GLXgetconfig(3G)

NAME
     GLXgetconfig - Get configuration information for GL rendering into an X
     window

SYNOPSIS
     #include  <gl/glws.h>

     typedef struct _GLXconfig {   /* from <gl/glws.h> */
         int   buffer;
         int   mode;
         int   arg;
     } GLXconfig;

     GLXconfig *
     GLXgetconfig(xDisplay, xScreenNo, sdesc)
     Display*  xDisplay;
     int       screenNo;
     GLXconfig*     sdesc;


DESCRIPTION
     GLXgetconfig takes the display, screen, and configuration information and
     returns the data needed to create and render GL into an X window.

     The "sdesc" input parameter is a null terminated array of "GLXconfig"
     triples, describing the configuration needed for GL rendering.

     The return value is a complete description of the actual configuration
     available.  This is useful to check what configuration was available, but
     it is also needed as an argument to GLXlink(3G).  It can be freed with
     free(3) when it is no longer needed.

   GLXconfig
     Values for GLXconfig.buffer specify which buffer the configuration is
     affecting.  Possible values are GLX_NORMAL, GLX_POPUP, GLX_OVERLAY and
     GLX_UNDERLAY.

     Values for GLXconfig.mode specify which attributes of the buffer are
     being configured.  The interpretation of GLXconfig.arg is dependent on
     the "mode" word.

     GLX_DOUBLE   In the input configuration single buffer is assumed unless
                  GLX_DOUBLE, True is specified.  On output, if double
                  buffering is not available, the "arg" field for GLX_DOUBLE
                  will be false.

     GLX_RGB      In the input configuration color index is assumed unless
                  "GLX_RGB, True" is specified.  On output, if RGB is not
                  available, the "arg" field for GLX_RGB will be false.

     GLX_BUFSIZE  If not specified, or the "arg" is GLX_NOCONFIG, then the
                  largest available number will be allocated.  On return the
                  "arg" field will contain the number allocated.

     GLX_RGBSIZE  The minimum of the requested size and the largest available
                  size will be returned.  If not specified, or the "arg" is
                  GLX_NOCONFIG, then the largest available size will be
                  returned.

     GLX_STENSIZE
     GLX_ACSIZE
     GLX_ZSIZE    If not specified none will be allocated.  If the "arg" is
                  GLX_NOCONFIG then the largest available number will be
                  allocated.  On return the "arg" field will contain the
                  number allocated.

     GLX_VISUAL   Ignored on input, in the output it contains the correct
                  visual id for the window to be created for that buffer.

     GLX_COLORMAP Ignored on input, in the output the value is the colormap
                  that traditional "winopen()" style GL windows will use for
                  that buffer.  This is for information only; colors in this
                  colormap may be queried, and this colormap id may be used in
                  creating windows.  But it's forbidden to write into this
                  colormap using XStoreColor(s).  If a client wants to do
                  XStoreColor(s), it needs to create its own colormap.  But
                  even if a client does not do XStoreColor(s), it is free to
                  create windows with a colormap other than the one returned
                  in GLX_COLORMAP.

     GLX_WINDOW   Ignored on input, in the output, for a supported buffer
                  request, a placeholder with value GLX_NONE.  Before the
                  output buffer is passed to GLXlink(3G), the value should be
                  replaced with the window which was created.

     GLX_MSSAMPLE On input, the "arg" field should contain the requested
                  number of multisample samples to be stored at each
                  framebuffer pixel location. On output, the "arg" will
                  contain the allocated number of samples. If not specified,
                  no samples will be allocated.

     GLX_MSZSIZE  On input, the "arg" field should contain the requested
                  number of bits per depth component desired in the
                  multisample buffer.  On output, the "arg" will contain the
                  allocated number of bits.  If not specified, no bits will be
                  allocated.

     GLX_MSSSIZE  On input, the "arg" field should contain the requested
                  number of bits per stencil field desired in the multisample
                  buffer.  On output, the "arg" will contain the allocated
                  number of bits.  If not specified, no bits will be
                  allocated.
     GLX_STEREOBUF
                  Monoscopic buffering is assumed unless GLX_STEREOBUF is
                  specified.  On input, the "arg" field is ignored.  On
                  output, the "arg" field will be true if stereoscopic
                  buffering is available, and false otherwise.

ERRORS
     A return of 0 means that no visual was found which matched the request.

BUGS
SEE ALSO
     GLXwinset(3G), GLXlink(3G), GLXunlink(3G), ~4Dgifts/examples/GLX