I've decided to take a step back from all of the technical tutorials and instead move over to a preference tutorial. If you want to make a use out of the unused Sonic 1 monitors, then follow this guide as I show you how to implement Negative Rings into Sonic 1. Reminder that we're using Hivebrain 2005, but I'm sure you can figure out the labels for GitHub. There are two things before we start. First, we need to define negative rings, as in, how will they work? You can find negative ring boxes scattered across levels (once they're placed into the levels). Upon breaking them, one of two things could happen. Either, you lose 10 rings, or, if you have less than 10 rings, your ring counter is negated and is set into the negatives, where the ring text will constantly flash red until you collect enough rings or ring boxes to get out of the negatives. That's how we're going to make them work in our tutorial. The other thing to mention is that you need a free RAM address. I'm using $FFFFF5C1 for our tutorial, defined as NegativeRingsFlag. Ok, now we can begin! First, replace the entirety of Obj2E_ChkS with this: Code: Obj2E_ChkS: cmpi.b #7,d0 ; does monitor contain 'S' bne.s Obj2E_ChkNegaring nop Obj2E_ChkNegaring: cmpi.b #8,d0 bne.s Obj2E_ChkEnd move.w ($FFFFFE20).w, d0 cmpi.b #$A, d0 blt.s Obj2E_IntoNegs Obj2E_RmvRings: subi.w #$A,($FFFFFE20).w ; subtract 10 rings from the number of rings you have ori.b #1,($FFFFFE1D).w ; update the ring counter move.w #$B5,d0 jmp (PlaySound).l ; play ring sound Obj2E_IntoNegs: tst.b NegativeRingFlag beq.s @yes bra.w Obj2E_RmvRings @yes: move.b #$01,(NegativeRingFlag).w move.w #$A1,d0 jmp (PlaySound).l ; play ring sound This is the code to make our negative ring box function. It's probably recommended that you change the sounds for this, I was using the checkpoint sound to tell me if we went into Negative mode. Next, you're going to want to replace Obj2E_ChkRings with this: Code: Obj2E_ChkRings: cmpi.b #6,d0 ; does monitor contain 10 rings? bne.s Obj2E_ChkS tst.b NegativeRingFlag bne.s Obj2E_ExitDebt addi.w #$A,($FFFFFE20).w ; add 10 rings to the number of rings you have ori.b #1,($FFFFFE1D).w ; update the ring counter cmpi.w #100,($FFFFFE20).w ; check if you have 100 rings bcs.s Obj2E_RingSound bset #1,($FFFFFE1B).w beq.w ExtraLife cmpi.w #200,($FFFFFE20).w ; check if you have 200 rings bcs.s Obj2E_RingSound bset #2,($FFFFFE1B).w beq.w ExtraLife Obj2E_RingSound: move.w #$B5,d0 jmp (PlaySound).l ; play ring sound Obj2E_ExitDebt: move.w ($FFFFFE20).w, d0 cmpi.b #$A, d0 ; do we have 10 negarings? blt.s @yes subi.w #$A,($FFFFFE20).w ; subtract 10 rings from the number of negarings you have move.b #$80,($FFFFFE1D).w ; update ring counter move.w #$B5,d0 jmp (PlaySound).l ; play ring sound @yes: move.w #0,($FFFFFE20).w ; reset number of rings to zero move.b #$80,($FFFFFE1D).w ; update ring counter move.b #$00,(NegativeRingFlag).w move.w #$B5,d0 jmp (PlaySound).l ; play ring sound Now, whenever you collect a ring box whilst in Negative mode, you can get rid of 10 negative rings or get rid of all of them entirely. Now, we need to actually make the rings themselves remove a negative ring. Go to CollectRing and replace that with this: Code: CollectRing: ; XREF: Obj25_Collect tst.b NegativeRingFlag bne.w CollectRingN addq.w #1,($FFFFFE20).w ; add 1 to rings ori.b #1,($FFFFFE1D).w ; update the rings counter move.w #$B5,d0 ; play ring sound cmpi.w #100,($FFFFFE20).w ; do you have < 100 rings? bcs.s Obj25_PlaySnd ; if yes, branch bset #1,($FFFFFE1B).w ; update lives counter beq.s loc_9CA4 cmpi.w #200,($FFFFFE20).w ; do you have < 200 rings? bcs.s Obj25_PlaySnd ; if yes, branch bset #2,($FFFFFE1B).w ; update lives counter bne.s Obj25_PlaySnd loc_9CA4: addq.b #1,($FFFFFE12).w ; add 1 to the number of lives you have addq.b #1,($FFFFFE1C).w ; add 1 to the lives counter move.w #$88,d0 ; play extra life music Obj25_PlaySnd: jmp (PlaySound_Special).l ; End of function CollectRing CollectRingN: subi.w #$1,($FFFFFE20).w ; subtract 1 ring from the number of negarings you have move.b #$80,($FFFFFE1D).w ; update ring counter move.w #$B5,d0 jmp (PlaySound).l ; play ring sound Next, go to Level_MainLoop and insert this before cmpi.b #8,($FFFFF600).w: Code: tst.w ($FFFFFE20).w beq.s @yes bra.w @skip @yes: move.b #$00,(NegativeRingFlag).w @skip: This will disable the Negative Ring flag when our counter hits zero, so that way, we don't underflow to 255 and glitch out the counter. Next, go to HurtSonic and add this below beq.w Hurt_NoRings: Code: tst.w NegativeRingFlag ; are we in the negatives? bne.w Hurt_NoRings Next, go to Obj3A_RingBonus and add this below beq.s Obj3A_ChkBonus: Code: tst.w NegativeRingFlag ; are we in the negatives? bne.s Obj3A_ChkBonus ; if so, branch This will prevent the negative rings from being added to your score! Finally, go to Obj21_Flash and replace it with this: Code: Obj21_Flash: ; XREF: Obj21_Main moveq #0,d0 btst #3,($FFFFFE05).w bne.s Obj21_Display tst.w NegativeRingFlag ; are we in the negatives? bne.s @flashred ; if so, branch tst.w ($FFFFFE20).w ; do you have any rings? bne.s Obj21_Flash2 ; if not, branch @flashred: addq.w #1,d0 ; make ring counter flash red You've finally implemented Negative Rings into Sonic 1, but, that Goggles monitor is sort of ugly. Lucky for you, I'm willing to give away the simple edit I did for the Monitor art. You can download it below. Happy hacking! :b Quick Edit: Forgot a step! Quick Edit: Forgot another step!
