/usr/share/doc/opencl-1.2-html-doc/cl_khr_gl

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</style>
    <title>cl_khr_gl_sharing</title>
    <meta name="generator" content="DocBook XSL Stylesheets V1.79.1" />
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    <div class="refentry">
      <a id="idm1"></a>
      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="cl_khr_gl_sharing"></a>
        <h1>cl_khr_gl_sharing</h1>
        <p>
Allow applications to use OpenGL buffer, texture and renderbuffer objects as OpenCL memory objects.
        </p>
      </div>
      <div class="refsect2">
        <a id="synopsis"></a>
        <h3>
        </h3>
        <div class="informaltable">
          <table class="informaltable" border="0">
            <colgroup>
              <col align="left" class="col1" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">
cl_khr_gl_sharing
                        </td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
           This is a Kronos-approved extension
          name. If this extension is supported, "cl_khr_gl_sharing" will
          be returned for <code class="constant">CL_DEVICE_EXTENSIONS</code> using
          <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>.
        </p>
        <p>
           The OpenCL specification in section 9.7 defines how to
          share data with texture and buffer objects in a parallel OpenGL implementation,
          but does not define how the association between an OpenCL context and an OpenGL
          context or share group is established. This extension defines optional attributes
          to OpenCL context creation routines which associate a GL context or share group
          object with a newly created OpenCL context. If this extension is supported by an
          implementation, the string <code class="function">cl_khr_gl_sharing</code> will be present in the
          <code class="constant">CL_PLATFORM_EXTENSIONS</code> or <code class="constant">CL_DEVICE_EXTENSIONS</code>
          string described in the table of allowed values for <code class="varname">param_name</code>
          for <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>
        </p>
        <p>
           An OpenGL implementation supporting buffer objects and
          sharing of texture and buffer object images with OpenCL is required by this extension.
        </p>
        <p>
           This section discusses OpenCL functions that allow applications
          to use OpenGL buffer, texture, and renderbuffer objects as OpenCL memory objects. This
          allows efficient sharing of data between OpenCL and OpenGL. The OpenCL API may be used
          to execute kernels that read and/or write memory objects that are also OpenGL objects.
        </p>
        <p>
           An OpenCL image object may be created from an OpenGL texture or
          renderbuffer object. An OpenCL buffer object may be created from an OpenGL buffer object.
        </p>
        <p>
           OpenCL memory objects may be created from OpenGL objects
          if and only if the OpenCL context has been created from an OpenGL share group
          object or context. OpenGL share groups and contexts are created using platform
          specific APIs such as EGL, CGL, WGL, and GLX. On MacOS X, an OpenCL context may
          be created from an OpenGL share group object using the OpenCL platform extension
          cl_apple_gl_sharing. On other platforms including Microsoft Windows, Linux/Unix and
          others, an OpenCL context may be created from an OpenGL context using the Khronos
          platform extension <code class="function">cl_khr_gl_sharing</code>. Refer to the platform
          documentation for your OpenCL implementation, or visit the Khronos Registry at
          http://www.khronos.org/registry/cl/ for more information.
        </p>
        <p>
           Any supported OpenGL object defined within the GL share
          group object, or the share group associated with the GL context from which the CL
          context is created, may be shared, with the exception of the default OpenGL objects
          (i.e. objects named zero), which may not be shared.
        </p>
        <p>
            
    </p>
        <p>
       The table below (Table 9.4) describes
      the list of GL texture internal formats and the corresponding CL image formats. If a GL
      texture object with an internal format from the table below is successfully created by
      OpenGL, then there is guaranteed to be a mapping to one of the corresponding CL image
      format(s) in that table. Texture objects created with other OpenGL internal formats may
      (but are not guaranteed to) have a mapping to a CL image format; if such mappings exist,
      they are guaranteed to preserve all color components, data types, and at least the number
      of bits/component actually allocated by OpenGL for that format.
    </p>
        <p>

    </p>
        <div class="informaltable">
          <table class="informaltable" border="1">
            <colgroup>
              <col align="center" class="col1" />
              <col align="center" class="col2" />
            </colgroup>
            <thead>
              <tr>
                <th align="center">GL internal format</th>
                <th align="center">CL image format (channel order, channel data type)</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA8</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_UNORM_INT8 or CL_BGRA, CL_UNORM_INT8</code>
                </td>
              </tr>
              <tr>
                <td align="center"><code class="constant">GL_RGBA</code>, <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code></td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_UNORM_INT8</code>
                </td>
              </tr>
              <tr>
                <td align="center"><code class="constant">GL_BGRA</code>, <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code></td>
                <td align="center">
                  <code class="constant">CL_BGRA, CL_UNORM_INT8</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA16</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_UNORM_INT16</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA8I, GL_RGBA8I_EXT</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_SIGNED_INT8</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA16I, GL_RGBA16I_EXT</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_SIGNED_INT16</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA32I, GL_RGBA32I_EXT</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_SIGNED_INT32</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA8UI, GL_RGBA8UI_EXT</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_UNSIGNED_INT8</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA16UI, GL_RGBA16UI_EXT</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_UNSIGNED_INT16</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA32UI, GL_RGBA32UI_EXT</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_UNSIGNED_INT32</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA16F, GL_RGBA16F_ARB</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_HALF_FLOAT</code>
                </td>
              </tr>
              <tr>
                <td align="center">
                  <code class="constant">GL_RGBA32F, GL_RGBA32F_ARB</code>
                </td>
                <td align="center">
                  <code class="constant">CL_RGBA, CL_FLOAT</code>
                </td>
              </tr>
            </tbody>
          </table>
        </div>
        <p>




            
    </p>
        <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>

    </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 <code class="function">glFinish</code>
      command on all GL contexts with pending references to these objects.  Implementations
      may offer more efficient synchronization methods; for example on some platforms calling
      <code class="function">glFlush</code> 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 <code class="function">glFinish</code> are portable
      between OpenGL implementations at this time.
    </p>
        <p>

    </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="clFinish.html"><span class="citerefentry"><span class="refentrytitle">clFinish</span></span></a>.  As above, some
      implementations may offer more efficient methods.
    </p>
        <p>

    </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>

    </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 D ("Shared Objects and Multiple Contexts") of the OpenGL 3.1
      Specification. For prior versions of OpenGL, the requirements are implementation-dependent.
    </p>
        <p>

    </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>
        <p>

    </p>
        <p>
       If the
      <a class="citerefentry" href="cl_khr_gl_event.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_event</span></span></a> extension
      is supported, then the OpenCL implementation will ensure that any such pending OpenGL
      operations are complete for an OpenGL context bound to the same thread as the OpenCL
      context. This is referred to as implicit synchronization.
    </p>
        <p>




            
    </p>
        <h4><a id="idm138"></a>Lifetime of Shared Objects</h4>
        <p>

    </p>
        <p>
       An OpenCL memory object created from an OpenGL object
      (hereinafter refered to as a “shared CL/GL object”) remains valid as long as the
      corresponding GL object has not been deleted. If the GL object is deleted through the GL
      API (e.g. <code class="function">glDeleteBuffers</code>, <code class="function">glDeleteTextures</code>,
      or <code class="function">glDeleteRenderbuffers</code>), subsequent use of the CL buffer or image
      object will result in undefined behavior, including but not limited to possible CL errors
      and data corruption, but may not result in program termination.
    </p>
        <p>

    </p>
        <p>
       The CL context and corresponding command-queues are dependent
      on the existence of the GL share group object, or the share group associated with the
      GL context from which the CL context is created. If the GL share group object or all GL
      contexts in the share group are destroyed, any use of the CL context or command-queue(s)
      will result in undefined behavior, which may include program termination. Applications
      should destroy the CL command-queue(s) and CL context before destroying the corresponding
      GL share group or contexts.
    </p>
        <p>




        </p>
        <h4><a id="idm144"></a>OpenCL Functions That Allow Sharing</h4>
        <p>
            Click an item in the table for details about that function.
        </p>
      </div>
      <div class="refsect1">
        <a id="springboard"></a>
        <h2></h2>
        <div class="informaltable">
          <table class="informaltable" border="1">
            <colgroup>
              <col align="left" class="col1" />
              <col align="left" class="col2" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clGetGLContextInfoKHR.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clGetGLContextInfoKHR</span>
                    </span>
                  </a>
                </td>
                <td align="left">Query the device.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clCreateFromGLBuffer.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clCreateFromGLBuffer</span>
                    </span>
                  </a>
                </td>
                <td align="left">Creates an OpenCL buffer object from an OpenGL buffer object.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clCreateFromGLTexture.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clCreateFromGLTexture</span>
                    </span>
                  </a>
                </td>
                <td align="left">Creates an OpenCL image object, image array object, or image buffer object from an OpenGL
                     texture object, texture array object, texture buffer object, or a single face of an
                     OpenGL cubemap texture object.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clCreateFromGLRenderbuffer.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clCreateFromGLRenderbuffer</span>
                    </span>
                  </a>
                </td>
                <td align="left">Creates an OpenCL 2D image object from an OpenGL renderbuffer object.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clGetGLObjectInfo.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clGetGLObjectInfo</span>
                    </span>
                  </a>
                </td>
                <td align="left">Query an OpenGL memory object used to create an OpenCL memory object.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clGetGLTextureInfo.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clGetGLTextureInfo</span>
                    </span>
                  </a>
                </td>
                <td align="left">Get additional information about the GL texture object associated with a memory object.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clEnqueueAcquireGLObjects.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clEnqueueAcquireGLObjects</span>
                    </span>
                  </a>
                </td>
                <td align="left">Acquire OpenCL memory objects that have been created from OpenGL objects.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="clEnqueueReleaseGLObjects.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">clEnqueueReleaseGLObjects</span>
                    </span>
                  </a>
                </td>
                <td align="left">Release OpenCL memory objects that have been created from OpenGL objects.</td>
              </tr>
            </tbody>
          </table>
        </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-1.2-extensions.pdf#page=39" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a>,
            <a class="citerefentry" href="clGetGLContextInfoKHR.html"><span class="citerefentry"><span class="refentrytitle">clGetGLContextInfoKHR</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 © 2007-2011 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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opencl-1.2-html-doc 1.0~svn33624-1 / usr / share / doc / opencl-1.2-html-doc / cl_khr_gl_sharing.html
