glXChooseVisual man page on RedHat
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GLXCHOOSEVISUAL(3G) OpenGL Manual GLXCHOOSEVISUAL(3G)
NAME
glXChooseVisual - return a visual that matches specified attributes
C SPECIFICATION
XVisualInfo* glXChooseVisual(Display * dpy, int screen,
int * attribList);
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 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,
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specifications are superseded by attributes included in attribList.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 visuals 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 buffer 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 stencil 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 accumulation 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 accumulation 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 accumulation 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 accumulation 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 implementations 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()
COPYRIGHT
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
under the SGI Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 03/16/2013 GLXCHOOSEVISUAL(3G)
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