[A83] Delays and grayscales
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[A83] Delays and grayscales
I read the recent thread on 'Shading' (grayscales) and some very
interesting info came up. I had just written a grayscale routine
myself for my upcoming demo, but I only flipped between two pictures
that I displayed the same amount of time, thus I only got 3 shades.
The 1/3 - 2/3 approach to get 4 shades is much smarter, can't beleive I
didn't think of it!
Anyway, when I display the second picture I need to delay a bit before
showing the first again. At the moment I just do two 'fastCopy' calls
to get the delay, but updating the LCD again with the same picture seem
unnecessary. How do you people implement delays such as this (and delays
in general)?
Another thing that I find very strange is this. My first version of the
grayscale routine looked something like this:
loop:
(copy pic1 to PLOTSSCREEN using ldir)
call fastCopy
(copy pic2 to PLOTSSCREEN using ldir)
call fastCopy
call fastCopy
jr loop
Now I got the idea to let fastCopy get the data from the pic's directly
instead of going via PLOTSSCREEN to get a faster routine (with less
flickering). So I modified fastCopy a bit, and my routine looked like
this:
loop:
call fastCopy with pic1
call fastCopy with pic2
call fastCopy with pic2
jr loop
But this caused the screen to flicker noticeably MORE and the grayscale
effect was lost. What could be causing this? The second solution _should_ be
the better one, right?
/Andreas
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