[CoronaSDK] Coroutine 狀態機

最近手上的案子是個麻煩的遊戲，對於遊戲開發來說狀態機(state machine)是很重要的流程控制器，認真研究了一下 Lua 才發現原來它有 Coroutine（協同程序）這個有趣的功能（AS 系列是沒有這種東西的，請原諒我的無知），有興趣搞懂 Coroutine 的朋友可以參考：electronic_blue 的使用 Coroutine 改寫狀態機，它恰恰是以 CoronaSDK 為範本作教學，簡單參考了它的範例程式，打包成了 statemachine.lua 供 CoronaSDK 開發使用。

用法很簡單如同 statemachine.lua 上面寫的範例：

	local sm = require("statemachine")
	local process = sm.new(function(self, time)
	self:sleep(100)
	print("hello")
	self:sleep(100)
	print("hehe...")
	self:sleep(100)
	print("end")
	end)
	process:run()

view raw statemachine-example01 hosted with ❤ by GitHub

也特別提供了 waiting and continue 功能來做畫面等待與繼續的工作，範例如下：

	local sm = require("statemachine")
	local process = sm.new(function(self, time)
	local txt = display.newText( "Press Me", display.contentCenterX, display.contentCenterY, native.systemFont, 32)
	txt:addEventListener("touch", function(evt)
	self:continue()
	end)
	self:waiting()
	txt.text = "Hello!"
	end)
	process:run()

view raw statemachine-example02 hosted with ❤ by GitHub

statemachine.lua

	--[[
	statemachine.lua
	Copyright (c) 2013 Erin Lin
	erinylin.blogspot.com
	Licensed under the MIT license.
	Usage:
	local sm = require("statemachine")
	local process = sm.new(function(self, time)
	self:sleep(100)
	print("hello")
	self:sleep(100)
	print("hehe...")
	self:sleep(100)
	print("end")
	end)
	process:run()
	local process1 = sm.new(function(self, time)
	local txt = display.newText( "Press Me", display.contentCenterX, display.contentCenterY, native.systemFont, 32)
	txt:addEventListener("touch", function(evt)
	self:continue()
	end)
	self:waiting()
	txt.text = "Hello!"
	self:sleep(200)
	txt.text = "Bye Bye!"
	end)
	process1:run()
	]]--
	local StateMachine = {}
	local StateMachine_mt = { __index = StateMachine }
	local coroutine = {
	yield = coroutine.yield,
	resume = coroutine.resume,
	create = coroutine.create,
	status = coroutine.status
	}
	function StateMachine:sleep(msec)
	self._wakeup = system.getTimer() + msec
	while self._wakeup > 0 do
	coroutine.yield()
	end
	end
	function StateMachine:enterFrame(event)
	if self._wakeup > 0 then
	if event.time > self._wakeup then
	self._wakeup = 0
	end
	else
	local state = coroutine.status(self._co)
	if state == "suspended" then
	coroutine.resume(self._co, self)
	elseif state == "dead" then
	if self._isLoop then
	self._co = coroutine.create( self._callback )
	else
	Runtime:removeEventListener("enterFrame", self)
	self._co = nil
	end
	end
	end
	end
	function StateMachine:pause()
	self._stopTime = system.getTimer()
	Runtime:removeEventListener("enterFrame", self)
	end
	function StateMachine:resume()
	if self._co then
	if self._wakeup > 0 then
	self._wakeup = self._wakeup + system.getTimer() - self._stopTime
	end
	Runtime:addEventListener("enterFrame", self)
	else
	self:run()
	end
	end
	-- you can loop this.
	function StateMachine:run(isLoop)
	self._isLoop = isLoop
	if not self._co then
	self._wakeup = 0
	self._stopTime = 0
	Runtime:addEventListener("enterFrame", self )
	self._co = coroutine.create( self._callback )
	end
	end
	function StateMachine:isRunning()
	return self._co ~= nil
	end
	function StateMachine:destroy()
	Runtime:removeEventListener("enterFrame", self )
	self._callback, self._co, self = nil, nil, nil
	end
	function StateMachine:cancel()
	Runtime:removeEventListener("enterFrame", self )
	self._co = nil
	end
	function StateMachine:waiting()
	self._isPass = false
	while not self._isPass do
	coroutine.yield()
	end
	end
	function StateMachine:continue()
	self._isPass = true
	end
	local function new(callback)
	local ds = {}
	setmetatable(ds, StateMachine_mt)
	ds._callback = callback
	ds._wakeup = 0
	return ds
	end
	return {new=new}

view raw statemachine.lua hosted with ❤ by GitHub