Disk 111 (Mar 1989) : radioii_read

 RADIOII    10-FEB-89

     RadioII is a SA4D (Sculpt-Animate 4D) overscan video mode animation of
 a radiometer doing its thing. Since this was my first animation, I wanted
 something simple so I borrowed the idea from an animation called Radio by
 Dr Gandolf. I hope he doesn't mind. Since the animation repeats itself
 every quarter turn of the solar vanes, only nine images were required with
 a 10 degree rotation of the vanes per cube (ray-trace). When played back at
 one video frame per image, the looping animation would make the vanes appear
 to make a full rotation. Those nine frames however took 3 days to render
 (whew!) running 24 hours a day on an almost stock Amiga 2000. Not stock
 because I do have some fast ram and are running on a 68010. The 68010 only
 gives a marginal increase in performance, but worth the $25.00 I guess. One
 thing to keep in mind though is that any object with a glass surface takes
 a long time to render. All those visible surfaces, reflections and like
 that. I think I see a 68020/68881 accelerator with 32 bit ram in my near
 future (ahhhhhh!).

     I have included Movie 1.3 so just click on the provided icon to view
 the animation. One strange thing though. The SA4D manual states that the
 current version (Movie 1.3) will not play back animations using the SA4D
 new video mode. In a moment of lunacy in the light of a full moon, I
 decided to try it anyway. It flashed into my thoughts "The pale orb is
 affecting me, grab the wolfbane!", because it actually worked! Of course it
 is still necessary to invoke the incantation of setting the stack to 8000
 or higher. However those words will be spoken for you, if you run the
 animation using my icon.

     For those of you who are interested in how the real thing works. It is
 composed of lightweight vanes alternately blackened on one side and white
 on the other. These vanes are suspended in a partial vacuum so as to revolve
 about a central axis when exposed to sunlight. The light falling on these
 vanes transfers heat to each one, but not to the same degree. The lighter
 side reflects the rays, while the dark side absorbs them. When the freely
 moving particles of air in the partial vacuum inside the Radiometer strike
 the reflective white sides of the vanes, they take on very little energy
 and bounce off slowly. However, when the atoms strike the dark side, they
 take on a great deal of energy and bounce off very fast. The "opposite
 reaction" forces being greater on one side than the other then moves the

     I hope you enjoy my animation. The only thing I ask is that this readme
 file is kept intact with the animation in any archive file or distribution.
 If you wish to contact me, I can be reached at the following BBS's.

 El Amigo       (619) 299-9804 8N1  San Diego, Ca
 The Mouse Trap (619) 462-3975 8N1  San Diego, Ca

 or on Genie at address "BagEnd"

						Larry D Crandall
						SDAUG Librarian
						San Diego, California