littlespacegame/entities/enemy.lua

--! file enemy.lua
require("blaster")
Enemy = Object:extend()

--int x, y, radius
--playableArea -> {int[2]}
function Enemy:new(x, y, radius, playableArea)
	self.origin = { x, y }
	self.image = love.graphics.newImage("/assets/enemy/e-fighter.png")

	self.x = x
	self.y = y
	self.playableLeft = playableArea[1]
	self.playableRight = playableArea[2]

	self.type = "enemy"
	self.health = 10
	self.move_radius = radius
	self.speed = 80
	self.fireRate = 1
	self.destroy = false

	self.height = 22
	self.width = 24
	self.x_offset = 18
	self.y_offset = 20

	self.hitbox = {
		(self.x + self.x_offset),
		(self.x + self.x_offset + self.width),
		(self.y + self.y_offset),
		(self.y + self.y_offset + self.height),
	}

	self.move_bounds = self:setMoveBounds()
	--print("Move Bounds: ", self.move_bounds[1], " , ", self.move_bounds[2])
	self.fireTime = love.timer.getTime()
	self.enemyBullets = {}
end

function Enemy:draw()
	--draw stuff
	love.graphics.rectangle("line", self.hitbox[1], self.hitbox[3], self.width, self.height)
	--TODO: Resolve this magic number bullshit on line 52. (Why do I subtract 4?)
	love.graphics.draw(
		self.image,
		self.x,
		self.y,
		3.14159,
		1,
		1,
		(self.x_offset + self.width * 2 - 4),
		(self.y_offset + self.height * 2)
	)

	for _, v in ipairs(self.enemyBullets) do
		v:draw()
	end
end

function Enemy:update(dt, player)
	-- if spawn location is near the edge, adjust the bounds such that the radius
	-- does not overlap the bounds of the playable area
	local window_height = love.graphics.getHeight()

	self.x = self.x + self.speed * dt
	--self.hitbox = { (self.x + 18), (self.x + 44), (self.y + 20), (self.y + 44) }
	self:setHitbox()

	--movement
	if self.hitbox[1] < self.move_bounds[1] then
		--self.x = self.move_bounds[1]
		self.speed = -self.speed
	elseif self.hitbox[2] > self.move_bounds[2] then
		--self.x = self.move_bounds[2] - self.width - self.x_offset
		self.speed = -self.speed
	end

	--firing!
	self:fire()

	for i, v in ipairs(self.enemyBullets) do
		v:update(dt)

		if v.y > window_height then
			v.destroy = true
		end

		if v.destroy == true then
			--print("Enemy Bullet Removed! Bullets in table remaining: ", #enemyBullets)
			table.remove(self.enemyBullets, i)
		end

		v:checkCollision(player)
	end
	--health check
	if self.health < 0 then
		self.destroy = true
	end
end

--shoot at the player a variable number of seconds
function Enemy:fire()
	--local fire_origin = { self.x + 26, self.y + 44 }
	local fire_origin = { ((self.x + (self.width / 2)) + self.x_offset), (self.y + self.height + self.y_offset) }
	if love.timer.getTime() - self.fireTime > self.fireRate then
		table.insert(self.enemyBullets, Blaster(fire_origin[1], fire_origin[2], "enemy"))
		self.fireTime = love.timer.getTime()
	end
end

function Enemy:setMoveBounds()
	local result = {}

	if (self.hitbox[1] - self.move_radius) < self.playableLeft then
		result[1] = self.playableLeft
		--result[2] = self.playableLeft + self.hitbox[1] + self.move_radius
		result[2] = self.playableLeft + (self.move_radius * 2)
	elseif (self.hitbox[2] + self.move_radius) > self.playableRight then
		--result[1] = self.playableRight - self.hitbox[2] - self.move_radius
		result[1] = self.playableRight - (self.move_radius * 2)
		result[2] = self.playableRight
	else
		result[1] = self.x - self.move_radius
		result[2] = self.x + self.move_radius
	end
	return result
end

function Enemy:setHitbox()
	self.hitbox = {
		(self.x + self.x_offset),
		(self.x + self.width + self.x_offset),
		(self.y + self.y_offset),
		(self.y + self.height + self.y_offset),
	}
end