Cocos2D - Adding holes and different heights between buildings - path

Question

I'm trying to build something similar to Canabalt, adding holes and different heights between buildings (modules). You can see a screenshot of how the game is looking right now at: http://twitpic.com/4kb5jd
Here is the code I'm currently using:
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init] )) {
moduleSize = 160;
screenSize = [[CCDirector sharedDirector] winSize];
CCSpriteFrameCache* frameCache = [CCSpriteFrameCache sharedSpriteFrameCache];
[frameCache addSpriteFramesWithFile:#"ModulesScene1.plist"];
CCTexture2D* gameArtTexture = [[CCTextureCache sharedTextureCache] addImage:#"ModulesScene1.png"];
// Create the background spritebatch
spriteBatch = [CCSpriteBatchNode batchNodeWithTexture:gameArtTexture];
[self addChild:spriteBatch];
numStripes = 1;
/* BEGIN MODULES */
NSString* frameName = [NSString stringWithFormat:#"Module0-hd.png"];
CCSprite* sprite = [CCSprite spriteWithSpriteFrameName:frameName];
sprite.anchorPoint = CGPointMake(0, 0.5f);
sprite.position = CGPointMake(0, screenSize.height / 2);
[spriteBatch addChild:sprite z:0 tag:0];
frameName = [NSString stringWithFormat:#"Module0-hd.png"];
sprite = [CCSprite spriteWithSpriteFrameName:frameName];
sprite.anchorPoint = CGPointMake(0, 0.5f);
sprite.position = CGPointMake((moduleSize - 1.1f), screenSize.height / 2);
[spriteBatch addChild:sprite z:1 tag:1];
frameName = [NSString stringWithFormat:#"Module1-hd.png"];
sprite = [CCSprite spriteWithSpriteFrameName:frameName];
sprite.anchorPoint = CGPointMake(0, 0.5f);
sprite.position = CGPointMake((moduleSize * 2) - 1.1f, screenSize.height / 2);
[spriteBatch addChild:sprite z:2 tag:2];
frameName = [NSString stringWithFormat:#"Module2-hd.png"];
sprite = [CCSprite spriteWithSpriteFrameName:frameName];
sprite.anchorPoint = CGPointMake(0, 0.5f);
sprite.position = CGPointMake(((moduleSize * 3) - 1.1f), screenSize.height / 2);
[spriteBatch addChild:sprite z:3 tag:3];
frameName = [NSString stringWithFormat:#"Module0-hd.png"];
sprite = [CCSprite spriteWithSpriteFrameName:frameName];
sprite.anchorPoint = CGPointMake(0, 0.5f);
sprite.position = CGPointMake(((moduleSize * 4) - 1.1f), screenSize.height / 2);
[spriteBatch addChild:sprite z:4 tag:4];
frameName = [NSString stringWithFormat:#"Module1-hd.png"];
sprite = [CCSprite spriteWithSpriteFrameName:frameName];
sprite.anchorPoint = CGPointMake(0, 0.5f);
sprite.position = CGPointMake(((moduleSize * 5) - 1.1f), screenSize.height / 2);
[spriteBatch addChild:sprite z:5 tag:5];
/* END MODULES */
// Get current scrollSpped
scrollSpeed = [[GameManager sharedGameManager] scrollSpeed];
speedFactors = [[CCArray alloc] initWithCapacity:numStripes];
[speedFactors addObject:[NSNumber numberWithFloat:2.5f]];
NSAssert([speedFactors count] == numStripes, #"speedFactors count does not match numStripes!");
[self scheduleUpdate];
}
return self;
}
-(void) update:(ccTime)delta
{
CCSprite* sprite;
scrollSpeed = [[GameManager sharedGameManager] scrollSpeed];
CCARRAY_FOREACH([spriteBatch children], sprite)
{
NSNumber* factor = [speedFactors objectAtIndex:0];
CGPoint pos = sprite.position;
pos.x -= scrollSpeed * [factor floatValue];
if (pos.x < -screenSize.width)
{
pos.x += ((screenSize.width * 2) - 2);
int x = (arc4random() % 3);
int xHole = (arc4random() % 10);
NSString *randomName = nil;
CCSpriteFrame *randomFrame = [[CCSpriteFrameCache sharedSpriteFrameCache] spriteFrameByName:randomName];
[sprite setDisplayFrame:randomFrame];
}
sprite.position = pos;
}
}

Answer 1

to add holes between the buildings you could add a simple rand() function like that in the init method:
...
sprite.position = CGPointMake(((moduleSize * 3) - 1.1f + (rand()%40)), screenSize.height / 2);
...
this will add a random gap (max 40 points)