helper.lua

-- Library of helper functions

helper = {}

-- Returns magnitude of 2D input vector
function helper.getMagnitude(x, y)
	return math.sqrt((x * x) + (y * y))
end

function helper.getObjectDist(obj1, obj2)
	return helper.getMagnitude(obj1.x - obj2.x, obj1.y - obj2.y)
end

-- Returns the normalized coordinates of the 2D input vector
function helper.normalize(x, y)
	-- Check if zero
	if x == 0 and y == 0 then return 0, 0 end
	
	local magnitude = helper.getMagnitude(x, y)
	
	return x / magnitude, y / magnitude
end

-- Scales up a vector by the given number
function helper.scale(size, x, y)
	return x * size, y * size
end

-- Checks if two circles are colliding
function helper.circlesColliding(x1, y1, r1, x2, y2, r2)
	local dist = helper.getMagnitude(x2 - x1, y2 - y1)
	return (dist <= (r1 + r2))
end

function helper.objectsColliding(obj1, obj2)
	return helper.circlesColliding(obj1.x, obj1.y, obj1.radius, obj2.x, obj2.y, obj2.radius)
end

-- Checks if something is facing something else, within a certain radius
function helper.isFacing(x1, y1, dir, x2, y2, threshold)
	threshold = threshold or (math.pi / 8)
	
	local realDir = math.atan2(y2 - y1, x2 - x1)
	if realDir < 0 then realDir = realDir + (2 * math.pi) end
	
	local diff = realDir - dir
	
	while diff < (-math.pi) do diff = diff + (2 * math.pi) end
	while diff >= (math.pi) do diff = diff - (2 * math.pi) end
	
	return (math.abs(diff) < (threshold / 2)), diff
end

function helper.isFacingObject(obj1, obj2, threshold)
	return helper.isFacing(obj1.x, obj1.y, obj1.dir, obj2.x, obj2.y, threshold)
end

function helper.getAllBullets()
	local bullets = {}
	
	for _, obj in pairs(state.objects) do
		if getmetatable(obj) == objects.bullet then
			table.insert(bullets, obj)
		end
	end
	
	return bullets
end

function helper.getAllAmmoPacks()
	local ammoPacks = {}
	
	for _, obj in pairs(state.objects) do
		if getmetatable(obj) == objects.ammoPack then
			table.insert(ammoPacks, obj)
		end
	end
	
	return ammoPacks
end

function helper.getAllAlivePlayers()
	local alivePlayers = {}
	
	for _, obj in pairs(state.players) do
		if not obj.dead then
			table.insert(alivePlayers, obj)
		end
	end
	
	return alivePlayers
end

-- Returns a list of buttons that go in a direction relative to that angle
-- i.e. if you pass in a dir of 0, it will press will_be_left. If you pass in pi, it will go will_be_rights. If you pass in
-- 3 * pi / 4, it will go will_be_rights and right.
function helper.dirButtons(dir)
	while dir < 0 do dir = dir + (2 * math.pi) end
	while dir >= (2 * math.pi) do dir = dir - (2 * math.pi) end
	
	local inputs = {}
	if (dir < (math.pi / 8)) or (dir >= (15 * math.pi / 8)) then
		inputs.forward = true
	elseif dir < (3 * math.pi / 8) then
		inputs.forward = true
		inputs.rightstrafe = true
	elseif dir < (5 * math.pi / 8) then
		inputs.rightstrafe = true
	elseif dir < (7 * math.pi / 8) then
		inputs.rightstrafe = true
		inputs.backward = true
	elseif dir < (9 * math.pi / 8) then
		inputs.backward = true
	elseif dir < (11 * math.pi / 8) then
		inputs.backward = true
		inputs.leftstrafe = true
	elseif dir < (13 * math.pi / 8) then
		inputs.leftstrafe = true
	elseif dir < (15 * math.pi / 8) then
		inputs.leftstrafe = true
		inputs.forward = true
	end
	return inputs
end