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Have a functional Eggman monitor in Sonic 1

From Sonic Retro

Revision as of 17:09, 1 September 2010 by Nineko (talk | contribs) (For the sake of it :U)
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(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:

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
And replace it with this:
Obj2E_ChkEggman:    ; XREF: Obj2E_Move
        addq.b    #2,$24(a0)
        move.w    #29,$1E(a0)
        move.b    $1C(a0),d0
        cmpi.b    #1,d0; does monitor contain Eggman?
        bne.s    Obj2E_ChkSonic
        move.l    a0,a1
        move.l    a0,-(sp)
        lea    ($FFFFD000).w,a0
        jsr    Touch_ChkHurt
        move.l    (sp)+,a0
        rts
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.