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SCHG How-to

Add final spindash to Sonic 2 Beta

From Sonic Retro

Hello everyone shadow05 here. Have you playing sonic 2 beta and been annoyed about the incomplete spindash. Well this guide is for people who can do basic asm editing inspired by the sonic 1 spindash guide. I was using the super egg disassembly but this will work on the original esrael disassembly.

Directly copying the object code

First we'll have to get a slightly modified sonic 1 spindash code

Replace the entire routine with this

Sonic_SpinDash:
		tst.b	$39(a0)
		bne.s	loc_1AC8E
		cmpi.b	#8,$1C(a0)
		bne.s	locret_1AC8C
		move.b	($FFFFF603).w,d0
		andi.b	#$70,d0
		beq.w	locret_1AC8C
		move.b	#9,$1C(a0)
		move.w	#$E0,d0
                jsr     (Play_Sfx)
		addq.l	#4,sp
		move.b	#1,$39(a0)
		move.w	#0,$3A(a0)
		cmpi.b	#$C,$28(a0)
		bcs.s	loc_1AC84
		move.b	#2,($FFFFD11C).w
loc_1AC84:
locret_1AC8C:
		rts	
; ---------------------------------------------------------------------------

loc_1AC8E:
		move.b	($FFFFF602).w,d0
		btst	#1,d0
		bne.w	loc_1AD30
		move.b	#$E,$16(a0)
		move.b	#7,$17(a0)
		move.b	#2,$1C(a0)
		addq.w	#5,$C(a0)
		move.b	#0,$39(a0)
		moveq	#0,d0
		move.b	$3A(a0),d0
		add.w	d0,d0
		move.w	Dash_Speeds(pc,d0.w),$14(a0)
		move.w	$14(a0),d0
		subi.w	#$800,d0
		add.w	d0,d0
		andi.w	#$1F00,d0
		neg.w	d0
		addi.w	#$2000,d0
		move.w	d0,($FFFFEED0).w
		btst	#0,$22(a0)
		beq.s	loc_1ACF4
		neg.w	$14(a0)

loc_1ACF4:
		bset	#2,$22(a0)
		move.b	#0,($FFFFD11C).w
		move.w	#$BC,d0
		jsr     (Play_Sfx)
		bra.s	loc_1AD78
; ===========================================================================
Dash_Speeds:	dc.w  $800		; 0
		dc.w  $880		; 1
		dc.w  $900		; 2
		dc.w  $980		; 3
		dc.w  $A00		; 4
		dc.w  $A80		; 5
		dc.w  $B00		; 6
		dc.w  $B80		; 7
		dc.w  $C00		; 8
; ===========================================================================

loc_1AD30:				; If still charging the dash...
		tst.w	$3A(a0)
		beq.s	loc_1AD48
		move.w	$3A(a0),d0
		lsr.w	#5,d0
		sub.w	d0,$3A(a0)
		bcc.s	loc_1AD48
		move.w	#0,$3A(a0)

loc_1AD48:
		move.b	($FFFFF603).w,d0
		andi.b	#$70,d0	; 'p'
		beq.w	loc_1AD78
		move.w	#$900,$1C(a0)
		move.w	#$E0,d0  ; changed from #$E0
                jsr     (Play_Sfx)
		addi.w	#$200,$3A(a0)
		cmpi.w	#$800,$3A(a0)
		bcs.s	loc_1AD78
		move.w	#$800,$3A(a0)

loc_1AD78:
		addq.l	#4,sp
		cmpi.w	#$60,($FFFFEED8).w
		beq.s	loc_1AD8C
		bcc.s	loc_1AD88
		addq.w	#4,($FFFFEED8).w

loc_1AD88:
		subq.w	#2,($FFFFEED8).w

loc_1AD8C:
		rts
; End of subroutine Sonic_SpinDash

Fixing an error

when you build it you most likely an error to fix this go to line 25863

        bra     loc_FBF4

See this line delete it!

If your doing this on the nick arcade text disassembly the error won't happen.

Also if I was doing a part 2 a lot of steps for the Nick arcade will be the same as the sonic 1 tutorial like fixing the monitor bug and adding the sound.

Thank you for reading this guide and hopefully you'll be less annoyed

SCHG How-To Guide: Sonic 2 Beta (16-bit)
Design Choices
Add final spindash to Sonic 2 Beta | SCHG How-to:How to port paralax plouds to the Nick Arcade prototype


SCHG How-To Guide: Sonic the Hedgehog 2 (16-bit)
Fixing Bugs
Fix Demo Playback | Fix a Race Condition with Pattern Load Cues | Fix Super Sonic Bugs | Use Correct Height When Roll Jumping | Fix Jump Height Bug When Exiting Water | Fix Spin Dash Code and Add Spin Dash Speeds | Fix Screen Boundary Spin Dash Bug | Correct Drowning Bugs | Fix Camera Y Position for Tails | Fix Tails Subanimation Error | Fix Tails' Respawn Speeds | Fix Accidental Deletion of Scattered Rings | Fix Ring Timers | Fix Rexon Crash | Fix Monitor Collision Bug | Fix EHZ Deformation Bug | Correct CPZ Boss Attack Behavior | Fix Bug in ARZ Boss Arrow's Platform Behavior | Fix ARZ Boss Walking on Air Glitch | Fix ARZ Boss Sprite Behavior | Fix Multiple CNZ Boss Bugs | Fix HTZ Background Scrolling Mountains | Fix OOZ Launcher Speed Up Glitch | Fix DEZ Giant Mech Collision Glitch | Fix Boss Deconstruction Behavior | Fix Speed Bugs
Design Choices
Remove the Air Speed Cap | Disable Floor Collision While Dying | Modify Super Sonic Transformation Methods & Behavior | Enable/Disable Tails in Certain Levels | Collide with Water After Being Hurt | Retain Rings When Returning at a Star Post | Improve the Fade In\Fade Out Progression Routines | Fix Scattered Rings' Underwater Physics | Insert LZ Water Ripple Effect | Restore Lost CPZ Boss Feature | Prevent SCZ Tornado Spin Dash Death | Improve ObjectMove Subroutines | Port S3K Rings Manager | Port S3K Object Manager | Port S3K Priority Manager | Edit Level Order with ASM‎ | Alter Ring Requirements in Special Stages | Make Special Stage Characters Use Normal DPLCs | Speed Up Ring Loss Process | Add beta spindash to Sonic 2 | Change spike behaviour in Sonic 2
Adding Features
Create Insta-kill and High Jump Monitors | Create Clone and Special Stage Monitors | Port Knuckles
Sound Features
Port Sonic 1 Sound Driver | Port Sonic 2 Clone Driver | Port Sonic 3 Sound Driver | Expand the Music Index to Start at $00 (Sonic 2 Clone Driver Version)
Extending the Game
Extend the Level Index Past $10 | Extend the Level Select | Extend Water Tables | Add Extra Characters | Free Up 2 Universal SSTs