Fix for #1761: [Feature Request] Add Math.distanceSq(). Also, first attempt at a pull request for Phaser.

src/math/Math.js

@@ -1095,6 +1095,26 @@ Phaser.Math = {
 
     },
 
+    /**
+    * Returns the euclidian distance squared between the two given set of
+    * coordinates (cuts out a square root operation before returning).
+    *
+    * @method Phaser.Math#distanceSq
+    * @param {number} x1
+    * @param {number} y1
+    * @param {number} x2
+    * @param {number} y2
+    * @return {number} The distance squared between the two sets of coordinates.
+    */
+    distanceSq: function (x1, y1, x2, y2) {
+
+        var dx = x1 - x2;
+        var dy = y1 - y2;
+
+        return dx * dx + dy * dy;
+
+    },
+
     /**
     * Returns the distance between the two given set of coordinates at the power given.
     *