Cocos2d v2.x (ios) - how to do circular scrolling?

Question

I want to do a little game for IOS-devices with Cocos2d v2.x. One of it's features is circular map scrolling - it's like when you scroll the screen to the most right edge of map, it jumps back to the left-most side. Like you rotate the globe. My problem: in some point of time i has to render map (all the game graphics) twice - when you move screen to the most right edge and even bit further one half of screen should display a piece of map left-end, and half should display right-end of map. How to achieve it with less pain?

Map is sub-class of CCNode with lots of childs and some custom draw methods.

I see two ways: 1. Just make a copy of map-CCNode and render it near first one:

     [---map---][---map-copy---]
           |-/screen/-|

1. Make CCRenderTexture, render map to it and display part of map + part of RenderTexture.

   [----map----][RenderTex]
             |-/ screen /-]

Both of my ideas has disadvantages:

• CCRenderTexture horribly slows performance, even on iPad-4 full-screen-size renderTexture works at about 20fps only;

• second copy of map root-CCNode will eat much of memory, especially if it has lots of children;

Maybe is there a way of rendering root-map CCNode second time with applied offset? Like:

     [self offsetMap:deltaX];
     [self.map vizit];

? Thank for ideas!

Answer 1

quite an easy )

class worldMap : CCNode;

@interface mainScene : CCNode
{
-(id)init;
}
@property worldMap theMap;
@end

@implementation
-(id)init
{
... usual blah-blah here
 [self addChild:theMap];
}

-(void)visit
{
  [super visit];

  CGPoint oldMapPos = self.theMap.position;
  CGPoint newMapPos = ccp(oldMapPos.x + self.theMap.width, oldMapPos.y);
  self.theMap.position = newMapPos;
  [self.theMap visit];
  self.theMap.position = oldMapPos;
}
@end