Mail Archives: djgpp/1998/12/22/12:50:31
Programmer <pekkaka AT dlc DOT fi> writes:
> So i was thinking, is software scroll smoother?...it is right?
I would say so, yes. Hardware scrolling is great when it works (ie.
in mode-X, when you are running under clean DOS), but most SVGA cards
can't scroll smoothly along the horizontal axis, and a lot of VESA
drivers are very buggy in their support for the scrolling functions.
So I think you will almost always be better off using a software
method, or at least providing both options and letting the user
select between them.
> how can i write that, that's my problem..
Very simple: you just have to redraw all the parts of the screen that
have changed! If you have a hardware accelerator (using VBE/AF) you
could perhaps use a hardware blit to copy the existing screen image
and then just redraw the new section along the border, but doing
this will be painfully slow if you don't have acceleration (reading
from video memory is very slow), so you will be much better off to
just redraw the entire image.
Shawn Hargreaves.
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