🚀 go-pugleaf

I posted here almost a week ago asking if anyone could tell me how
to flip between two graphics screens using the VBL interrupt.

Well, I didn't get any replies telling me how to do it, although
many people asked if they could have my results when I was done :-)

(BTW, almost all of my reply mail bounced back with a "host unknown",
or something similar.. If you want to re-write me, by all means ...)

I got it working on my own, and now have a slight degree of gray
scaling for diplaying certain specific pictures (I use it to display
the fractals I generate on a NeXT computer up at the university
on my monochrome monitor at home, which is originally why I wanted
to do the page flipping in the first place. Fratals are more
interesting in "colour").

The only problem is this: The flicker is annoying. It's not really
extreme unless you start working with more than 3 shades, but STILL.
The flicker would probably go away if I was doing the page flipping
on a colour monitor, between two colour images (to generate a
possibility of 512 colours on a medium rez. screen at a time instead
of 16), but that's just an educated guess (I havn't tried it).
I say this because if two corresponding bit mapped "pixels" are
roughly the same colour, as you flip between them there shouldn't
be a big shock to the eye. Rather, if you flip between a white
"pixel" and a black "pixel" at 70 Hz (I think that's the value,
or is it 60?), then they eye CAN perceive the change.

Can anyone think of a way to get rid of the flicker for a monochrome
picture? Maybe using the HBL would have certain advantages.

  Thanks,

 
  /\ _  _      \        iNet/Envoy : m.schroeder (org. id = kort)
 (  / \/ \    / \       e-mail     : marc@cpsc.UCalgary.CA
   /  /  /   /   \                   ms@flip.cpsc.UCalgary.CA
  /  /  / (_/____/      Fidonet    : Marc Schroeder @ 1:134/47
        \__/
 
 Marc A. Schroeder      * 1st year computer science
                          University of Calgary