Flocking hell!!

[tiny_legoman]

Hey - inspired by watching One Man and His Dog I thought it would be a good idea to create a game based around sheep herding, it seemed like a pretty easy game mechanic. In essence you have a fixed vantage point from where you control your dog with left/right/speed up/slow down commands. The sheep naturally want to flock together until the dog encroaches on their safety zone. At this point the sheep as a flock want to move away from the dog. Using this you can then drive the sheep around a course of gates and finally into a pen. The difficultly is set by either 1 or 2 dogs and there can be either 4 or 8 sheep. The dog is faster than the sheep and therefore can penetrate the flock and split them into 2 groups, of indeterminate numbers e.g. 1/7, 4/4, 3/5 etc.
I had a quick go a couple of weeks ago, but didn’t get very far with it here is my first attempt based on hitTest and safety zones;

Root Code

sheepArr = new Array();
for(i=0; i<8; i++){
	sheepArr.push(this.attachMovie("sheep", "sheep"+i, 100+i, {_y: Math.random()*100, _x: Math.random()*100}));
}
this.attachMovie("dog", "dog", 100+i, {_y: 250, _x: 250});

Sheep code

this.onEnterFrame = function(){
	
	if(this._x-_root.dog._x < 75 && this._x-_root.dog._x > -75 && this._y-_root.dog._y > -75 && this._y-_root.dog._y < 75){
		//run from dog
		if(this._x < _root.dog._x) this._x-=1;
		if(this._x > _root.dog._x) this._x+=1;
		if(this._y < _root.dog._y) this._y-=1;
		if(this._y > _root.dog._y) this._y+=1;
		
	} else {
		//flock
		for(i=0; i<_root.sheepArr.length; i++){
				if(_root.sheepArr[i] != this && !this.hitTest(_root.sheepArr[i])){
					if(this._x > _root.sheepArr[i]._x) this._x-=1;
					if(this._x < _root.sheepArr[i]._x) this._x+=1;
					
					if(this._y > _root.sheepArr[i]._y) this._y-=1;
					if(this._y < _root.sheepArr[i]._y) this._y+=1;
				}
		}
		
	}
	
}

Dog code

this.onEnterFrame = function(){
	if(this._x < _root._xmouse){
		this._x+=3;
	}
	if(this._x > _root._xmouse){
		this._x-=3;
	}
	if(this._y < _root._ymouse){
		this._y+=3;
	}
	if(this._y > _root._ymouse){
		this._y-=3;
	}
}

This was basically rubbish! I picked this up again a couple of nights ago and did some more experiments but realised that I’m coming at this from totally the wrong direction. So I’ve done a couple of searches on things like attraction and repulsion and flocking and seem to have opened a whole can on maths and physics worms. I’m ok with actionscript but maths fries my brain!!! Also a lot the flocking examples i’ve seen seem to have an oscillation associated with them, which isn’t what im looking for. Any help on this would be greatly appreciated.

[realMakc]

have sheep flock center running away from dog(s), and sheeps following the center.

[tiny_legoman]

Yeah, I tried that during some initial experiments. At the moment the sheep look for the location of the other sheep and test whether they are in their vicinity. They also test their vicinity to the dog but are more concerned to get away from it than stay in formation. What is nice about this is how it makes the sheep interact when the dog gets close. They move away from the dog and therefore split up the flock, this gives it an organic feel. It also creates an optimum distance from which to drive the sheep – there is the challenge. You lose this dynamic when the flock moves as a whole. Is this what you meant!?

[realMakc]

so you want them to split up, or not? decide.

[tiny_legoman]

this is what i cant get my brain around - they kinda need to do both!? they need to flock when they are too far apart from each other, but split if neccessary to get away from the dog!? whats your opinion?

[tiny_legoman]

ok ive had another play round with the flocking concept you suggested, ive ripped a "clumping" example to govern the movement. its working ok...