LÖVE

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-- An attempt to implement a scenes system for LOVE 2D,
-- Made by mattyhex {mattyhex@mattyhex.net}
-- Free for all uses and free to edit/redistribute on grounds that my name +
-- this notice remains intact and unmodified.
-- I accept no liability for the fullness or reliabilty of this code...yaddayadda.

-- First the global scenes table, for access to all scenes
scenes = {}
scenes.__index = scenes

-- Next the setup for individual scenes
local scene = {}
scene.__index = scene


-- Make a new scene
-- @param name: string to indentify the scene in the scenes table
-- @param bg: false for no background, else rgb table or img
function newScene(name, bg, update, draw)
	local s = {}
	if bg then -- check for a background
		if type(bg) == 'userdata' then -- determine the type
			s.bg = bg -- set the background value
		elseif type(bg) == 'table' then
			if #bg < 4 then -- pad the table for 0.8.0
				for i=1,4-#bg do
					table.insert(bg, 0)
				end
			end
			s.bg = bg -- set the background value
		else -- fallback value
			s.bg = {0,0,0,0}
		end
	end
	if type(update) == 'function' then
		s.update = update -- set any update functions
	end
	if type(draw) == 'function' then
		s.draw = draw -- set any drawing functions
	end

	setmetatable(s, scene)
	scenes[name] = s -- add the scene!
end

-- Makes the background appear
function scene:drawBG()
	if self.bg then
		if type(self.bg) == 'table' then
			love.graphics.setBackgroundColor(unpack(self.bg))
		elseif type(self.bg) == 'userdata' then
			love.graphics.draw(self.bg, 0, 0)
		end
	end
end

-- Gets and draws the active scene background,
-- calls the draw functions if present
-- @param .../arg: any variables not defined globally
function scenes:draw(...)
	local active = scenes:getActive()
	scenes[active]:drawBG()
	if type(scenes[active].draw) == 'function' then
		scenes[active].draw(unpack(arg))
	end
end

-- Gets and updates the active scene,
-- calls the update functions if present
-- [@param dt: delta time - from parent function]
-- [@param .../args: any global variables not defined in the function itself]
function scenes:update(dt,...)
	if not dt then dt = love.timer.getDelta() end
	local active = scenes:getActive()
	if type(scenes[active].update) == 'function' then
		scenes[active].update(dt,unpack(arg))
	end
end

-- Make a specific scene active
-- @param name: the identifier of the scene to make active
function scenes:setActive(name)
	scenes.active = name
end

-- Tell me the active scene
-- returns: the active scene table
function scenes:getActive()
	return scenes.active
end

-- Grab the scene by the passed identifier, set any update functions
-- @param name: the scene name/identifier
-- @param func: update function(s) just like a per scene love.update(dt)
function scenes:setUpdate(name, func)
	if scenes[name] then
		if type(func) == 'function' then
			scenes[name].update = func
		end
	end
end

-- Grab the scene by the passed identifier, set any draw functions
-- @param name: the scene name/identifier
-- @param func: draw function(s) just like a per scene love.draw()
function scenes:setDraw(name, func)
	if scenes[name] then
		if type(func) == 'function' then
			scenes[name].draw = func
		end
	end
end