glXSelectEvent(3G)

NAME
     glXSelectEvent - select GLX events for a window or a GLX pixel buffer


C SPECIFICATION
     void glXSelectEvent( Display *dpy,
                          GLXDrawable drawable,
                          unsigned long event_mask )


PARAMETERS
     dpy         Specifies the connection to the X server.

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

     event_mask  Specifies the events to be returned for drawable.


DESCRIPTION
     glXSelectEvent sets the GLX event mask for a GLX pixel buffer or a
     window. Calling glXSelectEvent overrides any previous event mask that was
     set by the client for drawable. Note that it does not affect the event
     masks that other clients may have specified for drawable since each
     client rendering to drawable 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;

     The valid bit masks used in buffer_mask are:

               _____________________________________________________
               Bitmask                      Corresponding Buffer
               _____________________________________________________
               GLX_FRONT_LEFT_BUFFER_BIT    Front left color buffer
               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 multiple
     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 indicating 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 version is
     1.3, then the GL version must be 1.2.

ERRORS
     GLXBadDrawable is generated if drawable is not a valid window or a valid
     GLX pixel buffer.

ASSOCIATED GETS
     glXGetSelectedEvent


SEE ALSO
     glXCreatePbuffer