The hardest thing I ever wrote was just a fun project. It was intended to be a screen saver and was written to run under dos of all things! At the time 640x480 resolution was HiRes and nobody did any real 3d graphics mapping in that res. My screen saver was a 3 dimensional cube that bounces inside of a 3 dimensional box. The cube has pictures mapped on it's sides which stay in proportion as it bounces, spins and goes toward and away. The box changes in size also. It is written in Borland C and the innermost operations are in Turbo Assembler. The code had to be optimized down to the very last processor instruction in order to get it to run on the machines of the day. The last version was written using the original Win G library that MS put out with windows 3.1. heheh Anyone remember that? After I finished it, I put it in the drawer and its remained there ever since. Reading this thread made me remember it. If anyone is curious, I'm going to post a copy as an attachement. I realize, no one outside the house has ever seen it until now. You have to set your screen color to 256 or it won't run.