Hi Thomas!
>Manuel wrote:
>> That won't work. +8 does the trick, nothing else.
>> Consider this:
>> Horizontal scrolling works with +-1 and vertical
>> scrolling with +-8 pixels.
>> If you shift only a single line with anything else than
>> +8, the vertical scrolling is out of sync immediately.
>Hm, I do not understand:
>1. Why is vertical scrolling limited to 8 pixels? (your demo
>scrolls with single pixels in both directions)
Sorry, that was unprecise.
Uhm... hm... how do I explain that...
Ok, the stars are shifted 8 pixels from one line to the next.
Looks like this for example:
-------*----------------
---------------*--------
-----------------------*
Now to scroll left or right, you'd shift the starting position +-1 I
think that's clear.
Now the trick:
To shift that picture 'up', you do nothing else than shifting the
starting position +8!
Look here, the result:
---------------*--------
-----------------------*
-------*----------------
See, the middle and the right star moved up, and the leftmost reappeared
at the bottom!
>2. Why can't you correct the x-position for the first star
>*outside* the kernel and then HMOVE with every value
>you like?
That'd probably work too, I think. But why all the overhead? ;-)
That 'every value you like?' might not be so trivial to achieve, at
least not without sacrificing either RAM, ROM or cycles. And I doubt
that you really gain that much. Try looking at Solaris and EDS, it's Ok
that way I think.
>You know that there is no "Total randomness" in a computer. ;-)
At least not in computers where the soundchip has no generator for white
noise ;-)
Greetings,
Manuel
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