Creating and dispatching Event more efficiently

totebo · June 2016

Resurrection!

I've started making a DragSelect class (similar to AceSlide but more minimalist). I'm going to use my new, and favourite, CallbackBroadcaster class to trigger callbacks.

To keep things neat DragSelect inherits from Sprite. A class can't inherit from two classes (I think), so what is the best way to have DragSelect use CallbackBroadcaster? I can think of three options:

1. Create an instance of CallbackBroadcaster and use that.
2. Inject methods into Sprite to send the events, as if Sprite inherited from CallbackBroadcaster.
3. Inherit from CallbackBroadcaster instead of Sprite and manually add the required Sprite functions in DragSelect.

Is there a fourth option? Not keen on the ones above.

hgy29 · June 2016

4. Have CallbackBroadcaster inherits from Sprite and DragSelect inherit from CallbackBroadcaster

But obivously this would waste resources...

antix · June 2016

5. When you create CallbackBroadcaster, also create a global var called CALLBACKBROADCASTER. When you init DragSelect just cache that with self.CallbackBroadcaster = CALLBACKBROADCASTER.

I assign global vars to pretty much all of my classes. It's so easy to use them in other classes if you stick to a naming system. This is my goto init.lua file..

ATLAS = RenderTarget.new(2048, 2048)
FONT = Font.new("fonts/Londrina70.fnt", "fonts/Londrina70.png")
 
AGUI = require("modules/agui")
AGUI.init()
 
FILE = File.new()
ACRYPT = SimpleCrypt.new()
 
PREFS = Prefs.new()
PREFS:loadPrefs()
 
SFX = Sfx.new()
SFX:enable(PREFS.soundEnabled)
SFX:setMasterVolume((1 / 100) * PREFS.soundVolume)
 
MUSIC = Music.new()
MUSIC:enable(PREFS.musicEnabled)
MUSIC:setVolume((1 / 100) * PREFS.musicVolume)
 
PLAYER = Player.new()
ENEMYPOOL = EnemyPool.new()
 
ANIMATOR = Animator.new()
TIMELINE = TimeLine.new()
 
BUMP = require("modules/bump").newWorld(128)
COLLISIONMAKER = CollisionMaker.new()
 
PARALLAX = Parallax.new()
LEVELMANAGER = LevelManager.new()

Damn your tidy code!

totebo · June 2016

Thanks guys, great to have more options. One day I may learn to love the Pandora's Box that is global vars.

Paulo777 · February 2018

Hello!
Is there a way to call

self.value += 1

ONCE inside an ENTER_FRAME event?

This way, when called, it increments forever... I'm wondering if there is a way to do this... 'Cause I've tried everything and I am convinced that it is not possible and That I'll have to find another way out

Apollo14 · February 2018

wow this old topic is extremely interesting, thx @Paulo777

Guys, can somebody please share simple example of code with&without callbacks?
I just don't understand - what the "callback" actually is? Thanks a lot, guys!

totebo · February 2018

An event is a created object that is passed via the EventDispatcher.

A callback is a pointer to a function. Calling a function directly, rather than doing it via EventDispatcher, is much faster.

In my experience you should only use EventDispatcher if you're not calling it very often. If you need to create an EventDispatcher every frame, for instance, it will slow your game down.

hgy29 · February 2018

I did something like this for Arthur:

EVENTMAP={}
local function dispatchEvent(e)
	e.processed=false
	for k,f in pairs(EVENTMAP) do
		if e.processed then return end
		f(k,e)
	end
end
 
stage:addEventListener(Event.MOUSE_DOWN,dispatchEvent)
local ok,controller=pcall(function() return require("controller") end)
if ok then 
	controller:addEventListener(Event.KEY_DOWN,dispatchEvent)
	controller:addEventListener(Event.KEY_UP,dispatchEvent)
	controller:addEventListener(Event.DISCONNECTED,dispatchEvent)
end

Then whenever I need to register an event:

EVENTMAP.Context1=function (ctx,e)
	local et=e:getType()
	if et==Event.MOUSE_DOWN then
            -- Do something
	end
	if et==Event.KEY_DOWN then
            -- Do something
	end
end

And to unregsiter:

EVENTMAP.Context1=nil

Paulo777 · February 2018

@Apollo14 you're welcome!

What I need is to call a function only once, but I have to call it inside a function that works only in an ENTER_FRAME event

What I need is simple, just increment a value ONCE every time a collision happens

What actually goes on is that every collision happens, it starts to increment forever... I just want to STOP IT and increment only once.

Can anybody give some light over it?

Paulo777 · February 2018

Hello everybody! Doing more tests, thinking hard putting my neurons to work I got to a solution:

Initially my collision condition was inside a eventListener explicit

self.addEventLinstener(Event.ENTER_FRAME, function (self,
 e)
 
-- code here
 
end, self)

but then, I created a separate function and called inside a function that had that explicit code before:

self:onDetectCollision()

in the onDetectCollision function I have

onDetectCollision(event)
 
if shot:collidesWith(self.ship) then
    --code
 
    self.collided = true
end
 
	self:addEventListener(Event.ENTER_FRAME, self.onDetectCollision, self)
 
	if self.collided then
		self.increment += 1
		self:removeEventListener(Event.ENTER_FRAME, self.onDetectCollision, self)
		self.collided = false
	end
end

All I needed was to create a function that has the ENTER_FRAME event and call it in the trigger function.
Inside the function with ENTER_FRAME event, set boolean to true if collided, down in the if condition that verifies if collided, increment, remove the event listener and set collided to false.

Howdy, Stranger!

Categories

In this Discussion

Top Posters

Creating and dispatching Event more efficiently

Comments

Howdy, Stranger!

Quick Links

Categories

In this Discussion

Top Posters

Creating and dispatching Event more efficiently

Comments