Difference between revisions of "Have a functional Eggman monitor in Sonic 1"

Revision as of 08:45, 30 April 2013

(Original guide by nineko) This very simple guide will tell you how to get a functional Eggman monitor in Sonic 1. It targets the Hivebrain 2005 Disassembly.

Find this code: <asm>Obj2E_ChkEggman: ; XREF: Obj2E_Move

       addq.b    #2,$24(a0)
       move.w    #29,$1E(a0)
       move.b    $1C(a0),d0
       cmpi.b    #1,d0; does monitor contain Eggman?
       bne.s    Obj2E_ChkSonic
       rts    ; Eggman monitor does nothing</asm>And replace it with this:

<asm>Obj2E_ChkEggman: ; XREF: Obj2E_Move

       addq.b    #2,$24(a0)
       move.w    #29,$1E(a0)
       move.b    $1C(a0),d0
       cmpi.b    #1,d0; does monitor contain Eggman?
       bne.s    Obj2E_ChkSonic ; if not, go and check for the next monitor type (1-up icon)
       move.l    a0,a1 ; move a0 to a1, because Touch_ChkHurt wants the damaging object to be in a1
       move.l    a0,-(sp) ; push a0 on the stack, and decrement stack pointer
       lea    ($FFFFD000).w,a0 ; put Sonic's ram address in a0, because Touch_ChkHurt wants the damaged object to be in a0
       jsr    Touch_ChkHurt ; run the Touch_ChkHurt routine
       move.l    (sp)+,a0 ; pop the previous value of a0 from the stack, and increment stack pointer
       rts ; The Eggman monitor now does something!</asm>Simple, isn't it? And it's set up in a way to use the regular "Touch_ChkHurt" routine, so shields and invincibilities are already taken in account by existing code, and the Eggman monitor will damage you like every other hazard would.

SCHG How-To Guide: Sonic the Hedgehog (16-bit)
Fixing Bugs
Fix Demo Playback \| Fix a Race Condition with Pattern Load Cues \| Fix the SEGA Sound \| Display the Press Start Button Text \| Fix the Level Select Menu \| Fix the Hidden Points Bug \| Fix Accidental Deletion of Scattered Rings \| Fix Ring Timers \| Fix the Walk-Jump Bug \| Correct Drowning Bugs \| Fix the Death Boundary Bug \| Fix the Camera Follow Bug \| Fix Song Restoration Bugs \| Fix the HUD Blinking \| Fix the Level Select Graphics Bug \| Fix a remember sprite related bug
Changing Design Choices
Change Spike Behavior \| Collide with Water After Being Hurt \| Fix Special Stage Jumping Physics \| Improve the Fade In\Fade Out Progression Routines \| Fix Scattered Rings' Underwater Physics \| Remove the Speed Cap \| Port the REV01 Background Effects \| Port Sonic 2's Level Art Loader \| Retain Rings Between Acts \| Add Sonic 2 (Simon Wai Prototype) Level Select \| Improve ObjectMove Subroutines \| Port Sonic 2 Level Select
Adding Features
Add Spin Dash ( Part 1 / Part 2 / Part 3 / Part 4 ) \| Add Eggman Monitor \| Add Super Sonic \| Add the Air Roll
Sound Features
Expand the Sound Index \| Play Different Songs Per Act \| Port Sonic 2 Final Sound Driver \| Port Sonic 3's Sound Driver \| Port Flamewing's Sonic 3 & Knuckles Sound Driver \| Change The SEGA Sound
Extending the Game
Load Chunks From ROM \| Add Extra Characters \| Make an Alternative Title Screen \| Use Dynamic Tilesets \| Make GHZ Load Alternate Art \| Make Ending Load Alternate Art \| Add a New Zone \| Set Up the Goggle Monitor \| Add New Moves \| Add a Dynamic Collision System \| Dynamic Special Stage Walls System \| Extend Sprite Mappings and Art Limit \| Enigma Credits \| Use Dynamic Palettes
Miscellaneous
Convert the Hivebrain 2005 Disassembly to ASM68K
Split Disassembly Guides
Set Up a Split Disassembly \| Basic Level Editing \| Basic Art Editing \| Basic ASM Editing (Spin Dash)

SCHG How-to

Difference between revisions of "Have a functional Eggman monitor in Sonic 1"

From Sonic Retro

Revision as of 08:45, 30 April 2013

@@ Line 3: / Line 3: @@
 Find this code:
-<pre>Obj2E_ChkEggman:    ; XREF: Obj2E_Move
+<asm>Obj2E_ChkEggman:    ; XREF: Obj2E_Move
          addq.b    #2,$24(a0)
          move.w    #29,$1E(a0)
@@ Line 9: / Line 9: @@
          cmpi.b    #1,d0; does monitor contain Eggman?
          bne.s    Obj2E_ChkSonic
-         rts    ; Eggman monitor does nothing</pre>And replace it with this:
+         rts    ; Eggman monitor does nothing</asm>And replace it with this:
-<pre>Obj2E_ChkEggman:    ; XREF: Obj2E_Move
+<asm>Obj2E_ChkEggman:    ; XREF: Obj2E_Move
          addq.b    #2,$24(a0)
          move.w    #29,$1E(a0)
@@ Line 21: / Line 21: @@
          jsr    Touch_ChkHurt ; run the Touch_ChkHurt routine
          move.l    (sp)+,a0 ; pop the previous value of a0 from the stack, and increment stack pointer
-         rts ; The Eggman monitor now does something!</pre>Simple, isn't it? And it's set up in a way to use the regular "Touch_ChkHurt" routine, so shields and invincibilities are already taken in account by existing code, and the Eggman monitor will damage you like every other hazard would.{{S1Howtos}}
+         rts ; The Eggman monitor now does something!</asm>Simple, isn't it? And it's set up in a way to use the regular "Touch_ChkHurt" routine, so shields and invincibilities are already taken in account by existing code, and the Eggman monitor will damage you like every other hazard would.{{S1Howtos}}
 [[Category:SCHG How-tos|Have_a_functional_Eggman_monitor_in_Sonic_1]]