cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   rifts
   Member

   Hey!

   I'm going absolutely insane here. I made a simple infinitely scrolling background using two images.

   The problem is after a while the images seem to slowly split apart and show a 2-3 pixel gap. I don't understand how to fix this. I saw a video tutorial and copied the guys code and it still did it but his in the video did not.

   Here is my code WTF?

   the image is a full screen size, 480x320

   bg1 = [CCSprite spriteWithFile:@"trackbg.png"];
           bg1.anchorPoint = ccp(0,0);
           bg1.position = ccp(0,0);
           [self addChild:bg1];
   
           bg2 = [CCSprite spriteWithFile:@"trackbg.png"];
           bg2.anchorPoint = ccp(0,0);
           bg2.position = ccp(479,0);
           [self addChild:bg2];
   
           [self schedule:@selector(updatedSpeed:) interval: .02 ];
   
       }
   	return self;
   }
   
   -(void) updatedSpeed:(ccTime)dt {
   
       bg1.position = ccp( bg1.position.x - 2 , 0 );
       bg2.position = ccp( bg2.position.x - 2 , 0 );
   
       if (bg1.position.x == -bg1.contentSize.width) {
           bg1.position = ccp(479,0);
       }
       if (bg2.position.x == -bg2.contentSize.width) {
           bg2.position = ccp(479,0);
       }
   
   }

   I'm using 479 because if I use 480 there will be a gap I tried making them overlap more by using 475 but it still creating the gap.

   Posted 6 months ago #
2. 

   Wayne
   Member

   I think it would be better to place both images on a layer, and move the whole layer as below :

   in your .h file add
   

   CCLayer *scrollLayer;

   In your .m file add
   

   // main scrolling layer
   scrollLayer = [[CCLayer alloc] init];
   scrollLayer.anchorPoint = ccp( 0, 0 );
   scrollLayer.position = ccp( ScollPosition_X, ScollPosition_Y );
   [self addChild:scrollLayer z:1];
   
   //now add your sprites to the scroll Layer instead of "self"
   
   // now move the whole scroll Layer instead of each sprite
   
   // in your dealloc add
   [scrollLayer release];

   When moving a layer with large (1024x768) tiled sprites on iPad, I've found I had to set the sprite position with a float, i.e. I had to set the position to 384.5 instead of 384 or else I'd get a black line on every other position I set the layer to. Setting [[CCDirector sharedDirector] setProjection:CCDirectorProjection2D]; didn't work, but changing ccconfig CC_COCOSNODE_RENDER_SUBPIXEL 0
   and ccconfig CC_ATLAS_SPRITE_RENDER_SUBPIXEL 0 , did with also setting my location to a float as mentioned. So maybe setting your sprites to 480.5 along with the ccconfig changes might help.

   You could also add CCPanZoomController from Cocos2d extensions.

   Posted 6 months ago #
3. 

   hm50
   Member

   Why not just set bg2.position.x = bg1.position.x + (bg1.contentSize.width-1) ?

   Posted 6 months ago #
4. 

   Martin
   Member

   There is also some trick to set an openGL attribute or something like that to make the texture tile endlessly. Google "GL_REPEAT" together with "cocos2D background" and you should find solutions. Or search for GL_REPEAT on the forum.

   P.S.: only works with power of two textures.

   Posted 6 months ago #
5. 

   phil_me_up
   Member

   I'd also watch out for this:

   if (bg1.position.x == -bg1.contentSize.width) {
           bg1.position = ccp(479,0);
       }
       if (bg2.position.x == -bg2.contentSize.width) {
           bg2.position = ccp(479,0);
       }

   This is pretty static and will only reset the position if you meet the exact criteria. Probably best to replace '==' with '<='

   Posted 6 months ago #

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