Sonic 1 water guide!

Surely some of you have tried to add water to another zone in sonic 1 without creating problems in Labirynth Zone .. here I will explain one easy way to do this ..

Well, well, well .. After 10 long years, I came back to update this code. Let's do this in a more organized way
Note: I know the disassemblies of now are more modern, but I kept
"S1 Hiverbrain", then find the equivalent addresses in your
disassemblies and make the changes​

add these addresses at the beginning of the rom:

Code:

Water_Flag         equ       $FFFFFFBC  ; if the level has water
Saved_Music                 equ       $FFFFFFBD  ; store level music

Initially search for "loc_B9A:" and you will see:

Code:

loc_B9A:
        cmpi.b    #1,($FFFFFE10).w ; is level LZ ?
        bne.w    loc_B5E        ; if not, branch

Replace this with:

Code:

loc_B9A:
        tst.b    (Water_flag).w  ; does level have water ?
        beq.w    loc_B5E        ; if not, branch

Search for loc_1DFA, loc_1F20, Level_ClrVars3, LZWaterEffects, Sonic_Water and Obj79_LoadInfo and do the same changes in the equivalent lines, changing the check "cmpi.b # 1, ($ FFFFFE10) .w" by "tst.b (Water_flag) .w", always remembering to invert the command on the bottom line: If "beq", replace with "bne" and vice versa.

Note: There are other checks for Labyrinth Zone remaining, but we will work with them
more specific way later.

Now let's create a specific routine to work with water, in a more organized way, like
in S3K.

Above "LZWaterEffects:", at the end of the "Level_MainLoop" routine, insert this:

Code:

; ===========================================================================
; ---------------------------------------------------------------------------
; Subroutine to work with water
; ---------------------------------------------------------------------------

LoadWaterLevel:
; Initially check which zones work with this
                cmpi.b    #1,($FFFFFE10).w   ; Check Labyrinth Zone
                beq.s   LoadWater          ; If LZ, continue

                move.b  #0,(Water_flag).w  ; Prevent water from appearing outside the above stages.

                rts
; ===========================================================================

LoadWater:
                move.b  #1,(Water_flag).w  ; Enable water in the checked level
        moveq    #0,d0
        move.w    ($FFFFFE10).w,d0   ; Now this check every zone and act
        lsl.b    #6,d0
                 lsr.w    #5,d0
        andi.w  #$FFFE,d0
                lea    (WaterHeight).l,a1 ; load water    height array
        move.w    (a1,d0.w),d0
        move.w    d0,($FFFFF646).w   ; set water heights
        move.w    d0,($FFFFF648).w
        move.w    d0,($FFFFF64A).w
        clr.b    ($FFFFF64D).w       ; clear water routine counter
        clr.b    ($FFFFF64E).w      ; clear water movement
        move.b    #1,($FFFFF64C).w   ; enable water

                ; If you don't want these objects to be read, check your zone here!
                ;cmpi.b  #X,($FFFFFE10).w
                ;beq.s   LoadWaterPalette

                move.b    #$1B,($FFFFD780).w ; load water    surface    objects
        move.w    #$60,($FFFFD788).w
        move.b    #$1B,($FFFFD7C0).w
        move.w    #$120,($FFFFD7C8).w

; ||||||||||||||| S U B    R O U T    I N E |||||||||||||||||||||||||||||||||||||||

; Load underwater palettes
LoadWaterPalette:
                cmpi.b  #1,($FFFFFE10).w          ; check if zone is LZ
        bne.s   .newzone                  ; if not, skip to next zone
                moveq    #$B,d0                    ; read palette number $B (Normal LZ underwater)
                cmpi.w  #$103,($FFFFFE10).w       ; check if act number is $103 (SBZ3)
                bne.s   .newzone                  ; if not, skip to next zone
                moveq    #$D,d0                    ; read palette number $D (SBZ3 underwater)
                bra.s   .waterpal                 ; branch to .waterpal routine (read underwater palettes)
; ---------------------------------------------------------------------------
.newzone:       cmpi.b  #XX,($FFFFFE10).w         ; zone is???
        bne.s   .waterpal                 ; not? Skip to the next!
                moveq    #YY,d0                    ; read palette number X
; ---------------------------------------------------------------------------

.waterpal:
                move.w    d0,d1
        bsr.w    PalLoad3_Water
        move.w    d1,d0
        bsr.w    PalLoad4_Water
                tst.b    (Water_flag).w
        beq.s    WaterPal_End
                move.b    ($FFFFFE53).w,($FFFFF64E).w
WaterPal_End:
                rts

Now go to Level_ClrVars3 and delete all these lines

Code:

moveq    #0,d0
        move.b    ($FFFFFE11).w,d0
        add.w    d0,d0
        lea    (WaterHeight).l,a1 ; load water    height array
        move.w    (a1,d0.w),d0
        move.w    d0,($FFFFF646).w ; set water heights
        move.w    d0,($FFFFF648).w
        move.w    d0,($FFFFF64A).w
        clr.b    ($FFFFF64D).w    ; clear    water routine counter
        clr.b    ($FFFFF64E).w    ; clear    water movement
        move.b    #1,($FFFFF64C).w ; enable water

and..

Code:

cmpi.b    #1,($FFFFFE10).w ; is level LZ?
        bne.s    Level_GetBgm    ; if not, branch
        moveq    #$F,d0        ; pallet number    $0F (LZ)
        cmpi.b    #3,($FFFFFE11).w ; is act number 3?
        bne.s    Level_WaterPal    ; if not, branch
        moveq    #$10,d0        ; pallet number    $10 (SBZ3)

Level_WaterPal:
        bsr.w    PalLoad3_Water    ; load underwater pallet (see d0)
        tst.b    ($FFFFFE30).w
        beq.s    Level_GetBgm
        move.b    ($FFFFFE53).w,($FFFFF64E).w

Level_GetBgm:

The code should look like this:

Code:

Level_ClrVars3:
        move.l    d0,(a1)+
        dbf    d1,Level_ClrVars3 ; clear object variables

        move    #$2700,sr
        bsr.w    ClearScreen
        lea    ($C00004).l,a6
        move.w    #$8B03,(a6)
        move.w    #$8230,(a6)
        move.w    #$8407,(a6)
        move.w    #$857C,(a6)
        move.w    #$9001,(a6)
        move.w    #$8004,(a6)
        move.w    #$8720,(a6)
        move.w    #$8ADF,($FFFFF624).w
        move.w    ($FFFFF624).w,(a6)
; ---------------------------------------------------------------------------
; Water reading routine
            move.w    #$1E,($FFFFFE14).w     ; T: set Sonic air left
        jsr     (LoadWaterLevel).l     ; T: init water
        tst.b    (Water_flag).w         ; T: in water level?
        beq.s    Level_LoadPal          ; T: if not, branch
        move.w    #$8014,(a6)            ; T: load water internal features
        lea    ($FFFFFAA0).w,a1       ; T: fix palette
        moveq    #0,d0
        move.w    #$17,d1

@loop        move.l    d0,(a1)+
        dbf    d1,@loop
; ---------------------------------------------------------------------------
Level_LoadPal:
        move    #$2300,sr
        moveq    #3,d0
        bsr.w    PalLoad2    ; load Sonic's pallet line

Go to "Level_ChkWater:" and remove these lines:

Code:

cmpi.b    #1,($FFFFFE10).w ; is level LZ?
        bne.s    Level_LoadObj    ; if not, branch
        move.b    #$1B,($FFFFD780).w ; load water    surface    object
        move.w    #$60,($FFFFD788).w
        move.b    #$1B,($FFFFD7C0).w
        move.w    #$120,($FFFFD7C8).w

Now, go to "Level_ChkWaterPal:" and remove these lines:

Code:

cmpi.b    #1,($FFFFFE10).w ; is level LZ/SBZ3?
        bne.s    Level_Delay    ; if not, branch
        moveq    #$B,d0        ; pallet $0B (LZ underwater)
        cmpi.b    #3,($FFFFFE11).w ; is level SBZ3?
        bne.s    Level_WaterPal2    ; if not, branch
        moveq    #$D,d0        ; pallet $0D (SBZ3 underwater)

Level_WaterPal2:
        bsr.w    PalLoad4_Water

Level_Delay:

Done! Now the entire Sonic 1 water system has been modified. Now we just need to make some fixes!

PROBLEM 1: The dynamic water index!

This code controls water movements (and changes the layout of the LZ3 at a certain point), but it only works
on the LZ itself. We need this to be extended to all stages.

Go to LZDynamicWater and change this:

Code:

               moveq    #0,d0
        move.b    ($FFFFFE11).w,d0
        add.w    d0,d0
        move.w    DynWater_Index(pc,d0.w),d0
        jsr    DynWater_Index(pc,d0.w)

To this:

Code:

               moveq    #0,d0
        move.w    ($FFFFFE10).w,d0
        lsl.b    #6,d0
        lsr.w    #5,d0
        andi.w    #$FFFE,d0
                 move.w    DynWater_Index(pc,d0.w),d0
                 jsr    DynWater_Index(pc,d0.w)

And this:

Code:

DynWater_Index:
                dc.w DynWater_LZ1-DynWater_Index
        dc.w DynWater_LZ2-DynWater_Index
        dc.w DynWater_LZ3-DynWater_Index
        dc.w DynWater_SBZ3-DynWater_Index

To this:

Code:

DynWater_Index:
                 dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
                dc.w DynWater_LZ1-DynWater_Index    ; LZ is here
        dc.w DynWater_LZ2-DynWater_Index
        dc.w DynWater_LZ3-DynWater_Index
        dc.w DynWater_SBZ3-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index
        dc.w locret_3C5A-DynWater_Index

Done! Each zone has 4 pointers.. each pointer corresponding to an act.

PROBLEM 2: The wind tunnels and water slides!

These routines are specific to Labirynth Zone. With all the changes made, they are being loaded on at all stages now. We need to fix this!

Go to "LZWaterEffects" and insert this under "bcc.s LZMoveWater"

Code:

                cmpi.b  #1,(FFFFFE10).w
                bne.s   LZMoveWater     ; don't load this in any other zone

move up the "bsr.w LZDynamicWater" to above these lines, like this:

Code:

                bsr.w   LZDynamicWater
                cmpi.b  #1,($FFFFFE10).w
                bne.s   LZMoveWater     ; don't load this in any other zone
                bsr.w    LZWindTunnels
        bsr.w    LZWaterSlides

LZMoveWater:

Done!

PROBLEM 3: Music restoring!
You will have problems every time you get out of the water after the drowing countdown music starts playing. this is because Sonic 1 was programmed
only to load the correct music in LZ, SBZ3 and in the cases of Boss or Invincibility. Let's copy something interesting that Sonic 2 has brought.

Go to "Level_PlayBgm:" and under "move.b (a1,d0.w),d0", insert this:

Code:

move.w    d0,(Saved_Music).w    ; store level music

Go to "Obj01_ChkInvin:" and replace these lines:

Code:

               moveq    #0,d0
        move.b    ($FFFFFE10).w,d0
        cmpi.w    #$103,($FFFFFE10).w ; check if level is    SBZ3
        bne.s    Obj01_PlayMusic
        moveq    #5,d0        ; play SBZ music

Obj01_PlayMusic:
        lea    (MusicList).l,a1
        move.b    (a1,d0.w),d0

With:

Code:

move.w    (Saved_Music).w,d0

Now, go to "ResumeMusic:" and replace this:

Code:

               moveq    #$82,d0    ; play LZ music
        cmpi.w    #$103,($FFFFFE10).w ; check if level is    0103 (SBZ3)
        bne.s    loc_140A6
        moveq    #$86,d0    ; play SBZ music

loc_140A6:

With:

Code:

move.w    (Saved_Music).w,d0    ; prepare to play current level's music

Done! after exiting water during drowning countdown music, the correct bgm will play.

PROBLEM 4: Water Heights!

Very Simple! You only need to create 4 entries for each stage.

Go to "WaterHeight:" and change this:

Code:

WaterHeight:    incbin    misc\lz_heigh.bin
        even

With:

Code:

WaterHeight:    dc.w    $600,$600,$600,$600
             dc.w    $0B8,$328,$900,$228   ; LZ default water heights
             dc.w    $600,$600,$600,$600
             dc.w    $600,$600,$600,$600
             dc.w    $600,$600,$600,$600
             dc.w    $600,$600,$600,$600
             dc.w    $600,$600,$600,$600
        even

I confess that I prefer to deal with this within the asm file itself. If you prefer, you can also include ".bin" extensions instead.
Done! Sonic 1 work with water perfectly!

Additional fix (Optional):


Since our songs can now be saved to be loaded again after some events, we can extend this to other parts of codes that load songs from the stages.

Find these addresses:

loc_179E0, loc_18112, loc_1856C, loc_18BB4 and loc_194E0 and replace the "move.w #XX,d0" with:

Code:

move.w    (Saved_Music).w,d0

XX is the music id, restored after a boss fight.

Be sure to include the pointers of the new color palettes at the end of "PalPointers", and point to them in the "LoadWaterPalette" routine.

Code:

        dc.l Pal_Ending
    dc.w $FB00
    dc.w $1F
  
    dc.l Pal_NewZoneWater ; $14 - new palette
    dc.w $FB00
    dc.w $1F

I hope I have not become such an obsolete romhacker all this time

 

I am NOT going to read a single word before you change those codeboxes to ASM boxes.

 

Eh? What are you on about? It is ASM =P

 

Ugly code box:

Code:

loc_B9A:
		;cmpi.b #1,($FFFFFE10).w
		;bne.w loc_B5E
		tst.b (Water_flag).w
		beq.w loc_B5E ; if not, branch
		....

Nice ASM box:



loc_B9A:
;cmpi.b #1,($FFFFFE10).w


;bne.w loc_B5E


tst.b (Water_flag).w


beq.w loc_B5E ; if not, branch


....

 

This is fantastic!!! It will be very useful for me.


Nice work.

 

This is what I was searching for so much time ago. Nice work, mate. I always wanted an Green Hill Zone with water. Once again nice work.

 

is there some way to stop those code boxes changing when I am trying to read them? great guide apart from that !!!

 

Water surface object causes lag if the level uses lots of sprites at the same place...


...But yeah, I have to admit the fact that this is a great work. Certainly I will use it on my hacks.

 

Truly awesome. It's real useful for me. I used it in the ice level in my hack

 

Sorry for double posting, but will you teach how to edit the heights in hex and fixing the surface? That would be awesome.

 

It's definitely a useful guide especially if you want to flood Labyrinth Zone and keep the bubbles in the same place they were originally without adding more, or you can get rid of all the bubbles and make sonic 1 impossible if you flood every level. I'll do that I'm evil what can I say.

 

Ok I have followed the guide and its great however - there are a couple of bits i need help understanding - firstly how do i change the pallet used in water? and secondly is there anyway to change the water height?

 

firstly how do i change the pallet used in water?


I explained in the tutorial, how to change the palette used:


Go to Level_ChkWaterPal, and change to:



Level_ChkWaterPal:
cmpi.b #0,($FFFFFE10).w


beq.s Ghz_ChkWaterPal


bne.s Level_ChkWaterPal_Cont


rts


; ===========================================================================


Ghz_ChkWaterPal:


moveq #$1E,d0 ; pallet $1E (GHZ underwater)


bsr.w PalLoad4_Water


move.w #3,d1


jmp Level_DelayLoop


; ===========================================================================


Level_ChkWaterPal_Cont:


...



will be including brief tutorial in the guide to change the water line

 

I really dont want to sound stupid but I dont understand what you are saying? I changed the 1E to something else and stull the underwater pallets dont look right... can you explain in a little more detail please?

 

Open _inc\pallet pointers.asm and you will see:



; ---------------------------------------------------------------------------
; Pallet pointers


; ---------------------------------------------------------------------------


PalPointers:


dc.l Pal_SegaBG ;0 ; pallet address


dc.w $FB00 ; RAM address


dc.w $1F ; (pallet length / 2) - 1


dc.l Pal_Title ;1


dc.w $FB00


dc.w $1F


dc.l Pal_LevelSel;2


dc.w $FB20


dc.w $17


dc.l Pal_Sonic ;3


dc.w $FB00


dc.w 7


dc.l Pal_GHZ ;4


dc.w $FB20


dc.w $17


dc.l Pal_LZ ;5


dc.w $FB20


dc.w $17


dc.l Pal_MZ ;6


dc.w $FB20


dc.w $17


dc.l Pal_SLZ ;7


dc.w $FB20


dc.w $17


dc.l Pal_SYZ ;8


dc.w $FB20


dc.w $17


dc.l Pal_SBZ1 ;9


dc.w $FB20


dc.w $17


dc.l Pal_Special ;$A


dc.w $FB00


dc.w $1F


dc.l Pal_LZWater ;$B


dc.w $FB00


dc.w $1F


dc.l Pal_SBZ3 ;$C


dc.w $FB20


dc.w $17


dc.l Pal_SBZ3Water ;$D


dc.w $FB00


dc.w $1F


dc.l Pal_SBZ2 ; $E


dc.w $FB20


dc.w $17


dc.l Pal_LZSonWater ;$F


dc.w $FB00


dc.w 7


dc.l Pal_SBZ3SonWat ;$10


dc.w $FB00


dc.w 7


dc.l Pal_SpeResult ;$11


dc.w $FB00


dc.w $1F


dc.l Pal_SpeContinue ;$12


dc.w $FB00


dc.w $F


dc.l Pal_Ending ;$13


dc.w $FB00


dc.w $1F



Ending Sequence palette is $13, add below:



dc.l Pal_New_Level_Water ; $14
dc.w $FB20


dc.w $17



change $1E to $14 .. and do not forget to include the palette in the rom

 

Sorry to bump such an old topic, but where is the little guide on how to change the water height? I have tried HEX-Editing the ghz_heigh.bin file to all possible values, but the water level never changes?!

 

I didn't even know there is a file called ghz_heigh.bin (because there isn't, there is no water in GHZ unless you add it). The file you are looking for is probably lz_heigh.bin (in the misc folder).

 

Oddest reply I ever saw... why did you just quoted my post without a comment?