Add some code review comments.

springy.js

@@ -349,6 +349,9 @@ Layout.ForceDirected.prototype.applyCoulombsLaw = function()
 			if (point1 !== point2)
 			{
 				var d = point1.p.subtract(point2.p);
+				// Why is distance = mag + 1.0? If there's a good reason for
+				// it, leave a comment. Is it to keep the repulsion from being
+				// way too strong at small distances?
 				var distance = d.magnitude() + 1.0;
 				var direction = d.normalise();
 
@@ -385,6 +388,8 @@ Layout.ForceDirected.prototype.attractToCentre = function()
 Layout.ForceDirected.prototype.updateVelocity = function(timestep)
 {
 	this.eachNode(function(node, point) {
+		// Is this, along with updatePosition below, the only places that your
+		// integration code exist?
 		point.v = point.v.add(point.f.multiply(timestep)).multiply(this.damping);
 		point.f = new Vector(0,0);
 	});
@@ -393,6 +398,8 @@ Layout.ForceDirected.prototype.updateVelocity = function(timestep)
 Layout.ForceDirected.prototype.updatePosition = function(timestep)
 {
 	this.eachNode(function(node, point) {
+		// Same question as above; along with updateVelocity, is this all of
+		// your integration code?
 		point.p = point.p.add(point.v.multiply(timestep));
 	});
 };
@@ -402,6 +409,8 @@ Layout.ForceDirected.prototype.totalEnergy = function(timestep)
 	var energy = 0.0;
 	this.eachNode(function(node, point) {
 		var speed = point.v.magnitude();
+		// A comment might be warranted explaining why the factor of 1/2 is
+		// unnecessary.
 		energy += speed * speed;
 	});
 
@@ -547,11 +556,14 @@ Layout.ForceDirected.Point = function(position, mass)
 	this.p = position; // position
 	this.m = mass; // mass
 	this.v = new Vector(0, 0); // velocity
+	// Based on the usage, the "force" member looks more like an
+	// "acceleration".
 	this.f = new Vector(0, 0); // force
 };
 
 Layout.ForceDirected.Point.prototype.applyForce = function(force)
 {
+	// Ditto on acceleration, here: a = F/m
 	this.f = this.f.add(force.divide(this.m));
 };