IGL is an Open Source drop-in replacement for IrisGL using OpenGL under X11. It
implements about 450 functions of the original IrisGL library from SGI, and has
stubs for about 80 more (mostly legacy stuff, with the notable exception of
multisampling, feedback, and ilbuffer, which are all unimplemented).

It also supports a decent subset of functions from libfm, the SGI font manager.

As a side effect, you also get networking capabilities beyond those SGI offered
with its dgl approach, since that only ran on SGI systems.


IGL was originally written by Matevz Bradac as an IrisGL to OpenGL wrapper for
Windows and X11. I used his work as a basis for my work, abandoning the Windows
support on the way, as it wasn't needed for my goals. However, I retained and
maintained the PLATFORM_X11 markers, such that any interested party should be
able to resurrect Windows support if needed.

See his original readme file attached at the end of this file. I also kept the
original docs directory, so you might read that for further information.

Current version is 0.4.2.


IGL was tested on SGI hardware with as much software using IrisGL as I could
get my hands on, using IGL as a drop-in replacement for the original IrisGL
and a xubuntu linux system as display.

Since this approach is still using SGI's original OpenGL libraries, it is
unfortunately limited to a rather old version of OpenGL, version 1.2. It might
not run on some of the original SGI hardware, since older SGI graphics hardware
is only supporting OpenGL 1.1, while igl makes use of 1.2 features.
(Yes, I know, it's really ancient. OpenGL 1.2 was released in another century!)

As a side note, IrisGL was also available on AIX system from IBM. However, as
I don't have access neither to hardware nor to software supporting this, I
can't make any statement as to whether IGL may work with that or not, although
some of the AIX extensions to GL are implemented,

Nonetheless, IGL also compiles and runs on todays linux systems, as long as it
is compiled for 32 bit (see below), and X and OpenGl is available.


Compiling:
==========
I guess IrisGL was specified at times where 64 bit systems weren't fathomable.
Its data type usage restricts it to 32 bit, hence you need to install a
compiler capable of producing 32 bit binaries. See the tutorials available for
this on the net, or just install a 32 bit system somewhere.
Don't even think about a 64 bit version. AFAIK even SGI never provided one.

You must have installed X11, OpenGL, GLX and GLU libraries and headers.

On an x86 linux system run make like this:
	make ABI=-m32

On IRIX, use gcc. Don't bother with the MIPSpro compilers, they are just too
ancient (although I took some care that it's basically possible to compile IGL
at least in n32 mode with it). To produce both o32 and n32 versions of IGL,
you need to run make twice:
	make MIPSABI=32 LIBDIR=lib && make MIPSABI=n32 LIBDIR=lib32

On other systems, determine which ABI switch is needed to enforce a 32 bit
build, and use that for ABI in the make arguments.


Install:
========
Target files are installed in $INSTALLDIR/{include|$LIBDIR} by running
	make install ABI=-m32
On IRIX, install IGL with
	make install MIPSABI=32 LIBDIR=lib
	make install MIPSABI=n32 LIBDIR=lib32
The default INSTALLDIR is /usr/local, which can be changed by adding
INSTALLDIR=<path> to the make parameters.


Usage:
======
Compile and link your software with IGL, or, in case of precompiled binaries,
add $INSTALLDIR/lib and/or $INSTALLDIR/lib32 to your LD_LIBRARY_PATH and
run your software. It should now use the IGL version of libgl.so and libfm.so.

Enable remote access for your X server, and use xhost to allow access for your
IGL system. Also enable indirect GLX contexts. Note, however, that both may
present potential security issues.

The font manager has a built-in font list to map the SGI font names to X11
names. Only fonts that could be accessed by the names in that font list can be
used by the font manager. Either get these fonts from /usr/lib/X11/fonts/Type1
on your SGI, or map those fonts you don't have to other names.

IGL has some environment variables you can use to control some aspects of it:

IGL_WINSIZE
    default size of new windows (default 100x100)
IGL_FONT
    system font, font(0) (default -*-fixed-medium-r-normal-*-14)
IGL_COMPAT
    set "SOFTATTACH" and/or "SLOWMAPCOLORS" compatibility option (default "")
IGL_NOLAYERS
    turn off layer support, layers will not be visible
IGL_GVERSION
    set the graphics type gversion() should return (default GL4DIMP)
IGL_YIELD
    sleep time if event queue is empty in qtest() (microseconds, default 1000)
IGL_SCRBOX
    rectangle to return in getscrbox(), which is not supported in OpenGL
    ("<left>,<right>,<bottom>,<top>", defaults to viewport dimensions)
IGL_VERSION
    print IGL's version information
IGL_DEBUG
    provide function tracing if IGL has been compiled with -DDEBUG (default 0)
XSCREENSAVER_WINDOW
    special support for this, allowing electropaint to be run remotely as a
    screen saver :-)


Known Problems:
===============
- A lot of IrisGL stuff can't be fully emulated on OpenGL, since OpenGL isn't
supporting it (e.g. PYM_HOLLOW, depthcueing, concave() etc). This is documented
in the source code with a NOTE explaining the restrictions.

- Another lot of IrisGL stuff can't easily be emulated, because the OpenGL
client version on IRIX is way too old (e.g. TX_SHARPEN, TX_DETAIL, shadow maps).

- IGL has no real colormap mode. Color maps are internally emulated onto an
RGB visual. So, no blinking, no changing color map entries for visual effects,
no reading of colormap pixel data, and so on. However, drawing color indexed
pixels is supported, with the possible exception of ranges (lshaderange() etc).

- support for writemasks is very limited, partly because OpenGL doesn't provide
support for this, partly because IGL doesn't provide support for this :-)

- support for multibyte characters isn't implemented.

- IGL isn't prepared for multithreading or multiprocessing. It works if only a
single thread or process uses IrisGL calls, though.

- A compositing window manager is needed for anything using overlays. Even then
problems are to be expected. In that case you will most probably have an
opaque overlay fully obscuring the NORMALDRAW layer. Try IGL_NOLAYERS.
Layers are hard to do since SGI's X stuff is too old to support compositing,
hence it was delegated to the window manager by reparenting all layers to the
root windows. It depends on the window manager if this is working or not.

- overlays are restricted in size to the window onto which they were generated.
No support for extending layers over the whole screen using fullscreen().

- underlay support isn't implemented yet.

- graphics isn't pixel perfect. You'll note leftovers and glitches on and off.

- IGL is rather unoptimized, since I focussed on the functionality. Don't expect
too much.

- the TODO list (currently only available in the source files) is still rather
long. I may put up with some of the tasks in there, but OTOH, I might also
spend some time with the family :-).
As you are obviously interested in dusty old stuff as well, how about you?

send bug reports, fixes etc to <[email protected]>
Kai-Uwe Bloem


Original IGL readme:
==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==
IGL is an Open Source port of IrisGL library to OpenGL (Win32/X11)
Current version is 0.1.8.

For information on compiling, installing etc., browse the 'docs' directory.
Licensing information is contained in 'license.txt'.

Additional information, bug reports, suggestions:
email: [email protected]
URL: http://users.volja.net/wesley/igl.html

Hope you like using it, as much as I did coding...
Matevz Bradac
==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==>8==

Original BUGS (what's left of it):
==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==8<==
This is a list of bugs and known problems:
==========================================
- one word: flickering
- getgdesc() needs a window to function properly
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