How to fix Tails' respawn speeds

Spoiler

I couldn't see a topic about this subject, or I couldn't see it on the bug list, or anywhere else, so I thought I'd post my fix here

How to fix Tails' respawn speeds




The problem




Bye, Tails! I'm leaving you behind.





Oh, Tails! You're back!





Keep up, Tails! Oh wait, you can't, you still think you're underwater!




The problem here is when you and Tails enter the water, your speed, acceleration and deceleration are decreased, to give you the underwater physics. The problem is, if you lose Tails when underwater, when he next respawns (in Sonic 2, he only respawns when you've come out of water), he will still have his underwater speeds. Hence why Tails suddenly cannot keep up. This bug only occurs when you lose Tails underwater, and his underwater speed will remain this way until he enters/exits water again (no matter how many times you lose him and he respawns).


The bug is NOT fixed in S3K either, but to fix it, you have to do an extra check, so follow the S3K fix.




The fix



Sonic 2


This can be done in Xenowhirl's 2007 disassembly or the SVN disassembly.


Go to "loc_1BC68:" and you'll see this:

Code (ASM):

1. loc_1BC68:
2.     lea (Sonic_Stat_Record_Buf).w,a2
3.     move.b  2(a2,d3.w),d2
4.     andi.b  #$D2,d2
5.     bne.s   return_1BCDE
6.     or.w    d0,d1
7.     bne.s   return_1BCDE
8. ;   etc...

Right after the 2nd "bne.s return_1BCDE" command, insert this:

Code (ASM):

1.     move.w  #$600,(Tails_top_speed).w   ; set Tails' top speed
2.     move.w  #$C,(Tails_acceleration).w  ; set Tails' acceleration
3.     move.w  #$80,(Tails_deceleration).w ; set Tails' deceleration

So, you have something like this:

Code (ASM):

1. loc_1BC68:  ; Fix for Tails' underwater respawn
2.     lea (Sonic_Stat_Record_Buf).w,a2
3.     move.b  2(a2,d3.w),d2
4.     andi.b  #$D2,d2
5.     bne.s   return_1BCDE
6.     or.w    d0,d1
7.     bne.s   return_1BCDE
8.     move.w  #$600,(Tails_top_speed).w   ; set Tails' top speed
9.     move.w  #$C,(Tails_acceleration).w  ; set Tails' acceleration
10.     move.w  #$80,(Tails_deceleration).w ; set Tails' deceleration
11. ;   etc...

Done



Sonic 3 and Knuckles


This can be done in SVN disassembly.


Go to "loc_13CD2:" and you'll see this:

Code (ASM):

1. loc_13CD2:
2.         lea (Stat_table).w,a2
3.         move.b  2(a2,d3.w),d2
4.         andi.b  #$80,d2
5.         bne.s   loc_13D42
6.         or.w    d0,d1
7.         bne.s   loc_13D42
8. ;       etc...

Right after the 2nd "bne.s loc_13D42" command, insert this:

Code (ASM):

1.         btst    #6,$2A(a0)      ; test underwater flag
2.         bne.s   +
3.         move.w  #$600,($FFFFFEC0).w ; set Tails' top speed
4.         move.w  #$C,($FFFFFEC2).w   ; set Tails' acceleration
5.         move.w  #$80,($FFFFFEC4).w  ; set Tails' deceleration
6. +

So, you have something like this:

Code (ASM):

1. loc_13CD2:      ; Fix for Tails' underwater respawn
2.         lea (Stat_table).w,a2
3.         move.b  2(a2,d3.w),d2
4.         andi.b  #$80,d2
5.         bne.s   loc_13D42
6.         or.w    d0,d1
7.         bne.s   loc_13D42
8.         btst    #6,$2A(a0)      ; test underwater flag
9.         bne.s   +
10.         move.w  #$600,($FFFFFEC0).w ; set Tails' top speed
11.         move.w  #$C,($FFFFFEC2).w   ; set Tails' acceleration
12.         move.w  #$80,($FFFFFEC4).w  ; set Tails' deceleration
13. +
14. ;       etc...

Done




The bug explained

Now, when you lose Tails, he goes through lots of commands to move him about and to respawn him on certain conditions. BUT, none of these commands reset Tails' speeds. Because of this, when Tails respawns, he has the exact same speeds as when you lost him. So, if you lose him underwater, when he respawns, he will still have underwater speeds. So, all we've done here is added the command to reset his speeds. So...

In Sonic 2, all we've done is set Tails to use his normal speeds no matter what when he respawns. This is fine because he only respawns when you're not in water, so he will always be out of water when he arrives. So we want his normal speed.

In Sonic 3 and Knuckles, we have to do a check first to see if Tails is respawning in water or not. If not, do not bother resetting the speeds because he's going to spawn in water. On the other hand, if not in water, it will reset to his normal speeds because he's going to respawn out of water.



That's it. If anyone wants to add this to the hacking guide, feel free.

Enjoy

redhotsonic

 

Yeah, I'd thought I'd get more reception on this topic, but meh.


Anyway, that never crossed my mind. Thanks for that; I have edited both S2 and S3K guides in my first post. Anyone who has already applied this to their hack may want to have a quick revision.


EDIT: Spellings.

 

Cheers, mate. It's just the indexes that needs to be made under Sonic 2 and Sonic 3K. I would do it, but I don't know to wiki-editing much =P



EDIT: And your wiki edits still says 1! Mine says 24 (for some reason).

 

This guide was only an easy fix, so that's not going to help much. But my other guides haven't really got me anywhere either, and I thought I did well with them =P



I see you put links on the index at the bottom. But there isn't any here. I looked myself, but I don't know how it works =P