Spirex started out as a graphical ditty in DJGCC, an early port of Gnu C to MS-DOS (now called DJGPP). Spirex is based on the geometry of a Spirograph, only with continuously varying wheel sizes. In a fit of nostalgia I ported it to Java many years later. Due to popular demand I rewrote it in C and turned it into a Windows and Macintosh screen saver, adding many features along the way.
Swirling images based on a 3D extension of a Spirograph
Texture mapping of 3D solids. Several textures are supplied, but you can also use your own images.
Anti-aliased lines in 2D modes.
Many parameters to explore so it never gets stale.
Saving of user presets. Optional random switching among presets.
Optional battery saver mode (Windows only).
Multiple monitor systems get a screen saver on each one.
Automatic checking for updates.
It's free, (as in beer and as in speech.)