Infinite scrolling on a sprite(Parallax) - iphone

Question

I am a newbie to the world of cocos2d i am developing my first tutorial and facing one problem
my problem is i have an image (1024 X 320) and my orientation is landscape i need to move that image continuously from right to left for this purpose i have used space shooter tutorial by Ray(Thanks to him) but the image doesn't seem to be appearing again and again.
my code is..
-(id) init
{
if( (self=[super init])) {
CGSize screenSize = [CCDirector sharedDirector].winSize;
// 1) Create the CCParallaxNode
backgroundNode = [CCParallaxNode node];
[self addChild:backgroundNode z:-1];
// 2) Create the sprites we'll add to the CCParallaxNode
Back = [CCSprite spriteWithFile:#"bg_front_spacedust.png"];
//Back.position=ccp(screenSize.width/2, screenSize.height/2);
Back.rotation = -90;
Back1 = [CCSprite spriteWithFile:#"bg_front_spacedust.png"];
Back1.rotation = -90;
// 3) Determine relative movement speeds for space dust and background
CGPoint dustSpeed = ccp(0.1, 0.1);
// 4) Add children to CCParallaxNode
[backgroundNode addChild:Back z:0 parallaxRatio:dustSpeed positionOffset:ccp(screenSize.width/2, screenSize.height/2)];
NSLog(#"back.content width is...%f",Back.contentSize.width);
[backgroundNode addChild:Back1 z:1 parallaxRatio:dustSpeed positionOffset:ccp(screenSize.width/2, screenSize.height*2)];
// 5) Enable updates
[self scheduleUpdate];
}
return self;
}
- (void)update:(ccTime)dt {
// 1) Update background position
CGPoint backgroundScrollVel = ccp(0,-1000);
backgroundNode.position = ccpAdd(backgroundNode.position, ccpMult(backgroundScrollVel, dt));
// 2) Check for background elements moving offscreen
NSArray *spaceDusts = [NSArray arrayWithObjects:Back, Back1, nil];
for (CCSprite *spaceDust in spaceDusts) {
if ([backgroundNode convertToWorldSpace:spaceDust.position].x < -spaceDust.contentSize.width) {
[backgroundNode incrementOffset:ccp(2*spaceDust.contentSize.width,0) forChild:spaceDust];
}
}
}
please help me out of this
Thanks in advance.

Answer 1

try this one
if (backgroundNode.position.y <-screenSize.height*2)
backgroundNode.position = ccp(0,0);
As init method is called only once the approach you are doing will be done only one time you need to again set the Position of the backgroundNode to 0 in your update method.
here the multiple may vary

Answer 2

Try this code it is creating a paralax moving from bottom to top change CGPointMake(0, 1.0) to this CGPointMake(1.0,0) in paraNode addChild line.
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super's" return value
if( (self=[super init]) )
{
float yPos =0.0;
NSMutableString *fileNameString = [[NSMutableString alloc]initWithCapacity:0];
if (IS_IPHONE_5)
{
[fileNameString appendString:#"Background-568h.png"];
yPos= 560.0;
}
else
{
[fileNameString appendString:#"Background.png"];
yPos= 470.0;
}
background1 = [CCSprite spriteWithFile:fileNameString];
background1.tag = 1;
background1.anchorPoint = CGPointMake(0,0);
background2 = [CCSprite spriteWithFile:fileNameString];
background2.tag = 2;
background2.anchorPoint = CGPointMake(0,0);
background3 = [CCSprite spriteWithFile:fileNameString];
background3.tag = 3;
background3.anchorPoint = CGPointMake(0,0);
background4 = [CCSprite spriteWithFile:fileNameString];
background4.tag = 4;
background4.anchorPoint = CGPointMake(0,0);
paraNode = [CCParallaxNode node];
[paraNode addChild:background1 z:1 parallaxRatio:CGPointMake(0, 1.0) positionOffset:CGPointMake(0, 0)];
[paraNode addChild:background2 z:2 parallaxRatio:CGPointMake(0, 1.0) positionOffset:CGPointMake(0, -yPos)];
[paraNode addChild:background3 z:3 parallaxRatio:CGPointMake(0, 1.0) positionOffset:CGPointMake(0, -yPos*2)];
[paraNode addChild:background4 z:4 parallaxRatio:CGPointMake(0, 1.0) positionOffset:CGPointMake(0, -yPos*3)];
[self addChild:paraNode z:-1 tag:123];
[self updateFrameRate:0.7 andYposition:yPos];
[fileNameString release];
fileNameString = nil;
}
return self;
}
-(void)updateFrameRate:(float)speedValue andYposition:(float)yposToSet
{
move1 = [CCMoveBy actionWithDuration:speedValue position:CGPointMake(0, yposToSet)];
move2 = [CCMoveBy actionWithDuration:0.0 position:CGPointMake(0, -yposToSet)];
move3 = [CCMoveBy actionWithDuration:0.0 position:CGPointMake(0, 0)];
CCSequence* sequence = [CCSequence actions:move1,move2,move3, nil];
CCRepeatForever* repeat = [CCRepeatForever actionWithAction:sequence];
[paraNode runAction:repeat];
}