SS SS CC CC RR RR OO OO LL LL II NNN NN GG GG
SS CC RR RR OO OO LL LL II NNNN NN GG
SSSSS CC RR RR OO OO LL LL II NN NN NN GG
- SS CC RRRRR OO OO LL LL II NN NNNN GG GGG
+ SS CC RRRRR OO OO LL LL II NN NNNN GG GGG
SS SS CC CC RR RR OO OO LL LL II NN NNN GG GG
SSSSS CCCCC RR RR OOOOO LLLLL LLLLL IIIIII NN NN GGGGG
- by Alec Thomas (Kestrel) of FORGE Software Australia
- (c9223826@cs.newcastle.edu.au)
+ by Alec Thomas (Kestrel) of FORGE Software Australia
+ (c9223826@cs.newcastle.edu.au)
------------
the same with columns (except 0-319), etc. unless otherwise stated)
********************************************************************************
-* X-MODE SCROLLING *
+* X-MODE SCROLLING *
********************************************************************************
------------------
VERTICAL SCROLLING
standard X-mode addressing scheme with the OFFSET register set to 80.
ROW OFFSET
- 0 0 ========================
- 1 80 [ ]
- 2 160 [ ]
- .. .. [ VISIBLE ]
- [ SCREEN ]
- [ ]
- [ ]
- .. .. [ ]
+ 0 0 ========================
+ 1 80 [ ]
+ 2 160 [ ]
+ .. .. [ VISIBLE ]
+ [ SCREEN ]
+ [ ]
+ [ ]
+ .. .. [ ]
199 15920 ========================
and the next diagram is of a modified addressing scheme with the OFFSET
register set to 82 (to give us 4 extra pixels on each side of the screen)
ROW OFFSET
-0 0 ------========================------
-1 82 | V [ ] V |
-2 164 | I [ ] I |
-.. .. | N S [ VISIBLE ] N S |
- | O I [ SCREEN ] O I |
- | T B [ ] T B |
- | L [ ] L |
-.. .. | E [ ] E |
+0 0 ------========================------
+1 82 | V [ ] V |
+2 164 | I [ ] I |
+.. .. | N S [ VISIBLE ] N S |
+ | O I [ SCREEN ] O I |
+ | T B [ ] T B |
+ | L [ ] L |
+.. .. | E [ ] E |
199 16318 ------========================------
Beautiful!!!
********************************************************************************
-* STANDARD VGA SCROLLING *
+* STANDARD VGA SCROLLING *
********************************************************************************
Without X-mode, there is no easy way to do scrolling using the VGA hardware.
So basically, you have to resort to redrawing the entire screen for every
********************************************************************************
-* PARALLAX SCROLLING *
+* PARALLAX SCROLLING *
********************************************************************************
Parallax scrolling is when the "world" appears to have different levels
of perspective. That is, images further away from the viewer move
********************************************************************************
-* DISCLAIMER *
+* DISCLAIMER *
********************************************************************************
I'm sorry if any of this is confusing, but hey that's half the fun of it -
figuring out what the hell I'm raving on about :)