Friction in famo.us? - famo.us

Question

If I have some bodies that are repulsed and also have a distance. Right now they bounce back and forth endlessly. Is there a way to add a resistance to the physics engine so that they may come to rest?
var context = Engine.createContext();
var contextSize = context.getSize();
var handler = new EventHandler();
var physicsEngine = new PhysicsEngine();
function addBall(color, i) {
var ball = new Surface ({
size: [50,50],
properties: {
backgroundColor: color,
borderRadius: '100px'
}
});
ball.state = new StateModifier({origin:[0.5,0.5]});
ball.particle = new Circle({radius:50, mass: 20 + i * 1});
return ball;
}
var leftWall = new Wall({normal : [1,0,0], distance : contextSize[0]/2.0, restitution : 0.7});
var rightWall = new Wall({normal : [-1,0,0], distance : contextSize[0]/2.0, restitution : 0.7});
var topWall = new Wall({normal : [0,1,0], distance : contextSize[1]/2.0, restitution : 0.7});
var bottomWall = new Wall({normal : [0,-1,0], distance : contextSize[1]/2.0, restitution : 0.7});
var walls = [leftWall,rightWall,bottomWall,topWall];
var bodies = [];
_.each(['yellow', 'blue','green', 'red', 'orange', 'purple','gray', 'black'],function(color, index) {
var body = addBall(color, index);
bodies.push(body);
});
_.each(bodies, function (body) {
physicsEngine.addBody(body.particle);
context.add(body.state).add(body);
});
var particles = _.map(bodies, function(body){
return body.particle;
});
_.each(particles, function(particle, index){
var r = new Repulsion({strength: 61});
var d = new Distance({length: 80, minLength: 0});
physicsEngine.attach(r, [particles[(index + 4) % 8]], particle);
physicsEngine.attach(r, [particle], particles[(index + 4) % 8]);
physicsEngine.attach(d, [particles[(index + 1) % 8]], particle);
if (index == 0) {
physicsEngine.attach(d, [particle], particles[7]);
} else {
physicsEngine.attach(d, [particle], particles[(index - 1) % 8]);
}
particle.setVelocity([0.004101*index,0.004101*index,0 ]);
});
_.each(walls, function(wall) {
physicsEngine.attach(wall);
});
Engine.on('prerender', function(){
_.each(bodies, function(body) {
body.state.setTransform(body.particle.getTransform());
});
});

Answer 1

I was looking for Drag!
var drag = new Drag({strength: 0.1})
physicsEngine.attach(drag, [particle]);