GLE
---
GLE is a library package of C functions that draw
extruded surfaces, including surfaces of revolution,
sweeps, tubes, polycones, polycylinders and helicoids.
Generically, the extruded surface is specified with a
2D polyline that is extruded along a 3D path. A local
coordinate system allows for additional flexibility in
the primitives drawn. Extrusions may be texture mapped
in a variety of ways. The GLE library generates 3D
triangle coordinates, lighting normal vectors and
texture coordinates as output. GLE uses the GL or
OpenGL(R) API's to perform the actual rendering.
The demos use GLUT and require GLUT to be installed.
Obtaining OpenGL
----------------
OpenGL is available on most UNIX(R) workstations,
as well as OS/2(R) and Windows NT. Contact your
workstation vendor for more information; the URL
http://www.opengl.org/ points to a variety of
information, including a list of OpenGL vendors.
GLE also works with Mesa, a public-domain
OpenGL-like API. Mesa can be found at
http://www.mesa3d.org/
Obtaining GLUT
--------------
The demos require that the GLUT windowing and
utility library be installed. GLUT can be obtained
at http://reality.sgi.com/mjk_asd/glut3/glut3.html
Compiling
---------
GLE uses the standard GNU automake/autoconf build process,
and thus should be portable to essentially all computing
platforms. At the command line simply type 'configure'
to set things up for your CPU & operating system. Then run
'make' to compile. Finally, cd to the examples directory,
and run the script 'rundemo' to launch each of the demos
in order (from most basic, to advanced). Use the left
mouse button to move, the middle mouse button to access
the pop-down menu.
If 'configure' fails, its probably because some library
or another is missing. Look at the file 'config.log'
to see what actually went wrong. In particular, pay
attention to the short program at the end: trying to
compile it by hand will give you a good idea on why
it failed.
configure flags:
--enable-lenient-tess
If you have a tesselator that is happy with anything,
including degenerate points, colinear segments, etc.
then define this. Otherwise, don't specify this flag.
Setting this flag provides a minor performance improvement.
I beleive that the stock SGI tesselator is "lenient",
despite explicit disclaimers in the documentation.
(circa 1995).
Early versions of the MesaGL tesselator are not at all
forgiving of degenerate points. This resulted in frequent
crashes and/or hangs. (circa 1997-2000). Recent versions
(as of 2001) seem to work fine. If you have an old version
of MesaGL, do not set <tt>--enable-lenient-tess</tt>
--disable-auto-texture
Disable texture mapping code. Disabling texture
mapping may provide a very minor performance improvement.
--enable-irisgl
Compile for old IrisGL/GL-3.2 API. This used to work, but
hasn't been tested in a long time.
--enable-debug
Will compile sources so printf routines will be called instead
of OpenGL routines. Warning: this will generate a *lot* of
output!
More information about building, as well as this package,
can be found in the directory "public_html".
RedHat RPM's
------------
RedHat RPM's can be built using the gle.spec file.
Python, SWIG
------------
Python bindings for gle can be found in the /swig directory.
Be sure to read the readme.
Compiling for Windows NT
------------------------
To compile with Visual C++, just do the following:
cd src
cl -c -DWIN32 *.c
lib -out:libgle.lib *.obj
Alternately, there are a set of Microsoft Visual C Studio Project
files in the directory ms-visual-c that should do the same thing.
Running
-------
Some of the example programs will hang or crash when run on
older versions of MesaGL/Linux. This is due to bugs in the
MesaGL tesellator. Newer versions should work fine.
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