Math.rotateTowards = function(source, target, step)
    {
       var diff = Math.abs(source - target);

       var result = source;

       if(diff < Math.PI && target > source)
       {
           result = source + step;
       }
       else if(diff < Math.PI && target < source)
       {
           result = source - step;
       }
       else if(diff > Math.PI && target > source)
       {
           result = source - step;
       }
       else if(diff > Math.PI && target < source)
       {
           result = source + step;
       }
       else if(diff == Math.PI)
       {
           result = source + step;
       }

       //Normalize angle
       result = Math.atan2(Math.sin(result), Math.cos(result));

       if ((result > target && result - step < target))
       {
           result = target;
       }

       return result;
    }