added body sleepStart and sleepEnd events, closes #91

demo/js/Demo.js

@@ -862,6 +862,13 @@
         
         World.add(_world, stack);
 
+        for (var i = 0; i < stack.bodies.length; i++) {
+            Events.on(stack.bodies[i], 'sleepStart sleepEnd', function(event) {
+                var body = this;
+                console.log('body id', body.id, 'sleeping:', body.isSleeping);
+            });
+        }
+
         _engine.enableSleeping = true;
     };
 

src/body/Body.js

@@ -604,6 +604,32 @@ var Body = {};
         return properties;
     };
 
+    /*
+    *
+    *  Events Documentation
+    *
+    */
+
+    /**
+    * Fired when a body starts sleeping (where `this` is the body).
+    *
+    * @event sleepStart
+    * @this {body} The body that has started sleeping
+    * @param {} event An event object
+    * @param {} event.source The source object of the event
+    * @param {} event.name The name of the event
+    */
+
+    /**
+    * Fired when a body ends sleeping (where `this` is the body).
+    *
+    * @event sleepEnd
+    * @this {body} The body that has ended sleeping
+    * @param {} event An event object
+    * @param {} event.source The source object of the event
+    * @param {} event.name The name of the event
+    */
+
     /*
     *
     *  Properties Documentation

src/core/Sleeping.js

@@ -92,6 +92,8 @@ var Sleeping = {};
      * @param {boolean} isSleeping
      */
     Sleeping.set = function(body, isSleeping) {
+        var wasSleeping = body.isSleeping;
+
         if (isSleeping) {
             body.isSleeping = true;
             body.sleepCounter = body.sleepThreshold;
@@ -106,9 +108,17 @@ var Sleeping = {};
             body.speed = 0;
             body.angularSpeed = 0;
             body.motion = 0;
+
+            if (!wasSleeping) {
+                Events.trigger(body, 'sleepStart');
+            }
         } else {
             body.isSleeping = false;
             body.sleepCounter = 0;
+
+            if (wasSleeping) {
+                Events.trigger(body, 'sleepEnd');
+            }
         }
     };