Smooth Scrolling

[omni]

Could someone explain how to do smooth scrolling?

[John Barrus]

Basically:

to move the screen up one row:
ld bc,768
ld hl,gbuf+12
ld de, gbuf
ldir

to move screen down one row:
ld bc,768
ld hl,gbuf+756
ld de,gbuf+768
lddr

Now you populate to empty lines (how ever you want)
To move left and right, it's a bit more complicated. You have to use the srl, rr, etc. opcodes. I suggest looking in the source for mario to find how to do it.

[MaxVT103]

I agree with john on the scrolling. If you want to get even better scrolling, create a custom buffer or re-alocate saferam areas for the buffer and you can write above and below the screen without errors and it scrolls so nicely.

Donald

[John Barrus]

I guess you could do that, but I think it's more convenient to just write a routine to scroll and repopulate on the fly using the tilemap data, instead of loading it all into a second buffer and then into the graphscreen.

[omni]

May you elaborate on that John?

[John Barrus]

Well, do you know how to make tilemaps?
Basically, I would write a routine to read from the tilemap data in your source, and then load it into the graph buffer.