ref: c84667c4df36918071bb7487c456d7adafb921ca
dir: /engine/pathfinding.asm/
FindPathToPlayer: xor a ld hl, hFindPathNumSteps ld [hli], a ; hFindPathNumSteps ld [hli], a ; hFindPathFlags ld [hli], a ; hFindPathYProgress ld [hl], a ; hFindPathXProgress ld hl, wNPCMovementDirections2 ld de, $0 .loop ld a, [hFindPathYProgress] ld b, a ld a, [hNPCPlayerYDistance] ; Y distance in steps call CalcDifference ld d, a and a jr nz, .asm_f8da ld a, [hFindPathFlags] set 0, a ; current end of path matches the player's Y coordinate ld [hFindPathFlags], a .asm_f8da ld a, [hFindPathXProgress] ld b, a ld a, [hNPCPlayerXDistance] ; X distance in steps call CalcDifference ld e, a and a jr nz, .asm_f8ec ld a, [hFindPathFlags] set 1, a ; current end of path matches the player's X coordinate ld [hFindPathFlags], a .asm_f8ec ld a, [hFindPathFlags] cp $3 ; has the end of the path reached the player's position? jr z, .done ; Compare whether the X distance between the player and the current of the path ; is greater or if the Y distance is. Then, try to reduce whichever is greater. ld a, e cp d jr c, .yDistanceGreater ; x distance is greater ld a, [hNPCPlayerRelativePosFlags] bit 1, a jr nz, .playerIsLeftOfNPC ld d, NPC_MOVEMENT_RIGHT jr .next1 .playerIsLeftOfNPC ld d, NPC_MOVEMENT_LEFT .next1 ld a, [hFindPathXProgress] add 1 ld [hFindPathXProgress], a jr .storeDirection .yDistanceGreater ld a, [hNPCPlayerRelativePosFlags] bit 0, a jr nz, .playerIsAboveNPC ld d, NPC_MOVEMENT_DOWN jr .next2 .playerIsAboveNPC ld d, NPC_MOVEMENT_UP .next2 ld a, [hFindPathYProgress] add 1 ld [hFindPathYProgress], a .storeDirection ld a, d ld [hli], a ld a, [hFindPathNumSteps] inc a ld [hFindPathNumSteps], a jp .loop .done ld [hl], $ff ret CalcPositionOfPlayerRelativeToNPC: xor a ld [hNPCPlayerRelativePosFlags], a ld a, [wSpriteStateData1 + 4] ; player's sprite screen Y position in pixels ld d, a ld a, [wSpriteStateData1 + 6] ; player's sprite screen X position in pixels ld e, a ld hl, wSpriteStateData1 ld a, [hNPCSpriteOffset] add l add $4 ld l, a jr nc, .noCarry inc h .noCarry ld a, d ld b, a ld a, [hli] ; NPC sprite screen Y position in pixels call CalcDifference jr nc, .NPCSouthOfOrAlignedWithPlayer .NPCNorthOfPlayer push hl ld hl, hNPCPlayerRelativePosFlags bit 0, [hl] set 0, [hl] pop hl jr .divideYDistance .NPCSouthOfOrAlignedWithPlayer push hl ld hl, hNPCPlayerRelativePosFlags bit 0, [hl] res 0, [hl] pop hl .divideYDistance push hl ld hl, hDividend2 ld [hli], a ld a, 16 ld [hli], a call DivideBytes ; divide Y absolute distance by 16 ld a, [hl] ; quotient ld [hNPCPlayerYDistance], a pop hl inc hl ld b, e ld a, [hl] ; NPC sprite screen X position in pixels call CalcDifference jr nc, .NPCEastOfOrAlignedWithPlayer .NPCWestOfPlayer push hl ld hl, hNPCPlayerRelativePosFlags bit 1, [hl] set 1, [hl] pop hl jr .divideXDistance .NPCEastOfOrAlignedWithPlayer push hl ld hl, hNPCPlayerRelativePosFlags bit 1, [hl] res 1, [hl] pop hl .divideXDistance ld [hDividend2], a ld a, 16 ld [hDivisor2], a call DivideBytes ; divide X absolute distance by 16 ld a, [hQuotient2] ld [hNPCPlayerXDistance], a ld a, [hNPCPlayerRelativePosPerspective] and a ret z ld a, [hNPCPlayerRelativePosFlags] cpl and $3 ld [hNPCPlayerRelativePosFlags], a ret ConvertNPCMovementDirectionsToJoypadMasks: ld a, [hNPCMovementDirections2Index] ld [wNPCMovementDirections2Index], a dec a ld de, wSimulatedJoypadStatesEnd ld hl, wNPCMovementDirections2 add l ld l, a jr nc, .loop inc h .loop ld a, [hld] call ConvertNPCMovementDirectionToJoypadMask ld [de], a inc de ld a, [hNPCMovementDirections2Index] dec a ld [hNPCMovementDirections2Index], a jr nz, .loop ret ConvertNPCMovementDirectionToJoypadMask: push hl ld b, a ld hl, NPCMovementDirectionsToJoypadMasksTable .loop ld a, [hli] cp $ff jr z, .done cp b jr z, .loadJoypadMask inc hl jr .loop .loadJoypadMask ld a, [hl] .done pop hl ret NPCMovementDirectionsToJoypadMasksTable: db NPC_MOVEMENT_UP, D_UP db NPC_MOVEMENT_DOWN, D_DOWN db NPC_MOVEMENT_LEFT, D_LEFT db NPC_MOVEMENT_RIGHT, D_RIGHT db $ff ; unreferenced ret