Add matter component for inertia - useful for platformers

Author: mikewesthad

src/physics/matter-js/MatterImage.js

@@ -16,6 +16,7 @@ var MatterImage = new Class({
         Components.Force,
         Components.Friction,
         Components.Gravity,
+        Components.Inertia,
         Components.Mass,
         Components.Sensor,
         Components.SetBody,

src/physics/matter-js/MatterSprite.js

@@ -17,6 +17,7 @@ var MatterSprite = new Class({
         Components.Force,
         Components.Friction,
         Components.Gravity,
+        Components.Inertia,
         Components.Mass,
         Components.Sensor,
         Components.SetBody,

src/physics/matter-js/components/Inertia.js

@@ -0,0 +1,21 @@
+var Body = require('../lib/body/Body');
+
+var Inertia = {
+
+    setInertia: function (value)
+    {
+        Body.setInertia(this.body, value);
+
+        return this;
+    },
+
+    // Useful to prevent rotation on body, e.g. for player in a platformer
+    setMaxInertia: function ()
+    {
+        Body.setInertia(this.body, Number.POSITIVE_INFINITY);
+
+        return this;
+    }
+};
+
+module.exports = Inertia;

src/physics/matter-js/components/index.js

@@ -7,6 +7,7 @@ module.exports = {
     Force: require('./Force'),
     Friction: require('./Friction'),
     Gravity: require('./Gravity'),
+    Inertia: require('./Inertia'),
     Mass: require('./Mass'),
     Static: require('./Static'),
     Sensor: require('./Sensor'),