In 2015, I created a tutorial for a modified version of MarkeyJester's palette fading subroutine which would smoothly fade from and to white. It turns out that tutorial had a pretty big flaw in that when fading in from white, the colors would be a shade darker than they should be. Special thanks to Iso Kilo for bringing this to my attention. In Sonic 1's Hivebrain disassembly, just replace the beginning of Pal_MakeWhite to the end of Pal_AddColor2. Implementing this into other disassemblies or Sonic games should just require replacing the variables and calls to outside subroutines with your disassembly's equivalent. Code: ; --------------------------------------------------------------------------- ; Subroutine to fill the pallet with white (special stage) ; --------------------------------------------------------------------------- ; ||||||||||||||| S U B R O U T I N E ||||||||||||||||||||||||||||||||||||||| Pal_MakeWhite: ; XREF: SpecialStage move.w #$3F,($FFFFF626).w moveq #0,d0 lea ($FFFFFB00).w,a0 move.b ($FFFFF626).w,d0 adda.w d0,a0 move.w #$EEE,d1 move.b ($FFFFF627).w,d0 PalWhite_Loop: move.w d1,(a0)+ dbf d0,PalWhite_Loop ; fill pallet with $000 (black) moveq #$0E,d4 ; MJ: prepare maximum colour check moveq #$00,d6 ; MJ: clear d6 loc_1EF4: bsr.w RunPLC_RAM move.b #$12,($FFFFF62A).w bsr.w DelayProgram bchg #$00,d6 ; MJ: change delay counter beq loc_1EF4 ; MJ: if null, delay a frame bsr.s Pal_WhiteToBlack subq.b #$02,d4 ; MJ: decrease colour check bne loc_1EF4 ; MJ: if it has not reached null, branch move.b #$12,($FFFFF62A).w ; MJ: wait for V-blank again (so colours transfer) bra DelayProgram ; MJ: '' ; End of function Pal_MakeWhite ; ||||||||||||||| S U B R O U T I N E ||||||||||||||||||||||||||||||||||||||| Pal_WhiteToBlack: ; XREF: Pal_MakeWhite moveq #0,d0 lea ($FFFFFB00).w,a0 lea ($FFFFFB80).w,a1 move.b ($FFFFF626).w,d0 adda.w d0,a0 adda.w d0,a1 move.b ($FFFFF627).w,d0 loc_1F20: bsr.s Pal_DecColor2 dbf d0,loc_1F20 cmpi.b #1,($FFFFFE10).w bne.s locret_1F4A moveq #0,d0 lea ($FFFFFA80).w,a0 lea ($FFFFFA00).w,a1 move.b ($FFFFF626).w,d0 adda.w d0,a0 adda.w d0,a1 move.b ($FFFFF627).w,d0 loc_1F44: bsr.s Pal_DecColor2 dbf d0,loc_1F44 locret_1F4A: rts ; End of function Pal_WhiteToBlack ; ||||||||||||||| S U B R O U T I N E ||||||||||||||||||||||||||||||||||||||| Pal_DecColor2: ; XREF: Pal_WhiteToBlack move.b (a1),d5 ; MJ: load blue move.w (a1)+,d1 ; MJ: load green and red move.b d1,d2 ; MJ: load red lsr.b #$04,d1 ; MJ: get only green andi.b #$0E,d2 ; MJ: get only red move.w (a0),d3 ; MJ: load current colour in buffer cmp.b d5,d4 ; MJ: is it time for blue to fade? bls FCI2_NoBlue ; MJ: if not, branch subi.w #$0200,d3 ; MJ: dencrease blue FCI2_NoBlue: cmp.b d1,d4 ; MJ: is it time for green to fade? bls FCI2_NoGreen ; MJ: if not, branch subi.b #$20,d3 ; MJ: dencrease green FCI2_NoGreen: cmp.b d2,d4 ; MJ: is it time for red to fade? bls FCI2_NoRed ; MJ: if not, branch subq.b #$02,d3 ; MJ: dencrease red FCI2_NoRed: move.w d3,(a0)+ ; MJ: save colour rts ; MJ: return ; End of function Pal_DecColor2 ; --------------------------------------------------------------------------- ; Subroutine to make a white flash when you enter a special stage ; --------------------------------------------------------------------------- ; ||||||||||||||| S U B R O U T I N E ||||||||||||||||||||||||||||||||||||||| Pal_MakeFlash: ; XREF: SpecialStage move.w #$3F,($FFFFF626).w moveq #$07,d4 ; MJ: set repeat times moveq #$00,d6 ; MJ: clear d6 loc_1F86: bsr.w RunPLC_RAM move.b #$12,($FFFFF62A).w bsr.w DelayProgram bchg #$00,d6 ; MJ: change delay counter beq loc_1F86 ; MJ: if null, delay a frame bsr.s Pal_ToWhite dbf d4,loc_1F86 rts ; End of function Pal_MakeFlash ; ||||||||||||||| S U B R O U T I N E ||||||||||||||||||||||||||||||||||||||| Pal_ToWhite: ; XREF: Pal_MakeFlash moveq #0,d0 lea ($FFFFFB00).w,a0 move.b ($FFFFF626).w,d0 adda.w d0,a0 move.b ($FFFFF627).w,d0 loc_1FAC: bsr.s Pal_AddColor2 dbf d0,loc_1FAC moveq #0,d0 lea ($FFFFFA80).w,a0 move.b ($FFFFF626).w,d0 adda.w d0,a0 move.b ($FFFFF627).w,d0 loc_1FC2: bsr.s Pal_AddColor2 dbf d0,loc_1FC2 rts ; End of function Pal_ToWhite ; ||||||||||||||| S U B R O U T I N E ||||||||||||||||||||||||||||||||||||||| Pal_AddColor2: ; XREF: Pal_ToWhite move.w (a0),d5 ; MJ: load colour cmpi.w #$EEE,d5 beq.s FCO2_NoRed move.w d5,d1 ; MJ: copy to d1 move.b d1,d2 ; MJ: load green and red move.b d1,d3 ; MJ: load red andi.w #$0E00,d1 ; MJ: get only blue cmpi.w #$0E00,d1 beq FCO2_NoBlue ; MJ: if blue is finished, branch addi.w #$0200,d5 ; MJ: increase blue FCO2_NoBlue: andi.w #$00E0,d2 ; MJ: get only green (needs to be word) cmpi.w #$00E0,d2 beq FCO2_NoGreen ; MJ: if green is finished, branch addi.b #$20,d5 ; MJ: increase green FCO2_NoGreen: andi.b #$0E,d3 ; MJ: get only red cmpi.b #$0E,d3 beq FCO2_NoRed ; MJ: if red is finished, branch addq.b #$02,d5 ; MJ: increase red FCO2_NoRed: move.w d5,(a0)+ ; MJ: save new colour rts ; MJ: return ; End of function Pal_AddColor2
You may want to actually include an example of the issue. As well as an explanation as to what you changed from last time: Just helps give a better understanding as to what's being done.
