function stageStart()
	doStageStep = true
  doStageDraw = true
  EnemyTimer = 0
  EnemyPeriod = 0.8
  Score = 0
  ScoreShown = 0
	t = 0
  You = Player:New(1/2*windowWidth,4/5*windowHeight)
end

function stageStep()
    -- [PLAYER STEP]
    You:Input()

    -- [WORLD STEP]
    -- first, simulate basic interaction
    for _, obj in pairs(List.Simulate) do
  		obj:Step()
  	end
    -- develop extra interactions:
    -- 1. friendly bullets
  	for _, bullet in pairs(List.FriendlyBullet) do
  		for _, enemy in pairs(List.Enemy) do
  			if bullet:DistanceWith(enemy, enemy.hitbox + bullet.hitbox) then
  				if bullet.hits > 0 then
  					enemy:Damage(bullet.damage)
  					Score = Score +bullet.damage
  					bullet.hits = bullet.hits - 1
  					if bullet.hits <= 0 then
  						bullet:Kill()
  					end
  				end
  			end
  		end
  	end
    -- 2. ememy bullets
  	for _, bullet in pairs(List.EnemyBullet) do
  		if bullet:DistanceWith(You, You.hitbox + bullet.hitbox) then
  			if bullet.hits > 0 then
  				--You:Damage(bullet.damage)
  				bullet.hits = bullet.hits - 1
  				if bullet.hits <= 0 then
  					bullet:Kill()
  				end
  			end
  		else
  			if bullet:DistanceWith(You, 200) then
  				bullet.grazeTimer = bullet.grazeTimer + 1
  				if bullet.grazeTimer > 30
  				and bullet.Grazed ~= true then
  					--Score = Score +3
  					bullet.Grazed = true
  				end
  			else
  				bullet.grazeTimer = 0
  			end
  		end
  	end

		for _, bullet in pairs(List.EnemyBullet) do
			if love.keyboard.isDown("lshift") then
				bullet:Kill()
			end
		end
    -- [POST WORLD STEP]
    -- update shown score
    AddScore()

    -- if game is not paused
  	t = t + current_dt
  	EnemyTimer = EnemyTimer + current_dt

  	if EnemyTimer >= 0 then --EnemyPeriod then
  		--EnemyTimer = EnemyTimer - EnemyPeriod
  		EnemyTimer = -1000000000000
  		for i=1, 1 do
  			local rand = 1 --math.random(10)
  			if rand == 1 then
  				local rand_x = math.random(-100,100)
  				local rand_y = math.random(-100,100)
  			  local x = Shooter:New(1/2*windowWidth,1/5*windowHeight)
  			else
  				local rand_x = math.random(-10,10)
  				local rand_y = math.random(-10,10)
  				local x = Fang:New(windowWidth/2+rand_x,windowHeight/2+rand_y)
  			end
  		end
  	end
end

function stageDraw()
    --[GAME WORLD]

    -- draw background (unimplemented)

    -- draw objects
  	for _, obj in pairs(List.Simulate) do
  		obj:Draw()
  	end

    --[HEADS UP DISPLAY (HUD)]
    -- show enemies healthbars
  	for _, enemy in pairs(List.Enemy) do
  		if enemy.show_health == true then enemy:DrawHealth() end
  	end

    -- show recollection zone
  	love.graphics.line(0,1/5*windowHeight,windowHeight,1/5*windowHeight)
    -- show game area
  	love.graphics.rectangle("line",0,0,windowWidth,windowHeight)

    -- show score
    love.graphics.print(ScoreShown, 10, 60)

    --[DEBUGGING]
    love.graphics.print(#List.Simulate, windowWidth-100, windowHeight-10)
end