1 files changed, 349 insertions, 0 deletions
diff --git a/engine/overworld/trainer_sight.asm b/engine/overworld/trainer_sight.asm
new file mode 100755
index 00000000..5a68b627
--- /dev/null
+++ b/engine/overworld/trainer_sight.asm
@@ -0,0 +1,349 @@
+_GetSpritePosition1::
+	ld hl, wSpriteStateData1
+	ld de, $4
+	ld a, [wSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	call GetSpriteDataPointer
+	ld a, [hli] ; c1x4 (screen Y pos)
+	ld [$ffeb], a
+	inc hl
+	ld a, [hl] ; c1x6 (screen X pos)
+	ld [$ffec], a
+	ld de, (wSpriteStateData2 + $4) - (wSpriteStateData1 + $6)
+	add hl, de
+	ld a, [hli] ; c2x4 (map Y pos)
+	ld [$ffed], a
+	ld a, [hl] ; c2x5 (map X pos)
+	ld [$ffee], a
+	ret
+
+_GetSpritePosition2::
+	ld hl, wSpriteStateData1
+	ld de, $4
+	ld a, [wSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	call GetSpriteDataPointer
+	ld a, [hli] ; c1x4 (screen Y pos)
+	ld [wSavedSpriteScreenY], a
+	inc hl
+	ld a, [hl] ; c1x6 (screen X pos)
+	ld [wSavedSpriteScreenX], a
+	ld de, (wSpriteStateData2 + $4) - (wSpriteStateData1 + $6)
+	add hl, de
+	ld a, [hli] ; c2x4 (map Y pos)
+	ld [wSavedSpriteMapY], a
+	ld a, [hl] ; c2x5 (map X pos)
+	ld [wSavedSpriteMapX], a
+	ret
+
+_SetSpritePosition1::
+	ld hl, wSpriteStateData1
+	ld de, $4
+	ld a, [wSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	call GetSpriteDataPointer
+	ld a, [$ffeb] ; c1x4 (screen Y pos)
+	ld [hli], a
+	inc hl
+	ld a, [$ffec] ; c1x6 (screen X pos)
+	ld [hl], a
+	ld de, (wSpriteStateData2 + $4) - (wSpriteStateData1 + $6)
+	add hl, de
+	ld a, [$ffed] ; c2x4 (map Y pos)
+	ld [hli], a
+	ld a, [$ffee] ; c2x5 (map X pos)
+	ld [hl], a
+	ret
+
+_SetSpritePosition2::
+	ld hl, wSpriteStateData1
+	ld de, 4
+	ld a, [wSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	call GetSpriteDataPointer
+	ld a, [wSavedSpriteScreenY]
+	ld [hli], a ; c1x4 (screen Y pos)
+	inc hl
+	ld a, [wSavedSpriteScreenX]
+	ld [hl], a ; c1x6 (screen X pos)
+	ld de, (wSpriteStateData2 + $4) - (wSpriteStateData1 + $6)
+	add hl, de
+	ld a, [wSavedSpriteMapY]
+	ld [hli], a ; c2x4 (map Y pos)
+	ld a, [wSavedSpriteMapX]
+	ld [hl], a ; c2x5 (map X pos)
+	ret
+
+TrainerWalkUpToPlayer::
+	ld a, [wSpriteIndex]
+	swap a
+	ld [wTrainerSpriteOffset], a
+	call ReadTrainerScreenPosition
+	ld a, [wTrainerFacingDirection]
+	and a ; SPRITE_FACING_DOWN
+	jr z, .facingDown
+	cp SPRITE_FACING_UP
+	jr z, .facingUp
+	cp SPRITE_FACING_LEFT
+	jr z, .facingLeft
+	jr .facingRight
+.facingDown
+	ld a, [wTrainerScreenY]
+	ld b, a
+	ld a, $3c           ; (fixed) player screen Y pos
+	call CalcDifference
+	cp $10              ; trainer is right above player
+	ret z
+	swap a
+	dec a
+	ld c, a             ; bc = steps yet to go to reach player
+	xor a
+	ld b, a           ; a = direction to go to
+	jr .writeWalkScript
+.facingUp
+	ld a, [wTrainerScreenY]
+	ld b, a
+	ld a, $3c           ; (fixed) player screen Y pos
+	call CalcDifference
+	cp $10              ; trainer is right below player
+	ret z
+	swap a
+	dec a
+	ld c, a             ; bc = steps yet to go to reach player
+	ld b, $0
+	ld a, $40           ; a = direction to go to
+	jr .writeWalkScript
+.facingRight
+	ld a, [wTrainerScreenX]
+	ld b, a
+	ld a, $40           ; (fixed) player screen X pos
+	call CalcDifference
+	cp $10              ; trainer is directly left of player
+	ret z
+	swap a
+	dec a
+	ld c, a             ; bc = steps yet to go to reach player
+	ld b, $0
+	ld a, $c0           ; a = direction to go to
+	jr .writeWalkScript
+.facingLeft
+	ld a, [wTrainerScreenX]
+	ld b, a
+	ld a, $40           ; (fixed) player screen X pos
+	call CalcDifference
+	cp $10              ; trainer is directly right of player
+	ret z
+	swap a
+	dec a
+	ld c, a             ; bc = steps yet to go to reach player
+	ld b, $0
+	ld a, $80           ; a = direction to go to
+.writeWalkScript
+	ld hl, wNPCMovementDirections2
+	ld de, wNPCMovementDirections2
+	call FillMemory     ; write the necessary steps to reach player
+	ld [hl], $ff        ; write end of list sentinel
+	ld a, [wSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	jp MoveSprite_
+
+; input: de = offset within sprite entry
+; output: hl = pointer to sprite data
+GetSpriteDataPointer:
+	push de
+	add hl, de
+	ld a, [H_SPRITEINDEX]
+	swap a
+	ld d, $0
+	ld e, a
+	add hl, de
+	pop de
+	ret
+
+; tests if this trainer is in the right position to engage the player and do so if she is.
+TrainerEngage:
+	push hl
+	push de
+	ld a, [wTrainerSpriteOffset]
+	add $2
+	ld d, $0
+	ld e, a
+	ld hl, wSpriteStateData1
+	add hl, de
+	ld a, [hl]             ; c1x2: sprite image index
+	sub $ff
+	jr nz, .spriteOnScreen ; test if sprite is on screen
+	jp .noEngage
+.spriteOnScreen
+	ld a, [wTrainerSpriteOffset]
+	add $9
+	ld d, $0
+	ld e, a
+	ld hl, wSpriteStateData1
+	add hl, de
+	ld a, [hl]             ; c1x9: facing direction
+	ld [wTrainerFacingDirection], a
+	call ReadTrainerScreenPosition
+	ld a, [wTrainerScreenY]          ; sprite screen Y pos
+	ld b, a
+	ld a, $3c
+	cp b
+	jr z, .linedUpY
+	ld a, [wTrainerScreenX]          ; sprite screen X pos
+	ld b, a
+	ld a, $40
+	cp b
+	jr z, .linedUpX
+	xor a
+	jp .noEngage
+.linedUpY
+	ld a, [wTrainerScreenX]        ; sprite screen X pos
+	ld b, a
+	ld a, $40            ; (fixed) player X position
+	call CalcDifference  ; calc distance
+	jr z, .noEngage      ; exact same position as player
+	call CheckSpriteCanSeePlayer
+	jr c, .engage
+	xor a
+	jr .noEngage
+.linedUpX
+	ld a, [wTrainerScreenY]        ; sprite screen Y pos
+	ld b, a
+	ld a, $3c            ; (fixed) player Y position
+	call CalcDifference  ; calc distance
+	jr z, .noEngage      ; exact same position as player
+	call CheckSpriteCanSeePlayer
+	jr c, .engage
+	xor a
+	jp .noEngage
+.engage
+	call CheckPlayerIsInFrontOfSprite
+	ld a, [wTrainerSpriteOffset]
+	and a
+	jr z, .noEngage
+	ld hl, wFlags_0xcd60
+	set 0, [hl]
+	call EngageMapTrainer
+	ld a, $ff
+.noEngage
+	ld [wTrainerSpriteOffset], a
+	pop de
+	pop hl
+	ret
+
+; reads trainer's Y position to wTrainerScreenY and X position to wTrainerScreenX
+ReadTrainerScreenPosition:
+	ld a, [wTrainerSpriteOffset]
+	add $4
+	ld d, $0
+	ld e, a
+	ld hl, wSpriteStateData1
+	add hl, de
+	ld a, [hl] ; c1x4 (sprite Y pos)
+	ld [wTrainerScreenY], a
+	ld a, [wTrainerSpriteOffset]
+	add $6
+	ld d, $0
+	ld e, a
+	ld hl, wSpriteStateData1
+	add hl, de
+	ld a, [hl] ; c1x6 (sprite X pos)
+	ld [wTrainerScreenX], a
+	ret
+
+; checks if the sprite is properly lined up with the player with respect to the direction it's looking. Also checks the distance between player and sprite
+; note that this does not necessarily mean the sprite is seeing the player, he could be behind it's back
+; a: distance player to sprite
+CheckSpriteCanSeePlayer:
+	ld b, a
+	ld a, [wTrainerEngageDistance] ; how far the trainer can see
+	cp b
+	jr nc, .checkIfLinedUp
+	jr .notInLine         ; player too far away
+.checkIfLinedUp
+	ld a, [wTrainerFacingDirection]         ; sprite facing direction
+	cp SPRITE_FACING_DOWN
+	jr z, .checkXCoord
+	cp SPRITE_FACING_UP
+	jr z, .checkXCoord
+	cp SPRITE_FACING_LEFT
+	jr z, .checkYCoord
+	cp SPRITE_FACING_RIGHT
+	jr z, .checkYCoord
+	jr .notInLine
+.checkXCoord
+	ld a, [wTrainerScreenX]         ; sprite screen X position
+	ld b, a
+	cp $40
+	jr z, .inLine
+	jr .notInLine
+.checkYCoord
+	ld a, [wTrainerScreenY]         ; sprite screen Y position
+	ld b, a
+	cp $3c
+	jr nz, .notInLine
+.inLine
+	scf
+	ret
+.notInLine
+	and a
+	ret
+
+; tests if the player is in front of the sprite (rather than behind it)
+CheckPlayerIsInFrontOfSprite:
+	ld a, [wCurMap]
+	cp POWER_PLANT
+	jp z, .engage       ; bypass this for power plant to get voltorb fake items to work
+	ld a, [wTrainerSpriteOffset]
+	add $4
+	ld d, $0
+	ld e, a
+	ld hl, wSpriteStateData1
+	add hl, de
+	ld a, [hl]          ; c1x4 (sprite screen Y pos)
+	cp $fc
+	jr nz, .notOnTopmostTile ; special case if sprite is on topmost tile (Y = $fc (-4)), make it come down a block
+	ld a, $c
+.notOnTopmostTile
+	ld [wTrainerScreenY], a
+	ld a, [wTrainerSpriteOffset]
+	add $6
+	ld d, $0
+	ld e, a
+	ld hl, wSpriteStateData1
+	add hl, de
+	ld a, [hl]          ; c1x6 (sprite screen X pos)
+	ld [wTrainerScreenX], a
+	ld a, [wTrainerFacingDirection]       ; facing direction
+	cp SPRITE_FACING_DOWN
+	jr nz, .notFacingDown
+	ld a, [wTrainerScreenY]       ; sprite screen Y pos
+	cp $3c
+	jr c, .engage       ; sprite above player
+	jr .noEngage        ; sprite below player
+.notFacingDown
+	cp SPRITE_FACING_UP
+	jr nz, .notFacingUp
+	ld a, [wTrainerScreenY]       ; sprite screen Y pos
+	cp $3c
+	jr nc, .engage      ; sprite below player
+	jr .noEngage        ; sprite above player
+.notFacingUp
+	cp SPRITE_FACING_LEFT
+	jr nz, .notFacingLeft
+	ld a, [wTrainerScreenX]       ; sprite screen X pos
+	cp $40
+	jr nc, .engage      ; sprite right of player
+	jr .noEngage        ; sprite left of player
+.notFacingLeft
+	ld a, [wTrainerScreenX]       ; sprite screen X pos
+	cp $40
+	jr nc, .noEngage    ; sprite right of player
+.engage
+	ld a, $ff
+	jr .done
+.noEngage
+	xor a
+.done
+	ld [wTrainerSpriteOffset], a
+	ret