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<HTML><BODY><PRE>     <STRONG>NAME</STRONG>	  <STRONG>glXChooseVisual</STRONG> - return a visual that matches specified	  attributes     <STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>	  XVisualInfo* <STRONG>glXChooseVisual</STRONG>(	Display	*<EM>dpy</EM>,					int <EM>screen</EM>,					int *<EM>attribList</EM>	)     <STRONG>PARAMETERS</STRONG>	  <EM>dpy</EM>	      Specifies	the connection to the X	server.	  <EM>screen</EM>      Specifies	the screen number.	  <EM>attribList</EM>  Specifies	a list of boolean attributes and		      integer attribute/value pairs.  The last		      attribute	must be	<STRONG>None</STRONG>.     <STRONG>DESCRIPTION</STRONG>	  <STRONG>glXChooseVisual</STRONG> 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 specified	  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, <STRONG>NULL</STRONG> is returned.  To free the	  data returned	by this	function, use <STRONG>XFree</STRONG>.	  All boolean GLX attributes default to	<STRONG>False</STRONG> except	  <STRONG>GLX_USE_GL</STRONG>, which defaults to	<STRONG>True</STRONG>.  All integer GLX	  attributes default to	zero.  Default specifications are	  superseded by	attributes included in <EM>attribList</EM>.  Boolean	  attributes included in <EM>attribList</EM> are	understood to be <STRONG>True</STRONG>.	  Integer attributes and enumerated type attributes are	  followed immediately by the corresponding desired or minimum	  value.  The list must	be terminated with <STRONG>None</STRONG>.	  The interpretations of the various GLX visual	attributes are	  as follows:	  <STRONG>GLX_USE_GL</STRONG>		Ignored.  Only visuals that can	be				rendered with GLX are considered.	  <STRONG>GLX_BUFFER_SIZE</STRONG>	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				<STRONG>GLX_RGBA</STRONG> is asserted.	  <STRONG>GLX_LEVEL</STRONG>		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.	  <STRONG>GLX_RGBA</STRONG>		If present, only TrueColor and				DirectColor visuals are	considered.				Otherwise, only	PseudoColor and				StaticColor visuals are	considered.	  <STRONG>GLX_DOUBLEBUFFER</STRONG>	If present, only double-buffered				visuals	are considered.	  Otherwise,				only single-buffered visuals are				considered.	  <STRONG>GLX_STEREO</STRONG>		If present, only stereo	visuals	are				considered.  Otherwise,	only				monoscopic visuals are considered.	  <STRONG>GLX_AUX_BUFFERS</STRONG>	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.	  <STRONG>GLX_RED_SIZE</STRONG>		Must be	followed by a nonnegative				minimum	size specification.  If	this				value is zero, the smallest available				red buffer is preferred.  Otherwise,				the largest available red buffer of at				least the minimum size is preferred.	  <STRONG>GLX_GREEN_SIZE</STRONG>	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.	  <STRONG>GLX_BLUE_SIZE</STRONG>		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.	  <STRONG>GLX_ALPHA_SIZE</STRONG>	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.	  <STRONG>GLX_DEPTH_SIZE</STRONG>	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.	  <STRONG>GLX_STENCIL_SIZE</STRONG>	Must be	followed by a nonnegative				integer	that indicates the desired				number of stencil bitplanes.  The				smallest stencil buffer	of at least				the specified size is preferred.  If				the desired value is zero, visuals				with no	stencil	buffer are preferred.	  <STRONG>GLX_ACCUM_RED_SIZE</STRONG>	Must be	followed by a nonnegative				minimum	size specification.  If	this				value is zero, visuals with no red				accumulation buffer are	preferred.				Otherwise, the largest possible	red				accumulation buffer of at least	the				minimum	size is	preferred.	  <STRONG>GLX_ACCUM_GREEN_SIZE</STRONG>	Must be	followed by a nonnegative				minimum	size specification.  If	this				value is zero, visuals with no green				accumulation buffer are	preferred.				Otherwise, the largest possible	green				accumulation buffer of at least	the				minimum	size is	preferred.	  <STRONG>GLX_ACCUM_BLUE_SIZE</STRONG>	Must be	followed by a nonnegative				minimum	size specification.  If	this				value is zero, visuals with no blue				accumulation buffer are	preferred.				Otherwise, the largest possible	blue				accumulation buffer of at least	the				minimum	size is	preferred.	  <STRONG>GLX_ACCUM_ALPHA_SIZE</STRONG>	Must be	followed by a nonnegative				minimum	size specification.  If	this				value is zero, visuals with no alpha				accumulation buffer are	preferred.				Otherwise, the largest possible	alpha				accumulation buffer of at least	the				minimum	size is	preferred.     <STRONG>EXAMPLES</STRONG>	  <EM>attribList</EM> =		      {<STRONG>GLX_RGBA</STRONG>, <STRONG>GLX_RED_SIZE</STRONG>, 4, <STRONG>GLX_GREEN_SIZE</STRONG>, 4,		      <STRONG>GLX_BLUE_SIZE</STRONG>, 4,	<STRONG>None</STRONG>};	  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.     <STRONG>NOTES</STRONG>	  <STRONG>XVisualInfo</STRONG> is defined in <EM>Xutil</EM>.<EM>h</EM>.  It is a structure	that	  includes <EM>visual</EM>, <EM>visualID</EM>, <EM>screen</EM>, and <EM>depth</EM> elements.	  <STRONG>glXChooseVisual</STRONG> is implemented as a client-side utility	  using	only <STRONG>XGetVisualInfo</STRONG> and	<STRONG>glXGetConfig</STRONG>.  Calls to	these	  two routines can be used to implement	selection algorithms	  other	than the generic one implemented by <STRONG>glXChooseVisual</STRONG>.	  GLX implementers are strongly	discouraged, but not	  proscribed, from changing the	selection algorithm used by	  <STRONG>glXChooseVisual</STRONG>.  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	<STRONG>GLX_BUFFER_SIZE</STRONG>	is one of the pixmap depths supported	  by the X server.     <STRONG>ERRORS</STRONG>	  <STRONG>NULL</STRONG> is returned if an undefined GLX attribute is	  encountered in <EM>attribList</EM>.     <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>	  <STRONG>glXCreateContext</STRONG>, <STRONG>glXGetConfig</STRONG></PRE></BODY></HTML>
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