fglAsyncMarkerSGIX(3G)

NAME
     fglAsyncMarkerSGIX - set a marker for tracking asynchronous commands


FORTRAN SPECIFICATION
     SUBROUTINE fglAsyncMarkerSGIX( INTEGER*4 marker )


PARAMETERS
     marker  Specifies a marker value for tracking asynchronous commands.

DESCRIPTION
     fglAsyncMarkerSGIX is part of the SGIX_async extension.  This extension
     provides a framework within which particular sets of OpenGL commands can
     become "asynchronous" via specific further OpenGL extensions.  Currently
     the SGIX_async_pixel extension is the only such defined extension.

     Asynchronous commands are commands that may complete out-of-order with
     respect to other OpenGL commands.  An asynchronous command samples the
     OpenGL state vector when it is issued.  The sampled state includes the
     results from the complete execution of all synchronous (normal) commands
     issued prior to the asynchronous command.  However, the results of an
     asynchronous command (state changes or framebuffer updates) are not
     necessarily committed in order.  An asynchronous command may commit its
     results any time after the completion of all synchronous commands issued
     prior to the asynchronous command.  An implementation may choose to
     execute asynchronous commands in parallel with subsequent commands or at
     some convenient time in the future.

     Implementations of asynchronous commands may also be non-blocking.  For
     example, a non-blocking query command returns control to the program
     immediately rather than stalling the program until the results of the
     query are available.

     Note that this language allows any particular asynchronous command to
     behave exactly as if it were not asynchronous, if the implementation
     chooses.

     fglAsyncMarkerSGIX sets the value of GL_ASYNC_MARKER_SGIX.  When an
     asynchronous command is issued, the current value of GL_ASYNC_MARKER_SGIX
     is associated with the particular invocation of the command.  This value
     is an integer called a "marker" which can be used by the application to
     identify a particular command when it completes.  It is not an error to
     invoke multiple asynchronous commands without changing
     GL_ASYNC_MARKER_SGIX, although such a situation may make it impossible
     for the application to distinguish the completion status of the commands.

     Note that the marker name space is never shared across contexts, as the
     name spaces for texture objects and display lists may be.
     The initial value for GL_ASYNC_MARKER_SGIX is 0.

ERRORS
     GL_INVALID_OPERATION is generated if fglAsyncMarkerSGIX is executed
     between the execution of fglBegin and the corresponding execution of
     fglEnd.


MACHINE DEPENDENCIES
     The SGIX_async and SGIX_async_pixel extensions are implemented only on
     Octane2 VPro systems.


SEE ALSO
     fglDeleteAsyncMarkersSGIX, fglFinishAsyncSGIX, fglGenAsyncMarkersSGIX,
     fglIsAsyncMarkerSGIX, fglPollAsyncSGIX, fglDrawPixels, fglGet,
     fglReadPixels, fglTexImage1D, fglTexImage2D, fglTexImage3D,
     fglTexSubImage1D, fglTexSubImage2D, fglTexSubImage3D