Werewolf

Monster data
HP	11
Points	300

Entity data
Entity pointer	$81:ABF5

The werewolf is a respawning monster. Werewolves will only spawn if the level has palette fade that has completed, though this condition can be bypassed by using $81:ABFB as the entity pointer instead.

Behavior

Werewolves can be in one of three states:

• Walking: Move towards the nearest targetable sprite at an average rate of 1.5 px/frame. Werewolves start in this state.
  • If the werewolf is exactly 360 pixels away from the target, then despawn.
  • If the werewolf's health has changed, jump in a random diagonal direction a distance of 20-51 pixels on the X axis and 15-46 pixels on the Y axis.
  • If the werewolf is between 70 and 344 pixels of the target, then there is a 15/255 (5.88%) chance to jump at the target.
    • If the target is a victim, jump 28 pixels past the target on the X axis.
    • Otherwise, jump 124 pixels past the target on the X axis.
  • If the werewolf is less than 4 pixels from the target on the Y axis and less than 29 pixels on the X axis, then attack.
• Jumping: Jumping is implemented as three separate states:
  • Pre-jump: Do a 17 frame pre-jump animation.
  • Main jump: Move at a constant speed towards the destination point. The total duration of the jump (in frames) is the distance on the larger of the two axes divided by 4. The werewolf has no collision during this phase. After the jump is complete, the game attempts to adjust the werewolf's position if it lands too close to the target, but this is bugged.
  • Post-jump: Do a 15 frame landing animation. Then attack if the werewolf is less than 4 pixels from the target on the Y axis and less than 29 pixels on the X axis. If not attacking, wait a random amount of time from 1 to 16 frames, then go back to the walking state.
• Attacking: Perform a 27 frame attack animation. During the last 12 frames of this, there is an additional sprite hitbox created 25 pixels to the left or right of the werewolf. Once complete, go back to the walking state.

Weapon damage

Werewolves take normal damage from all weapons except silverware, which kills them in one hit.

Bugs

• Werewolves attempt to adjust their position upon landing if they are within 9 pixels of the target on the X axis. It is intended to move an additional 15 pixels on the X axis and 8 pixels on the Y axis, but there are several bugs in the implementation.
  • The position offset table has the wrong values for the down-left entry (uses values for up-left instead).
  • The table is indexed incorrectly and reads the wrong values for each direction.
  • The function that determines the direction of the jump is bugged to only return left, right, or none. This bug actually prevents reading past the end of the table due to the incorrect indexing.
  • The end result of these bugs is that the werewolf will move down 15 pixels if the jump was to the right, and up 15 pixels if it was to the left.
• Werewolves only despawn if they are exactly 360 pixels away from the nearest targetable sprite. Since players move at 2 px/frame orthogonally, the distance can go directly from 359 to 361, causing the werewolf not to despawn.
• It's not clear if this is a bug or intended behavior, but werewolves will never jump straight up or down. This is because their target position would be exactly on top of the sprite they are trying to jump at, and since all target sprites are solid to monsters, the jump is not allowed.

RAM map

Entity arguments

Address	Length	Type	Name	Description
$00	2	int16	x	X position
$02	2	int16	y	Y position

Entity memory

Address	Length	Type	Name	Description
$08	2	pointer16	sprite	Pointer to sprite
$0A	2	pointer16	state	Current state subroutine pointer
$0C	2	uint16	animationFrame	Current animation frame (x2 during attack animation)
$0E	2	int16 0-based	framesUntilAnimUpdate	Number of frames until next animation frame
$10	2	boolean	dead	Dead
$12	2	int16	x	X position
$14	2	int16	y	Y position
$16	2	int16	newX	New X position
$18	2	int16	newY	New Y position
$1A	2	direction	direction	Current direction
$1C	2	unused		Unused
$1E	2	optional pointer16	jumpTargetSprite	Pointer to sprite that is being jumped at (0xFFFF if empty)
$20	2	int16	jumpTargetX	Jump target X position
$22	2	int16	jumpTargetY	Jump target Y position
$24	2	int16 x4	zVelocity	Z velocity during jump
$26	2	uint16	jumpDuration	Duration of jump in frames
$28	2	uint16	xFraction	Fractional portion of X position during jump (full X position = $12 + ($28/$26))
$2A	2	uint16	yFraction	Fractional portion of Y position during jump (full Y position = $14 + ($2A/$26))
$2C	2	uint16	jumpXMagnitude	Jump distance X magnitude
$2E	2	uint16	jumpYMagnitude	Jump distance Y magnitude
$30	2	int16	jumpXSign	Jump distance X sign (1 if jump is right, -1 if left)
$32	2	int16	jumpYSign	Jump distance Y sign (1 if jump is down, -1 if up)
$34	2	direction	jumpDirection	Jump direction (only left or right due to a bug)
$36	2	uint16	temp	Temporary storage
$38	2	optional pointer16	attackSprite	Extra attack hitbox sprite (0xFFFF if empty)
$3A	2	int16 0-based	prevHealth	Previous health
$3C	2	int16 0-based	health	Health
$3E	2	sprite type	collidedSpriteType	Type of weapon shot sprite collided with
$40	2	unused		Unused
$42	2	pointer16	targetSprite	Pointer to target sprite
$44	2	uint16	targetDistance	Distance to target sprite
$7E	2	int16 0-based	freezeTimer	Amount of time to stay frozen

Pseudocode

init() {
	createMonsterSprite()
	this.x = args.x
	this.y = args.y
	this.sprite.tileData = $90:E9D8
	this.sprite.alternatePalette = 6
	this.sprite.visible = true
	this.sprite.type = MONSTER
	this.animationFrame = 0
	this.framesUntilAnimUpdate = 0
	this.attackSprite = -1
	this.jumpTargetSprite = -1
	this.freezeTimer = 0
	this.collidedSpriteType = NONE
	this.dead = false
	waitFrames(20)
	this.health = 10
	this.prevHealth = 10
	setStateToWalking()
}

updateWalkingAnimation() {
	if (this.direction == 0) {
		return
	}
	this.sprite.tileData.bank = 0x90
	this.sprite.tileData.lowBytes = walkingAnimations[this.direction - 1][this.animationFrame][1]
	this.sprite.flipX = walkingAnimations[this.direction - 1][this.animationFrame][0]
}

walkingAnimations = {
	{ false, 0xEA3A }, { false, 0xEA6B }, { false, 0xEA9C }, { false, 0xEACD },
	{ false, 0xE8B2 }, { false, 0xE8E3 }, { false, 0xE914 }, { false, 0xE945 },
	{ false, 0xE8B2 }, { false, 0xE8E3 }, { false, 0xE914 }, { false, 0xE945 },
	{ false, 0xE8B2 }, { false, 0xE8E3 }, { false, 0xE914 }, { false, 0xE945 },
	{ false, 0xE976 }, { false, 0xE9A7 }, { false, 0xE9D8 }, { false, 0xEA09 },
	{ true , 0xE8B2 }, { true , 0xE8E3 }, { true , 0xE914 }, { true , 0xE945 },
	{ true , 0xE8B2 }, { true , 0xE8E3 }, { true , 0xE914 }, { true , 0xE945 },
	{ true , 0xE8B2 }, { true , 0xE8E3 }, { true , 0xE914 }, { true , 0xE945 }
}

walk() {
	if (getRandomByte() & 2 == 0) {
		doWalk()
	}
	doWalk()
}

doWalk() {
	if (this.targetDistance == 360) {
		this.dead = true
		this.collidedSpriteType = NONE
		return
	}

	snapToTarget(this.sprite, this.targetSprite)
	this.direction = getDirectionToTarget(this.sprite, this.targetSprite)
	if (this.direction == NONE) {
		return
	}

	this.newX = this.sprite.x + moveAmount[this.direction][0]
	this.newY = this.sprite.y + moveAmount[this.direction][1]
	if (!bgSolidToMonsters(this.newX, this.y) &&
	    !touchingSpriteSolidToMonsters(this.sprite, this.newX, this.y)) {
		this.x = this.newX
	}
	if (!bgSolidToMonsters(this.x, this.newY) &&
	    !touchingSpriteSolidToMonsters(this.sprite, this.x, this.newY)) {
		this.y = this.newY
	}
	this.sprite.x = this.x
	this.sprite.y = this.y
}

moveAmount = {
	{  0,  0 },
	{  0, -1 },
	{  1, -1 },
	{  1,  0 },
	{  1,  1 },
	{  0,  1 },
	{ -1,  1 },
	{ -1,  0 },
	{ -1, -1 }
}

canJumpToTarget() {
	// Note: the following function is bugged to only return LEFT, RIGHT, or NONE
	this.jumpDirection = getDirectionToTargetPosition(this.sprite, this.jumpTargetX, this.jumpTargetY)

	offset = this.jumpTargetX - this.x
	this.jumpXMagnitude = abs(offset)
	this.jumpXSign = offset < 0 ? -1 : 1
	if (this.jumpXMagnitude == 19) {
		return false
	}

	offset = this.jumpTargetY - this.y
	this.jumpYMagnitude = abs(offset)
	this.jumpYSign = offset < 0 ? -1 : 1

	greaterMagnitude = max(this.jumpXMagnitude, this.jumpYMagnitude)
	this.jumpDuration = greaterMagnitude / 4
	this.zVelocity = greaterMagnitude / 8

	if (!bgSolidToSpecialMonsters(this.jumpTargetX, this.jumpTargetY) &&
	    !touchingSpriteSolidToMonsters(this.sprite, this.jumpTargetX, this.jumpTargetY) &&
	    !outsideOfLevel(this.jumpTargetX, this.jumpTargetY))
		this.xFraction = 0
		this.yFraction = 0
		return true, this.zVelocity, this.jumpDirection
	}
	return false
}

updateJumpZ() {
	this.sprite.z += this.zVelocity / 4
	this.zVelocity -= 1
}

updateJumpPosition() {
	f = this.xFraction + this.jumpXMagnitude
	while (f >= this.jumpDuration) {
		this.x += this.jumpXSign
		f -= this.jumpDuration
	}
	this.xFraction = f

	f = this.yFraction + this.jumpYMagnitude
	while (f >= this.jumpDuration) {
		this.y += this.jumpYSign
		f -= this.jumpDuration
	}
	this.yFraction = f
}

checkIfShouldJump() {
	if (health != prevHealth) {
		this.temp = getRandomByte()
		this.jumpTargetX = (getRandomByte() % 32) + 20 // Random value 20-51
		this.jumpTargetY = (getRandomByte() % 32) + 15 // Random value 15-46
		if (this.temp & 1 != 0) {
			this.jumpTargetX = -this.jumpTargetX
		}
		if (this.temp & 2 != 0) {
			this.jumpTargetY = -this.jumpTargetY
		}
		this.jumpTargetX += this.x
		this.jumpTargetY += this.y
		this.prevHealth = this.health
		this.jumpTargetSprite = -1
	} else {
		if (getRandomByte() >= 15 || this.targetDistance >= 325) {
			return
		}

		this.jumpTargetSprite = this.targetSprite
		this.jumpTargetX = this.jumpTargetSprite.x
		this.jumpTargetY = this.jumpTargetSprite.y
		if (abs(this.jumpTargetX - this.x) + abs(this.jumpTargetY - this.y) < 70) {
			return
		}
		this.jumpTargetX += jumpXSpacing[this.direction]
		if (this.jumpTargetSprite.type != VICTIM) {
			this.jumpTargetX += nonVictimJumpAdditionalXSpacing[this.direction]
		}
	}

	canJump, zVelocity, jumpDirection = canJumpToTarget()
	if (canJump) {
		this.zVelocity = zVelocity
		this.direction = jumpDirection
		setStateToPreJump()
	}
}

nonVictimJumpAdditionalXSpacing = { 0, 0, 96, 96, 96, 0, -96, -96, -96 }
jumpXSpacing = { 0, 0, 28, 28, 28, 0, -28, -28, -28 }

setStateToPreJump() {
	this.state = preJumpState
}

preJumpState() {
	this.sprite.flipX = preJumpFlipPerDirection[this.direction]
	showAnimation(preJumpAnimation)
	setStateToJumping()
}

preJumpAnimation = { { 0xEAFE, 7 }, { 0xEB27, 5 }, { 0xEB58, 5 }, { 0, 0 } }

preJumpFlipPerDirection = { false, false, false, false, false, false, true, true, true }

setStateToJumping() {
	this.state = jumpingState
	this.sprite.tileData.lowBytes = 0xEB89
	this.sprite.visible = true
	this.sprite.bgPriority = true
	this.sprite.type = NONE
}

jumpingState() {
	updateJumpZ()
	updateJumpPosition()
	this.sprite.x = this.x
	this.sprite.y = this.y

	if (this.sprite.z == 0) {
		if (this.jumpTargetSprite >= 0 && abs(this.jumpTargetSprite.x - this.jumpTargetX) < 9) {
			this.jumpTargetX += jumpLandingOffsets[this.direction * 2]
			this.jumpTargetY += jumpLandingOffsets[this.direction * 2 + 1]
		}
		this.x = this.jumpTargetX
		this.sprite.x = this.jumpTargetX
		this.y = this.jumpTargetY
		this.sprite.y = this.jumpTargetY
		setStateToPostJump()
	}
}

jumpLandingOffsets = {
	 0,
	 15, -9,
	 15, -9,
	 15,  0,
	 15,  8,
	 15,  8,
	-15, -9,
	-15,  0,
	-15, -9
}

setStateToPostJump() {
	this.state = postJumpState
}

postJumpState() {
	this.sprite.bgPriority = false
	this.sprite.type = MONSTER
	showAnimation(postJumpAnimation)

	if (canAttack()) {
		setStateToAttacking()
	} else {
		waitFrames((getRandomByte % 16) + 1)
		setStateToWalking()
	}
}

postJumpAnimation = { { 0xEBC2, 5 }, { 0xEBFB, 5 }, { 0xEC24, 5 }, { 0, 0 } }

setStateToAttacking() {
	this.state = attackingState
	this.attackSprite = createAttackSprite()
	this.framesUntilAnimUpdate = 0
	this.animationFrame = 0
	this.sprite.flipX = attackFlipPerDirection[this.direction]
}

attackingState() {
	this.framesUntilAnimUpdate -= 1
	if (this.framesUntilAnimUpdate < 0) {
		this.framesUntilAnimUpdate = 2
		this.animationFrame += 1

		tileData = attackAnimation[this.animationFrame]
		if (tileData != 0) {
			this.sprite.tileData.lowBytes = tileData
			if (this.animationFrame >= 6) {
				this.attackSprite.visible = true
			}
		} else {
			deleteSprite(this.attackSprite)
			this.attackSprite = -1
			setStateToWalking()
		}
	}
}

attackAnimation = {
	0, 0xEC55, 0xEC7E, 0xECAF, 0xECF8, 0xED29, 0xED52, 0xED8B
	0xEDBC, 0xEDF5, 0
}

attackFlipPerDirection = { false, false, false, false, false, false, true, true, true }

createAttackSprite() {
	sprite = createSprite()
	sprite.x = this.sprite.x + attackSpriteXOffsetPerDirection[this.direction]
	sprite.z = 0
	sprite.y = this.sprite.y
	sprite.type = MONSTER
	sprite.entity = currentEntity
	sprite.tileData = null
	return sprite
}

attackSpriteXOffsetPerDirection = { 0, 0, -25, -25, -25, 0, 25, 25, 25 }

canAttack() {
	if (this.targetDistance >= 325) {
		return false
	}

	if (abs(this.targetSprite.y - this.y) >= 4) {
		return false
	}
	xOffset = this.targetSprite.x - this.x
	if (abs(xOffset) >= 29) {
		return false
	}
	this.direction = xOffset >= 0 ? LEFT : RIGHT // Note: this is backwards
	return true
}

setStateToWalking() {
	setCollisionHandler(collisionHandler)
	this.state = walkingState
}

walkingState() {
	this.targetDistance, this.targetSprite = findTarget(this.x, this.y)
	walk()

	this.framesUntilAnimUpdate -= 1
	if (framesUntilAnimUpdate < 0) {
		this.framesUntilAnimUpdate = 3
		this.animationFrame = (this.animationFrame + 1) % 4
		updateWalkingAnimation()
	}

	checkIfShouldJump()
	if (canAttack()) {
		setStateToAttacking()
	}
}

main() {
	if (!paletteFadeComplete) {
		return
	}

	$7E:00DE += 0x1C
	if (currentExtraSounds == 1) {
		playSound(0x2B)
	}
	init()

	while (!this.dead) {
		waitFrames(1)
		this.state()
	}

	setCollisionHandler(null)
	if (this.attackSprite != -1) {
		deleteSprite(this.attackSprite)
	}
	if (this.collidedSpriteType != NONE) {
		givePoints(this.collidedSpriteType & 0x8000, 300)
		werewolvesKilled += 1
		this.sprite.type = NONE
		this.sprite.tileData.bank = 0x8F
		playSound(0x2D)
		showAnimation(deathAnimation)
	}

	$7E:00DE -= 0x1C
	while ($7E:00DE < 0) { }
	deleteSprite(this.sprite)
}

deathAnimation = {
	{ 0xDA43, 12 }, { 0xDA7C, 12 }, { 0xDACD, 12 }, { 0xDB26, 12 },
	{ 0xDB6F, 12 }, { 0, 0 }
}

collisionHandler(spriteType) {
	if (spriteType < SQUIRT_GUN) {
		return false
	}
	this.collidedSpriteType = spriteType

	weaponType = spriteType & 0x7FFF
	if (weaponType == MARTIAN_BUBBLE_GUN) {
		return bubbleMonster()
	} else if (weaponType == FIRE_EXTINGUISHER) {
		return freezeMonster()
	} else if (weaponType == SILVERWARE) {
		return killed(weaponType)
	} else {
		newHealth = this.health - weaponDamage[weaponType - SQUIRT_GUN]
		if (newHealth < 0) {
			return killed(newHealth)
		} else if (newHealth != this.health) {
			this.health = newHealth
			return showDamageAnimation()
		}
		return false
	}
}

killed(newHealth) {
	this.dead = true
	this.health = newHealth
	this.freezeTimer = 0
	return true
}