Created a Group, not sure how to Remove it!

Getting Started Newbie Questions
#1

Hello!  I’m kinda new to Lua (spent a lot of time in UnityScript) and I’ve managed to get lines, buttons, and physics going after searching the web and putting it together.  What I need to do now is to delete the line group after a button press (no matter the number of lines).  For the most part my script has worked, until there are no lines left or I try to redraw.  I’ve removed my code from the button section.  Can anyone help me?  I feel like this is a VERY simple thing to do, but I’m consistently wrong on my approach.  Thanks.

–codeBelow:

display.setStatusBar( display.HiddenStatusBar )

local physics = require “physics”

physics.start()

local widget = require( “widget” )

local lines = {}

local lineGroup = display.newGroup()

local prevX,prevY

local isDrawing = false

local i = 0

local kittenCrate = display.newRect(10,10,25,25)

physics.addBody(kittenCrate, “dynamic”, { density = 1, friction = 0.5, bounce = 1.6})

local function distanceBetween(x1, y1, x2, y2)

    local dist_x = x2 - x1

    local dist_y = y2 - y1

    local distanceBetween = math.sqrt((dist_x*dist_x) + (dist_y*dist_y))

    return distanceBetween

end

local function drawLine(e)

    if(e.phase == “began”) then

        prevX = e.x

        prevY = e.y

        isDrawing = true

        i = i + 1

    elseif(e.phase == “moved”) then

        local distance = distanceBetween(prevX, prevY, e.x, e.y)

        if(isDrawing and distance < 100) then

            if(lines[i]) then lineGroup:remove(i) end

            lines[i] = display.newLine(prevX, prevY, e.x, e.y)

            lines[i]:setColor(255, 255, 0)

            lines[i].width = 5

            local dist_x = e.x - prevX

            local dist_y = e.y - prevY

            physics.addBody(lines[i], “static”, { density = 1, friction = 0.5, bounce = 1, shape = {0, 0, dist_x, dist_y, 0, 0} } )

            lineGroup:insert(lines[i])

        end

    elseif(e.phase == “ended”) then

        isDrawing = false

    end

end

Runtime:addEventListener(“touch”,drawLine)

local function handleButtonEvent( event )

    if ( “ended” == event.phase ) then

        print( “Button was pressed and released” )

        

    end

  

end

– Create the widget

local button1 = widget.newButton

{

    left = 100,

    top = 200,

    id = “button1”,

    label = “Remove Rifts”,

    onEvent = handleButtonEvent

}

#2

Have you tried

lineGroup:remove()

take a look on https://docs.coronalabs.com/api/type/GroupObject/remove.html

#3

I did.  The button realizes that I press it, but nothing happens.  If I put a number in the lineGroup:remove() parenthesis, it will take away one, but then error if I try and redraw.  I have no idea why this is being so difficult!  Thanks for the reply!

#4

This new code is almost there:

local function handleButtonEvent( event )

    if ( “ended” == event.phase ) then

        print( “Button was pressed and released” )

        for i = 1, #lines do

                

                lines[i]:removeSelf()

                lines[i] = nil

        end

        

        

        

    end

    

end

It erases everything.  However, when I go back to Corona, the whole thing crashes, taking the console along with it.  Any ideas?

#5

You aren’t having a squabble with the physics engine ? I note that you are adding the lines to that - if you remove a line from a view group, perhaps this does not remove it from the physics engine ?

#6

Have you tried

lineGroup:remove()

take a look on https://docs.coronalabs.com/api/type/GroupObject/remove.html

#7

I did.  The button realizes that I press it, but nothing happens.  If I put a number in the lineGroup:remove() parenthesis, it will take away one, but then error if I try and redraw.  I have no idea why this is being so difficult!  Thanks for the reply!

#8

This new code is almost there:

local function handleButtonEvent( event )

    if ( “ended” == event.phase ) then

        print( “Button was pressed and released” )

        for i = 1, #lines do

                

                lines[i]:removeSelf()

                lines[i] = nil

        end

        

        

        

    end

    

end

It erases everything.  However, when I go back to Corona, the whole thing crashes, taking the console along with it.  Any ideas?

#9

You aren’t having a squabble with the physics engine ? I note that you are adding the lines to that - if you remove a line from a view group, perhaps this does not remove it from the physics engine ?