glutInitDisplayString (3xglut)
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.
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.
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".
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.
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
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)