GLE - The GL Extrusion Library

This git repo contains an update to the very old (1991-2001) GLE library, which is still available from the old website. That original website is mirrored here, in the doc/html directory.

This update is a snapshot of the final version 3.1.0 of the codebase, and includes work from Dave Richards, providing a MSWindows-friendly C++ wrapper. Dave's work is in the cgle-c++ directory.

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 UNIX, Linux, Mac and Windows. Find more about OpenGL at https://www.opengl.org/

Obtaining GLUT

The demos require that the GLUT windowing and utility library be installed. Most OpenGL distributions come with GLUT (I think).

On Linux/Debian

On modern Linux systems, skip the above, and instead, just say:

sudo apt-get install libgle3-dev

This will give you everything in this git repo, precompiled. If you want to compile from source, you will need this:

apt-get install libgl1-mesa-dev libxmu-dev libxi-dev freeglut3-dev

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.

Flags that can be supplied to ./configure:

--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.

--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!

Website Mirror

More information about building, as well as this package, can be found in the mirror of the original website, in the doc/html directory.

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

To compile with Visual C++, just do the following:

cd src
cl -c -DWIN32 -DOPENGL_10=1 *.c
lib -out:gle.lib *.obj

Alternately, there are a set of Microsoft Visual 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 (pre-2001) versions of MesaGL/Linux. This was due to bugs in the MesaGL tesellator. Newer versions should work fine.