- Also known as RHS
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- Project:Sonic 2 Recreation
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Spoiler
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:
loc_1BC68: lea (Sonic_Stat_Record_Buf).w,a2 move.b 2(a2,d3.w),d2 andi.b #$D2,d2 bne.s return_1BCDE or.w d0,d1 bne.s return_1BCDE ; etc...
Right after the 2nd "bne.s return_1BCDE" command, insert this:
move.w #$600,(Tails_top_speed).w ; set Tails' top speed move.w #$C,(Tails_acceleration).w ; set Tails' acceleration move.w #$80,(Tails_deceleration).w ; set Tails' deceleration
So, you have something like this:
loc_1BC68: ; Fix for Tails' underwater respawn lea (Sonic_Stat_Record_Buf).w,a2 move.b 2(a2,d3.w),d2 andi.b #$D2,d2 bne.s return_1BCDE or.w d0,d1 bne.s return_1BCDE move.w #$600,(Tails_top_speed).w ; set Tails' top speed move.w #$C,(Tails_acceleration).w ; set Tails' acceleration move.w #$80,(Tails_deceleration).w ; set Tails' deceleration ; etc...
Done
Sonic 3 and Knuckles
This can be done in SVN disassembly.
Go to "loc_13CD2:" and you'll see this:
loc_13CD2: lea (Stat_table).w,a2 move.b 2(a2,d3.w),d2 andi.b #$80,d2 bne.s loc_13D42 or.w d0,d1 bne.s loc_13D42 ; etc...
Right after the 2nd "bne.s loc_13D42" command, insert this:
btst #6,$2A(a0) ; test underwater flag bne.s + move.w #$600,($FFFFFEC0).w ; set Tails' top speed move.w #$C,($FFFFFEC2).w ; set Tails' acceleration move.w #$80,($FFFFFEC4).w ; set Tails' deceleration +
So, you have something like this:
loc_13CD2: ; Fix for Tails' underwater respawn lea (Stat_table).w,a2 move.b 2(a2,d3.w),d2 andi.b #$80,d2 bne.s loc_13D42 or.w d0,d1 bne.s loc_13D42 btst #6,$2A(a0) ; test underwater flag bne.s + move.w #$600,($FFFFFEC0).w ; set Tails' top speed move.w #$C,($FFFFFEC2).w ; set Tails' acceleration move.w #$80,($FFFFFEC4).w ; set Tails' deceleration + ; 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
This post has been edited by redhotsonic: 30 May 2012 - 06:00 PM
