Simple lua game with corona sdk

Question

I'm trying to write a simple corona SDK game but i have some problems. The draw function in my game doesn't work properly. You can draw before you tap the start button. And when you double tap the game crashes.

the main.lua file

display.setStatusBar( display.HiddenStatusBar )

--requiring libraries
local physics = require ("physics")
physics.start(true)
physics.setGravity(0,9)

  --constants
 local _W = display.contentWidth /2;
 local _H = display.contentHeight /2;

 -- game variables
local games = display.newGroup()
local orkHeight = 42;
local orkWidth = 40;
local score = 1;
local currentlevel;
local gameEvent = "";
local draw

--menu screen
local titleScreenGroup;
local titleScreen;
local playBtn;

--game screen
local background;
local goal;
local player;
local objective;

--Text box group
local objectiveText;
local levelText;
local levelNum;

 -- textBoxGroup
local textBoxGroup;
local textBox;
local conditionDisplay;
local messageText;


local bx, by=0, 0 -- Create our variables for drawing the line
local lines={}


local p=0
local e=0

function main()
    showTitleScreen();
end

function showTitleScreen()
    --alle title elementen in een groep ;p
    titleScreenGroup = display.newGroup();

    --background
    background = display.newImage("titleScreen.png")
    background.x = _W
    background.y = _H

    --play button
    playBtn = display.newImage("playButton.png")
    playBtn.x = _W;
    playBtn.y = _H + 50
    playBtn.name = "loadGame"

    --inserting 
    titleScreenGroup:insert(background)
    titleScreenGroup:insert(playBtn)

    --press button
    playBtn:addEventListener("tap", loadGame)   
end

--load actual game
function loadGame(event)
    if event.target.name == "loadGame" then
    transition.to(titleScreenGroup,{time = 0, alpha=0, onComplete =
    initializeGameScreen});
    playBtn:removeEventListener("tap", loadGame)
    end 
end

function initializeGameScreen()
    whiteBackground = display.newRect(0, 0, 480, 320)
    whiteBackground:setFillColor(255,255,255)

    player = display.newImage("ork.png")
    player.x = _W - 125
    player.y = _H - 50
    physics.addBody(player, "static", {density=0, bounce=.0, friction=.2})  

    --goto level 1 :)
    changelevel1()
end

function changelevel1()
    print("HOI")
    whiteBackground:addEventListener("tap", startGame)
end

function startGame()
draw:addEventListener("touch", drawALine)

drawALine(event)
end

function drawALine(event)

        if "began"==event.phase then
        bx, by=event.x, event.y -- Store the values, if you don't it starts from 0, 0

        elseif "moved"==event.phase then

       lines[p]=display.newLine(bx, by, event.x, event.y) -- Make a normal line
        --adding physics to the lines

        physics.addBody(lines[p], "static", {density=.2, friction=.0, bounce=0});
        --Width  
          lines[p].width=6 -- Just a boring old set width

        --color
          lines[p]:setColor(0,0,0)           


        bx, by=event.x, event.y -- Reset the bx and by, comment out for a "starburst" effect
        p=p+1
        e=e+1

        elseif "ended"==phase then

        end    


end




main()

I know the images and stuff don't fit well, but i'm just trying to make a simple game.

Thanks in advance.

Answer 1

In my opinion,addEventListener only for display object.In your code no draw object.so code like this: remove this line

draw:addEventListener("touch", drawALine)

replace

Runtime:addEventListener("touch", drawALine)

and remove this line drawALine(event)

it works for me.

function startGame()
Runtime:addEventListener("touch", drawALine)
--drawALine(event)
end