Issue cocos2d#739: Updating JumpBy with stackable actions.

Author: rboyd

cocos2d/actions/CCActionInterval.js

@@ -1073,7 +1073,7 @@ cc.JumpBy = cc.ActionInterval.extend(/** @lends cc.JumpBy# */{
      */
     startWithTarget:function (target) {
         cc.ActionInterval.prototype.startWithTarget.call(this, target);
-        this._startPosition = target.getPosition();
+        this._previousPosition = this._startPosition = target.getPosition();
     },
 
     /**
@@ -1084,8 +1084,16 @@ cc.JumpBy = cc.ActionInterval.extend(/** @lends cc.JumpBy# */{
             var frac = time * this._jumps % 1.0;
             var y = this._height * 4 * frac * (1 - frac);
             y += this._delta.y * time;
+
             var x = this._delta.x * time;
-            this._target.setPosition(cc.p(this._startPosition.x + x, this._startPosition.y + y));
+
+            var currentPos = this._target.getPosition();
+
+            var diff = cc.pSub(currentPos, this._previousPosition);
+            this._startPosition = cc.pAdd(diff, this._startPosition);
+            var newPos = cc.pAdd(this._startPosition, cc.p(x, y));
+            this._target.setPosition(newPos);
+            this._previousPosition = newPos;
         }
     },
 

cocos2d/actions/CCActionManager.js

@@ -98,7 +98,6 @@ cc.ActionManager = cc.Class.extend({
         }
         //creates a array for that eleemnt to hold the actions
         this._actionAllocWithHashElement(element);
-        cc.Assert((element.actions.indexOf(action) == -1), "ActionManager.addAction(),");
 
         element.actions.push(action);
         action.startWithTarget(target);