I'm wanting to stretch the picture 2x in the vertical direction. Assuming I can write during hblanks, I figured it would work to set the scroll every other scanline:
scanline 0, set to y scroll to 0
0
1, set to 1
1
2, set to 2
2
...
I could do a 2006, 2005, 2005, 2006 series of writes for each of those, but I'm hoping it's not necessary.
Some details:
- My x scroll is always 0
- The nametable number is 0
The best I've found is:
I noticed that y scroll is incremented only if rendering is enabled. Is it possible to disable rendering just before the end of the scanline, then re-enable it? Alternately, can a shorter series of writes set y in this way?
scanline 0, set to y scroll to 0
0
1, set to 1
1
2, set to 2
2
...
I could do a 2006, 2005, 2005, 2006 series of writes for each of those, but I'm hoping it's not necessary.
Some details:
- My x scroll is always 0
- The nametable number is 0
The best I've found is:
Code:
lda #0
sta 2006
sta 2005
lda #y
sta 2005
lda #(y & $f8) << 2
sta 2006
sta 2006
sta 2005
lda #y
sta 2005
lda #(y & $f8) << 2
sta 2006
I noticed that y scroll is incremented only if rendering is enabled. Is it possible to disable rendering just before the end of the scanline, then re-enable it? Alternately, can a shorter series of writes set y in this way?