jmunkki@kampi.hut.fi (Juri Munkki) (10/24/89)
I have always been interested in 3D-graphics. Unfortunately we can only view perspective projections of 3D objects on a 2D-screen. This can be somewhat helped by showing a different projection to each eye. A conventional display can not do this alone, but a reasonably good effect (at least for the price) can be achieved with high speed crystal shutters (the lens is either transparent or opaque). The Sega Master System offers such glasses as an option. The glasses cost about $50 and are available from toy stores. The low price made very interested in whether they can be interfaced to a Macintosh. A few weeks ago I asked for information on obtaining the Sega glasses. (At that time the Finnish company that sells the Sega system had not started its advertising campaign and the glasses & video game was practically unavailable.) Stan Lackey replied that he had looked at the interface and he even gave me a simple circuit that can control the glasses. I made minor modifications to that design and built the circuit. Today, I bought myself a pair of glasses (they weren't quite as cheap as in the USA) and tested my circuit. To my great surprise, the interface worked exactly as I had planned. The Macintosh serial port can be used to control both lenses individually (the original circuit always had the other lens opaque). In its shortest form, the controlling program is only five lines long. The interface works with any RS-422 port. It will need to be modified to work with a D-9 connector, since that connector does not have the DTR signal. The modification is quite small and retains 100% software compatibility with the version that uses the DTR signal. If there is enough interest, I could draw the circuit and post it along with the control routines and some instructions on how to build the interface and program for it. In exchange, I _want_ some information on the Macintosh II video card. I want to change the clut _OR_ the video buffer location from within a vertical interrupt task. Doing this with a MacPlus is almost trivial, but it's a lot harder on a Mac II. Apple usually doesn't give out information on device-dependent interfaces, but this really is an application where optimal speed is necessary. If someone can think of a better way to change the screen contents 60 times per second, please post an article. (BTW: Does the Portable have an alternate screen buffer?) I'm interested in using the glasses for 3D-CAD and I'll also write games... Milo: How about converting your maze program to work with the glasses? Should be fun... I'd also like to hear your opinions on where and how I should post the article. I could post it in comp.sys.mac.hardware and announce it in quite a few other groups. comp.sys.mac.programmer, comp.sys.next, comp.graphics, rec.games.programmer, rec.games.video come to mind. I've only started programming in stereo, but it looks promising... _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._ | Juri Munkki jmunkki@hut.fi jmunkki@fingate.bitnet I Want Ne | | Helsinki University of Technology Computing Centre My Own XT | ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^