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SCHG How-to

Fix Sonic 2 Sega Screen

From Sonic Retro

Made For Sonic 2 all revisions, Originally made in AMPS sonic 2 but adapted for regular sonic 2 github

Guide By RobiWanKenobi

Github

If you have ported in sprites from other Sonic games or other games in general, you may have noticed the Sega screen is messed up.

This is good to do if you plan on porting sprites without that aren't converted to sonic 2's mappings and DPLCs.

Make a copy of the Sonic 2 sprites, mappings, and DPLCs for Sonic. Make in art/uncompressed SegaSonic.bin with a copy of the sonic 2 sprites, Also SegaSonicMap.bin and in mappings/spriteDPLC make SegaSonic.bin with the sonic 2 DPLCS

Now in s2.asm

Find this line of code for Sonic's art.


;---------------------------------------------------------------------------------------
; Uncompressed art
; Patterns for Sonic  ; ArtUnc_50000:
;---------------------------------------------------------------------------------------
	align $20
ArtUnc_Sonic:	BINCLUDE	"art/uncompressed/Sonic's art.bin"
;---------------------------------------------------------------------

Right after the art import for Sonic add in.


;---------------------------------------------------------------------
	align $20
ArtUnc_SegaSonic:	BINCLUDE	"art/uncompressed/SegaSonic.bin"
;---------------------------------------------------------------------------------------

Now right below this section of code.


;--------------------------------------------------------------------------------------
; Sprite Mappings
; Sonic			; MapUnc_6FBE0: SprTbl_Sonic:
;--------------------------------------------------------------------------------------

Add this line of code

;--------------------------------------------------------------------------------------
Mapunc_SegaSonic:	BINCLUDE	"mappings/sprite/SegaSonicMap.bin"
;--------------------------------------------------------------------------------------

Now replace this line of code.


;--------------------------------------------------------------------------------------
; Sprite Dynamic Pattern Reloading
; Sonic DPLCs   		; MapRUnc_714E0:
;--------------------------------------------------------------------------------------
; WARNING: the build script needs editing if you rename this label
;          or if you move Sonic's running frame to somewhere else than frame $2D
;Sega Screen Sonic
MapRUnc_Sonic:	BINCLUDE	"mappings/spriteDPLC/Sonic.bin"
;--------------------------------------------------------------------------------------

With this line of code.


;--------------------------------------------------------------------------------------
; Sprite Dynamic Pattern Reloading
; Sonic DPLCs   		; MapRUnc_714E0:
;--------------------------------------------------------------------------------------
; WARNING: the build script needs editing if you rename this label
;          or if you move Sonic's running frame to somewhere else than frame $2D
;Sega Screen Sonic
MapRUnc_Sonic:	BINCLUDE	"mappings/spriteDPLC/SegaSonic.bin"
;--------------------------------------------------------------------------------------
;--------------------------------------------------------------------------------------
;Sonic's ingame sprites
MapRUnc_Sonic3:	BINCLUDE	"mappings/spriteDPLC/Sonic.bin"
;--------------------------------------------------------------------------------------
But now, if you have other sprites, you will notice that the sonic sprites are messed up, to fix that, go to
 LoadSonicDymPLC_Part2
and change this.


LoadSonicDynPLC_Part2:
	cmp.b	(Sonic_LastLoadedDPLC).w,d0
	beq.s	return_1B89A
	move.b	d0,(Sonic_LastLoadedDPLC).w
	lea	(MapRUnc_Sonic).l,a2
	add.w	d0,d0
	adda.w	(a2,d0.w),a2
	move.w	(a2)+,d5
	subq.w	#1,d5
	bmi.s	return_1B89A
	move.w	#tiles_to_bytes(ArtTile_ArtUnc_Sonic),d4

To this


LoadSonicDynPLC_Part2:
	cmp.b	(Sonic_LastLoadedDPLC).w,d0
	beq.s	return_1B89A
	move.b	d0,(Sonic_LastLoadedDPLC).w
	lea	(MapRUnc_Sonic3).l,a2
	add.w	d0,d0
	adda.w	(a2,d0.w),a2
	move.w	(a2)+,d5
	subq.w	#1,d5
	bmi.s	return_1B89A
	move.w	#tiles_to_bytes(ArtTile_ArtUnc_Sonic),d4

Now change this


ObjB0_Init:
	bsr.w	LoadSubObject
	move.w	#$1E8,x_pixel(a0)
	move.w	#$F0,y_pixel(a0)
	move.w	#$B,objoff_2A(a0)
	move.w	#2,(SegaScr_VInt_Subrout).w
	bset	#0,render_flags(a0)
	bset	#0,status(a0)

	; Initialize streak horizontal offsets for Sonic going left.
	; 9 full lines (8 pixels) + 6 pixels, 2-byte interleaved entries for PNT A and PNT B
	lea	(Horiz_Scroll_Buf + 2 * 2 * (9 * 8 + 6)).w,a1
	lea	Streak_Horizontal_offsets(pc),a2
	moveq	#0,d0
	moveq	#$22,d6	; Number of streaks-1
-	move.b	(a2)+,d0
	add.w	d0,(a1)
	addq.w	#2 * 2 * 2,a1	; Advance to next streak 2 pixels down
	dbf	d6,-

	lea	off_3A294(pc),a1 ; pointers to mapping DPLC data
	lea	(ArtUnc_Sonic).l,a3
	lea	(Chunk_Table).l,a5
	moveq	#4-1,d5 ; there are 4 mapping frames to loop over


To this


ObjB0_Init:
	bsr.w	LoadSubObject
	move.w	#$1E8,x_pixel(a0)
	move.w	#$F0,y_pixel(a0)
	move.w	#$B,objoff_2A(a0)
	move.w	#2,(SegaScr_VInt_Subrout).w
	bset	#0,render_flags(a0)
	bset	#0,status(a0)

	; Initialize streak horizontal offsets for Sonic going left.
	; 9 full lines (8 pixels) + 6 pixels, 2-byte interleaved entries for PNT A and PNT B
	lea	(Horiz_Scroll_Buf + 2 * 2 * (9 * 8 + 6)).w,a1
	lea	Streak_Horizontal_offsets(pc),a2
	moveq	#0,d0
	moveq	#$22,d6	; Number of streaks-1
-	move.b	(a2)+,d0
	add.w	d0,(a1)
	addq.w	#2 * 2 * 2,a1	; Advance to next streak 2 pixels down
	dbf	d6,-

	lea	off_3A294(pc),a1 ; pointers to mapping DPLC data
	lea	(ArtUnc_SegaSonic).l,a3
	lea	(Chunk_Table).l,a5
	moveq	#4-1,d5 ; there are 4 mapping frames to loop over

if done right, it works, even with sonic 3 sprites.

FixedSegaScreen.png

S3 SpritesInFix.png

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 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 | Fix 14 Continues Cheat | Fix Debug Mode Crash | Fix 99+ Lives | Fix Sonic 2's Sega Screen
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 | 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
Expand Music Index to Start at $00 | Port Sonic 1 Sound Driver | Port Sonic 2 Clone Driver | Port Sonic 3 Sound Driver | Port Flamewing's Sonic 3 & Knuckles Sound Driver | Expand the Music Index to Start at $00 (Sonic 2 Clone Driver Version) | Play Different Songs Per Act
Extending the Game
Extend the Level Index Past $10 | Extend the Level Select | Extend Water Tables | Add Extra Characters | Free Up 2 Universal SSTs