Game speed increases itself on every restart - Corona

Question

am trying to make a jetpack joyride concept game on corona. First of all unlike other sdk where when you change a scene, the previous scene is automatically removed, in corona you have to remove each and object and function yourself.

After a week I was finally able to remove objects while changing scene, but now I have ran into a new problem. Everytime when I change scenes and come back to the gameScreen the speed of lasers and missiles increases every time ( maybe twice? ). How can I reset its speed? I even added another "gameStatus" variable to remove the event listener and tried to print it, but game status never actually returned "ended", it was always "running". Here is the gameScene screen where everything happens

---

EDIT : I just noticed something, For example if 3 objects have already spawned then after reloading the screen only first 3 objects seem to be fast and its normal from fourth.

local composer = require( "composer" )
local scene = composer.newScene()
local physics = require( "physics" )
physics.start()

local image, text1

local function onSceneTouch( self, event )
    if event.phase == "began" then      
        composer.gotoScene( "startScreen", "fade", 400  )       
        return true
    end
end

function scene:create( event )
    local sceneGroup = self.view

    -- Variable
    ---------------------------------------
    sW = display.contentWidth
    sH = display.contentHeight

    -- trying to reset gameStatus on restart
    gameStatus = "ended"
    gameStatus = "running"


    --------------------------------------------------------
    backgroundTiles = {}

    drawBackground = function()
        cieling = display.newRect( 0, 0, 2 * sW, sH * 0.05)
        physics.addBody( cieling, "static", { density=0, friction=0, bounce=0 } )
        cieling.x, cieling.y = cieling.contentWidth / 4, cieling.contentHeight * 0.25
        cieling.alpha = 0
        cieling.name = "ceiling"

        ground = display.newRect( 0, sH, 2 * sW, sH * 0.05)
        physics.addBody( ground, "static", { density=3, friction=1, bounce=0.1 } )
        ground.x, ground.y = ground.contentWidth / 4, sH - ground.contentHeight * 0.25
        ground.alpha = 0
        ground.name = "ground"

    end

    drawBackground()
    --------------------------------------------------------


    --------------------------------------------------------
    drawBird = function()
        bird = display.newImageRect( "a/img/hero/hero.png", 80, 58)
        bird.x, bird.y = 0 - sW * 0.1, ground.y - ground.contentHeight - 10
        bird.isFixedRotation = true; bird.angularVelocity = 0;
        physics.addBody( bird, { density=1, friction=0.5, bounce=0.1 } )
        bird.name = "bird"
        sceneGroup:insert( bird )

        bird:addEventListener( "collision", onCollision )
    end

    coinsCollected, tokensCollected = 0, 0

    birdFlight = function()
        if ( gameStatus == "running" ) then
            transition.to(bird, {
                y = bird.y - 75,
                transition = easing.outQuad,
                onComplete = function() end
            })
            function birdFlight()
                --transition.to( bird, { rotation=-45, time=300 } )
            end
            birdFlight()
            function birdFall()
                --transition.to( bird, { rotation=90, time=300 } )
            end
            timer.performWithDelay(700, birdFall, 1)
        end
    end
    display.currentStage:addEventListener( "tap", birdFlight )

    function onCollision(event)
        if event.phase == "began" then
            if event.other.name == "coin" then
                coinsCollected = coinsCollected + 1
            end
            if event.other.name == "token" then
                tokensCollected = tokensCollected + 1
            end
            if event.other.name == "missile" or event.other.name == "laser" or event.other.name == "rod" then
               -- game ended
            end
        end
    end

    drawBird()

    function atFrame(event)
        if gameStatus == "running" then
            bird.x,bird.y = sW / 3,bird.y + 9
            if ( bird.y > sH - 70) then bird.y = sH - 70 end
            if ( gameStatus == "ended" ) then bird.y = bird.y + 15 end
        end
    end
    Runtime:addEventListener( "enterFrame", atFrame )

    --------------------------------------------------------



    --------------------------------------------------------
    missile, missileAlert, missileMoving = {}, {}, {}

    function removeMissile(i)
        local onEnterFrame = function( event )
            if missile[i] ~= nil and missile[i].x ~= nil and gameStatus == "running" then
                if missile[i].x < -100 then
                    display.remove( missile[i] )
                    missile[i] = nil
                end
            end
        end
        Runtime:addEventListener( "enterFrame", onEnterFrame )

        print(gameStatus)

        if gameStatus == "ended" then
            Runtime:removeEventListener( "enterFrame", onEnterFrame )
        end 
    end


    function flyMissile(i)
        local onEnterFrame = function( event )
            if missile[i] ~= nil and missile[i].x ~= nil and missile[i].y ~= nil and gameStatus == "running" then
                if missileMoving[i] == true then
                    missile[i].y = bird.y
                end
                missile[i].x = missile[i].x - 5
                if missileAlert[i] ~= nil then
                    if missileMoving[i] == true then
                        missileAlert[i].y = bird.y
                    end                 
                    if missile[i].x < sW then
                        display.remove( missileAlert[i] )
                        missileAlert[i] = nil
                    end                 
                end
            end
        end
        Runtime:addEventListener( "enterFrame", onEnterFrame )

        print(gameStatus)

        if gameStatus == "ended" then
            Runtime:removeEventListener( "enterFrame", onEnterFrame )
        end 
    end


    function holdMissile(i)
        local onEnterFrame = function( event )
            if missile[i] ~= nil and missile[i].x ~= nil and gameStatus == "running" then
                if missile[i].x < sW * 1.5 then
                    if missileAlert[i] ~= nil then
                        missileAlert[i]:setFillColor(1,1,0)
                    end
                    missileMoving[i] = false
                end
            end
        end
        Runtime:addEventListener( "enterFrame", onEnterFrame )

        print(gameStatus)

        if gameStatus == "ended" then
            Runtime:removeEventListener( "enterFrame", onEnterFrame )
        end 
    end


    function spawnMissile(i)

        missile[i] = display.newRect( sW*2, sH/2, 80, 80 )
        missileAlert[i] = display.newRect( sW-80, bird.y, 80, 80 )
        physics.addBody(missile[i],"kinematic",{isSensor=true})
        missile[i].name = "missile"
        sceneGroup:insert( missile[i] )
        sceneGroup:insert( missileAlert[i] )

        missileMoving[i] = true

        flyMissile(i)
        removeMissile(i)
        holdMissile(i)

    end

    spawnMissile(1)
    --------------------------------------------------------


    --------------------------------------------------------
    laser = {}

    function moveAndRemovelaser(i)
        local onEnterFrame = function( event )
            if laser[i] ~= nil and laser[i].x ~= nil and gameStatus == "running" then               
                laser[i].x = laser[i].x - 5
                if laser[i].x < 0 - sW / 2 then
                    display.remove( laser[i] )
                    laser[i] = nil
                end
            end
        end
        Runtime:addEventListener( "enterFrame", onEnterFrame )

        print(gameStatus)

        if gameStatus == "ended" then
            Runtime:removeEventListener( "enterFrame", onEnterFrame )
        end 
    end

    function spawnlaser(i)

        laserSize = math.random(1,2)
        laserPosition = math.random(1,3)
        laserRotation = math.random(1,4)

        if laserSize == 1 then
            laser[i] = display.newRect( 100,100,50,sH/3 )
        else
            laser[i] = display.newRect( 100,100,50,sH/2 )
        end

        sceneGroup:insert( laser[i] )

        laser[i].x = sW * 2
        laser[i].y = sH / 2
        laser[i].name = "laser"

        if laserPosition == 1 and laserRotation ~= 4 then
            laser[i].y = sH * 0.05 + 12
            laser[i].anchorY = 0
        elseif laserPosition == 3 and laserRotation ~= 4 then
            laser[i].y = sH * 0.95 - 12
            laser[i].anchorY = 1
        end

        if laserPosition == 1 and laserRotation == 4 then
            laser[i].y = sH * 0.05 + laser[i].contentHeight / 2
        elseif  laserPosition == 3 and laserRotation == 4 then
            laser[i].y = sH * 0.95 - laser[i].contentHeight / 2
        end

        if laserRotation == 1 then
            laser[i].rotation = -45
        elseif laserRotation == 2 then
            laser[i].rotation = 0
        elseif laserRotation == 3 then
            laser[i].rotation = 45
        elseif laserRotation == 4 then
            local onEnterFrame = function( event )
                if laser[i] ~= nil and laser[i].rotation ~= nil then
                    laser[i].rotation = laser[i].rotation + 5
                end
            end
            Runtime:addEventListener( "enterFrame", onEnterFrame )
        end

        laser[i]:setFillColor(1,1,0)
        physics.addBody(laser[i],"kinematic",{isSensor=true})

        moveAndRemovelaser(i)
    end

    spawnlaser(1)
    --------------------------------------------------------




    image = display.newRect (100,100,100,100)
    image.x = display.contentCenterX
    image.y = display.contentCenterY

    sceneGroup:insert( image )

    image.touch = onSceneTouch

    text1 = display.newText( "Game Screen", 0, 0, native.systemFontBold, 24 )
    text1:setFillColor( 255 )
    text1.x, text1.y = display.contentWidth * 0.5, 50
    sceneGroup:insert( text1 )
end

function scene:show( event )

    local phase = event.phase

    if "will" == phase then
        gameStatus = "ended"
    end

    if "did" == phase then
        print( "4" )
        composer.removeScene( "startScreen" )
        image:addEventListener( "touch", image )
        gameStatus = "running"
    end

end

function scene:hide( event )
    local phase = event.phase
    if "will" == phase then
        print( "5" )
        gameStatus = "ended"
        image:removeEventListener( "touch", image )
        Runtime:removeEventListener( "enterFrame", onEnterFrame )
    end
end

function scene:destroy( event ) 
    print( "6" )
end


scene:addEventListener( "create", scene )
scene:addEventListener( "show", scene )
scene:addEventListener( "hide", scene )
scene:addEventListener( "destroy", scene )


return scene

Answer 1

So I ended up creating a function and putting all the removeEventListeners in that function and called that function when the game ended. For future reference always keep a list of all the timer and event listeners that you have created anywhere in the screen and remove them all together when ending the game

Answer 2

You are getting this problem because you are registering an event listener twice.

You need to add and remove them only when the scene enters and exits. The proper place to remove game objects is scene:destroy() and scene:hide()

My advice is that you try to re-organize your code and try to follow these guidelines:

• scene:create() : This happens the first time a scene is used. You want create your game objects here. This event will only happen once, unless the scene is destroyed and then used again.

• scene:show() : You want to register all your event listeners here (touch, etc) and setup your game. This function gets called every-time the scene is shown. Every event listener that is registered here should be un-registered to prevent double-triggering.

• scene:hide() : You want to un-register all event listeners here. This will prevent the next scene from triggering events on your previous scene's listeners too.

• scene:destroy() : You want to remove all game objects here (images, text, widgets, etc). The scene is no longer needed and everything should be cleaned.

To better understand how the Scene's work I recommend reading this doc: http://coronalabs.com/blog/2014/01/21/introducing-the-composer-api-plus-tutorial/