Actions.IncX has 3 new arguments: step, index and direction.

Author: photonstorm

src/actions/IncX.js

@@ -4,25 +4,30 @@
  * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
  */
 
+var PropertyValueInc = require('./PropertyValueInc');
+
 /**
- * [description]
+ * Takes an array of Game Objects, or any objects that have a public `x` property,
+ * and then adds the given value to each of their `x` properties.
+ * 
+ * The optional `step` property is applied incrementally, multiplied by each item in the array.
+ * 
+ * To use this with a Group: `IncX(group.getChildren(), value, step)`
  *
  * @function Phaser.Actions.IncX
  * @since 3.0.0
  * 
- * @param {array} items - An array of Game Objects. The contents of this array are updated by this Action.
- * @param {number} value - [description]
+ * @param {array|Phaser.GameObjects.GameObject[]} items - The array of items to be updated by this action.
+ * @param {number} value - The amount to be added to the `x` property.
+ * @param {number} [step=0] - This is added to the `value` amount, multiplied by the iteration counter.
+ * @param {integer} [index=0] - An optional offset to start searching from within the items array.
+ * @param {integer} [direction=1] - The direction to iterate through the array. 1 is from beginning to end, -1 from end to beginning.
  *
- * @return {array} The array of Game Objects that was passed to this Action.
+ * @return {array} The array of objects that were passed to this Action.
  */
-var IncX = function (items, value)
+var IncX = function (items, value, step, index, direction)
 {
-    for (var i = 0; i < items.length; i++)
-    {
-        items[i].x += value;
-    }
-
-    return items;
+    return PropertyValueInc(items, 'x', value, step, index, direction);
 };
 
 module.exports = IncX;