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glutInitDisplayString(3GLUT)	     GLUT	  glutInitDisplayString(3GLUT)

NAME
       glutInitDisplayString - sets the	initial	display	mode via a string.

SYNTAX
       void glutInitDisplayString(char *string);

ARGUMENTS
       string	 Display mode description string, see below.

DESCRIPTION
       The  initial display mode description string is used when creating top-
       level windows, subwindows, and overlays to determine the	OpenGL display
       mode for	the to-be-created window or overlay.

       The  string is a	list of	zero or	more capability	descriptions separated
       by spaces and tabs.  Each capability description	is a  capability  name
       that  is	 optionally followed by	a comparator and a numeric value.  For
       example,	"double" and "depth>=12" are both valid	criteria.

       The capability descriptions are translated into a set of	criteria  used
       to select the appropriate frame buffer configuration.

       The  criteria  are  matched in strict left to right order of precdence.
       That is,	the first specified criteria (leftmost)	takes precedence  over
       the  later  criteria  for  non-exact criteria (greater than, less than,
       etc. comparators).  Exact criteria (equal, not equal  compartors)  must
       match exactly so	precedence is not relevant.

       The  numeric  value  is an integer that is parsed according to ANSI C's
       strtol(str, strptr, 0) behavior.	 This means that decimal, octal	(lead-
       ing 0), and hexidecimal values (leading 0x) are accepeted.

       The valid compartors are:

       =       Equal.

       !=      Not equal.

       <       Less than and preferring	larger difference (the least is	best).

       >       Greeater	 than  and  preferring larger differences (the most is
	       best).

       <=      Less than or equal and preferring larger	difference (the	 least
	       is best).

       >=      Greater	than  or  equal	 and  preferring more instead of less.
	       This comparator is useful for allocating	resources  like	 color
	       precsion	 or  depth buffer precision where the maximum precison
	       is generally preferred.	Contrast with the tilde	(~) comprator.

       ~       Greater than or equal but  preferring  less  instead  of	 more.
	       This compartor is useful	for allocating resources such as sten-
	       cil bits	or auxillary color buffers where you would rather  not
	       over allocate.

	       When  the  compartor  and numeric value are not specified, each
	       capability name has a different default (one default is to  re-
	       quire a a compartor and numeric value).

       The valid capability names are:

       alpha   Alpha color buffer precision in bits.  Default is ">=1".

       acca    Red,  green,  blue,  and	alpha accumulation buffer precision in
	       bits.  Default is ">=1" for red,	green, blue, and  alpha	 capa-
	       bilities.

       acc     Red, green, and green accumulation buffer precision in bits and
	       zero bits of alpha accumulation buffer precision.   Default  is
	       ">=1"  for  red,	green, and blue	capabilities, and "~0" for the
	       alpha capability.

       blue    Blue color buffer precision in bits.  Default is	">=1".

       buffer  Number of bits in the color index  color	 buffer.   Default  is
	       ">=1".

       conformant
	       Boolean indicating if the frame buffer configuration is confor-
	       mant  or	 not.	Conformance  information  is  based  on	 GLX's
	       EXT_visual_rating  extension if supported.  If the extension is
	       not supported, all visuals are assumed conformat.   Default  is
	       "=1".

       depth   Number  of  bits	 of  precsion in the depth buffer.  Default is
	       ">=12".

       double  Boolean indicating if the color buffer is double	buffered.  De-
	       fault is	"=1".

       green   Green color buffer precision in bits.  Default is ">=1".

       index   Boolean	if  the	 color	model  is color	index or not.  True is
	       color index.  Default is	">=1".

       num     A special capability name indicating where the value represents
	       the  Nth	 frame	buffer	configuration matching the description
	       string.	When not specified, glutInitDisplayString also returns
	       the  first  (best matching) configuration.  num requires	a com-
	       partor and numeric value.

       red     Red color buffer	precision in bits.  Default is ">=1".

       rgba    Number of bits of red, green, blue, and alpha in	the RGBA color
	       buffer.	Default	is ">=1" for red, green, blue, and alpha capa-
	       bilities, and "=1" for the RGBA color model capability.

       rgb     Number of bits of red, green, and blue in the RGBA color	buffer
	       and  zero  bits	of  alpha  color buffer	precision.  Default is
	       ">=1" for the red, green, and blue capabilities,	and  "~0"  for
	       alpha capability, and "=1" for the RGBA color model capability.

       luminance
	       Number  of bits of red in the RGBA and zero bits	of green, blue
	       (alpha not specified) of	color buffer  precision.   Default  is
	       ">=1"  for the red capabilitis, and "=0"	for the	green and blue
	       capabilities, and "=1" for the  RGBA  color  model  capability,
	       and,  for X11, "=1" for the StaticGray ("xstaticgray") capabil-
	       ity.

	       SGI InfiniteReality  (and  other	 future	 machines)  support  a
	       16-bit  luminance  (single channel) display mode	(an additional
	       16-bit alpha channel can	also be	requested).  The  red  channel
	       maps  to	 gray scale and	green and blue channels	are not	avail-
	       able.  A	16-bit precision luminance display mode	is  often  ap-
	       propriate for medical imaging applications.  Do not expect many
	       machines	to support extended precision luminance	display	modes.

       stencil Number of bits in the stencil buffer.

       single  Boolean indicate	the color buffer is single  buffered.	Double
	       buffer capability "=1".

       stereo  Boolean	indicating  the	 color buffer is supports OpenGL-style
	       stereo.	Default	is "=1".

       samples Indicates the number of multisamples  to	 use  based  on	 GLX's
	       SGIS_multisample	 extension  (for  antialiasing).   Default  is
	       "<=4".  This default means that a GLUT application can  request
	       multipsampling if available by simply specifying	"samples".

       slow    Boolean indicating if the frame buffer configuration is slow or
	       not.  Slowness information is based on GLX's  EXT_visual_rating
	       extension if supported.	If the extension is not	supported, all
	       visuals are assumed fast.  Note that  slowness  is  a  relative
	       designation  relative  to  other	 frame	buffer	configurations
	       available.  The intent of the slow capability is	to  help  pro-
	       grams  avoid  frame  buffer configurations that are slower (but
	       perhaps higher precision) for the current machine.  Default  is
	       ">=0".	This default means that	slow visuals are used in pref-
	       erence to fast visuals, but fast	visuals	will still be allowed.

       win32pfd
	       Only recognized on GLUT implementations for Win32,  this	 capa-
	       bility name matches the Win32 Pixel Format Descriptor by	numer.
	       win32pfd	requires a compartor and numeric value.

       xvisual Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  this  capability  name matches the	X visual ID by number.
	       xvisual requires	a compartor and	numeric	value.

       xstaticgray
	       Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  boolean  indicating if the	frame buffer configuration's X
	       visual is of type StaticGray.  Default is "=1".

       xgrayscale
	       Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  boolean  indicating if the	frame buffer configuration's X
	       visual is of type GrayScale.  Default is	"=1".

       xstaticcolor
	       Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  boolean  indicating if the	frame buffer configuration's X
	       visual is of type StaticColor.  Default is "=1".

       xpseudocolor
	       Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  boolean  indicating if the	frame buffer configuration's X
	       visual is of type PsuedoColor.  Default is "=1".

       xtruecolor
	       Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  boolean  indicating if the	frame buffer configuration's X
	       visual is of type TrueColor.  Default is	"=1".

       xdirectcolor
	       Only recongized on GLUT implementations for the X  Window  Sys-
	       tem,  boolean  indicating if the	frame buffer configuration's X
	       visual is of type DirectColor.  Default is "=1".

       Unspecifed capability descriptions will result in unspecified  criteria
       being generated.	 These unspecified criteria help glutInitDisplayString
       behave sensibly with terse display mode description strings.

EXAMPLE
       Here is an examples using glutInitDisplayString:

	 glutInitDisplayString("stencil~2 rgb double depth>=16 samples");

       The above call requests a window	with an	RGBA color model (but request-
       ing no bits of alpha), a	depth buffer with at least 16 bits of precsion
       but preferring more, mutlisampling if available,	and at least 2 bits of
       stencil	(favoring  less	 stencil  to more as long as 2 bits are	avail-
       able).

SEE ALSO
       glutInit, glutCreateWindow, glutInitDisplayMode

AUTHOR
       Mark J. Kilgard (mjk@nvidia.com)

GLUT				      3.7	  glutInitDisplayString(3GLUT)

NAME | SYNTAX | ARGUMENTS | DESCRIPTION | EXAMPLE | SEE ALSO | AUTHOR

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