A new version 1.9.1 of the Polyray raytracer may be downloaded here:
Older versions of the Polyray Raytracer were posted at the Polyray Download website.
Polyray is a popular free raytracer which was ported to Windows and updated. There are new plans for Polyray which may include a new open source version.
The program Polyray is a rendering program for producing scenes of 3D shapes and surfaces. The means of description range from standard primitives like box, sphere, etc. to 3 variable polynomial expression, and finally (and slowest of all) surfaces containing transcendental functions like sin, cos, log. It may be used from the command line or from within TextPad.
Some videos illustrating the use of Polyray.