Ygl Version 4.1 Description
Ygl is distributed in terms of the GNU LIBRARY
GENERAL PUBLIC LICENSE. Please see the file
LICENSE for further details. You may not
distribute this project without this file (ReadMe.html) and the
LICENSE file included.
Here you can read the Changes history and
the Ygl FAQ.
Description
Ygl emulates SGI's GL routines
under X11. It compiles fine under AIX >3.2, HP-UX >7.0, Linux
with XFree/Xorg, SunOS, ConvexOS, Mac A/UX, Mac OS/X and many others,
but needs an ANSI-C compiler (gcc is ok). It was written for two reasons:
- On our RS/6000 GT4 hardware, 2D Ygl is up to
twenty times faster (circf()) than GL (strange, isn't it?...)
- 2D (and 3D using OpenGL) graphics runs on non GL hardware and
even on remote X-Servers.
Included are most of the two-dimensional graphics routines, the queue
device routines, the query routines, doublebuffering, RGB mode with
dithering, window attribute routines, FORTRAN bindings and more (see
below).
3D stuff was added with version 4.0 using OpenGL calls.
Since Version 2.8, all Ygl functions do have a
FORTRAN interface. The
FORTRAN versions of all functions have an underscore appended, so the
FORTRAN compiler must append a '_' to all function names.
f2c does this,
xlf
(under AIX 3.2) requires the option -qextname. See
smile_f77.f for an example program. Set
FortranBindings to 0 in Imakefile or change
Makefile.std if you don't want these bindings. FORTRAN bindings are
not tested because I have no programs.f to test. If you find bugs,
feel free to report them to me.
You can always find the latest version of Ygl in
the directory
ftp.thp.Uni-Duisburg.de/pub/source/X11/.
Note that perl,
python
and tcl bindings
for Ygl are available
here
thanks to Prabhu Ramachandran.
Details
Environment variables:
Several environment variables are referenced in the library to control
the behavior of Ygl:
- The environment variable YGL_PRIVATECOLORMAP or
YGL_PCM can be set to 1 to force
Ygl to use a private colormap. While GL
always uses a private colormap, Ygl uses
the global map by default to avoid technicolor effects on
X-Servers not capable of more than one colormap at a
time. Note that you can only redefine the color of
already drawn objects when you use a private colormap.
- The environment variable YGL_FLUSHTIME or YGL_FT
(default value: 0.1) can be used to adjust the time in seconds
between flushes of the graphics pipeline. It can be set to 0
to disable the automatic update via interval timer. Setting
YGL_FLUSHTIME to -1 will put the X-Server into synchronous
mode (see XSynchronize).
This mode seems to be veeeryyy slooow, but is good for
debugging...
- The environment variable YGL_BACKINGSTORE or
YGL_BS can be set to 1 to enable BackingStore support
for all Ygl windows. With BackingStore,
the X-Server remembers the contents of a window when it gets
obscured or iconified. You must start your X-Server with the
option "-bs" ("+bs" on some systems) to use this feature.
- The environment variables YGL_CMAPVISUAL or
YGL_CV and YGL_RGBVISUAL or YGL_RV
control the selection of visuals for cmapmode and RGBmode. Set
these variables to the visual id of the desired visual as
returned by xdpyinfo (both hex and decimal is ok). Setting one
of these variables to -1 forces Ygl to use
the default visual of the screen instead of the best visual.
- The environment variable YGL_SINGLEGC or YGL_GC
can be set to 1 to force Ygl to use a
single graphics context for colormap windows. Per default
Ygl uses one GC for each color, i.e. 256
GCs for a 8 bit colormap window, because this speeds up
drawing with many color changes by a factor of 2 or so on many
systems. Using a single GC may be faster if you use many
mapcolor calls as in colormap animation. Note that if
the used colormap visual has more than 256 colors YGL_GC
defaults to 1.
- The environment variable YGL_PARENTWID or
YGL_PWID controls the parent window of
Ygl. Per default the root window of the
default screen of the given display is the parent window of
windows opened with winopen(). Set this variable to the window
id of the desired window as returned by xwininfo (both hex and
decimal is ok).
- The environment variable
YGL_DITHERSIZE or YGL_DSZ controls dithering in
RGB mode.With this variable you can specify the size of the
dither matrix. The default value is 4, leading to a 4x4 dither
matrix. Valid values range from 0 to 6. On a normal 8 bit
TrueColor visual ({3,3,2} bits {red,green,blue}) you obtain
113x113x49 = 625681 different "colors" with YGL_DSZ=4, leading
to an effective screen depth of approx. 19 bits. The other
values and the effective screendepth are:
| 8 bit (3-3-2) | 12 bit (4-4-4) | 16 bit (6-5-5)
YGL_DSZ| # colors (bits) | # colors (bits) | # colors (bits)
-------------------------------------------------------------
0,1 | 256 ( 8 ) | 4096 (12 ) | 65536 (16 )
2 | 10933 (13.4) | 226981 (17.8) | 3953125 (21.9)
3 | 114688 (16.8) | 2515456 (21.3) | 44531200 (25.4)
4 | 625681 (19.3) | 13997521 (23.7) | 249232081 (27.9)
5 | 2354176 (21.2) | 53157376 (25.7) | 949029376 (29.8)
6 | 6976981 (22.7) |158340421 (27.2) |2831006341 (31.4)
Note that dithering costs speed. You may set YGL_DSZ=0
to disable dithering. If you are lucky and have a 24 bit
TrueColor visual, YGL_DSZ is automatically set to zero.
Doublebuffering:
Ygl supports doublebuffering via the XServer
extensions "DOUBLE-BUFFER" (new in X11R6.1) and "Multi-Buffering". The
related routines are doublebuffer(), swapbuffer()
and singlebuffer().
Notes:
- OpenGL:
-
You can use the routine gsync() to wait for the next
vertical retrace. If you use doublebuffering, it might help to set
the environment variable __GL_SYNC_TO_VBLANK to 1 to swap
buffers at a vertical retrace.
- X11R6.1:
-
If you have X11R6.1 or later, set DoubleBuffer to 1 in
Imakefile.
- AIX < 3.2.5:
-
The extension "Multi-Buffering" is new in X11R5 and is included in
the lpp X11dev.src under AIX. To use doublebuffering you have to
link the "Multi-Buffering" extension into your X-Server (under AIX,
see /usr/lpp/X11/Xamples/README, "Linking the Sample Extensions
into the Server").
- AIX >= 3.2.5:
-
You don't need to recompile the X-Server anymore to use
doublebuffering under AIX 3.2.5 (AIXWindows 1.2.3). You simply have
to add the option "-x mbx" to the X-Servers command line on
startup.
- AIX >= 4.1:
-
You need the LPP X11.adt.ext to compile Ygl
with doublebuffering enabled.
RGB mode:
Ygl can run in a per window RGB mode, if the
X-Server has a TrueColor or DirectColor
visual. Ygl will always select the appropiate
visual for the desired mode, independent of the default visual, i.e.:
Colormap mode <-> PseudoColor, StaticColor,
GrayScale, StaticGray,
TrueColor or DirectColor visual
RGB mode <-> TrueColor or DirectColor visual
A RGB mode window is a child of the initially created colormap mode
window. Ygl uses the property
WM_COLORMAP_WINDOWS to tell the window manager, which
colormaps are to be installed. To toggle the colormaps when a RGB
window is subwindow of a colormap window, use the window manager
function f.colormap in twm
or f.next_cmap in mwm.
Ygl will automatically dither all output if the
X-Server doesn't support 24 bits. See the section
environment variables for details.
Multiple Expose events (REDRAW) in qread:
Ygl ignores all Expose events that have
e.xexpose.count != 0 (see
XExposeEvent(3X11)) AND all
Expose events when another Expose event for the same window is in the
Event queue. This procedure minimizes unnessesary
redraws. Nevertheless, a REDRAW event is generated when a window is
moved even when the contents of the window does not have to be
redrawn. This is to be compatible with SGI's GL, where no extra event
for window moves exist :-(
Automatic flushing of the graphics pipeline:
The process virtual interval timer (see
setitimer(3))
is used to flush the graphics pipeline every 0.1 seconds. This
interval is adjustable (see above). The system functions sleep() and
usleep() are covered by the library to flush the pipeline, too. This
had to be done because the GL hardware flushes the pipeline
automatically on every vertical retrace and has no command to
flush.
Note that sleep() and usleep() always return 0.
You can use "sleep(0)" to flush the graphics pipeline explicitly.
If you have problems with sleep() and usleep(), undefine COVERSLEEP in
header.h.
Supported routines
Finally a list of supported GL routines is included. For a detailed
description of the routines see the GL manuals in the Info-Explorer
(under AIX) or click at the command below.
Window related routines:
minsize,
maxsize,
prefsize,
prefposition,
stepunit,
keepaspect,
winopen,
winclose,
gconfig,
gexit,
winset,
winget,
getsize,
getorigin,
getXdpy,
getXwid,
getbutton,
getvaluator,
winmove,
winposition,
ginit,
winpop,
winpush,
swinopen,
winconstraints,
noport,
winX.
Note:
The routine winX(Display *dpy, Window win) will
ignore the first argument dpy. Ygl
always uses the XServer specified in the environment variable DISPLAY.
Color related routines:
RGBmode,
RGBcolor,
cmode,
color,
mapcolor,
getplanes,
getmcolor,
getmcolors,
getcolor,
gRGBcolor,
c3s, c3i, c3f,
cpack.
Device related routines:
qdevice,
unqdevice,
qreset,
qtest,
qread,
qenter,
tie.
Notes:
- Currently supported devices are:
REDRAW, KEYBD, INPUTCHANGE, LEFTMOUSE, MIDDLEMOUSE, RIGHTMOUSE
(MENUBUTTON), MOUSEX, MOUSEY, WINQUIT, and all individual keys as
F1KEY, ESCKEY, UPARROWKEY, and so on.
- qenter does only support the REDRAW device.
Menu routines:
defpup,
newpup,
addtopup,
dopup,
freepup,
setpup.
Note:
The routines addpup() and defpup()
accept an additional modifier '%M'. If you define a submenu anchor
with '%M' instead of '%m', Ygl calls the function
defined with '%F' with the two arguments menu-return and
submenu-return, i.e.:
int callback(Int32 m, Int32 s) {
sleep(s);
switch(m) {
case 1: explode(); break;
case 2: implode(); break;
}
return(m << 8 + s);
}
main() {
...
sub = defpup("Seconds%t|1|2|3|4|5");
menu = defpup("Menu%t%F|Explode%M|Implode%M", callback, sub, sub);
...
}
See examples/popup.c for details.
Font routines:
loadXfont,
font,
strwidth,
getheight,
getdescender,
getfont,
getfontencoding.
Doublebuffer routines:
singlebuffer,
doublebuffer,
swapbuffers,
frontbuffer,
backbuffer.
Misc routines:
gflush,
gsync,
gversion,
gversion,
lrectread,
lrectwrite,
rectcopy,
readsource,
rectread,
rectwrite,
readpixels,
writepixels,
readRGB,
writeRGB,
linewidth,
getlwidth,
deflinestyle,
setlinestyle,
getlstyle,
lsrepeat,
getlsrepeat,
logicop,
getcpos,
getdisplaymode,
getgdesc,
setbell,
ringbell.
Coordinate transformation routines:
viewport,
getviewport,
reshapeviewport,
ortho2,
getmatrix.
Drawing routines:
pnt2s, pnt2i, pnt2,
move2s, move2i, move2,
draw2s, draw2i, draw2,
rmv2s, rmv2i, rmv2,
rdr2s, rdr2i, rdr2,
arcs, arci, arc,
arcfs, arcfi, arcf,
circs, circi, circ,
circfs, circfi, circf,
rects, recti, rect,
rectfs, rectfi, rectf,
sboxs, sboxi, sbox,
sboxfs, sboxfi, sboxf,
pmv2s, pmv2i, pmv2,
rpmv2s, rpmv2i, rpmv2,
pdr2s, pdr2i, pdr2,
rpdr2s, rpdr2i, rpdr2,
poly2s, poly2i, poly2,
polf2s, polf2i, polf2,
bgnpoint, endpoint,
bgnline, endline,
bgnclosedline, endclosedline,
bgnpolygon, endpolygon,
v2s, v2i, v2f, v2d,
cmov2s, cmov2i, cmov2,
clear,
charstr,
pclos,
concave.
Note:
It's not possible to change drawing attributes (color, ...)
in the middle of a vertex pipeline in Ygl.
This affects the routines
{bgn|end}{point|line|closedline|polygon}() and
pdr(), rpdr().
3D routines
Drawing:
c4s, c4i, c4f,
cmovs, cmovi, cmov,
pnts, pnti, pnt,
moves, movei, move,
draws, drawi, draw,
rmvs, rmvi, rmv,
rdrs, rdri, rdr,
pmvs, pmvi, pmv,
rpmvs, rpmvi, rpmv,
pdrs, pdri, pdr,
rpdrs, rpdri, rpdr,
polys, polyi, poly,
polfs, polfi, polf,
v3s, v3i, v3f, v3d,
v4s, v4i, v4f, v4d,
swaptmesh.
Coordinate Systems:
ortho,
lookat,
window,
perspective,
polarview,
rot,
rotate,
scale,
translate,
loadmatrix,
multmatrix,
pushmatrix,
popmatrix,
getmmode,
mmode.
Polygon specs:
shademodel,
n3f,
normal,
backface,
frontface.
z-Buffer:
zbuffer,
zclear,
zdraw,
zfunction,
czclear,
depthcue,
lRGBrange,
lsetdepth,
lshaderange.
Display lists:
genobj,
isobj,
makeobj,
getopenobj,
closeobj,
callobj,
delobj.
Misc:
lmbind,
lmcolor,
lmdef,
RGBwritemask,
pushattributes,
popattributes,
scrmask.
NOPs:
drawmode,
iconsize,
overlay,
fullscrn,
endfullscrn.
Routines not in SGI's GL:
The following routines are added to standard GL:
Acknowledgements
The author would like to thank
Michael Staats (michael(AT)thp.Uni-Duisburg.DE) and
Ralf Meyer (ralf(AT)thp.Uni-Duisburg.DE) for some hints and tips.
GL is a registered trademark of
Silicon Graphics, Inc.