Siege: Tower Defense

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This article is a work-in-progress. If you are interested in more details feel free to contact me at [email protected]

Siege is a tower defense style game. The player is presented with a map which they may modify by placing defensive towers or deploying troops to attack the enemy. The goal of the game is to prevent enemy troops from reaching your castle whilst simultaneously attacking the enemy castle with your troops.

Map Design

LAVA
Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile
Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile
CASTLE WALL	Tile	TOWER	Tile	Tile	Tile	Tile	TOWER	Tile	CASTLE WALL
CASTLE WALL	Tile	PATH			Tile				CASTLE WALL
PLAYER CASTLE			Tile				Tile		ENEMY CASTLE
CASTLE WALL	Tile	Tile	Tile	TOWER	TOWER	Tile	Tile	Tile	CASTLE WALL
CASTLE WALL	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	CASTLE WALL
Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile
Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile	Tile
LAVA

Data Serialization

To implement game saving/loading there will need to be an efficient way of serializing dynamic objects. A node-based system will be implemented, an example of how data will be stored can be seen in Figure 15.

Figure 15 - A hierarchical view of a node based file storage system

The way this system works is that objects are broken down into their simplest form and then stored. If a simple value (Such as a string, integer, character, etc.) is being saved it is simply attached to the root node with a variable name it can be accessed through. However, if an object is being serialized, a new ‘child node’ will be created which will contain its data, this allows for the hierarchy of objects to be maintained through serialization allowing them to be reconstructed when loaded. The objects will need to have pre-defined serializers and deserializers for this to be possible.

Pathfinding

Frontier = new PriorityQueue
VisitedTilesFrom = Map[Tile, Tile]
TileTravelCost = Map[Tile, Integer]

VisitedTilesFrom Add [Start, Start]
TileTravelCost Add [Start, 0]
Queue into Frontier Start
While Frontier is not empty
    SearchTile = Dequeue Frontier
    
    If SearchTile is End
       Break
    End If
    
    For Tile from SearchTile Neighbours
        TravelCost = TileTravelCost[SearchTile] + Tile Weight
      
        If TileTravelCost[Tile] not exists 
              OR TravelCost <  TileTravelCost[Tile]
            TileTravelCost[Tile] = TravelCost
            VisitedTilesFrom[Tile] = [SearchTile]
              
            QueuePriority = TravelCost + Distance from Tile to End
            Queue into Frontier Tile
        End If
    End For
End While

From VisitedTilesFrom calculate route from Start to End