split code out of main.asm

engine/overworld/push_boulder.asm

@@ -0,0 +1,105 @@
+TryPushingBoulder:
+	ld a, [wd728]
+	bit 0, a ; using Strength?
+	ret z
+	ld a, [wFlags_0xcd60]
+	bit 1, a ; has boulder dust animation from previous push played yet?
+	ret nz
+	xor a
+	ld [hSpriteIndexOrTextID], a
+	call IsSpriteInFrontOfPlayer
+	ld a, [hSpriteIndexOrTextID]
+	ld [wBoulderSpriteIndex], a
+	and a
+	jp z, ResetBoulderPushFlags
+	ld hl, wSpriteStateData1 + 1
+	ld d, $0
+	ld a, [hSpriteIndexOrTextID]
+	swap a
+	ld e, a
+	add hl, de
+	res 7, [hl]
+	call GetSpriteMovementByte2Pointer
+	ld a, [hl]
+	cp BOULDER_MOVEMENT_BYTE_2
+	jp nz, ResetBoulderPushFlags
+	ld hl, wFlags_0xcd60
+	bit 6, [hl]
+	set 6, [hl] ; indicate that the player has tried pushing
+	ret z ; the player must try pushing twice before the boulder will move
+	ld a, [hJoyHeld]
+	and D_RIGHT | D_LEFT | D_UP | D_DOWN
+	ret z
+	predef CheckForCollisionWhenPushingBoulder
+	ld a, [wTileInFrontOfBoulderAndBoulderCollisionResult]
+	and a ; was there a collision?
+	jp nz, ResetBoulderPushFlags
+	ld a, [hJoyHeld]
+	ld b, a
+	ld a, [wSpriteStateData1 + 9] ; player's sprite facing direction
+	cp SPRITE_FACING_UP
+	jr z, .pushBoulderUp
+	cp SPRITE_FACING_LEFT
+	jr z, .pushBoulderLeft
+	cp SPRITE_FACING_RIGHT
+	jr z, .pushBoulderRight
+.pushBoulderDown
+	bit 7, b
+	ret z
+	ld de, PushBoulderDownMovementData
+	jr .done
+.pushBoulderUp
+	bit 6, b
+	ret z
+	ld de, PushBoulderUpMovementData
+	jr .done
+.pushBoulderLeft
+	bit 5, b
+	ret z
+	ld de, PushBoulderLeftMovementData
+	jr .done
+.pushBoulderRight
+	bit 4, b
+	ret z
+	ld de, PushBoulderRightMovementData
+.done
+	call MoveSprite
+	ld a, SFX_PUSH_BOULDER
+	call PlaySound
+	ld hl, wFlags_0xcd60
+	set 1, [hl]
+	ret
+
+PushBoulderUpMovementData:
+	db NPC_MOVEMENT_UP,$FF
+
+PushBoulderDownMovementData:
+	db NPC_MOVEMENT_DOWN,$FF
+
+PushBoulderLeftMovementData:
+	db NPC_MOVEMENT_LEFT,$FF
+
+PushBoulderRightMovementData:
+	db NPC_MOVEMENT_RIGHT,$FF
+
+DoBoulderDustAnimation:
+	ld a, [wd730]
+	bit 0, a
+	ret nz
+	callab AnimateBoulderDust
+	call DiscardButtonPresses
+	ld [wJoyIgnore], a
+	call ResetBoulderPushFlags
+	set 7, [hl]
+	ld a, [wBoulderSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	call GetSpriteMovementByte2Pointer
+	ld [hl], $10
+	ld a, SFX_CUT
+	jp PlaySound
+
+ResetBoulderPushFlags:
+	ld hl, wFlags_0xcd60
+	res 1, [hl]
+	res 6, [hl]
+	ret