Difference between revisions of "Improve the fade in\fade out progression routines in Sonic 2"
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The main palette fading routines are known as "Pal_FadeTo" and "Pal_FadeFrom", you'll need to go to the routine "Pal_FadeTo" and replace everything from there down to "; End of function Pal_DecColor" with this: | The main palette fading routines are known as "Pal_FadeTo" and "Pal_FadeFrom", you'll need to go to the routine "Pal_FadeTo" and replace everything from there down to "; End of function Pal_DecColor" with this: | ||
− | <asm>Pal_FadeTo: | + | <syntaxhighlight lang="asm">Pal_FadeTo: |
move.w #$3F,($FFFFF626).w | move.w #$3F,($FFFFF626).w | ||
moveq #0,d0 | moveq #0,d0 | ||
Line 210: | Line 210: | ||
At routine "ObjC9", you'll find this code below: | At routine "ObjC9", you'll find this code below: | ||
− | <asm>ObjC9: | + | <syntaxhighlight lang="asm">ObjC9: |
moveq #0,d0 | moveq #0,d0 | ||
move.b routine(a0),d0 | move.b routine(a0),d0 | ||
Line 267: | Line 267: | ||
There's a problem here however, that first ori.b #$46,d4 is infact two words of pointer data being 0004 and 0046, these are the routines address minus the table start address, this means that the "; unused/dead code" isn't actually unused, the table was just disassembled incorrectly, below I have provided a fix for this mistake, along with the necessary changes required for the fading to perform correctly: | There's a problem here however, that first ori.b #$46,d4 is infact two words of pointer data being 0004 and 0046, these are the routines address minus the table start address, this means that the "; unused/dead code" isn't actually unused, the table was just disassembled incorrectly, below I have provided a fix for this mistake, along with the necessary changes required for the fading to perform correctly: | ||
− | <asm>ObjC9: | + | <syntaxhighlight lang="asm">ObjC9: |
moveq #0,d0 | moveq #0,d0 | ||
move.b routine(a0),d0 | move.b routine(a0),d0 | ||
Line 332: | Line 332: | ||
This will ensure the object uses our new fading routines correctly, the next thing to do is at: | This will ensure the object uses our new fading routines correctly, the next thing to do is at: | ||
− | <asm>off_1338C: C9PalInfo Pal_AddColor, Pal_1342C, $60, $F,2,$15</syntaxhighlight> | + | <syntaxhighlight lang="asm">off_1338C: C9PalInfo Pal_AddColor, Pal_1342C, $60, $F,2,$15</syntaxhighlight> |
Because of the nature of the new fade in routine being faster in the transition, we need to change the end value $15 to something smaller, say $07: | Because of the nature of the new fade in routine being faster in the transition, we need to change the end value $15 to something smaller, say $07: | ||
− | <asm>off_1338C: C9PalInfo Pal_AddColor, Pal_1342C, $60, $F,2,$07 ; MJ: 15 to 7</syntaxhighlight> | + | <syntaxhighlight lang="asm">off_1338C: C9PalInfo Pal_AddColor, Pal_1342C, $60, $F,2,$07 ; MJ: 15 to 7</syntaxhighlight> |
This ensures the fading in routine is used correctly by the object, now there's one more fix to look at, if the player presses start to skip the transition halfway through fading in, the object continues fading in even though the entire full palette is loaded, to fix this goto "loc_135D6:": | This ensures the fading in routine is used correctly by the object, now there's one more fix to look at, if the player presses start to skip the transition halfway through fading in, the object continues fading in even though the entire full palette is loaded, to fix this goto "loc_135D6:": | ||
− | <asm>loc_135D6: | + | <syntaxhighlight lang="asm">loc_135D6: |
move.l (a1)+,(a2)+ | move.l (a1)+,(a2)+ | ||
dbf d6,loc_135D6 | dbf d6,loc_135D6 | ||
Line 350: | Line 350: | ||
And place this instruction just after the "dbf d6,loc_135D6" instruction: | And place this instruction just after the "dbf d6,loc_135D6" instruction: | ||
− | <asm> sf.b (Object_RAM+($100+$32)).w ; set fade counter to 00 (finish)</syntaxhighlight> | + | <syntaxhighlight lang="asm"> sf.b (Object_RAM+($100+$32)).w ; set fade counter to 00 (finish)</syntaxhighlight> |
This will set the palette fading objects fade counter to 0 and set the object to delete itself, thus preventing it from messing with the palette if the transition was skipped. | This will set the palette fading objects fade counter to 0 and set the object to delete itself, thus preventing it from messing with the palette if the transition was skipped. |
Revision as of 21:46, 20 December 2015
(Original guide by MarkeyJester)
The palette fading routines in Sonic 1 and Sonic 2 (and possibly to a degree Sonic 3 & Knuckles) known as "Pal_FadeTo" and "Pal_FadeFrom", are not 100% true to their name. Here is a screenshot of Sonic 2's title screen 6 frames during fade in:
From Sonic Team's point of view, it may not be incorrect and is possibly intentional, however, from a logical point of view, this is incorrect fading, what happens here is it fades the blue parts in first, then fades the green parts in, and then finally fades the red parts in, the same goes for fading out, red first, then green, finally blue. Strictly speaking for a the nearest possible perfect fade, all colours need to be fading in and out simultaneously (At the correct timing of course), so for example the colour 06E4 should fade in the pattern of:
0020 | 0040 | 0060 | 0080 | 02A0 | 04C2 | 06E4 |
And fade out in the pattern of:
04C2 | 02A0 | 0080 | 0060 | 0040 | 0020 | 0000 |
To make the above function for Sonic 2, there are two main places to look at:
The Main Routine
The main palette fading routines are known as "Pal_FadeTo" and "Pal_FadeFrom", you'll need to go to the routine "Pal_FadeTo" and replace everything from there down to "; End of function Pal_DecColor" with this:
Pal_FadeTo:
move.w #$3F,($FFFFF626).w
moveq #0,d0
lea (Normal_palette).w,a0
move.b ($FFFFF626).w,d0
adda.w d0,a0
moveq #0,d1
move.b ($FFFFF627).w,d0
; loc_23DE:
Pal_ToBlack:
move.w d1,(a0)+
dbf d0,Pal_ToBlack ; fill palette with $000 (black)
moveq #$0E,d4 ; MJ: prepare maximum colour check
moveq #$00,d6 ; MJ: clear d6
- bsr.w RunPLC_RAM
move.b #$12,(Delay_Time).w
bsr.w DelayProgram
bchg #$00,d6 ; MJ: change delay counter
beq - ; MJ: if null, delay a frame
bsr.s Pal_FadeIn
subq.b #$02,d4 ; MJ: decrease colour check
bne - ; MJ: if it has not reached null, branch
move.b #$12,(Delay_Time).w ; MJ: wait for V-blank again (so colours transfer)
bra DelayProgram ; MJ: ''
; End of function Pal_FadeTo
; ---------------------------------------------------------------------------
; Palette fade-in subroutine
; ---------------------------------------------------------------------------
; ||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
; sub_23FE:
Pal_FadeIn:
moveq #0,d0
lea (Normal_palette).w,a0
lea (Second_palette).w,a1
move.b ($FFFFF626).w,d0
adda.w d0,a0
adda.w d0,a1
move.b ($FFFFF627).w,d0
- bsr.s Pal_AddColor
dbf d0,-
tst.b (Water_flag).w
beq.s return_243C
moveq #0,d0
lea (Underwater_palette).w,a0
lea (Underwater_palette_2).w,a1
move.b ($FFFFF626).w,d0
adda.w d0,a0
adda.w d0,a1
move.b ($FFFFF627).w,d0
- bsr.s Pal_AddColor
dbf d0,-
return_243C:
rts
; End of function Pal_FadeIn
; ||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
; sub_243E:
Pal_AddColor:
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?
bhi FCI_NoBlue ; MJ: if not, branch
addi.w #$0200,d3 ; MJ: increase blue
FCI_NoBlue:
cmp.b d1,d4 ; MJ: is it time for green to fade?
bhi FCI_NoGreen ; MJ: if not, branch
addi.b #$20,d3 ; MJ: increase green
FCI_NoGreen:
cmp.b d2,d4 ; MJ: is it time for red to fade?
bhi FCI_NoRed ; MJ: if not, branch
addq.b #$02,d3 ; MJ: increase red
FCI_NoRed:
move.w d3,(a0)+ ; MJ: save colour
rts ; MJ: return
; End of function Pal_AddColor
; ||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
; sub_246A:
Pal_FadeFrom:
move.w #$3F,($FFFFF626).w
moveq #$07,d4 ; MJ: set repeat times
moveq #$00,d6 ; MJ: clear d6
- bsr.w RunPLC_RAM
move.b #$12,(Delay_Time).w
bsr.w DelayProgram
bchg #$00,d6 ; MJ: change delay counter
beq - ; MJ: if null, delay a frame
bsr.s Pal_FadeOut
dbf d4,-
rts
; End of function Pal_FadeFrom
; ---------------------------------------------------------------------------
; Palette fade-out subroutine
; ---------------------------------------------------------------------------
; ||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
; sub_248A:
Pal_FadeOut:
moveq #0,d0
lea (Normal_palette).w,a0
move.b ($FFFFF626).w,d0
adda.w d0,a0
move.b ($FFFFF627).w,d0
- bsr.s Pal_DecColor
dbf d0,-
moveq #0,d0
lea (Underwater_palette).w,a0
move.b ($FFFFF626).w,d0
adda.w d0,a0
move.b ($FFFFF627).w,d0
- bsr.s Pal_DecColor
dbf d0,-
rts
; End of function Pal_FadeOut
; ||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
; sub_24B8:
Pal_DecColor:
move.w (a0),d5 ; MJ: load colour
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
beq FCO_NoBlue ; MJ: if blue is finished, branch
subi.w #$0200,d5 ; MJ: decrease blue
FCO_NoBlue:
andi.b #$E0,d2 ; MJ: get only green
beq FCO_NoGreen ; MJ: if green is finished, branch
subi.b #$20,d5 ; MJ: decrease green
FCO_NoGreen:
andi.b #$0E,d3 ; MJ: get only red
beq FCO_NoRed ; MJ: if red is finished, branch
subq.b #$02,d5 ; MJ: decrease red
FCO_NoRed:
move.w d5,(a0)+ ; MJ: save new colour
rts ; MJ: return
; End of function Pal_DecColor
Title Screen Specific Routine
Unfortunately, because of how unique the title screen is, the above change will not apply very well to it, hence, we have to change the specific routines responsible for its special fading/control.
At routine "ObjC9", you'll find this code below:
ObjC9:
moveq #0,d0
move.b routine(a0),d0
move.w loc_132FE(pc,d0.w),d1
jmp loc_132FE(pc,d1.w)
; ===========================================================================
loc_132FE:
ori.b #$46,d4
addq.b #2,routine(a0)
moveq #0,d0
move.b subtype(a0),d0
lea (PaletteChangerDataIndex).l,a1
adda.w (a1,d0.w),a1
move.l (a1)+,objoff_3A(a0)
movea.l (a1)+,a2
move.b (a1)+,d0
move.w d0,objoff_34(a0)
lea (Second_palette).w,a3
adda.w d0,a3
move.b (a1)+,d0
move.w d0,objoff_36(a0)
loc_1332E:
move.w (a2)+,(a3)+
dbf d0,loc_1332E
move.b (a1)+,d0
move.b d0,objoff_30(a0)
move.b d0,objoff_31(a0)
move.b (a1)+,objoff_32(a0)
rts
; ===========================================================================
; unused/dead code ; a0=object
subq.b #1,objoff_30(a0)
bpl.s return_1337A
move.b objoff_31(a0),objoff_30(a0)
subq.b #1,objoff_32(a0)
bmi.w DeleteObject
movea.l objoff_3A(a0),a2
movea.l a0,a3
move.w objoff_36(a0),d0
move.w objoff_34(a0),d1
lea (Normal_palette).w,a0
adda.w d1,a0
lea (Second_palette).w,a1
adda.w d1,a1
- jsr (a2) ; dynamic call! to Pal_AddColor, loc_1344C, or loc_1348A, assuming the PaletteChangerData pointers haven't been changed
dbf d0,-
movea.l a3,a0
return_1337A:
rts
There's a problem here however, that first ori.b #$46,d4 is infact two words of pointer data being 0004 and 0046, these are the routines address minus the table start address, this means that the "; unused/dead code" isn't actually unused, the table was just disassembled incorrectly, below I have provided a fix for this mistake, along with the necessary changes required for the fading to perform correctly:
ObjC9:
moveq #0,d0
move.b routine(a0),d0
move.w loc_132FE(pc,d0.w),d1
jmp loc_132FE(pc,d1.w)
; ===========================================================================
loc_132FE:
dc.w loc_13302-loc_132FE
dc.w NewRoutine-loc_132FE
loc_13302:
addq.b #2,routine(a0)
moveq #0,d0
move.b subtype(a0),d0
lea (PaletteChangerDataIndex).l,a1
adda.w (a1,d0.w),a1
move.l (a1)+,objoff_3A(a0)
movea.l (a1)+,a2
move.b (a1)+,d0
move.w d0,objoff_34(a0)
lea (Second_palette).w,a3
adda.w d0,a3
move.b (a1)+,d0
move.w d0,objoff_36(a0)
move.b #$0E,objoff_33(a0) ; MJ: set fade counter
loc_1332E:
move.w (a2)+,(a3)+
dbf d0,loc_1332E
move.b (a1)+,d0
move.b d0,objoff_30(a0)
move.b d0,objoff_31(a0)
move.b (a1)+,objoff_32(a0)
rts
; ===========================================================================
; unused/dead code ; a0=object
NewRoutine:
subq.b #1,objoff_30(a0)
bpl.s return_1337A
move.b objoff_31(a0),objoff_30(a0)
subq.b #1,objoff_32(a0)
bmi.w DeleteObject
moveq #$00,d4 ; MJ: clear d4
move.b objoff_33(a0),d4 ; MJ: load fade counter
subq.b #$02,objoff_33(a0) ; MJ: decrease fade counter
movea.l objoff_3A(a0),a2 ; load routine to run
movea.l a0,a3 ; store current object
move.w objoff_36(a0),d0 ; load length
move.w objoff_34(a0),d1 ; load loadtooffset
lea (Normal_palette).w,a0
adda.w d1,a0
lea (Second_palette).w,a1
adda.w d1,a1
- jsr (a2) ; dynamic call! to Pal_AddColor, loc_1344C, or loc_1348A, assuming the PaletteChangerData pointers haven't been changed
dbf d0,-
movea.l a3,a0
return_1337A:
rts
This will ensure the object uses our new fading routines correctly, the next thing to do is at:
off_1338C: C9PalInfo Pal_AddColor, Pal_1342C, $60, $F,2,$15
Because of the nature of the new fade in routine being faster in the transition, we need to change the end value $15 to something smaller, say $07:
off_1338C: C9PalInfo Pal_AddColor, Pal_1342C, $60, $F,2,$07 ; MJ: 15 to 7
This ensures the fading in routine is used correctly by the object, now there's one more fix to look at, if the player presses start to skip the transition halfway through fading in, the object continues fading in even though the entire full palette is loaded, to fix this goto "loc_135D6:":
loc_135D6:
move.l (a1)+,(a2)+
dbf d6,loc_135D6
tst.b objoff_30(a0)
bne.s return_135E8
moveq #$19+$80,d0 ; title music
bsr.w JmpTo4_PlayMusic
And place this instruction just after the "dbf d6,loc_135D6" instruction:
sf.b (Object_RAM+($100+$32)).w ; set fade counter to 00 (finish)
This will set the palette fading objects fade counter to 0 and set the object to delete itself, thus preventing it from messing with the palette if the transition was skipped.
If the above instructions have been followed carefully, then this will ensure that the colour fading scheme fades normally and smoothly, here is the new fading routine in action, 6 frames after fading in: