Path: utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!dali.cs.montana.edu!milton!jmunkki@hila.hut.fi From: jmunkki@hila.hut.fi (Juri Munkki) Newsgroups: sci.virtual-worlds Subject: Re: Stereoglasses, active technology Message-ID: <7606@milton.u.washington.edu> Date: 14 Sep 90 21:54:05 GMT References: <7545@milton.u.washington.edu> <7571@milton.u.washington.edu> Sender: hlab@milton.u.washington.edu Organization: Helsinki University of Technology, FINLAND Lines: 69 Approved: hitl@hardy.u.washington.edu In article <7571@milton.u.washington.edu> dartvax!batcomputer!andyrose@uunet.UU. NET (Andy Rose) writes: >Bruce Land, manager of Visualization and Information Technologies >at Cornell Theory Center has plans for 3D glasses drawn up and >ready to go. These are based on SEGA game glasses ($30-$50) and >an RS-232 connector with some capacitors and stuff. Total cost is >well under $100. Connecting the glasses to just about any computer is really easy. My interface costs about $10 to $20, so I guess it must be pretty close to what Mr. Land has designed. A lot of people have been very interested in these glasses and some have built the interface. The big problem has been finding the glasses in the US. The glasses were discontinued at just about the same time I first posted the article about the glasses in comp.graphics and some other groups (virtual- worlds didn't exist at the time). I have heard of plans to resume production of the glasses, but so far no one has actually reported that they would be available again. Does Mr. Land sell the glasses and the interface or does he have a guaranteed way of getting the glasses? >For these to be effective you need a computer which can alternate >between two graphic buffers at rates quicker than 10 times a second. >30 times a second is of course great. 30 times per second is merely adequate. If you have any amount of backlighting, even 30 frames per second will flicker. I wouldn't want to use the glasses if I only had a 10 frames per second rate. >This is not to tough for >displaying a left eye frame and than a right eye frame of a static >image. If you wish to animate, you need to compute a left eye frame >and a right eye frame and display them at the above rates. This >is not easy. Silicon Graphics, Stardent, RS6000, and other machines >in this class can barely do it, especially as quantity of polygons >grows. If you wish to animate, you can use two frame buffers or use palette animation to do the switching. This method guarantees that you can switch every time your monitor does a vertical blanking, so you get the minimum amount of flicker. You need four buffers to do double- buffered animation in stereo. If I divide my Macintosh II screen into 4 2-bit bitplanes, I can do stereo animation with four colors. If you have a 32-bit frame buffer with a CLUT, it is quite probable that you can have 256 color animation in stereo. A graphics accelerator is recommended. :-) For an example of how to do animation with a display card that doesn't support multiple pages or cluts, blit from offscreen buffers at vertical blanking time and draw using four offscreen buffers. Any rate of animation can be achieved as long as there is time left after the blit. Sources and documentation can be found with anonymous ftp from vega.hut.fi. The files are stored in /pub/mac/finnish/sega3d, but there is an ASCII+GIF version of the document. Please also note that +-5V might be enough for the glasses, but at least I was informed that +-10V is the right voltage. My interface generates about +-9V on a Macintosh serial port. ____________________________________________________________________________ / Juri Munkki / Helsinki University of Technology / Wind / Project / / jmunkki@hut.fi / Computing Center Macintosh Support / Surf / STORM / ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~