From: Andrew Apted <ajapted@netspace.net.au>
  To  : ggi-develop@eskimo.com
  Date: Thu, 30 Jul 1998 22:04:36 +1000

Re: I've seen the stars too... [Re: kgicon, etc]

Geert writes:

>  > Yes, and apparently _reading_ the framebuffer is a lot slower than
>  > writing it.  Once we change to the smart scrolling, it should be a lot
>  > faster.
>  
>  Smart scrolling _is_ already available if you enable it:
>  
>      display->scrollmode = FBCON_REDRAW

Yes that's what I meant :).

>  > Splitline is no good.  I've tried it, but what happens is that when you
>  > _move_ the splitline (e.g. up 8 lines), you often miss the VGA's line
>  > counter.  It is an exact comparison, so no ywrap occurs for that frame,
>  > resulting in a flash of garbage on the screen.  Real ugly.
>  
>  You could do it during the vblank. On Amiga, the copper lists are changed
>  during the vblank only to prevent this kind of annoying effects.

Yes, assuming that today's PC video cards have a vblank interrupt.
(I doubt busy waiting on the vblank register would be a good idea).

Anyone here know what PC cards can and _can't_ give an interrupt for
vertical retrace ?

Cheers,
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  Andrew Apted   <andrew@ggi-project.org>       \/