1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
; inverts the BGP for 4 (6 on CGB due to lag) frames
InvertBGPal_4Frames: ; 2bd4c (a:7d4c)
call GetPredefRegisters ; leftover of red/blue, has no use here
ld a, [rBGP]
xor $ff
ld [rBGP], a
call UpdateGBCPal_BGP
ld c, 4
call DelayFrames
ld a, [rBGP]
xor $ff
ld [rBGP], a
call UpdateGBCPal_BGP
ret
PredefShakeScreenVertically: ; 2bd67 (a:7d67)
; Moves the window down and then back in a sequence of progressively smaller
; numbers of pixels, starting at b.
call GetPredefRegisters
ld a, 1
ld [wDisableVBlankWYUpdate], a
xor a
.loop
ld [$ff96], a
call .MutateWY
call .MutateWY
dec b
ld a, b
jr nz, .loop
xor a
ld [wDisableVBlankWYUpdate], a
ret
.MutateWY ; 2bd81 (a:7d81)
ld a, [$ff96]
xor b
ld [$ff96], a
ld [rWY], a
ld c, 3
jp DelayFrames
PredefShakeScreenHorizontally: ; 2bd8d (a:7d8d)
; Moves the window right and then back in a sequence of progressively smaller
; numbers of pixels, starting at b.
call GetPredefRegisters
xor a
.loop
ld [$ff97], a
call .MutateWX
ld c, 1
call DelayFrames
call .MutateWX
dec b
ld a, b
jr nz, .loop
; restore normal WX
ld a, 7
ld [rWX], a
ret
.MutateWX ; 2bda7 (a:4da7)
ld a, [$ff97]
xor b
ld [$ff97], a
bit 7, a
jr z, .skipZeroing
xor a ; zero a if it's negative
.skipZeroing
add 7
ld [rWX], a
ld c, 4
jp DelayFrames
|
