Time for action – beginning the implementation of A*

1. Add a new module called PathFinder to the Robot Rampage project.

2. Add declarations to the PathFinder module:

   #Region "Declarations"
   Private Enum NodeStatus 
     Open
     Closed
   End Enum
   
   Private statusTracker As Dictionary(Of Vector2, NodeStatus) = 
       New Dictionary(Of Vector2, NodeStatus)()
   
   Private Const CostStraight As Integer = 10
   Private Const CostDiagonal As Integer = 15
   
   Private openList As List(Of PathNode) = New List(Of PathNode)()
   
   Private costTracker As Dictionary(Of Vector2, Single) = 
       New Dictionary(Of Vector2, Single)()
   #End Region

3. Add the addNodeToOpenList() method to the PathFinder module:

   #Region "Helper Methods"
   Private Sub addNodeToOpenList(node As PathNode)
       Dim index As Integer = 0
       Dim cost As Single = node.TotalCost
   
       Do While (openList.Count() > index) AndAlso
           (cost < openList(index).TotalCost)
           index += 1
       Loop
   
       openList.Insert(index, node)
       costTracker(node.GridLocation) ...