Fix the EHZ Deformation bug
From Sonic Retro
(Original guide by qiuu)
In Sonic 2 is in EHZ a small deformation bug, the lowest two layers don't scroll as they are not affected by the deformation code:
To fix this, go to SwScrl_EHZ:. Scroll down until you see SwScrl_RippleData:. Above it you should have this piece of code:
<asm> move.w #($B4)/12-1,d1 ; $B4 bytes
- move.w d4,(a1)+
move.w d3,(a1)+
move.w d4,(a1)+
move.w d3,(a1)+
move.w d4,(a1)+
move.w d3,(a1)+
swap d3
add.l d0,d3
add.l d0,d3
add.l d0,d3
swap d3
dbf d1,-
rts</asm> Copy and paste this code twice into it: <asm> move.w d4,(a1)+ move.w d3,(a1)+</asm> In the end it should look like this: <asm> move.w #($B4)/12-1,d1 ; $B4 bytes - move.w d4,(a1)+ move.w d3,(a1)+ move.w d4,(a1)+ move.w d3,(a1)+ move.w d4,(a1)+ move.w d3,(a1)+ move.w d4,(a1)+ move.w d3,(a1)+ move.w d4,(a1)+ move.w d3,(a1)+ swap d3 add.l d0,d3 add.l d0,d3 add.l d0,d3 swap d3 dbf d1,-
rts</asm>
And that's it! Now it should look fixed: