Collision between GameCharacter and ScrollingLayer - iphone

Question

I'm new to cocos2d and I made my way through the 'Learning cocos2d' book.
Like in the Book I implemented a scrollingLayer for scrolling, when my gamecharacter moves.
My problem is the following: I'm using a normal Sprite to do the scrolling layer rendering who can I check if my character is touching the scorlling layer?
fyi: It's a fish and he needs to swim through a hole and there are walls above und underneath it and he should not be able to get in front or behind the rocks.
I've searched the internet and this forum, but was not be able to find any suitable solutions.
Is 'Tiled' the kay for happiness, I read about collisions implemented but can't make it out how they are implemented using tmx's
Can someone assist me with that?

Answer 1

For simplier, but powerful collision detection you most likely need physics engine.
I recommend SpaceManager extension for Chipmunk engine.
In Tiled you can add object layer to tmx file, where you can line out all obstacles.
That's how I parse this information in my game scene:
in init:
self.tileMap = [CCTMXTiledMap tiledMapWithTMXFile:#"TileMap.tmx"];
...
smgr = [[SpaceManagerCocos2d alloc] init];
smgr.constantDt = 1/60.0;
smgr.gravity=ccp(0, 0);
[smgr addWindowContainmentWithFriction:0.0 elasticity:0.0 size:CGSizeMake(1000, 1000) inset:cpvzero radius:1.0f]; //borders of your world, can be set from tmx size
player = [smgr addCircleAt:ccp(x,y) mass:6 radius:15];
and somewhere:
- (void) drawWalls {
//searching for object layer called "Collisions"
CCTMXObjectGroup *objects = [_tileMap objectGroupNamed:#"Walls"];
NSMutableDictionary * objPoint;
int x ;
int y ;
int w ;
int h ;
for (objPoint in [objects objects]) {
x = [[objPoint valueForKey:#"x"] intValue];
y = [[objPoint valueForKey:#"y"] intValue];
w = [[objPoint valueForKey:#"width"] intValue];
h = [[objPoint valueForKey:#"height"] intValue];
GameController *controller = [GameController sharedController];
if(controller.retina==1)
{
x=x/2;
y=y/2;
w=w/2;
h=h/2;
}
cpShape *staticShape = [smgr addRectAt:ccp(x+w/2,y+h/2) mass:STATIC_MASS width:w height:h rotation:0];
}
}
Then, you can apply force at "player" object and update your sprite position in "update" method:
playerSprite.position=ccp(player->body->p.x, player->body->p.y);
Of course you can use some other algorithm to detect collision, but this is just an example of storing and retrieving this information from tmx.