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From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.sys.amiga
Subject: Re: Swapping graphics pages at 60Hz
Message-ID: <617@neoucom.UUCP>
Date: Sun, 5-Jul-87 23:53:16 EDT
Article-I.D.: neoucom.617
Posted: Sun Jul  5 23:53:16 1987
Date-Received: Tue, 7-Jul-87 01:37:34 EDT
References: <187@mv05.ecf.toronto.edu>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 35
Keywords: stereographics, video signals, graphics buffers
Summary: 3d graphics isn't terribly difficult


I can't give the the absolute complete nitty gritty details, but I
did help one of our faculty member's son get going on a science
fair project on his Amiga.

He programmed the project in AmigaBasic (the Mircosoft, not
Metacomco interpreter).  He used the ScreeToFront() and
ScreenToBack() functions after opening two screens in Basic.  He
used the digital output lines of the printer port to darken and
clear two LCD sheets installed in the frames from a cheap pair of
sun glasses.  WaitTOF() can be used to wait for the retrace
interval so that the glasses can be switched at an unobtrusive
time.

The Addison-Wessley Rom Kernel Manual provides the necessay info on
the routines.  Note we used the printer port to control the
glasses, as we had difficulty setting the second mouse prot for
digital output.  Something kept switching it back to input mode.

Carolyn Schepner of CATS posted several nice examples of
manipulating screens in Basic a while back.  One thing that is
helpful is to find somebody that has the "FD" files from the C
compiler to feed into "ConvertFD" on the AmigaBasic disk to produce
the necessary ".BMAP" files that enalbe Basic's LIBRARY statement
to find the routines mentioned above.  The Amigabasic disk also
contians several example programs, LoadILBM, or some such name that
are useful examples.

Rather than swapping screens, you could also play with the color
table to avoid the complexity of dealing with screens.  That sould
be OK for your application, since you are only interested in wire
frame objects.

Hope this helps,
Bill (wtm@noeucom.UUCP)