Sprite has a jigging effect because of tracking - iphone

Question

I have a sprite that tracks and follows objects on the screen, moving towards them.
The method runs on a schedule and basically looks like this:
- (void) nextFrame:(ccTime)dt {
//calculate distance between the bubble and the fish
float dx = bubbleToChase.position.x - fish.position.x;
float dy = bubbleToChase.position.y - fish.position.y;
float d = sqrt(dx*dx + dy*dy);
float v = 400;
if (d > 190){
NSLog(#"moving the fish!");
fish.position = ccp( fish.position.x + dx/d * v *dt,
fish.position.y + dy/d * v *dt);
}
}
The code works pretty well, when the distance is greater than 190 the fish will swim towards it.
The issue is that the objects have physics, so they are sliding around the screen. This produces a jigging / staggering effect on the fish sprite, because the fish will stop once it reaches the bubble, but then jiggle and stop rapidly as the bubble drifts away as (d > 190) incrementally.
How can I get rid of this jigging effect? I'd like to just stop the fish from moving once it has reached the bubble's position. Or any alternative that smooths it out. Any help appreciated, thanks.

Answer 1

if (d > 190 && !fish.parked){
NSLog(#"moving the fish!");
fish.position = ccp( fish.position.x + dx/d * v *dt,
fish.position.y + dy/d * v *dt);
}else{
if( fish.parked ){
// what you want to do while parked
// just sit there, wander randomly,
// then unpark the fish...
if(unpark)
fish.parked=FALSE;
}else{
fish.parked=TRUE;
// set variables for parked state.
}
}