vthrc@brolga.cc.uq.oz.au (Danny Thomas) (02/12/91)
Hello netters,
One small project we've considered here is to allow
viewing of stereo images on a mac. In our case this mainly means
scanned stereo-pair photos taken with an electron microscope. Now
a friend of mine has a product for the Amiga called XSpecs 3D,
which I think is also available for the Atari and maybe others. It is
a set of LCD goggles with the left and right eyes being blacked out
for alternate video frames. It retails for around $100 and includes
a 3D shoot-em-up game and software for displaying stereo images
prepared with some commercial 3D packages. Adapting the goggles
to be driven by the mac is probably quite easy but the question is
how to display left and right views on alternate frames. Probably
we'd need to have both images held in the video RAM and merely
change the pointer to the start of the frame buffer. I've had a look
at the "Display Card Developer Notes for the Macintosh Display
Cards 4.8, 8.24, and 8.24GC" (M0857LL/A 6/18/90) but it says
about the frame buffer controller "Your applications should never
read or write directly to the hardware because the control
registers won't be compatible with other manufacturer's cards. For
this reason, the parameters stored in the JMFB's control registers
are not documented in this preliminary note..." This is more than
just a strongly-worded warning to remain hardware-independent
(just look at the PC world where each application can require a
driver for each possible display type, n*m combinatorial!), but I am
happy to live with the consequences for a one-off piece of
software.
IMV describes that there are now separate queues for each video
device to accomodate different frame rates, so that solves the
synchronization problem (some jitter probably wouldn't matter
given the slow response time of LCDs) but does anyone know how
the hardware frame pointer register(s?) could be set, or is there an
alternative approach that I could consider?
Thanks in advance, details will be posted if we get it working.
Danny Thomas,
Vision, Touch and Hearing Research Centre,
University of Queensland.