Kill level?

Paulo777 · March 2018

Hi all!
Can anyone tell me what can I do to literally kill a level? I want to restart a level, tried everything and the only thing that makes me go into here is when I tried everything and nothing absolutely nothing works.

I tried to collect garbage, no works
I tried to change where some sprites must start, (self, stage) just got trouble.

Is there a thing that I didn't try? Is there a thing that I still don't know?

I am since morning thinking hard and I don't know what to do anymore.

I have a level, and in this level I add a table with sprites in it. Inside a sprite, there is another sprite (bullets) that I load and inside this sprite it is generated inside 'stage'. It is working until I'm getting to restart the level... when the level is 'restarted' the sprites just gets invisible and 'shooting', it doesn't disappear and I'm getting hardly frustrated of how I can't understand how it works...

What I want is simple. Restart a level and kill everthing that has in it.

antix · March 2018

A simple restart level function is possible as long as you keep track of everything you created in that level.

Here is an example that creates a table of sprites, each with random numbers of child and grandchild sprites.

The table is then iterated and all sprites recursively removed.

In your own code you would have to remove any event listeners that each sprite might have (although in a perfect world they should not have any besides touch listeners if required).

Once all of the sprites have been removed, if there are no references to them anywhere else in your code, they should be garbage collected.

-- counters
local created = 0
local killed = 0
 
-- an empty table of sprites
local tableOfSprites = {}
 
-- create a random number of sprites with random numbers of children and grandchildren
for i = 1, math.random(2, 12) do
  -- create a new sprite
  local sprite = Sprite.new()
   -- each sprite in table gets a random number of children sprites
  for i = 1, math.random(2, 10) do
    sprite:addChild(Sprite.new())
    created += 1
    -- and a random number of grandchildren sprites
    for i = 1, math.random(2, 5) do
      sprite:getChildAt(math.random(1, sprite:getNumChildren())):addChild(Sprite.new())
      created += 1
    end
  end
  table.insert(tableOfSprites, sprite) -- add sprite to the table
  stage:addChild(sprite)
  created += 1
end
print('created ' .. created .. ' created')
 
-- kill all sprites
for i = #tableOfSprites, 1, -1 do -- always process from last to first
  local function killChild(sprite) -- a function to recursively kill a sprite, its children, grandchildren, etc, etc
    local count = sprite:getNumChildren()
    if count > 0 then
      for i = count, 1, -1 do -- always process from last to first
        killChild(sprite:getChildAt(i))
      end
    end
    -- actually kill the sprite
    sprite:removeFromParent() -- remove the sprite
    --
    -- remove event listeners here
    --
    killed += 1
  end
 
  killChild(table.remove(tableOfSprites, i)) -- kill it!!
end
 
print('killed ' .. killed .. ' sprites')
 
-- tableOFSprites will now be an empty table
 
collectgarbage('collect')

I hope this helps you grasp the concept. If not let us know

Apollo14 · March 2018

for i = #tableOfSprites, 1, -1 do -- always process from last to first
  local function killChild(sprite)

@antix thanks a lot! It wasn't my question, but the answer actually is extremely useful for me.

I guess function 'killChild(sprite)' would better be global?

Paulo777 · March 2018

Hello! Thank you for the answer!

To load my sprites, I'm doing this way:

counter += 1
local gears = {
		Gear.new(ship),
		Gear.new(ship),
		Gear.new(ship),
		Gear.new(ship),
		Gear.new(ship),
	}
 
if counter == 10 then
self:addChild(gears[1])
end
 
-- so on with the others and when I load the last one:
if counter == 500 then
self:addChild(gears[5])
counter = 0
end

when the couter is 0 repeat and load more sprites.

Is that a wrong way to do?

jdbc · March 2018

Just use SceneManager to create new instance of the level class

GameScene = Core.class(Sprite)

function GameScene:init()
# do some staff
end

In main.lua define your scenes

scenes = {"menu", "game"}
sceneManager = SceneManager.new({
["menu"] = MenuScene,
["game"] = GameScene,
})

to change to GameScene
sceneManager:changeScene(scenes[2]);

it will create new GameScene from scratch.

antix · March 2018

@Apollo14 It could be global but if it was just being used for that one table I'd make it local.

@jdbc That would work I suppose but if the scene to be discarded contains persistent game data, it would also be recycled. The best approach is most likely to manage the resources internally in the scene.

@Paulo777 So at the start of the scene you create 5 gears and then as counter increments you add gears to the stage at preset times right? If it works, then its fine. You can reiterate later and optimize it. So you could use something like this for your project..

local gears = {}
 
-- create a number of gears
local function createGears(count)
  for i = 1, count do
    gears[#gears + 1] = Gear.new(ship)
  end
end
 
-- kill all gears
local function killGears()
  local function kill(gear) -- recursively kill a sprite, its children, grandchildren, etc, etc
    local count = gear:getNumChildren()
    if count > 0 then
      for i = count, 1, -1 do
        kill(gear:getChildAt(i))
      end
    end
    gear:removeFromParent()
  end
 
  for i = #gears, 1, -1 do
    kill(table.remove(gears, i))
  end
end

jdbc · March 2018

antix said:
@Apollo14 It could be global but if it was just being used for that one table I'd make it local.

@jdbc That would work I suppose but if the scene to be discarded contains persistent game data, it would also be recycled. The best approach is most likely to manage the resources internally in the scene.

@Paulo777 So at the start of the scene you create 5 gears and then as counter increments you add gears to the stage at preset times right? If it works, then its fine. You can reiterate later and optimize it. So you could use something like this for your project..
local gears = {}
 
-- create a number of gears
local function createGears(count)
  for i = 1, count do
    gears[#gears + 1] = Gear.new(ship)
  end
end
 
-- kill all gears
local function killGears()
  local function kill(gear) -- recursively kill a sprite, its children, grandchildren, etc, etc
    local count = gear:getNumChildren()
    if count > 0 then
      for i = count, 1, -1 do
        kill(gear:getChildAt(i))
      end
    end
    gear:removeFromParent()
  end
 
  for i = #gears, 1, -1 do
    kill(table.remove(gears, i))
  end
end

Use datasaver before reload (change) scene to store your data. Use Core.class() and SceneManager, it is easier to keep the game state. I have done this in all my games and I have developed more than 10.

Take a look to the source code of my complete game. It has ads, social, leaderboard, scenemanager...
https://github.com/jdbcdev/Dots

All my scenes, ads and social manager, leaderboard are just classes. Easier and clean code.

Do not use global variables or functions to keep game state, it is really difficult to keep it.

Paulo777 · March 2018

antix said:
@Apollo14 It could be global but if it was just being used for that one table I'd make it local.

@jdbc That would work I suppose but if the scene to be discarded contains persistent game data, it would also be recycled. The best approach is most likely to manage the resources internally in the scene.

@Paulo777 So at the start of the scene you create 5 gears and then as counter increments you add gears to the stage at preset times right? If it works, then its fine. You can reiterate later and optimize it. So you could use something like this for your project..
local gears = {}
 
-- create a number of gears
local function createGears(count)
  for i = 1, count do
    gears[#gears + 1] = Gear.new(ship)
  end
end
 
-- kill all gears
local function killGears()
  local function kill(gear) -- recursively kill a sprite, its children, grandchildren, etc, etc
    local count = gear:getNumChildren()
    if count > 0 then
      for i = count, 1, -1 do
        kill(gear:getChildAt(i))
      end
    end
    gear:removeFromParent()
  end
 
  for i = #gears, 1, -1 do
    kill(table.remove(gears, i))
  end
end

I didn't understand the part of the 'gear'... woudn't that be "Gear"? I mean "gear" doesn't exists

pie · April 2018

@Paulo777 gear exists in

local function kill(gear)

It is how antix named the (parameter), which is the same as writing

 local function kill(par)  
local gear = par

Paulo777 · April 2018

pie said:
@Paulo777 gear exists in
local function kill(gear)
It is how antix named the (parameter), which is the same as writing
 local function kill(par)  
local gear = par

Omg! What an idiot I am! Thank you! hahah

Paulo777 · April 2018

jdbc said:
antix said:
@Apollo14 It could be global but if it was just being used for that one table I'd make it local.

@jdbc That would work I suppose but if the scene to be discarded contains persistent game data, it would also be recycled. The best approach is most likely to manage the resources internally in the scene.

@Paulo777 So at the start of the scene you create 5 gears and then as counter increments you add gears to the stage at preset times right? If it works, then its fine. You can reiterate later and optimize it. So you could use something like this for your project..
local gears = {}
 
-- create a number of gears
local function createGears(count)
  for i = 1, count do
    gears[#gears + 1] = Gear.new(ship)
  end
end
 
-- kill all gears
local function killGears()
  local function kill(gear) -- recursively kill a sprite, its children, grandchildren, etc, etc
    local count = gear:getNumChildren()
    if count > 0 then
      for i = count, 1, -1 do
        kill(gear:getChildAt(i))
      end
    end
    gear:removeFromParent()
  end
 
  for i = #gears, 1, -1 do
    kill(table.remove(gears, i))
  end
end
Use datasaver before reload (change) scene to store your data. Use Core.class() and SceneManager, it is easier to keep the game state. I have done this in all my games and I have developed more than 10.

Take a look to the source code of my complete game. It has ads, social, leaderboard, scenemanager...
https://github.com/jdbcdev/Dots

All my scenes, ads and social manager, leaderboard are just classes. Easier and clean code.

Do not use global variables or functions to keep game state, it is really difficult to keep it.

I took a brief look at your game. I felt really impressed about it. Congrats! It is really clean code and simple...

antix · April 2018

@jdbc yep you can totally save state between levels but I feel that is just wearing out the storage for no good reason

I find it pretty easy to manage global vars myself. I only save to the device when the user decides to (with options screens and stuff).

I use classes for pretty much everything too just because it makes things easier to manage (20,000+ lines of code in one file is daunting!) and it makes things easy to reuse in future projects.

antix · April 2018

@jdbc I was also just looking at your code for your dots game, great stuff

I noticed that in the key events you are using stopPropagation() which the Gideros documentation specifies is only required for mouse and touches.. unless the documentation is wrong?

Paulo777 · April 2018

@antix unfortunatelly I tried and keeps the same... The 'gears' on level restart gets invisible and shooting... it works for they don't appear in the game but they are not killed... keeps receiving events and shooting and they are only dead when I shoot with the 'ship' even invisible they receive events and die...

antix · April 2018

@Paulo777 If your gears have event listeners attached to them then you will need to remove those also...

local function killGears()
local function kill(gear) -- recursively kill a sprite, its children, grandchildren, etc, etc
  local count = gear:getNumChildren()
  if count > 0 then
    for i = count, 1, -1 do
      kill(gear:getChildAt(i))
    end
  end
 
  -- REMOVE EVENT LISTENERS HERE
 
  gear:removeFromParent()
end

Are you attaching an EnterFrame event to each one or other events?

hgy29 · April 2018

All of this makes me wonder: wouldn’t it be cool to have a Sprite:removeAllListeners(recursive) kind of call ? To cleanup a whole sprite hierarchy

Paulo777 · April 2018

@antix yes there is an enterFrame for its movement, and also the event... Strange that when I 'fire' I've just set a removefromparent inside gear class, so that when I fire, if it gets a given number of 'damage' it removes, and it works, why is it not working? I ask why should I have to worry about removing event listener if the other way (firing up against) works? I tried set Level = nil but also nothing...

@hgy29 that'd be great! I'd love that, hahah

jdbc · April 2018

antix said:
@jdbc I was also just looking at your code for your dots game, great stuff

I noticed that in the key events you are using stopPropagation() which the Gideros documentation specifies is only required for mouse and touches.. unless the documentation is wrong?

The documentation about Event class and stopPropagation

http://docs.giderosmobile.com/reference/gideros/Event/stopPropagation#Event:stopPropagation

Where did you see that is only for Touch or Mouse events? May be key events does nothing calling this method but it is working this code.

SceneManager creates a new instance of your GameScene class when changes the current scene, I guess the previous GameScene instance is destroyed and all listeners disabled. May be we could check SceneManager source code to make sure about it.

antix · April 2018

@Paulo777 If your gears have event listeners attached to them then they will still be receiving those events and therefore be processed each frame.

One way to make this work is to have a bool for each gear that lets the game logic know if it is alive or dead (should be processed or not).

Gear = Core.class(Sprite)
 
function Gear:init()
  self.alive = false
end
 
function Gear:respawn()
  self.alive = true
end
 
function Gear:update(dt)
  if self.alive then
    -- process gear logic here
  end
end

As well as that it seems that when you create each gear you are attaching an enter frame listener to it. It would be better to process the gears in your main enter frame listener.

function Game:update(e) -- update every frame
  local dt = e.deltaTime
 
  local gears = self.gears
  for i = #gears, 1, -1 do
    local gear = gears[i]
    gear:update(dt) -- process each gears AI etc here
  end
 
end

pie · April 2018

As far as I know, to completely get rid of a scene in scenemanager you should not changeScene to itself: just create a dummy/empty scene to changescene to, that 'redirects' to your game scene.

Ie.
Scenes:
Game
Dummy

When you are in Game and need to restart it changeScene to Dummy. In Dummy set the code to changeScene to Game. It should work.
If I remember, the issue in changing scene to itself is that you never stop referencing scene vars and objects, and gc does not collect everything properly.

Hope this helps

antix · April 2018

@pie I'll remember that tip

Still, it's pretty silly to just start a new blank scene, then start a new copy of the scene you want. In my opinion you really need to learn how to reset stuff without resorting to such methods

pie · April 2018

@antix it's not elegant but it's fast to setup and effective: just add a random ingame hint in the dummy scene to look like it's made on purpose..

Paulo777 · April 2018

People... Unfortunatelly I'm getting disapointed with Gideros... The code @antix posted simply doesn't works, once I set prints to see what it was doing, okay but now I see that it is not entering the functions... Actually I have no way to go there is nothing that kills them! Simply cannot understand its behaviour... I realized that The gears I set, the code is not taking them, It seems that gideros is allocating them in a part of the memory that is unrechable. Tried to set booleans inside Gear class, NOTHING! The only way to solve that is to call the creator of the engine... To at least understand what's going on!! I'm getting bored cuz I spend energy on that to nothing

pie · April 2018

@Paulo777 a bug is always possible, but I don't think that the issue is in the Engine at this level. Someone would have already noticed that. Which code exactly is not working? Sounds strange to be disappointed by gideros.. I guess you're missing something

sleep over it and look it again tomorrow. You could also zip your project, attach it here, and probably someone will tell you what's wrong there and why

Paulo777 · April 2018

Thanks for the help... I will really zip my project because I have no any resources and if I keep on It I will go to nowhere. If anyone is willing to help me by testing my project and dive into my codes i'm quite appreciated. I'm brazilian but all my code is in english then I guess it is understandable oh if you could tell me tips and best practices also on my code I'm also very appreciated.

jdbc · April 2018

Paulo777 said:
Thanks for the help... I will really zip my project because I have no any resources and if I keep on It I will go to nowhere. If anyone is willing to help me by testing my project and dive into my codes i'm quite appreciated. I'm brazilian but all my code is in english then I guess it is understandable oh if you could tell me tips and best practices also on my code I'm also very appreciated.

It seems that songs are missing

jdbc · April 2018

jdbc said:

Paulo777 said:
Thanks for the help... I will really zip my project because I have no any resources and if I keep on It I will go to nowhere. If anyone is willing to help me by testing my project and dive into my codes i'm quite appreciated. I'm brazilian but all my code is in english then I guess it is understandable oh if you could tell me tips and best practices also on my code I'm also very appreciated.
It seems that songs are missing

Why are you using this code?

self:removeEventListener(Event.ENTER_FRAME, self.onDetectCollision, self)

You are removing a wrong EventListener, it should be just
self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame)

and this?
stage:removeEventListener(Event.ENTER_FRAME, self.shot.onFire, self.shot)

why are you using stage instead of self (current scene)

jdbc · April 2018

Why are you using this code?

self:removeEventListener(Event.ENTER_FRAME, self.onDetectCollision, self)

You are removing a wrong EventListener, it should be just

self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame)

and this?

stage:removeEventListener(Event.ENTER_FRAME, self.shot.onFire, self.shot)

why are you using stage instead of self (current scene)

You have to stop music and removelisteners before change scene (reset same scene),
for instance:

self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame,self)
self:removeEventListener(Event.TOUCHES_BEGIN, self.onPaddleTouches, self)
self:removeEventListener(Event.TOUCHES_MOVE, self.onPaddleTouches, self)
self:removeEventListener(Event.TOUCHES_END, self.onPaddleTouchesEnd, self)

removes onEnterFrame listener, and touch listeners.

jdbc · April 2018

I guess you are not removing listeners properly.

Paulo777 · April 2018

@jdbc I had to remove songs beucause of file lenght, just comment that ones.

Paulo777 · April 2018

jdbc said:
Why are you using this code?
self:removeEventListener(Event.ENTER_FRAME, self.onDetectCollision, self)
ANSWER: It is an EnterFrame event to detect if a gear shot collided with ship.

You are removing a wrong EventListener, it should be just
self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame)
and this?
stage:removeEventListener(Event.ENTER_FRAME, self.shot.onFire, self.shot)
why are you using stage instead of self (current scene)

ANSWER: I had trouble using 'self', maybe something simple to solve but as it was working I left it this way.

You have to stop music and removelisteners before change scene (reset same scene),
for instance:

self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame,self)
self:removeEventListener(Event.TOUCHES_BEGIN, self.onPaddleTouches, self)
self:removeEventListener(Event.TOUCHES_MOVE, self.onPaddleTouches, self)
self:removeEventListener(Event.TOUCHES_END, self.onPaddleTouchesEnd, self)

removes onEnterFrame listener, and touch listeners.
This when? Level? Ship? Gear? all? Is this functions to add?

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