This is a visual demo for some of the noise functions, but it was written in 2011
to be compatible with MacOS X, which was still stuck at OpenGL 2.1 at the time.
The code hasn't aged well. In addition to using legacy OpenGL, it uses
the old version 2 of the GLFW library, which is still available but no longer
maintained. Trying to resurrect this code might prove painful.
In any case, this is not code you should learn from or build upon.