Help with Animation limit in S1

Hey guys, got a bit of a problem with my Sonic 1 hack.


So far everything's worked out fine for me, including ASM, music, adding Shadow as a character, and level art. But, I recently ported Knuckles and am fixing his animations. Only problem is, any sprite above sprite $80 for Knuckles doesn't work. It just freezes on the last loaded sprite until the animation's done and then it snaps back to normal when a sprite below sprite $80 is loaded in Knuckles' animation queue.


IIRC there was an anim limit in S1 of $80 that was taken out in Sonic 2 and 3 (correct me if I'm wrong on that). I've looked around for anything that would look like a sprite anim cap and have compared routines between sonic 1 and 2, but I haven't found anything. Do any of you know how to fix this problem?


And btw, for the most part I am familiar with programming ASM, I know how to work animation scripts, and I've already successfully added Shadow to my hack so I don't think there's a porting problem. I'm just at a loss here . And if you need a video, just ask (slow dialup is slow)

 

Just replace SAnim_Do2: with this:

Code:

SAnim_Do2:

				moveq   #0,d1

				move.b  $1B(a0),d1;  load current frame number

				move.b  1(a1,d1.w),d0;  read sprite number from script

			  &#59;bmi.s	SAnim_End_FF;  if animation is complete, branch

				cmpi.b  #$F0,d0			   &#59;++

				bcc.s	SAnim_End_FF   &#59;++if animation is complete, branch

 

The problem with sprites above $80 is not in animation routines, it's in BuildSprites routine, where the sprites are displayed. So that's not an animation limit, but mapping frames limit.


Go to loc_D700 and you'll see:



loc_D700:
movea.l 4(a0),a1 ; load mappings addr


moveq #0,d1


btst #5,d4


bne.s loc_D71C


move.b $1A(a0),d1 ; get mapping frame number


add.b d1,d1 ; double it


adda.w (a1,d1.w),a1 ; load mappings of this frame


move.b (a1)+,d1 ; get mapping rows count


subq.b #1,d1


bmi.s loc_D720



Mapping frame number is doubled there, but byte type is used, so if d1 is $80 and more, there will be overflow and incorrect frame will be displayed. In later Sonic games this was fixed by using word instead of byte.


So just replace that subroutine with this:



loc_D700:
movea.l 4(a0),a1 ; load mappings addr


moveq #0,d1


btst #5,d4


bne.s loc_D71C


move.b $1A(a0),d1 ; get mapping frame number


add.w d1,d1 ; double it


adda.w (a1,d1.w),a1 ; load mappings of this frame


moveq #0,d1


move.b (a1)+,d1 ; get mapping rows count


subq.b #1,d1


bmi.s loc_D720



But if you're porting Knuckles there will be another problem, in this time with animations. To fix it do what MAXXX309 said.

 

Thanks, guys. The fixes worked perfectly, can't believe I didn't see it before . That explains why I was looking at animation routines and not finding anything...


Thanks again, really appreciate it!