zRcube is a rendering engine. You can compare it to POV (www.povray.org) in some way. Nonetheless, and despite it takes a pov file as input, zRcube aims to be more modern than pov, using more recent algorithms.

Features (Complete features):

• Radiosity
  
• Paralell raytracing
• Nurbs
• Input : pov format

zRcube's development is currently stopped due to the lack of time of its developpers, however you can still use the code (according to GPL) to learn or to program your own renderer.

You can download the last version here