Licensing

Or, Why Ygdrasil is not exactly 100% free and open source

Ygdrasil itself, the language and the environment, are free and open source. However, it is based on two other software components (libraries) which are not - SGI's OpenGL Performer Graphics Library, and the CAVE Library. A fully-functional, free, demo version of OpenGL Performer is available from the SGI website - the only difference between it and the full registered version is that it puts an "OpenGL Performer" label at the top of the screen. The CAVE Library, which handles 3D tracking and stereoscopy, is a little more complicated. It's available commercially through VRCO. Educational institutions are encourage to contact the Electronic Visualization Lab at University of Illinois about research partnernships.
(c) Ben Chang