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118 lines
3.5 KiB
NASM
118 lines
3.5 KiB
NASM
; try to initiate a wild pokemon encounter
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; returns success in Z
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TryDoWildEncounter: ; 13870 (4:7870)
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ld a, [wNPCMovementScriptPointerTableNum]
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and a
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ret nz
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ld a, [wd736]
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and a
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ret nz
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callab IsPlayerStandingOnDoorTileOrWarpTile
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jr nc, .notStandingOnDoorOrWarpTile
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.CantEncounter
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ld a, $1
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and a
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ret
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.notStandingOnDoorOrWarpTile
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callab IsPlayerJustOutsideMap
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jr z, .CantEncounter
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ld a, [wRepelRemainingSteps]
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and a
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jr z, .asm_1389e
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dec a
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jr z, .lastRepelStep
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ld [wRepelRemainingSteps], a
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.asm_1389e
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; determine if wild pokémon can appear in the half-block we’re standing in
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; is the bottom right tile (9,9) of the half-block we're standing in a grass/water tile?
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hlCoord 9, 9
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ld c, [hl]
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ld a, [W_GRASSTILE]
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cp c
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ld a, [W_GRASSRATE]
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jr z, .CanEncounter
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ld a, $14 ; in all tilesets with a water tile, this is its id
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cp c
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ld a, [W_WATERRATE]
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jr z, .CanEncounter
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; even if not in grass/water, standing anywhere we can encounter pokémon
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; so long as the map is “indoor” and has wild pokémon defined.
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; …as long as it’s not Viridian Forest or Safari Zone.
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ld a, [W_CURMAP]
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cp REDS_HOUSE_1F ; is this an indoor map?
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jr c, .CantEncounter2
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ld a, [W_CURMAPTILESET]
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cp FOREST ; Viridian Forest/Safari Zone
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jr z, .CantEncounter2
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ld a, [W_GRASSRATE]
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.CanEncounter
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; compare encounter chance with a random number to determine if there will be an encounter
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ld b, a
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ld a, [hRandomAdd]
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cp b
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jr nc, .CantEncounter2
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ld a, [hRandomSub]
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ld b, a
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ld hl, WildMonEncounterSlotChances
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.determineEncounterSlot
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ld a, [hli]
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cp b
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jr nc, .gotEncounterSlot
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inc hl
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jr .determineEncounterSlot
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.gotEncounterSlot
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; determine which wild pokémon (grass or water) can appear in the half-block we’re standing in
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ld c, [hl]
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ld hl, W_GRASSMONS
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aCoord 8, 9
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cp $14 ; is the bottom left tile (8,9) of the half-block we're standing in a water tile?
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jr nz, .gotWildEncounterType ; else, it's treated as a grass tile by default
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ld hl, W_WATERMONS
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; since the bottom right tile of a "left shore" half-block is $14 but the bottom left tile is not,
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; "left shore" half-blocks (such as the one in the east coast of Cinnabar) load grass encounters.
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.gotWildEncounterType
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ld b, $0
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add hl, bc
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ld a, [hli]
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ld [W_CURENEMYLVL], a
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ld a, [hl]
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ld [wcf91], a
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ld [wEnemyMonSpecies2], a
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ld a, [wRepelRemainingSteps]
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and a
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jr z, .willEncounter
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ld a, [wPartyMon1Level]
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ld b, a
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ld a, [W_CURENEMYLVL]
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cp b
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jr c, .CantEncounter2 ; repel prevents encounters if the leading party mon's level is higher than the wild mon
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jr .willEncounter
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.lastRepelStep
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ld [wRepelRemainingSteps], a
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ld a, $d2
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ld [H_DOWNARROWBLINKCNT2], a
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call EnableAutoTextBoxDrawing
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call DisplayTextID
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.CantEncounter2
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ld a, $1
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and a
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ret
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.willEncounter
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xor a
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ret
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WildMonEncounterSlotChances: ; 13918 (4:7918)
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; There are 10 slots for wild pokemon, and this is the table that defines how common each of
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; those 10 slots is. A random number is generated and then the first byte of each pair in this
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; table is compared against that random number. If the random number is less than or equal
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; to the first byte, then that slot is chosen. The second byte is double the slot number.
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db $32, $00 ; 51/256 = 19.9% chance of slot 0
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db $65, $02 ; 51/256 = 19.9% chance of slot 1
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db $8C, $04 ; 39/256 = 15.2% chance of slot 2
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db $A5, $06 ; 25/256 = 9.8% chance of slot 3
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db $BE, $08 ; 25/256 = 9.8% chance of slot 4
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db $D7, $0A ; 25/256 = 9.8% chance of slot 5
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db $E4, $0C ; 13/256 = 5.1% chance of slot 6
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db $F1, $0E ; 13/256 = 5.1% chance of slot 7
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db $FC, $10 ; 11/256 = 4.3% chance of slot 8
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db $FF, $12 ; 3/256 = 1.2% chance of slot 9
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