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    <title>clEnqueueAcquireGLObjects</title>
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    <div class="refentry">
      <a id="id-1"></a>
      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="clEnqueueAcquireGLObjects"></a>
        <h1>clEnqueueAcquireGLObjects</h1>
        <p>
            Acquire OpenCL memory objects that have been created from OpenGL objects.
        </p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
            <tr valign="bottom">
              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef"><a class="link" href="scalarDataTypes.html" target="_top">cl_int</a>

                    <strong class="fsfunc">                   
                        clEnqueueAcquireGLObjects
                    </strong>
                (</code>
                <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="_top">cl_command_queue</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">command_queue</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="_top">cl_uint</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">num_objects</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>const <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="_top">cl_mem</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*mem_objects</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="_top">cl_uint</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">num_events_in_wait_list</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>const <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="_top">cl_event</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*event_wait_list</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="_top">cl_event</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*event</var><code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="parameters"></a>
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                    <code class="varname"> 
                        command_queue
                    </code>
                </span>
            </dt>
            <dd>
              <p> 
A valid command-queue. All devices used to create the OpenCL context
associated with <code class="varname">command_queue</code> must support acquiring shared CL/GL objects.
This constraint is enforced at context creation time.
                    </p>
            </dd>
            <dt>
              <span class="term">
                    <code class="varname"> 
                        num_objects
                    </code>
                </span>
            </dt>
            <dd>
              <p> 
The number of memory objects to be acquired in <code class="varname">mem_objects</code>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                    <code class="varname"> 
                        mem_objects
                    </code>
                </span>
            </dt>
            <dd>
              <p> 
A pointer to a list of CL memory objects that correspond to GL objects.
                    </p>
            </dd>
            <dt>
              <span class="term">
                    <code class="varname"> 
                        event_wait_list
                    </code>
                , </span>
              <span class="term">
                    <code class="varname"> 
                        num_events_in_wait_list
                    </code>
                </span>
            </dt>
            <dd>
              <p> 
Specify events that need to complete before this
particular command can be executed. If <code class="varname">event_wait_list</code> is NULL, then this particular command
does not wait on any event to complete. If <code class="varname">event_wait_list</code> is NULL,
<code class="varname">num_events_in_wait_list</code>
must be 0. If <code class="varname">event_wait_list</code> is not NULL,
the list of events pointed to by <code class="varname">event_wait_list</code> must
be valid and <code class="varname">num_events_in_wait_list</code> must be greater than 0.
The events specified in
<code class="varname">event_wait_list</code> act as synchronization points.
                    </p>
            </dd>
            <dt>
              <span class="term">
                    <code class="varname"> 
                        event
                    </code>
                </span>
            </dt>
            <dd>
              <p> 
                        Returns an event object that identifies this command and can be used to query or queue a 
                        wait for the command to complete. <code class="varname">event</code> 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.
                    </p>
              <p>
                        When the <a class="citerefentry" href="gl_event.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_event</span></span></a>
                        extension is enabled,   
                        If an OpenGL context is bound to the current thread, then any OpenGL commands which:
                    </p>
              <div class="itemizedlist">
                <ul class="itemizedlist" style="list-style-type: disc; ">
                  <li class="listitem" style="list-style-type: disc">
                            affect or access the contents of a memory object listed in the <code class="varname">mem_objects</code> list, and 
                        </li>
                  <li class="listitem" style="list-style-type: disc">
                            were issued on that OpenGL context prior to the call to 
                            <a class="citerefentry" href="clEnqueueAcquireGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueAcquireGLObjects</span></span></a></li>
                </ul>
              </div>
              <p>
                        will complete before execution of any OpenCL commands following the
                        <a class="citerefentry" href="clEnqueueAcquireGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueAcquireGLObjects</span></span></a>  
                        which affect or access any of those memory objects. If a non-NULL <code class="varname">event</code> object is 
                        returned, it will report completion only after completion of such OpenGL commands.
                    </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
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
<code class="varname">command_queue</code> and can therefore be used by all command-queues associated with the OpenCL
context.
        </p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
            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.
        </p>
        <p>
            Prior to calling <code class="function">clEnqueueAcquireGLObjects</code>, the application 
            must ensure that any pending GL operations which access the objects specified in 
             <code class="varname">mem_objects</code> have completed. This may be accomplished portably 
             by issuing and waiting for completion of a 
             <a class="citerefentry" href="glFinish.html"><span class="citerefentry"><span class="refentrytitle">glFinish</span></span></a> command on 
             all GL contexts with pending references to these objects. Implementations may 
             offer more efficient synchronization methods; for example on some platforms 
             calling <a class="citerefentry" href="glFlush.html"><span class="citerefentry"><span class="refentrytitle">glFlush</span></span></a>  
             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 
              <a class="citerefentry" href="glFinish.html"><span class="citerefentry"><span class="refentrytitle">glFinish</span></span></a> are 
              portable between OpenGL implementations at this time.
        </p>
        <p>
            Similarly, after calling <code class="function">clEnqueueReleaseGLObjects</code>, 
            the application is responsible for ensuring that any pending OpenCL operations 
            which access the objects specified in <code class="varname">mem_objects</code> have
completed prior to executing subsequent GL commands which reference these objects. This
may be accomplished portably by calling <a class="citerefentry" href="clWaitForEvents.html"><span class="citerefentry"><span class="refentrytitle">clWaitForEvents</span></span></a> with the event object returned by
<code class="function">clEnqueueReleaseGLObjects</code>, or by calling <a class="citerefentry" href="glFinish.html"><span class="citerefentry"><span class="refentrytitle">glFinish</span></span></a>. As above, some implementations may
offer more efficient methods.
        </p>
        <p>
The application is responsible for maintaining the proper order of operations if the CL and GL
contexts are in separate threads.
        </p>
        <p>
If a GL context is bound to a thread other than the one in which <code class="function">clEnqueueReleaseGLObjects</code>
is called, changes to any of the objects in <code class="varname">mem_objects</code> 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.
        </p>
        <p>
            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.
        </p>
      </div>
      <div class="refsect1">
        <a id="errors"></a>
        <h2>Errors</h2>
        <p>
            Returns <span class="errorname">CL_SUCCESS</span> if the function is executed successfully. If
<code class="varname">num_objects</code> is 0 and <code class="varname">mem_objects</code> is NULL
the function does nothing and returns <span class="errorname">CL_SUCCESS</span>.
Otherwise, it returns one of the following errors:
        </p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc; ">
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_VALUE</span> if <code class="varname">num_objects</code> is zero and 
                <code class="varname">mem_objects</code> is not a NULL value or if <code class="varname">num_objects</code> &gt; 0 
                and <code class="varname">mem_objects</code> is NULL.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_MEM_OBJECT</span> if memory objects in <code class="varname">mem_objects</code> 
                are not valid OpenCL memory objects.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_COMMAND_QUEUE</span> if <code class="varname">command_queue</code> is not a 
                valid command-queue.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_CONTEXT</span> if context associated with <code class="varname">command_queue</code> 
                was not created from an OpenGL context.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_GL_OBJECT</span> if memory objects in <code class="varname">mem_objects</code> 
                have not been created from a GL object(s).
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_EVENT_WAIT_LIST</span> if <code class="varname">event_wait_list</code> 
                is NULL and <code class="varname">num_events_in_wait_list</code> &gt; 0, or 
                <code class="varname">event_wait_list</code> is not NULL and 
                 <code class="varname">num_events_in_wait_list</code> is 0, or if event objects in 
                  <code class="varname">event_wait_list</code> are not valid events.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_OUT_OF_RESOURCES</span> if there is a failure to allocate resources 
                required by the OpenCL implementation on the device.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_OUT_OF_HOST_MEMORY</span> if there is a failure to allocate resources required 
                by the OpenCL implementation on the host.
            </li>
          </ul>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />
                                                 
            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.1.pdf#page=323" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a>,
            <a class="citerefentry" href="clEnqueueReleaseGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueReleaseGLObjects</span></span></a>,
            <a class="citerefentry" href="gl_event.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_event</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2010 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.
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