Help Creating A touch event

inveince · September 16, 2014, 8:42pm

Hi I’m new (2 months) toCorona Sdk , I’m basically trying to convert the FatFreddy Demo to Composer with a menu etc.I have the menu screen up , but right now I’m stuck on the touch event so I can drag the player( its just a square). My attachment shows the error that pops up and also the part of the code it has a problem with. I placed the code in the function scene: create (event) section of the composer template. I tested the code out in a simple main.lua file without Composer and everything works fine, but when I plug the code into my actual game with composer it produces the error below.

Im using the Corona Simulator 2014.2393

Error Message" game.lua 100 attempt to index global player1 (a nil value)

I know that the Fatfreddy demo game is old(outdated code) and I am basically using it as a point of reference for my game, but any advice on the simplest way to transfer a game with only one lua file to a actually complete game would help.

FatFreddy: http://www.cutemachine.com/corona-sdk-tutorial/a-complete-game-made-with-corona-sdk-tutorial-part-4/

rob · September 17, 2014, 12:01am

First, screen shots of code isn’t a very good way to post code to the forums. Its much better to select your code using your mouse and do a “copy” (CTRL-C PC or CMD-C on a Mac), then in the forums type :


paste your code (CTRL-V or CMD-V)

(Please leave space after the [ out)

But in your case you have a line 127 that references player1, which doens’t exist there. I can’t tell what line 127 is.

Rob

inveince · September 17, 2014, 12:11am

--Hide the status bar. display.setStatusBar( display.HiddenStatusBar) &nbsp; function onCollision( event ) if ( event.phase == "began" ) then composer.gotoScene( "menu" ) &nbsp; end end &nbsp; &nbsp; &nbsp; -- Actual Scene function scene:create( event ) &nbsp; &nbsp; &nbsp;local sceneGroup = self.view &nbsp; &nbsp;--Set the background color to white &nbsp; &nbsp;local background = display.newRect( 0, 0, display.contentWidth, display.contentHeight ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;background:setFillColor( 1 ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;background:setFillColor( 255, 255, 255 ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;background.x = display.contentCenterX&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;background.y = display.contentCenterY&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;sceneGroup:insert( background ) &nbsp; &nbsp; &nbsp; &nbsp; --Add as score label local score = 0 local scoreLabel = display.newText( &nbsp;score, 0,0, native.systemFontBold, 24) scoreLabel.x = display.viewableContentWidth / 1.5 scoreLabel.y = display.viewableContentHeight / 15 scoreLabel :setTextColor(0,0,0) &nbsp; ----Create Player &nbsp;local player1 = display.newRect( 0, 0, 20, 20 ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; player1:setFillColor( 0 ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; player1:setStrokeColor( 1, 0, 0 ) &nbsp; &nbsp; &nbsp; &nbsp;player1.x = display.viewableContentWidth / 2 &nbsp; &nbsp; &nbsp; &nbsp;player1.y = display.viewableContentHeight / 2 &nbsp; local function animate( event ) &nbsp; &nbsp; &nbsp; &nbsp;player1.rotation = player1.rotation + 20 &nbsp; end &nbsp; Runtime:addEventListener( "enterFrame", animate ); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; end &nbsp; ---Touch Event function player1:touch( event ) &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;if event.phase == "began" then &nbsp; &nbsp; &nbsp; &nbsp;self.markX = self.x &nbsp; &nbsp;self.markY = self.y &nbsp;&nbsp; &nbsp; &nbsp;elseif event.phase == "moved" then &nbsp; &nbsp; local x = (event.x - event.xStart) + self.markX local y = (event.y - event.yStart) + self.markY self.x,self.y = x, y ---moves object based on cal &nbsp; end &nbsp; &nbsp; &nbsp; &nbsp; return true end &nbsp; &nbsp; player1:addEventListener("touch", player1) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; -------------Start&nbsp; &nbsp;function scene: show (event) &nbsp; &nbsp;local sceneGroup = self.view &nbsp; &nbsp;local phase = event.phase &nbsp; &nbsp; &nbsp;if ( phase == "will" ) then &nbsp; &nbsp; &nbsp; -- Called when the scene is still off screen (but is about to come on screen). &nbsp; &nbsp;elseif ( phase == "did" ) then &nbsp; &nbsp; &nbsp; -- Called when the scene is now on screen. &nbsp; &nbsp; &nbsp; -- Insert code here to make the scene come alive. &nbsp; &nbsp; &nbsp; -- Example: start timers, begin animation, play audio, etc. &nbsp; &nbsp; end end &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;-- "scene:hide()" add end and this should b bottom &nbsp; &nbsp; function scene:hide( event ) &nbsp; &nbsp; &nbsp;local sceneGroup = self.view &nbsp; &nbsp;local phase = event.phase &nbsp; &nbsp; &nbsp;if ( phase == "will" ) then &nbsp; &nbsp;Runtime:removeEventListener("collision", onCollision) &nbsp; &nbsp;Runtime:removeEventListener("collision", onCollision) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; elseif ( phase == "did" ) then &nbsp; &nbsp; &nbsp; -- Called immediately after scene goes off screen. &nbsp; &nbsp;end end &nbsp; -- "scene:destroy()" function scene:destroy( event ) &nbsp; local sceneGroup = self.view &nbsp; &nbsp; &nbsp;-- Called prior to the removal of scene's view ("sceneGroup"). &nbsp; &nbsp;-- Insert code here to clean up the scene. &nbsp; &nbsp;-- Example: remove display objects, save state, etc. end --------------------------------------------------------------------------------- &nbsp; -- Listener setup scene:addEventListener( "create", scene ) scene:addEventListener( "show", scene ) scene:addEventListener( "hide", scene ) scene:addEventListener( "destroy", scene ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; physics.setGravity( 0, 0 ) &nbsp; --------------------------------------------------------------------------------- &nbsp; return scene &nbsp; &nbsp; &nbsp; &nbsp;

inveince · September 17, 2014, 12:13am

Thanks for the reply I was wondering how people did that.

I tried adjusting my code to this video from corona http://www.youtube.com/watch?v=3CpjU0l0wYI ,but got the same problem

rob · September 17, 2014, 1:44am

What is line 127?

inveince · September 17, 2014, 1:51am

Hi it is line 100 I made a correction to my post same problem though -line 100 is function player1:touch( event )

rob · September 17, 2014, 2:08am

You basically have a scope problem. It’s really hard to spot because your code isn’t indented very well. You can’t tell where functions begin and end, where if statements begin and in, etc.

You declare player1 local inside of scene:create(), but your touch handler is outside of the scene:create() function and at that point, player1 is unknown.

--Hide the status bar. display.setStatusBar( display.HiddenStatusBar) &nbsp; function onCollision( event ) &nbsp;&nbsp;&nbsp; if ( event.phase == "began" ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; composer.gotoScene( "menu" ) &nbsp;&nbsp;&nbsp; end end -- Actual Scene function scene:create( event ) &nbsp;&nbsp;&nbsp; local sceneGroup = self.view &nbsp;&nbsp;&nbsp; --Set the background color to white &nbsp;&nbsp;&nbsp; local background = display.newRect( 0, 0, display.contentWidth, display.contentHeight ) &nbsp;&nbsp;&nbsp; background:setFillColor( 1 ) &nbsp;&nbsp;&nbsp; background:setFillColor( 255, 255, 255 ) &nbsp; &nbsp;&nbsp;&nbsp; background.x = display.contentCenterX &nbsp;&nbsp;&nbsp; background.y = display.contentCenterY &nbsp;&nbsp;&nbsp; sceneGroup:insert( background ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; --Add as score label &nbsp;&nbsp;&nbsp; local score = 0 &nbsp;&nbsp;&nbsp; local scoreLabel = display.newText(&nbsp; score, 0,0, native.systemFontBold, 24) &nbsp;&nbsp;&nbsp; scoreLabel.x = display.viewableContentWidth / 1.5 &nbsp;&nbsp;&nbsp; scoreLabel.y = display.viewableContentHeight / 15 &nbsp;&nbsp;&nbsp; scoreLabel :setTextColor(0,0,0) &nbsp; &nbsp;&nbsp;&nbsp; ----Create Player &nbsp; &nbsp;&nbsp;&nbsp; local player1 = display.newRect( 0, 0, 20, 20 ) &nbsp;&nbsp;&nbsp; player1:setFillColor( 0 ) &nbsp;&nbsp;&nbsp; player1:setStrokeColor( 1, 0, 0 ) &nbsp;&nbsp;&nbsp; player1.x = display.viewableContentWidth / 2 &nbsp;&nbsp;&nbsp; player1.y = display.viewableContentHeight / 2 &nbsp; &nbsp;&nbsp;&nbsp; local function animate( event ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; player1.rotation = player1.rotation + 20 &nbsp;&nbsp;&nbsp; end &nbsp; &nbsp;&nbsp;&nbsp; Runtime:addEventListener( "enterFrame", animate ); end &nbsp; ---Touch Event function player1:touch( event ) &nbsp;&nbsp;&nbsp; if event.phase == "began" then &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; self.markX = self.x &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; self.markY = self.y &nbsp; &nbsp;&nbsp;&nbsp; elseif event.phase == "moved" then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; local x = (event.x - event.xStart) + self.markX &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; local y = (event.y - event.yStart) + self.markY &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; self.x,self.y = x, y ---moves object based on cal &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; return true end &nbsp; player1:addEventListener("touch", player1) &nbsp; -------------Start function scene: show (event) &nbsp; &nbsp;&nbsp;&nbsp; local sceneGroup = self.view &nbsp;&nbsp;&nbsp; local phase = event.phase &nbsp; &nbsp;&nbsp;&nbsp; if ( phase == "will" ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Called when the scene is still off screen (but is about to come on screen). &nbsp;&nbsp;&nbsp; elseif ( phase == "did" ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Called when the scene is now on screen. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Insert code here to make the scene come alive. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Example: start timers, begin animation, play audio, etc. &nbsp;&nbsp;&nbsp; end end &nbsp;&nbsp; -- "scene:hide()" add end and this should b bottom &nbsp; &nbsp; function scene:hide( event ) &nbsp;&nbsp;&nbsp; local sceneGroup = self.view &nbsp;&nbsp;&nbsp; local phase = event.phase &nbsp; &nbsp;&nbsp;&nbsp; if ( phase == "will" ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Runtime:removeEventListener("collision", onCollision) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Runtime:removeEventListener("collision", onCollision) &nbsp;&nbsp;&nbsp; elseif ( phase == "did" ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Called immediately after scene goes off screen. &nbsp;&nbsp;&nbsp; end end &nbsp; -- "scene:destroy()" function scene:destroy( event ) &nbsp;&nbsp;&nbsp; local sceneGroup = self.view &nbsp; &nbsp;&nbsp;&nbsp; -- Called prior to the removal of scene's view ("sceneGroup"). &nbsp;&nbsp;&nbsp; -- Insert code here to clean up the scene. &nbsp;&nbsp;&nbsp; -- Example: remove display objects, save state, etc. end --------------------------------------------------------------------------------- &nbsp; -- Listener setup scene:addEventListener( "create", scene ) scene:addEventListener( "show", scene ) scene:addEventListener( "hide", scene ) scene:addEventListener( "destroy", scene ) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; physics.setGravity( 0, 0 ) &nbsp; --------------------------------------------------------------------------------- &nbsp; return scene

inveince · September 17, 2014, 2:20am

Sorry for the lack of indents I’ll keep that in mind for future post. I follow what your saying about the scope , but where would you suggest I put the handler for the event? The only reason I placed it there was because of the tutorial.

rob · September 17, 2014, 11:46pm

The simplest thing would be to move that block of code inside your scene:create().

inveince · September 18, 2014, 1:00am

Ok, so I moved the code back into the scene: create() and everything is working- Thanks!! I didn’t recognize it was outside of it until you mentioned it.

rob · September 18, 2014, 1:02am

That’s why the indenting is important. You can’t tell what’s inside other things without it.

Rob

inveince · September 18, 2014, 1:08am

O ok that makes complete sense , I will adjust my code right now.

rob · September 17, 2014, 12:01am