Subject: Re: segavga program

From: [email-masked]
Date: Fri, 28 Aug 92 10:42:22 MDT

>-- From [email-masked] Fri Aug 28 09:16:18 1992
>-- To: [email-masked] (andrew longhorn )

STUFF DELETED
>-- 
>
>I hope we can work this out. I have a feeling the rend386 timing is wrong.
>Since (as you will see) the image is so astoundingly perfect with segavga.
>
>BTW: compile it with the -DREVERSE flag on or your image will be inside out.
>     (check the makefile).
>
>So far I have established that the 0,1,2 & 3 are set differently with segavga
>and rend386, (i think rend386 uses 1 or 2 for the right eye but segavga
>uses 3) this shouldn't effect it.
>
>I tried stealing some timing code from segavga into rend386 (version 3) to
>fix the problem, swapped some orderings, inserted vsyncs() etc, but any
>improvement in the right eye generally blew the left eye out of sync.
>
>The thing is that in both v3 and 4 or rend386 the image seems to bleed through
>regularly but not in every cycle, more like once every 5-10 frames.
>
>One thing I did notice that I thought was strange was when I did put a few
>vsync()s in the code just before switching the glasses, it didn't seem to do
>much until I loaded in metalman.fig and ROTATED him. I found there was a
>direct and re-producable correlation between the angle I rotated him and the
>frequency of the bleeds. In some positions I can even make the right image
>fade in and out entirely. (so metalman disappears entirely).
>
>Lastly, segavga seems to go:
>
>wait for vertical retrace;
>black right eye;
>show left page;
>wait for vertical retrace;
>black left eye;
>show right page;
>
>whereas rend386 goes:
>
>if right is shown
>  show leftimage
>  set phase left
>else
>  show right image
>  set phase right
>end
>outportb phase (meaning black out opposite eye).
>
>which means rend386 starts to flip the image then flips the glasses
>where segavga does this in the opposite order, I would think that if this
>was the problem, then both eyes would have a degraded image and I flipped
>the code order to check it, sure enough, it made it worse.
>
>Can anybody tell us what's going on? and why their circuit/rend386 combo
>works?
>
>Andrew

Andrew:
Got the code from plaza.aarnet.edu.au!  Thanks.  

I also noted the ordering you discuss above but ...  I got a pair of
Tohsiba glasses yesterday (they are MUCH nicer that the SEGA glasses) and
got the latest circuit working (doesn't have the 555 timer in it).  Using
this circuit, the Tohsiba glasses work with rend386 but I still have the
blurry, bleeding right eye problem.  The segavga code works fine but
doesn't seem to work with my current circuit/Tohsiba glasses.  The lenses
don't shutter at all.  I will have to look at the plaza\.. circuit diagram
and code in more detail and compare it to the what I'm using to determine
the problem.

I've lost track which circuit are you using?
--
tkl
--
---------------------------------------------------
T. K. Larson, Idaho National Engineering Laboratory
P.O. Box 1625, M/S 2090
Idaho Falls, Idaho 83415-2090
Phone (208) 525-5334; Fax (208) 525-5996
INTERNET: [email-masked]
---------------------------------------------------

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From: [email-masked]
Date: Fri, 28 Aug 92 12:50:47 MDT

Andrew:
Forget my previous message ;-{.  Apparently I don't know COM1 from COM2. 
Once I told segavga where the glasses REALLY were everything works fine
with my circuit.  Like you, I see no bleeding or right eye problems with
segavga!
--
tkl
--
---------------------------------------------------
T. K. Larson, Idaho National Engineering Laboratory
P.O. Box 1625, M/S 2090
Idaho Falls, Idaho 83415-2090
Phone (208) 525-5334; Fax (208) 525-5996
INTERNET: [email-masked]
---------------------------------------------------

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From: [email-masked] (andrew longhorn )
Date: Sat, 29 Aug 92 09:15:31 EST

I am using both the circuit that comes with rend386 (the well known one you're
using) and I also built the first 555 timer circuit as I thought the timing
could be better set using it's trimpot. (I got it to about 400+/-3 Hz).

My guess is that since the image isn't totally merged on the right eye, but
periodically flicks up, there must be some time-dependent interrupt or some
PC hardware/software dependent thing that gets in the way every x msecs.

I remember running the program in -r (or whatever reverse eyes mode is) to
see if it was page dependent. (-r mode swaps the left and right pages as
apposed to segavga which switches the eye constants). I don't remember the
findings of this, but you can easily try it.

So far, the main pointer falls to rend386 (sorry) but my circuit (the one
supplied with rend386) works perfectly with segavga.

Andy the Roo.

P.S. Bernie or Dave, I expect you have checked out the segavga program by now?
Are you both using the EXACT circuit you supply with rend386? The bleedthrough
I get in version 4 makes it too subtractive that I loose all depth cues.

P.P.S. Otherwise I love rend386, hope we can figure this out soon.