C SPECIFICATION

       void glXSelectEvent( Display *dpy,
                            GLXDrawable drawabl )
       void glXSelectEvent( Display *,
                            GLXDrawable GLXDrawable,
                            unsigned long )

PARAMETERS

       Specifies the connection to the X server.

       GLXDrawable  Specifies a GLX drawable. Must be a GLX pixel buffer or  a
                    window.

       long         Specifies the events to be returned for GLXDrawable.

DESCRIPTION

       glXSelectEvent sets the GLX event mask for a GLX pixel buffer or a win-
       dow.  Calling glXSelectEvent overrides any previous event mask that was
       set  by  the  client  for GLXDrawable. Note that it does not affect the
       event masks that other clients may have specified for GLXDrawable since
       each  client rendering to GLXDrawable has a separate event mask for it.

       Currently,  only  one  GLX  event,  GLX_PBUFFER_CLOBBER_MASK,  can   be
       selected.  The  following  data  is  returned  to  the  client  when  a
       GLX_PBUFFER_CLOBBER_MASK event occurs:

       typdef struct {

           int event_type;             /* GLX_DAMAGED or GLX_SAVED */
           int draw_type;              /* GLX_WINDOW or GLX_PBUFFER */
           unsigned long serial;       /* # of last request processed by server */
           Bool send_event;            /* true if this came for SendEvent request */
           Display *display;           /* display the event was read from */
           GLXDrawable drawable;       /* i.d. of Drawable */
           unsigned int buffer_mask;   /* mask indicating affectedbuffers */
           int x, y;
           int width, height;
           int count;                  /* if nonzero, at least this many more */
       } GLXPbufferClobberEvent;









                GLX_FRONT_RIGHT_BUFFER_BIT   Front right color buffer
                GLX_BACK_LEFT_BUFFER_BIT     Back left color buffer
                GLX_BACK_RIGHT_BUFFER_BIT    Back right color buffer
                GLX_AUX_BUFFERS_BIT          Auxillary buffer
                GLX_DEPTH_BUFFER_BIT         Depth buffer
                GLX_STENCIL_BUFFER_BIT       Stencil buffer
                GLX_ACCUM_BUFFER_BIT         Accumulation buffer
                ------------------------------------------------------

       A single X server operation can cause several buffer clobber events  to
       be sent. (e.g., a single GLX pixel buffer may be damaged and cause mul-
       tiple buffer clobber events to be generated). Each event specifies  one
       region of the GLX drawable that was affected by the X Server operation.
       The buffer_mask field  indicates  which  color  buffers  and  ancillary
       buffers  were  affected.  All  the buffer clobber events generated by a
       single X server action are guaranteed to be  contiguous  in  the  event
       queue.  The  conditions  under  which  this  event is generated and the
       event_type varies, depending on the type of the GLX drawable.

       When the GLX_AUX_BUFFERS_BIT is set in buffer_mask, then aux_buffer  is
       set  to indicate which buffer was affected. If more than one aux buffer
       was affected, then additional events are generated as part of the  same
       contiguous  event  group.  Each  additional  event  will  have only the
       GLX_AUX_BUFFERS_BIT set in buffer_mask, and the aux_buffer  field  will
       be      set      appropriately.      For      nonstereo      drawables,
       GLX_FRONT_LEFT_BUFFER_BIT  and  GLX_BACK_LEFT_BUFFER_BIT  are  used  to
       specify the front and back color buffers.

       For  preserved  GLX  pixel  buffers,  a  buffer clobber event with type
       GLX_SAVED is generated whenever the contents of the GLX pixel buffer is
       moved out of offscreen memory. The event(s) describes which portions of
       the GLX pixel buffer were affected. Clients  who  receive  many  buffer
       clobber  events,  referring  to different save actions, should consider
       freeing the GLX pixel buffer resource in order to  prevent  the  system
       from thrashing due to insufficient resources.

       For  an  unpreserved  GLXPbuffer,  a  buffer  clobber  event, with type
       GLX_DAMAGED, is generated whenever a portion of the  GLX  pixel  buffer
       becomes invalid. The client may wish to regenerate the invalid portions
       of the GLX pixel buffer.

       For Windows, buffer clobber events, with type GLX_SAVED, occur whenever
       an  ancillary  buffer,  associated  with  the window, gets clobbered or
       moved out of offscreen memory. The event contains information  indicat-
       ing  which  color  buffers  and ancillary buffers-and which portions of
       those buffers-were affected.

NOTES

       glXSelectEvent is available only if the GLX version is 1.3 or  greater.

       If  the  GLX version is 1.1 or 1.0, the GL version must be 1.0.  If the
       GLX version is 1.2, then the GL version must be 1.1.  If the  GLX  ver-
                                                            GLXSELECTEVENT(3G)