Difference between revisions of "Add Extra Characters To Sonic 2"
From Sonic Retro
(Went on a grammar nazi spree and rewrote a lot of parts since they rendered the guide unusable.) |
(FUUUU-did some more grammar nazi work and made myself a bit clearer on what you should find. Also fixed the ASM tags in some places where I fucked up :U) |
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| Line 1: | Line 1: | ||
(Guide By [[User:ManicRemix|Manic Remix]]) | (Guide By [[User:ManicRemix|Manic Remix]]) | ||
| − | (Revised by ThomasSpeedrunner) | + | (Revised by [[User:ThomasSpeedrunner|ThomasSpeedrunner]]) |
| − | I was very surprised that this guide didn't exist anywhere else. It seems like nowadays this is the what everybody has in their hacks. This guide will show you how to add extra characters to Sonic The Hedgehog 2 (16-bit). We will use the SVN disassembly. In this guide, I will refer to Knuckles | + | I was very surprised that this guide didn't exist anywhere else. It seems like nowadays this is the "what everybody has in their hacks" type of thing. This guide will show you how to add extra characters to Sonic The Hedgehog 2 (16-bit). We will use the SVN/Hg disassembly. In this guide, I will refer to Knuckles and Amy. |
First, open up s2.asm. Search for "Obj_Index:". | First, open up s2.asm. Search for "Obj_Index:". | ||
| − | You will see this or something like it: | + | You will see this or something like it (ignore the fire shield reference as I copy-pasted this from Sonic 2: Titanium Upgrade; Obj09 will be Special Stage Sonic in your hack unless, like me, you've gone and deleted the special stage code and objects): |
<asm> | <asm> | ||
| + | ; =========================================================================== | ||
| + | ; --------------------------------------------------------------------------- | ||
| + | ; OBJECT POINTER ARRAY ; object pointers ; sprite pointers ; object list ; sprite list | ||
| + | ; | ||
| + | ; This array contains the pointers to all the objects used in the game. | ||
| + | ; --------------------------------------------------------------------------- | ||
| + | Obj_Index: | ||
| + | ObjPtr_Sonic: dc.l Obj01 ; Sonic | ||
| + | ObjPtr_Tails: dc.l Obj02 ; Tails | ||
| + | ObjPtr_PlaneSwitcher: dc.l Obj03 ; Collision plane/layer switcher | ||
| + | ObjPtr_WaterSurface: dc.l Obj04 ; Surface of the water | ||
| + | ObjPtr_TailsTails: dc.l Obj05 ; Tails' tails | ||
| + | ObjPtr_Spiral: dc.l Obj06 ; Rotating cylinder in MTZ, twisting spiral pathway in EHZ | ||
| + | ObjPtr_Oil: dc.l Obj07 ; Oil in OOZ | ||
| + | ObjPtr_SpindashDust: | ||
| + | ObjPtr_Splash: dc.l Obj08 ; Water splash in Aquatic Ruin Zone, Spindash dust | ||
| + | ObjPtr_FireShield: dc.l Obj09 ; Fire Shield | ||
| + | ObjPtr_SmallBubbles: dc.l Obj0A ; Small bubbles from Sonic's face while underwater... </asm> | ||
| − | + | And it will go on in this format. Now, search for "dc.l ObjNull". Replace this: | |
| − | + | <asm> | |
| − | + | dc.l ObjNull ; Obj4C | |
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | And it will go on. Now, search for "dc.l ObjNull". | ||
| − | Replace | ||
| − | <asm> | ||
dc.l ObjNull ; Obj4D | dc.l ObjNull ; Obj4D | ||
</asm> | </asm> | ||
| − | + | with this: | |
| − | <asm>ObjPtr_Knuckles: dc.l Obj4C ; Knuckles | + | <asm> |
| + | ObjPtr_Knuckles: dc.l Obj4C ; Knuckles | ||
ObjPtr_Amy: dc.l Obj4D ; Amy | ObjPtr_Amy: dc.l Obj4D ; Amy | ||
</asm> | </asm> | ||
| − | You've now created | + | You've now created a Knuckles object and an Amy object. These are the object IDs that will be used for your two new characters. |
Next, search for "InitPlayers:". | Next, search for "InitPlayers:". | ||
| Line 86: | Line 94: | ||
<asm> dc.l TextOptScr_KnuxAlone | <asm> dc.l TextOptScr_KnuxAlone | ||
dc.l TextOptScr_AmyAlone | dc.l TextOptScr_AmyAlone | ||
| − | + | </asm> | |
Now, head here: | Now, head here: | ||
| − | <asm>off_92DE: | + | <asm> |
| + | off_92DE: | ||
dc.l TextOptScr_SonicAndTails | dc.l TextOptScr_SonicAndTails | ||
dc.l TextOptScr_SonicAlone | dc.l TextOptScr_SonicAlone | ||
| Line 94: | Line 103: | ||
</asm> | </asm> | ||
Add the same two lines as before under: | Add the same two lines as before under: | ||
| − | <asm> dc.l TextOptScr_TailsAlone | + | <asm> |
| + | dc.l TextOptScr_TailsAlone | ||
</asm> | </asm> | ||
Now find this: | Now find this: | ||
| − | <asm>TextOptScr_TailsAlone: menutxt "TAILS ALONE " ; byte_981C: | + | <asm> |
| + | TextOptScr_TailsAlone: menutxt "TAILS ALONE " ; byte_981C: | ||
</asm> | </asm> | ||
And add this below it: | And add this below it: | ||
| − | <asm>TextOptScr_KnuxAlone: menutxt "KNUCKLES ALONE " | + | <asm> |
| + | TextOptScr_KnuxAlone: menutxt "KNUCKLES ALONE " | ||
TextOptScr_AmyAlone: menutxt "AMY ALONE " | TextOptScr_AmyAlone: menutxt "AMY ALONE " | ||
</asm> | </asm> | ||
| − | + | And there you have it! You have two new characters. Now you will need to make new sprites, palette, and code for them to work. A good start would be to copy and paste Sonic's code into a new ASM file and change the labels so you don't get "symbol double defined" errors. Happy hacking! | |
{{S2Howtos}} | {{S2Howtos}} | ||
[[Category:SCHG How-tos|{{PAGENAME}}]] | [[Category:SCHG How-tos|{{PAGENAME}}]] | ||
Revision as of 09:32, 2 August 2013
(Guide By Manic Remix)
(Revised by ThomasSpeedrunner)
I was very surprised that this guide didn't exist anywhere else. It seems like nowadays this is the "what everybody has in their hacks" type of thing. This guide will show you how to add extra characters to Sonic The Hedgehog 2 (16-bit). We will use the SVN/Hg disassembly. In this guide, I will refer to Knuckles and Amy.
First, open up s2.asm. Search for "Obj_Index:".
You will see this or something like it (ignore the fire shield reference as I copy-pasted this from Sonic 2: Titanium Upgrade; Obj09 will be Special Stage Sonic in your hack unless, like me, you've gone and deleted the special stage code and objects): <asm>
- ===========================================================================
- ---------------------------------------------------------------------------
- OBJECT POINTER ARRAY ; object pointers ; sprite pointers ; object list ; sprite list
- This array contains the pointers to all the objects used in the game.
- ---------------------------------------------------------------------------
Obj_Index: ObjPtr_Sonic: dc.l Obj01 ; Sonic ObjPtr_Tails: dc.l Obj02 ; Tails ObjPtr_PlaneSwitcher: dc.l Obj03 ; Collision plane/layer switcher ObjPtr_WaterSurface: dc.l Obj04 ; Surface of the water ObjPtr_TailsTails: dc.l Obj05 ; Tails' tails ObjPtr_Spiral: dc.l Obj06 ; Rotating cylinder in MTZ, twisting spiral pathway in EHZ ObjPtr_Oil: dc.l Obj07 ; Oil in OOZ ObjPtr_SpindashDust: ObjPtr_Splash: dc.l Obj08 ; Water splash in Aquatic Ruin Zone, Spindash dust ObjPtr_FireShield: dc.l Obj09 ; Fire Shield ObjPtr_SmallBubbles: dc.l Obj0A ; Small bubbles from Sonic's face while underwater... </asm>
And it will go on in this format. Now, search for "dc.l ObjNull". Replace this: <asm> dc.l ObjNull ; Obj4C dc.l ObjNull ; Obj4D </asm> with this: <asm> ObjPtr_Knuckles: dc.l Obj4C ; Knuckles ObjPtr_Amy: dc.l Obj4D ; Amy </asm>
You've now created a Knuckles object and an Amy object. These are the object IDs that will be used for your two new characters.
Next, search for "InitPlayers:". You will see this or something like it: <asm>
InitPlayers_TailsAlone:
move.b #ObjID_Tails,(MainCharacter).w; load Obj02 Tails object at $FFFFB000 move.b #ObjID_SpindashDust,(Tails_Dust).w; load Obj08 Tails' spindash dust/splash object at $FFFFD100 addi.w #4,(MainCharacter+y_pos).w rts </asm>
Now, below: <asm> InitPlayers_TailsAlone </asm>
add <asm> subq.w #1,d0 bne.s InitPlayers_KnuxAlone ; branch if this is a Knuckles alone game </asm>
Now, below the "rts", add <asm>InitPlayers_KnuxAlone: subq.w #1,d0 bne.s InitPlayers_AmyAlone ; branch if this is an Amy alone game move.b #ObjID_Knuckles,(MainCharacter+id).w move.b #ObjID_SpindashDust,(Sonic_Dust+id).w rts
InitPlayers_AmyAlone: move.b #ObjID_Amy,(MainCharacter+id).w move.b #ObjID_SpindashDust,(Sonic_Dust+id).w rts </asm>
Now, go to s2.constants.asm. Find this line: <asm>ObjID_Buzzer = id(ObjPtr_Buzzer) ; 4B </asm> And insert this under it: <asm>ObjID_Knuckles = id(ObjPtr_Knuckles) ; 4C ObjID_Amy = id(ObjPtr_Amy) ; 4D </asm>
Next, go to "OptionScreen_Choices:", and find this line: <asm> dc.l (3-1)<<24|(Player_option&$FFFFFF) </asm> Change the 3 to a 5. This will allow for Knuckles and Amy player options. Now go here: <asm>off_92D2: dc.l TextOptScr_SonicAndMiles dc.l TextOptScr_SonicAlone dc.l TextOptScr_MilesAlone </asm> And add this under it: <asm> dc.l TextOptScr_KnuxAlone dc.l TextOptScr_AmyAlone </asm> Now, head here: <asm> off_92DE: dc.l TextOptScr_SonicAndTails dc.l TextOptScr_SonicAlone dc.l TextOptScr_TailsAlone </asm> Add the same two lines as before under: <asm> dc.l TextOptScr_TailsAlone </asm>
Now find this: <asm> TextOptScr_TailsAlone: menutxt "TAILS ALONE " ; byte_981C: </asm> And add this below it: <asm> TextOptScr_KnuxAlone: menutxt "KNUCKLES ALONE " TextOptScr_AmyAlone: menutxt "AMY ALONE " </asm>
And there you have it! You have two new characters. Now you will need to make new sprites, palette, and code for them to work. A good start would be to copy and paste Sonic's code into a new ASM file and change the labels so you don't get "symbol double defined" errors. Happy hacking!