Actions

SCHG How-to

Fix the EHZ Deformation bug

From Sonic Retro

(Original guide by qiuu)

In Sonic 2 is in EHZ a small deformation bug, the lowest two layers don't scroll as they are not affected by the deformation code:

S2-EHZ-Deform-Bug.png


To fix this, go to SwScrl_EHZ:. Scroll down until you see SwScrl_RippleData:. Above it you should have this piece of code:

	move.w	#($B4)/12-1,d1 ; $B4 bytes
-	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	swap	d3
	add.l	d0,d3
	add.l	d0,d3
	add.l	d0,d3
	swap	d3
	dbf	d1,-

	rts

Copy and paste this code twice into it:

	move.w	d4,(a1)+
	move.w	d3,(a1)+

In the end it should look like this:

	move.w	#($B4)/12-1,d1 ; $B4 bytes
-	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	swap	d3
	add.l	d0,d3
	add.l	d0,d3
	add.l	d0,d3
	swap	d3
	dbf	d1,-
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+

	rts

And that's it! Now it should look fixed:

S2-EHZ-Deform-Fixed.png

Sonic 2 Beta

This bug can also be fixed in the Sonic 2 Beta.

Just replace the code with this:

	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	swap	d3
	add.l	d0,d3
	add.l	d0,d3
	add.l	d0,d3
	swap	d3
	dbf	d1,loc_61B2
	move.w	d4,(a1)+
	move.w	d3,(a1)+
	move.w	d4,(a1)+
	move.w	d3,(a1)+

	rts


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