NAME

       clEnqueueReleaseGLObjects - Release OpenCL memory objects that have been created from
       OpenGL objects.

       cl_int clEnqueueReleaseGLObjects(cl_command_queue command_queue, cl_uint num_objects,
                                        const cl_mem *mem_objects,
                                        cl_uint num_events_in_wait_list,
                                        const cl_event *event_wait_list, cl_event *event);

PARAMETERS

        command_queue
           A valid command-queue.

        num_objects
           The number of memory objects to be released in mem_objects.

        mem_objects
           A pointer to a list of CL memory objects that correspond to GL objects.

         event_wait_list ,   num_events_in_wait_list
           These parameters specify events that need to complete before this command can be
           executed. If event_wait_list is NULL, then this particular command does not wait on
           any event to complete. If event_wait_list is NULL, num_events_in_wait_list must be 0.
           If event_wait_list is not NULL, the list of events pointed to by event_wait_list must
           be valid and num_events_in_wait_list must be greater than 0. The events specified in
           event_wait_list act as synchronization points.

        event
           Returns an event object that identifies this particular read/write command and can be
           used to query or queue a wait for the command to complete.  event 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.

           If the cl_khr_gl_sharing(3clc) extension is supported and if an OpenGL context is
           bound to the current thread, then any OpenGL commands which does:

           •    affect or access the contents of a memory object listed in the mem_objects list,
               and

           •    are issued on that context after the call to clEnqueueReleaseGLObjects.RE

               will not execute until after execution of any OpenCL commands preceding the
               clEnqueueReleaseGLObjects which affect or access any of those memory objects. If a
               non-NULL event object is returned, it will report completion before execution of
               such OpenGL commands.

DESCRIPTION

       Release OpenCL memory objects that have been created from OpenGL objects. These objects
       need to be released before they can be used by OpenGL. The OpenGL objects are released by
       the OpenCL context associated with command_queue.

NOTES

       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.

       Prior to calling clEnqueueAcquireGLObjects, the application must ensure that any pending
       GL operations which access the objects specified in mem_objects have completed. This may
       be accomplished portably by issuing and waiting for completion of a glFinish command on
       all GL contexts with pending references to these objects. Implementations may offer more
       efficient synchronization methods; for example on some platforms calling glFlush 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 glFinish are portable between OpenGL implementations at this time.

       Similarly, after calling clEnqueueReleaseGLObjects, the application is responsible for
       ensuring that any pending OpenCL operations which access the objects specified in
       mem_objects have completed prior to executing subsequent GL commands which reference these
       objects. This may be accomplished portably by calling clWaitForEvents(3clc) with the event
       object returned by clEnqueueReleaseGLObjects, or by calling clFinish(3clc). As above, some
       implementations may offer more efficient methods.

       The application is responsible for maintaining the proper order of operations if the CL
       and GL contexts are in separate threads.

       If a GL context is bound to a thread other than the one in which clEnqueueReleaseGLObjects
       is called, changes to any of the objects in mem_objects 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.

       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.

       If the cl_khr_gl_event(3clc) 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.

ERRORS

       clEnqueueReleaseGLObjects returns CL_SUCCESS if the function is executed successfully. If
       num_objects is 0 and mem_objects is NULL the function does nothing and returns CL_SUCCESS.
       Otherwise, it returns one of the following errors:

       •   CL_INVALID_VALUE if num_objects is zero and mem_objects is not a NULL value or if
           num_objects > 0 and mem_objects is NULL.

       •   CL_INVALID_MEM_OBJECT if memory objects in mem_objects are not valid OpenCL memory
           objects.

       •   CL_INVALID_COMMAND_QUEUE if command_queue is not a valid command-queue.

       •   CL_INVALID_CONTEXT if context associated with command_queue was not created from an
           OpenGL context.

       •   CL_INVALID_GL_OBJECT if memory objects in mem_objects have not been created from a GL
           object(s).

       •   CL_INVALID_EVENT_WAIT_LIST if event_wait_list is NULL and num_events_in_wait_list > 0,
           or event_wait_list is not NULL and num_events_in_wait_list is 0, or if event objects
           in event_wait_list are not valid events.

       •   CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL
           implementation on the device.

       •   CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the
           OpenCL implementation on the host.

SPECIFICATION

       OpenCL Specification[1]

SEE ALSO

       cl_khr_gl_sharing(3clc), clEnqueueAcquireGLObjects(3clc), cl_khr_gl_event(3clc)

AUTHORS

       The Khronos Group

COPYRIGHT

       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.

NOTES

        1. OpenCL Specification
           page 58, section 9.7.6 - Sharing memory objects that map to GL objects...