an OpenGL 3.1 (or later) context, the
requirements are described in Appendix G ("Shared Objects and Multiple Contexts") of the
OpenGL 3.1 Specification. For prior versions of OpenGL, the requirements are implementationdependent.
        </para>
        <para>
            Attempting to access the data store of an OpenGL object after it has been acquired by OpenCL
and before it has been released will result in undefined behavior. Similarly, attempting to access
a shared CL/GL object from OpenCL before it has been acquired by the OpenCL command
queue, or after it has been released, will result in undefined behavior.
        </para>
    </refsect1> 



<!-- ================================ ERRORS  -->

    <refsect1 id="errors"><title>Errors</title>
        <para>
            Returns <errorname>CL_SUCCESS</errorname> if the function is executed successfully. If
<varname>num_objects</varname> is 0 and <varname>mem_objects</varname> is NULL
the function does nothing and returns <errorname>CL_SUCCESS</errorname>.
Otherwise, it returns one of the following errors:
        </para>

        <itemizedlist mark="disc">

            <listitem>
                <errorname>CL_INVALID_VALUE</errorname> if <varname>num_objects</varname> is zero and 
                <varname>mem_objects</varname> is not a NULL value or if <varname>num_objects</varname> &gt; 0 
                and <varname>mem_objects</varname> is NULL.
            </listitem>

            <listitem>
                <errorname>CL_INVALID_MEM_OBJECT</errorname> if memory objects in <varname>mem_objects</varname> 
                are not valid OpenCL memory objects.
            </listitem>
            <listitem>
                <errorname>CL_INVALID_COMMAND_QUEUE</errorname> if <varname>command_queue</varname> is not a 
                valid command-queue.
            </listitem>
            <listitem>
                <errorname>CL_INVALID_CONTEXT</errorname> if context associated with <varname>command_queue</varname> 
                was not created from an OpenGL context.
            </listitem>
            <listitem>
                <errorname>CL_INVALID_GL_OBJECT</errorname> if memory objects in <varname>mem_objects</varname> 
                have not been created from a GL object(s).
            </listitem>
            <listitem>
                <errorname>CL_INVALID_EVENT_WAIT_LIST</errorname> if <varname>event_wait_list</varname> 
                is NULL and <varname>num_events_in_wait_list</varname> &gt; 0, or 
                <varname>event_wait_list</varname> is not NULL and 
                 <varname>num_events_in_wait_list</varname> is 0, or if event objects in 
                  <varname>event_wait_list</varname> are not valid events.
            </listitem>
            <listitem>
                <errorname>CL_OUT_OF_RESOURCES</errorname> if there is a failure to allocate resources 
                required by the OpenCL implementation on the device.
            </listitem>
            <listitem>
                <errorname>CL_OUT_OF_HOST_MEMORY</errorname> if there is a failure to allocate resources required 
                by the OpenCL implementation on the host.
            </listitem>
        </itemizedlist>
    </refsect1>

    
<!-- ================================ EXAMPLE  -->
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    <refsect2 id="example1">
        <title>
            Example
        </title>

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                        </entry>
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<!-- ================================ SPECIFICATION  -->
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    <refsect1 id="specification"><title>Specification</title>
        <para>
            <imageobject>
                <imagedata fileref="pdficon_small1.gif" format="gif" />
            </imageobject>
                                                 
            <olink uri="clEnqueueAcquireGLObjects">OpenCL Specification</olink>
        </para>
    </refsect1>


<!-- ================================ ALSO SEE  -->

    <refsect1 id="seealso"><title>Also see</title>
        <para>
            <citerefentry href="gl_sharing"><refentrytitle>cl_khr_gl_sharing</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>clEnqueueReleaseGLObjects</refentrytitle></citerefentry>,
            <citerefentry href="gl_event"><refentrytitle>cl_khr_gl_event</refentrytitle></citerefentry>
        </para>
    </refsect1>



<!-- ============================== COPYRIGHT -->
<!-- Content included from copyright.inc.xsl -->

    <refsect3 id="Copyright"><title></title>
        <imageobject>
                <imagedata fileref="KhronosLogo.jpg" format="jpg" />
        </imageobject>
        <para />
    </refsect3>

</refentry>