Moved the depth sorting functions into the DisplayList class, as it's really the one responsible for it, not System.

Author: photonstorm

src/actions/GridAlign.js

@@ -1,9 +1,10 @@
 var AlignIn = require('../display/align/in/QuickSet');
 var CONST = require('../display/align/const');
 var GetValue = require('../utils/object/GetValue');
+var NOOP = require('../utils/NOOP');
 var Zone = require('../gameobjects/zone/Zone');
 
-var tempZone = new Zone({ sys: { sortChildrenFlag: false }}, 0, 0, 1, 1);
+var tempZone = new Zone({ sys: { queueDepthSort: NOOP }}, 0, 0, 1, 1);
 
 /**
  * [description]

src/gameobjects/GameObject.js

@@ -121,7 +121,7 @@ var GameObject = new Class({
         this.body = null;
 
         //  Tell the Scene to re-sort the children
-        this.scene.sys.sortChildrenFlag = true;
+        this.scene.sys.queueDepthSort();
     },
 
     /**
@@ -294,7 +294,7 @@ var GameObject = new Class({
         }
 
         //  Tell the Scene to re-sort the children
-        this.scene.sys.sortChildrenFlag = true;
+        this.scene.sys.queueDepthSort();
 
         this.active = false;
         this.visible = false;

src/gameobjects/components/Depth.js

@@ -14,7 +14,7 @@ var Depth = {
 
         set: function (value)
         {
-            this.scene.sys.sortChildrenFlag = true;
+            this.scene.sys.queueDepthSort();
             this._depth = value;
         }
 

src/gameobjects/components/Transform.js

@@ -180,7 +180,7 @@ var Transform = {
 
         set: function (value)
         {
-            this.scene.sys.sortChildrenFlag = true;
+            this.scene.sys.queueDepthSort();
             this._depth = value;
         }
 

src/scene/local/Systems.js

@@ -29,8 +29,6 @@ var Systems = new Class({
         this.config = config;
         this.settings = Settings.create(config);
 
-        this.sortChildrenFlag = false;
-
         //  Set by the GlobalSceneManager
         this.canvas;
         this.context;
@@ -157,37 +155,23 @@ var Systems = new Class({
             return;
         }
 
-        //  inlined to avoid branching
-        if (this.sortChildrenFlag)
-        {
-            StableSort.inplace(this.displayList.list, this.sortZ);
+        var displayList = this.displayList;
 
-            this.sortChildrenFlag = false;
-        }
+        displayList.process();
 
-        this.cameras.render(renderer, this.displayList, interpolation);
+        this.cameras.render(renderer, displayList, interpolation);
     },
 
     //  Force a sort of the display list on the next render
     queueDepthSort: function ()
     {
-        this.sortChildrenFlag = true;
+        this.displayList.queueDepthSort();
     },
 
     //  Immediately sorts the display list if the flag is set
     depthSort: function ()
     {
-        if (this.sortChildrenFlag)
-        {
-            StableSort.inplace(this.displayList.list, this.sortZ);
-
-            this.sortChildrenFlag = false;
-        }
-    },
-
-    sortZ: function (childA, childB)
-    {
-        return childA._depth - childB._depth;
+        this.displayList.depthSort();
     },
 
     //  A paused Scene still renders, it just doesn't run ANY of its update handlers or systems

src/scene/plugins/DisplayList.js

@@ -1,4 +1,5 @@
 var Class = require('../../utils/Class');
+var StableSort = require('../../utils/array/StableSort');
 
 var DisplayList = new Class({
 
@@ -13,9 +14,43 @@ var DisplayList = new Class({
         //  The equivalent of the old `Sprite.children` array.
         this.list = [];
 
+        this.sortChildrenFlag = false;
+
         this.position = 0;
     },
 
+    process: function ()
+    {
+        if (this.sortChildrenFlag)
+        {
+            StableSort.inplace(this.list, this.sortZ);
+
+            this.sortChildrenFlag = false;
+        }
+    },
+
+    sortZ: function (childA, childB)
+    {
+        return childA._depth - childB._depth;
+    },
+
+    //  Force a sort of the display list on the next call to process
+    queueDepthSort: function ()
+    {
+        this.sortChildrenFlag = true;
+    },
+
+    //  Immediately sorts the display list if the flag is set
+    depthSort: function ()
+    {
+        if (this.sortChildrenFlag)
+        {
+            StableSort.inplace(this.list, this.sortZ);
+
+            this.sortChildrenFlag = false;
+        }
+    },
+
     add: function (child)
     {
         //  Is child already in this display list?