Removing Seafood and Birds from Special Stages

(I'm not sure if this has been posted before on here, a quick search only gave me this guide to remove the bubbles and clouds.)

So, I decided that the seafood and the stupid-ass birds in my special stage looked like ass. I wanted them gone. Hell, I wanted them to die in a ditch with Flash.

With that much set out, about two hours and 5 cans of coke later, I finally got rid of them. It is actually pretty easy - you just have to modify the routine that loads the BG patterns. And stuff.

You want the food gone from the special stages too? Then be my guest, and read the guide below.

First of all, find the label SS_BGLoad in your code. If you haven't touched it yet, it should look something like this:

Code (ASM):

1.  
2. SS_BGLoad:              ; XREF: SpecialStage
3.         lea ($FF0000).l,a1
4.         lea (Eni_SSBg1).l,a0 ; load mappings for the birds and fish
5.         move.w  #$4051,d0
6.         bsr.w   EniDec
7.         move.l  #$50000001,d3
8.         lea ($FF0080).l,a2
9.         moveq   #6,d7
10.  
11. loc_48BE:
12.         move.l  d3,d0
13.         moveq   #3,d6
14.         moveq   #0,d4
15.         cmpi.w  #3,d7
16.         bcc.s   loc_48CC
17.         moveq   #1,d4
18.  
19. loc_48CC:
20.         moveq   #7,d5
21.  
22. loc_48CE:
23.         movea.l a2,a1
24.         eori.b  #1,d4
25.         bne.s   loc_48E2
26.         cmpi.w  #6,d7
27.         bne.s   loc_48F2
28.         lea ($FF0000).l,a1
29.  
30. loc_48E2:
31.         movem.l d0-d4,-(sp)
32.         moveq   #7,d1
33.         moveq   #7,d2
34.         bsr.w   ShowVDPGraphics
35.         movem.l (sp)+,d0-d4
36.  
37. loc_48F2:
38.         addi.l  #$100000,d0
39.         dbf d5,loc_48CE
40.         addi.l  #$3800000,d0
41.         eori.b  #1,d4
42.         dbf d6,loc_48CC
43.         addi.l  #$10000000,d3
44.         bpl.s   loc_491C
45.         swap    d3
46.         addi.l  #$C000,d3
47.         swap    d3
48.  
49. loc_491C:
50.         adda.w  #$80,a2
51.         dbf d7,loc_48BE
52.         lea ($FF0000).l,a1
53.         lea (Eni_SSBg2).l,a0 ; load mappings for the clouds
54.         move.w  #$4000,d0
55.         bsr.w   EniDec
56.         lea ($FF0000).l,a1
57.         move.l  #$40000003,d0
58.         moveq   #$3F,d1
59.         moveq   #$1F,d2
60.         bsr.w   ShowVDPGraphics
61.         lea ($FF0000).l,a1
62.         move.l  #$50000003,d0
63.         moveq   #$3F,d1
64.         moveq   #$3F,d2
65.         bsr.w   ShowVDPGraphics
66.         rts
67. ; End of function SS_BGLoad
68.  

Now, you can see that it is loading the mappings. Simply un-commenting that won't do the trick. Un-comment everything up until

Code (ASM):

1.  
2. dbf d7, loc_48BE
3.  

Now you finally got rid of those hideous birds and fishes.

If you need some more VRAM in the special stage, continue reading. If not, you can do something else.
Open the file _inc/Pattern load cues.asm and find the label PLC_SpeStage You can see that right below the BGCloud entry, there's the entry for the fish and birds. As you can clearly see, they take up a whole lot of VRAM. Remove the entry for Nem_SSBgFish and update the PLC entry count. If you did this correctly, you should get this:

Code (ASM):

1.  
2. PLC_SpeStage:   dc.w $F
3.         dc.l Nem_SSBgCloud  ; bubble and cloud background
4.         dc.w 0
5.         dc.l Nem_SSWalls    ; walls
6.         dc.w $2840
7.         dc.l Nem_Bumper     ; bumper
8.         dc.w $4760
9.         dc.l Nem_SSGOAL     ; GOAL block
10.         dc.w $4A20
11.         dc.l Nem_SSUpDown   ; UP and DOWN blocks
12.         dc.w $4C60
13.         dc.l Nem_SSRBlock   ; R block
14.         dc.w $5E00
15.         dc.l Nem_SS1UpBlock ; 1UP block
16.         dc.w $6E00
17.         dc.l Nem_SSEmStars  ; emerald collection stars
18.         dc.w $7E00
19.         dc.l Nem_SSRedWhite ; red and white block
20.         dc.w $8E00
21.         dc.l Nem_SSGhost    ; ghost block
22.         dc.w $9E00
23.         dc.l Nem_SSWBlock   ; W block
24.         dc.w $AE00
25.         dc.l Nem_SSGlass    ; glass block
26.         dc.w $BE00
27.         dc.l Nem_SSEmerald  ; emeralds
28.         dc.w $EE00
29.         dc.l Nem_SSZone1    ; ZONE 1 block
30.         dc.w $F2E0
31.         dc.l Nem_SSZone2    ; ZONE 2 block
32.         dc.w $F400
33.         dc.l Nem_SSZone3    ; ZONE 3 block
34.         dc.w $F520
35.         dc.l Nem_SSZone4    ; ZONE 4 block
36.         dc.w $F2E0
37.         dc.l Nem_SSZone5    ; ZONE 5 block
38.         dc.w $F400
39.         dc.l Nem_SSZone6    ; ZONE 6 block
40.         dc.w $F520
41.  

See, it wasn't that hard, was it? Got questions, feedback or something else? Please post them below.

Also, I'd appreciate some credit if you add this to your hack, but it's not required.

EDIT: I added a few pictures just to show a sort of before and after effect:

BEFORE:


AFTER:

 

Why thank you. I was actually playing around with the BG layers in Gens one day and figured it out, and wanted to make that permanent.

Some people might want a different sort of BG for their special stages, and those birds/fishes/foodstuffs could interfere with it

Yes, I think I might have seen your video a while ago, but I'm not exactly sure if anyone ever wrote a guide for this, and thank you.

Can you come up with a better name? To be honest though, I was half asleep slaving over a keyboard and probably high on sugar too at the time of writing. =P

Still pondering if I should continue making guides like this. We'll see what sorts of weird things I can come up with in the time being that I find worth sharing