Updates World default coefficient of friction.

src/system.js

@@ -134,7 +134,7 @@ System._addWorld = function(world) {
  * @memberof System
  * @param {string} [opt_klass = 'Item'] The name of the class to add.
  * @param {Object} [opt_options=] A map of initial properties.
- * @param {string=} [opt_world = System._records[0]] An instance of World to contain the item.
+ * @param {Object} [opt_world = System._records[0]] An instance of World to contain the item.
  * @returns {Object} An instance of the added item.
  */
 System.add = function(opt_klass, opt_options, opt_world) {
@@ -283,6 +283,7 @@ System._stepForward = function() {
       }
     }
   }
+  System.clock++;
 };
 
 /**

src/world.js

@@ -50,7 +50,7 @@ World.prototype.init = function(world, opt_options) {
   this.borderStyle = options.borderStyle || 'none';
   this.borderColor = options.borderColor || [0, 0, 0];
   this.gravity = options.gravity || new Vector(0, 1);
-  this.c = options.c || 0.1;
+  this.c = typeof options.c !== 'undefined' ? options.c : 0.1;
   this.pauseStep = !!options.pauseStep;
   this.pauseDraw = !!options.pauseDraw;
   this.el.className = this.name.toLowerCase();

test/item.js

@@ -103,7 +103,7 @@ test('init() should initialize with default properties.', function(t) {
   t.equal(obj.controlCamera, false, 'default controlCamera.');
   t.equal(obj._force.x, 0, 'force cache x.');
   t.equal(obj._force.y, 0, 'force cache y.');
-  t.equal(obj.id, 'Item3', 'should have an id.');
+  t.ok(obj.id, 'should have an id.');
   t.equal(typeof obj.el, 'object', 'should have a DOM element as a view.');
   t.equal(obj.el.style.position, 'absolute', 'should have absolute positioning.');
   t.equal(obj.el.style.top, '-5000px', 'should be positioned off screen.');

test/world.js

@@ -10,7 +10,7 @@ test('load World.', function(t) {
   t.end();
 });
 
-test('new Item() should create a new Item and add its view to the DOM.', function(t) {
+test('new World() creates a new World.', function(t) {
   var obj = new World();
   t.equal(obj.el, document.body, 'should by default use document.body as a view.');
   t.equal(obj.name, 'World', 'should have a name.');
@@ -63,7 +63,7 @@ test('init() should initialize with custom properties.', function(t) {
     borderStyle: 'dotted',
     borderColor: [0, 0, 200],
     gravity: new Vector(10, 20),
-    c: 10,
+    c: 0,
     pauseStep: true,
     pauseDraw: true,
     location: new Vector(50, 50)
@@ -76,7 +76,7 @@ test('init() should initialize with custom properties.', function(t) {
   t.assert(obj.borderColor[0] === 0 && obj.borderColor[1] === 0 && obj.borderColor[2] === 200, 'Custom borderColor.');
   t.equal(obj.gravity.x, 10, 'Custom gravity x.');
   t.equal(obj.gravity.y, 20, 'Custom gravity y.');
-  t.equal(obj.c, 10, 'Custom c.');
+  t.equal(obj.c, 0, 'Custom c.');
   t.equal(obj.pauseStep, true, 'Custom pauseStep.');
   t.equal(obj.pauseDraw, true, 'Custom pauseDraw.');
   t.equal(obj.location.x, 50, 'Custom location x.');