Here you find some of the very first C programs of my life.
They are totally Public Domain, please use them and spread them as you like.

TDemo was at first an AmigaBASIC program to demonstrate fast area filling
      on the Amiga with triangles as examples. To make it more fun,
      I added modulations in the shape of the triangles and suddenly
      had a 3D effect, accidently. The last addition was color cycling.
      To enhance colors, I chose to generate new color values by a
      scheme that normally increases every color component by one for
      each step, but by adding decimals (you physicists out there will
      know that value...) and a modulation, again interesting effects
      appeared. I hope, the shape and color combination will not repeat
      before a very long time. - Another important point is that TDemo
      adapts to the actual screen size. You know, we guys here in Europe
      want to USE our 256/512 scan lines and dislike to leave a
      significant portion on the screen in background color.
      Perhaps some of you in US would like to change to a PAL AGNUS too
      to gain another 56/112 lines???

SetPAL, SetNTSC were developed to test TDemo, whether its adaption to
      PAL or NTSC worked sufficiently. Perhaps these little programs
      could be good also for others to test their software on NTSC
      machines, but pretending them to be PAL only for proofing the
      software runs in this environment.
      (Another point: PLEASE think of the many people outside with
       different keyboards! Allow use of SetMap!!!)

Contact me under:
      Dr. Peter Kittel
      Commodore Bueromaschinen GmbH
      Lyoner Str. 38
      6000 Frankfurt 71
      West Germany
      Tel. 0049 / 69 / 6638 - 171

Good hacking!