glutInitDisplayString(3GLUT) GLUT glutInitDisplayString(3GLUT)NAMEglutInitDisplayString - sets the initial display mode via a string.
SYNTAX
#include <GLUT/glut.h>
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 precedence.
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 comparators) 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 hexadecimal values (leading 0x) are accepted.
The valid comparators are:
= Equal.
!= Not equal.
< Less than and preferring larger difference (the least is best).
> Greater 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
precision or depth buffer precision where the maximum precision
is generally preferred. Contrast with the tilde (~) compara‐
tor.
~ Greater than or equal but preferring less instead of more.
This comparator is useful for allocating resources such as
stencil bits or auxiliary color buffers where you would rather
not over allocate.
When the comparator and numeric value are not specified, each
capability name has a different default (one default is to
require a a comparator 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 ">=8" 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
">=8" for red, green, and blue capabilities, and "~0" for the
alpha capability.
auxbufs Number of auxiliary color buffers. Default is "~1".
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 conformant. Default is
"=1".
depth Number of bits of precision in the depth buffer. Default is
">=12".
double Boolean indicating if the color buffer is double buffered.
Default 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".
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 capabilities, 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
appropriate for medical imaging applications. Do not expect
many machines to support extended precision luminance display
modes.
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‐
parator 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.
stencil Number of bits in the stencil buffer. Default is "~1".
single Boolean indicate the color buffer is single buffered. Double
buffer capability "=0".
stereo Boolean indicating the color buffer is supports OpenGL-style
stereo. Default is "=1".
samples Indicates the number of samples to use based on GLX's SGIS_mul‐
tisample extension (for antialiasing). Default is "<=4". This
default means that a GLUT application can request multisampling
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 num‐
ber. win32pfd requires a comparator and numeric value.
xvisual Only recognized on GLUT implementations for the X Window Sys‐
tem, this capability name matches the X visual ID by number.
xvisual requires a comparator and numeric value.
xstaticgray
Only recognized 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 recognized 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 recognized 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 recognized 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 recognized 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 recognized 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".
Unspecified 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 example 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 preci‐
sion but preferring more, multisampling if available, and at least 2
bits of stencil (favoring less stencil to more as long as 2 bits are
available).
SEE ALSO
glutInit, glutCreateWindow, glutInitDisplayMode
AUTHOR
Mark J. Kilgard (mjk@nvidia.com)
GLUT 3.7 glutInitDisplayString(3GLUT)
