GLXCHOOSEVISUAL()														 GLXCHOOSEVISUAL()

NAME

       glXChooseVisual - return a visual that matches specified attributes

C SPECIFICATION

       XVisualInfo* glXChooseVisual( Display *dpy,
				     int screen,
				     int *attribList )

       delim $$

PARAMETERS

       dpy	   Specifies the connection to the X server.

       screen	   Specifies the screen number.

       attribList  Specifies a list of boolean attributes and integer attribute/value pairs.  The last attribute must be None.

DESCRIPTION

       glXChooseVisual	returns  a pointer to an XVisualInfo structure describing the visual that best meets a minimum specification.  The boolean
       GLX attributes of the visual that is returned will match the specified values, and the integer GLX attributes will meet or exceed the spec-
       ified  minimum  values.	 If all other attributes are equivalent, then TrueColor and PseudoColor visuals have priority over DirectColor and
       StaticColor visuals, respectively.  If no conforming visual exists, NULL is returned.  To free the data	returned  by  this  function,  use
       XFree.

       All  boolean  GLX  attributes  default  to  False  except  GLX_USE_GL, which defaults to True.  All integer GLX attributes default to zero.
       Default specifications are superseded by attributes included in attribList.  Boolean attributes included in attribList are understood to be
       True.   Integer attributes and enumerated type attributes are followed immediately by the corresponding desired or minimum value.  The list
       must be terminated with None.

       The interpretations of the various GLX visual attributes are as follows:

       GLX_USE_GL	     Ignored.  Only visuals that can be rendered with GLX are considered.

       GLX_BUFFER_SIZE	     Must be followed by a nonnegative integer that indicates the desired color index buffer  size.   The  smallest  index
			     buffer of at least the specified size is preferred.  Ignored if GLX_RGBA is asserted.

       GLX_LEVEL	     Must be followed by an integer buffer-level specification.  This specification is honored exactly.  Buffer level zero
			     corresponds to the main frame buffer of the display.  Buffer level one is the first overlay frame buffer,	level  two
			     the second overlay frame buffer, and so on.  Negative buffer levels correspond to underlay frame buffers.

       GLX_RGBA 	     If present, only TrueColor and DirectColor visuals are considered.  Otherwise, only PseudoColor and StaticColor visu-
			     als are considered.

       GLX_DOUBLEBUFFER      If present, only double-buffered visuals are considered.	Otherwise, only single-buffered visuals are considered.

       GLX_STEREO	     If present, only stereo visuals are considered.  Otherwise, only monoscopic visuals are considered.

       GLX_AUX_BUFFERS	     Must be followed by a nonnegative integer that indicates the desired number of auxiliary buffers.	Visuals with the
			     smallest number of auxiliary buffers that meets or exceeds the specified number are preferred.

       GLX_RED_SIZE	     Must be followed by a nonnegative minimum size specification.  If this value is zero, the smallest available red buf-
			     fer is preferred.	Otherwise, the largest available red buffer of at least the minimum size is preferred.

       GLX_GREEN_SIZE	     Must be followed by a nonnegative minimum size specification.  If this value is zero, the	smallest  available  green
			     buffer is preferred.  Otherwise, the largest available green buffer of at least the minimum size is preferred.

       GLX_BLUE_SIZE	     Must  be  followed  by  a nonnegative minimum size specification.	If this value is zero, the smallest available blue
			     buffer is preferred.  Otherwise, the largest available blue buffer of at least the minimum size is preferred.

       GLX_ALPHA_SIZE	     Must be followed by a nonnegative minimum size specification.  If this value is zero, the	smallest  available  alpha
			     buffer is preferred.  Otherwise, the largest available alpha buffer of at least the minimum size is preferred.

       GLX_DEPTH_SIZE	     Must  be  followed  by a nonnegative minimum size specification.  If this value is zero, visuals with no depth buffer
			     are preferred.  Otherwise, the largest available depth buffer of at least the minimum size is preferred.

       GLX_STENCIL_SIZE      Must be followed by a nonnegative integer that indicates the desired number of stencil bitplanes.	The smallest sten-
			     cil buffer of at least the specified size is preferred.  If the desired value is zero, visuals with no stencil buffer
			     are preferred.

       GLX_ACCUM_RED_SIZE    Must be followed by a nonnegative minimum size specification.  If this value is zero, visuals with no  red  accumula-
			     tion  buffer  are preferred.  Otherwise, the largest possible red accumulation buffer of at least the minimum size is
			     preferred.

       GLX_ACCUM_GREEN_SIZE  Must be followed by a nonnegative minimum size specification.  If this value is zero, visuals with no green accumula-
			     tion buffer are preferred.  Otherwise, the largest possible green accumulation buffer of at least the minimum size is
			     preferred.

       GLX_ACCUM_BLUE_SIZE   Must be followed by a nonnegative minimum size specification.  If this value is zero, visuals with no blue  accumula-
			     tion  buffer are preferred.  Otherwise, the largest possible blue accumulation buffer of at least the minimum size is
			     preferred.

       GLX_ACCUM_ALPHA_SIZE  Must be followed by a nonnegative minimum size specification.  If this value is zero, visuals with no alpha accumula-
			     tion buffer are preferred.  Otherwise, the largest possible alpha accumulation buffer of at least the minimum size is
			     preferred.

EXAMPLES

       attribList =
		   {GLX_RGBA, GLX_RED_SIZE, 4, GLX_GREEN_SIZE, 4, GLX_BLUE_SIZE, 4, None};

       Specifies a single-buffered RGB visual in the normal frame buffer, not an overlay or underlay buffer.   The  returned  visual  supports	at
       least  four  bits  each of red, green, and blue, and possibly no bits of alpha.	It does not support color index mode, double-buffering, or
       stereo display.	It may or may not have one or more auxiliary color buffers, a depth buffer, a stencil buffer, or an accumulation buffer.

NOTES

       XVisualInfo is defined in Xutil.h.  It is a structure that includes visual, visualID, screen, and depth elements.

       glXChooseVisual is implemented as a client-side utility using only XGetVisualInfo and glXGetConfig.  Calls to these  two  routines  can	be
       used to implement selection algorithms other than the generic one implemented by glXChooseVisual.

       GLX  implementers  are strongly discouraged, but not proscribed, from changing the selection algorithm used by glXChooseVisual.	Therefore,
       selections may change from release to release of the client-side library.

       There is no direct filter for picking only visuals that support GLXPixmaps.  GLXPixmaps are supported for visuals whose GLX_BUFFER_SIZE	is
       one of the pixmap depths supported by the X server.

ERRORS

       NULL is returned if an undefined GLX attribute is encountered in attribList.

SEE ALSO

       glXCreateContext, glXGetConfig

																 GLXCHOOSEVISUAL()