collision-detection-challenge.lua

-- Collision Detection Challenge

function RandomizeWall()
	Wall.x = math.random(0, 200)
	Wall.y = math.random(24, 100)
	Wall.width = math.random(8, 100)
	Wall.height = math.random(8, 100)
end

function IsColliding()
	-- If the player's left is 
	-- to the right of the wall, it is 
	-- not colliding (return false)
	local wallRight = Wall.x + Wall.width
	local playerLeft = Player.x
	if playerLeft >= wallRight then 
	  return false 
	end
	
	-- TO DO: There are 3 more conditions 
	-- to finish collision detection. 
	-- What are they?
	
	-- playerRight < wallLeft
	local playerRight = Player.x + Player.width
	local wallLeft = Wall.x
	if playerRight < wallLeft then
	  return false
	end

-- If player bottom < wall top
	local playerBottom = Player.y + Player.height
	local wallTop = Wall.y
	if playerBottom < wallTop then
	  return false
	end
	
	local playerTop = Player.y
	local wallBottom = Wall.y + Wall.height
	if playerTop > wallBottom then
		return false
	end
	
	return true
end

-- You do not need to edit anything below this line

function BOOT()
	Player = CreateActor(200, 80, 10, 10, 1)
	Wall = CreateActor(112, 36, 8, 82, 2)
end

function CreateActor(x, y, w, h, c)
	local newWall = {}
	newWall.x = x
	newWall.y = y
	newWall.width = w
	newWall.height = h
	newWall.color = c
	return newWall
end

function TIC()
	Input()
	Update()
	Draw()
end

function Input()
	MoveInput()
end

function MoveInput()
	if btn(0) then Player.y = Player.y - 1 end
	if btn(1) then Player.y = Player.y + 1 end
	if btn(2) then Player.x = Player.x - 1 end
	if btn(3) then Player.x = Player.x + 1 end
	if btnp(4) then RandomizeWall() end
end

function Update()
	if IsColliding() then
		Player.color = 12
	else
		Player.color = 1
	end
end

function Draw()
	cls(0)
	DrawActor(Wall)
	DrawActor(Player)
	DrawInfo()
end

function DrawActor(a)
	rect(a.x, a.y, a.width, a.height, a.color)
end

function DrawInfo()
	print("Press 'A' to RandomizeWall", 0, 0, 12)
	print("Player Bounds: (" .. Player.x .. ", " .. Player.y .. ") - (" .. Player.x + Player.width .. ", " .. Player.y + Player.height .. ")", 0, 8, 12)
	print("Wall Bounds: (" .. Wall.x .. ", " .. Wall.y .. ") - (" .. Wall.x + Wall.width .. ", " .. Wall.y + Wall.height .. ")", 0, 16, 12)
end