Added a Stepped ease.

Author: photonstorm

v3/src/math/easing/EaseMap.js

@@ -9,6 +9,7 @@ var Quadratic = require('./quadratic');
 var Quartic = require('./quartic');
 var Quintic = require('./quintic');
 var Sine = require('./sine');
+var Stepped = require('./stepped');
 
 //  EaseMap
 module.exports = {
@@ -30,6 +31,7 @@ module.exports = {
     Elastic: Elastic.Out,
     Back: Back.Out,
     Bounce: Bounce.Out,
+    Stepped: Stepped,
 
     'Quad.easeIn': Quadratic.In,
     'Cubic.easeIn': Cubic.In,

v3/src/math/easing/index.js

@@ -12,6 +12,7 @@ module.exports = {
     Quadratic: require('./quadratic'),
     Quartic: require('./quartic'),
     Quintic: require('./quintic'),
-    Sine: require('./sine')
+    Sine: require('./sine'),
+    Stepped: require('./stepped')
 
 };

v3/src/math/easing/stepped/Stepped.js

@@ -0,0 +1,30 @@
+/**
+ * [description]
+ *
+ * @function Phaser.Math.Easing.Stepped
+ * @since 3.0.0
+ *
+ * @param {number} v - [description]
+ * @param {float} [steps=1] - [description]
+ *
+ * @return {number} [description]
+ */
+var Stepped = function (v, steps)
+{
+    if (steps === undefined) { steps = 1; }
+
+    if (v <= 0)
+    {
+        return 0;
+    }
+    else if (v >= 1)
+    {
+        return 1;
+    }
+    else
+    {
+        return (((steps * v) | 0) + 1) * (1 / steps);
+    }
+};
+
+module.exports = Stepped;

v3/src/math/easing/stepped/index.js

@@ -0,0 +1,3 @@
+//  Phaser.Math.Easing.Stepped
+
+module.exports = require('./Stepped');