I am receiving some errors, and I cannot figure out where I am going wrong. Any help will be greatly appreciated!
Eric
local composer = require( “composer” )
local scene = composer.newScene()
– Code outside of the scene event functions below will only be executed ONCE unless
– the scene is removed entirely (not recycled) via “composer.removeScene()”
local physics = require( “physics” )
physics.start()
physics.setGravity( 0, 0 )
– Configure image sheet
local sheetOptions =
{
frames =
{
{ – 1) asteroid 1
x = 0,
y = 0,
width = 102,
height = 85
},
{ – 2) asteroid 2
x = 0,
y = 85,
width = 90,
height = 83
},
{ – 3) asteroid 3
x = 0,
y = 168,
width = 100,
height = 97
},
{ – 4) ship
x = 0,
y = 265,
width = 98,
height = 79
},
{ – 5) laser
x = 98,
y = 265,
width = 14,
height = 40
},
},
}
local objectSheet = graphics.newImageSheet( “gameObjects.png”, sheetOptions )
– Initialize variables
local lives = 3
local score = 0
local died = false
local asteroidsTable = {}
local ship
local gameLoopTimer
local livesText
local scoreText
local backGroup
local mainGroup
local uiGroup
local function updateText()
livesText.text = "Lives: " … lives
scoreText.text = "Score: " … score
end
local function createAsteroid()
local newAsteroid = display.newImageRect( mainGroup, objectSheet, 1, 102, 85 )
table.insert( asteroidsTable, newAsteroid )
physics.addBody( newAsteroid, “dynamic”, { radius=40, bounce=0.8 } )
newAsteroid.myName = “asteroid”
end
local whereFrom = math.random( 3 )
if ( whereFrom == 1 ) then
– From the left
newAsteroid.x = -60
newAsteroid.y = math.random( 500 )
newAsteroid:setLinearVelocity( math.random( 40,120 ), math.random( 20,60 ) )
elseif ( whereFrom == 2) then
– From the top
newAsteroid.x = math.random( display.contentWidth )
newAsteroid.y = -60
newAsteroid:setLinearVelocity( math.random( -40,40 ), math.random( 40,120 ) )
elseif ( whereFrom == 3) then
– From the right
newAsteroid.x = display.contentWidth + 60
newAsteroid.y = math.random( 500 )
newAsteroid:setLinearVelocity( math.random( -120, -40 ), math.random( 20,60 ) )
end
local function fireLaser() – Firing mechanics
local newLaser = display.newImageRect( mainGroup, objectSheet, 5, 14, 40 )
physics.addBody( newLaser, “dynamic”, { isSensor=true } )
newLaser.isBullet = true
newLaser.myName = “laser”
newLaser.x = ship.x
newLaser.y = ship.y
newLaser:toBack()
transition.to( newLaser, { y=-40, time=500,
onComplete = function() display.remove( newLaser ) end
} )
end
ship:addEventListener( “tap”, fireLaser )
gameLoopTimer = timer.performWithDelay( 500, gameLoop, 0 )
local function dragShip( event )
local ship = event.target
local phase = event.phase
if ( “began” == phase ) then
– Set touch focus on the ship
display.currentStage:setFocus( ship )
– Store initial offset position
ship.touchOffsetX = event.x - ship.x
elseif ( “moved” == phase ) then
– Move the ship to the new touch position
ship.x = event.x - ship.touchOffsetX
elseif ( “ended” == phase or “cancelled” == phase ) then
– Release touch focus on the ship
display.currentStage:setFocus( nil )
end
return true – Prevents touch propogation to underlying objects
end
local function gameLoop()
– Create new asteroid
createAsteroid()
– Remove asteroids which have drifted off screen
for i = #asteroidsTable, 1, -1 do
local thisAsteroid = asteroidsTable[i]
if ( thisAsteroid.x < -100 or
thisAsteroid.x > display.contentWidth + 100 or
thisAsteroid.y < -100 or
thisAsteroid.y > display.contentHeight + 100 )
then
display.remove( thisAsteroid )
table.remove( asteroidsTable, i )
end
end
end
local function restoreShip()
ship.isBodyActive = false
ship.x = display.contentCenterX
ship.y = display.contentHeight - 100
– Fade in the ship
transition.to( ship, { alpha=1, time=4000,
onComplete = function()
ship.isBodyActive = true
died = false
end
})
end
local function onCollision( event )
if ( event.phase == “began” ) then
local obj1 = event.object1
local obj2 = event.object2
if ( ( obj1.myName == “laser” and obj2.myName == “asteroid” ) or
( obj1.myName == “asteroid” and obj2.myName == “laser” ) )
then
– Remove both the laser and the asteroid
display.remove( obj1 )
display.remove( obj2 )
for i = #asteroidsTable, 1, -1 do
if ( asteroidsTable[i] == obj1 or asteroidsTable[i] == obj2 ) then
table.remove( asteroidsTable, i )
break
end
end
– Increase score
score = score + 100
scoreText.text = "Score: " … score
elseif ( ( obj1.myName == “ship” and obj2.myName == “asteroid” ) or
( obj1.myName == “asteroid” and obj2.myName == “ship” ) )
then
if ( died == false ) then
died = true
– Update lives
lives = lives - 1
livesText.text = "Lives: " … lives
if ( lives == 0 ) then
display.remove( ship )
else
ship.alpha = 0
timer.performWithDelay( 1000, restoreShip )
end
end
end
end
end
– Scene event functions
– create()
function scene:create( event )
local sceneGroup = self.view
– Code here runs when the scene is first created but has not yet appeared on screen
physics.pause() – Temporarily pause the physics engine
– Set up display groups
backGroup = display.newGroup() – Display group for the background image
sceneGroup:insert( backGroup ) – Insert into the scene’s view group
mainGroup = display.newGroup() – Display group for the ship, asteroids, lasers, etc.
sceneGroup:insert( mainGroup ) – Insert into the scene’s view group
uiGroup = display.newGroup() – Display group for UI objects like the score
sceneGroup:insert( uiGroup ) – Insert into the scene’s view group
– Load the background
local background = display.newImageRect( backGroup, “background.png”, 800, 1400 )
background.x = display.contentCenterX
background.y = display.contentCenterY
ship = display.newImageRect( mainGroup, objectSheet, 4, 98, 79 )
ship.x = display.contentCenterX
ship.y = display.contentHeight - 100
physics.addBody( ship, { radius=30, isSensor=true } )
ship.myName = “ship”
– Display lives and score
livesText = display.newText( uiGroup, "Lives: " … lives, 200, 80, native.systemFont, 36 )
scoreText = display.newText( uiGroup, "Score: " … score, 400, 80, native.systemFont, 36 )
ship:addEventListener( “tap”, fireLaser )
ship:addEventListener( “touch”, dragShip )
end
– show()
function scene:show( event )
local sceneGroup = self.view
local phase = event.phase
if ( phase == “will” ) then
– Code here runs when the scene is still off screen (but is about to come on screen)
elseif ( phase == “did” ) then
– Code here runs when the scene is entirely on screen
physics.start()
Runtime:addEventListener( “collision”, onCollision )
gameLoopTimer = timer.performWithDelay( 500, gameLoop, 0 )
end
end
– hide()
function scene:hide( event )
local sceneGroup = self.view
local phase = event.phase
if ( phase == “will” ) then
– Code here runs when the scene is on screen (but is about to go off screen)
elseif ( phase == “did” ) then
– Code here runs immediately after the scene goes entirely off screen
end
end
– destroy()
function scene:destroy( event )
local sceneGroup = self.view
– Code here runs prior to the removal of scene’s view
end
– Scene event function listeners
scene:addEventListener( “create”, scene )
scene:addEventListener( “show”, scene )
scene:addEventListener( “hide”, scene )
scene:addEventListener( “destroy”, scene )
return scene