//Add a node to a parent node, ignoring if impassable or already closed,
//adding if new, updating if new and better route
private RouteNode AddAdjacentNode(int dx, int dy, int cost, RouteNode parent)
{
int x = parent.X + dx;
int y = parent.Y + dy;
int newCost = parent.MovementCost + cost;
//Get terrain cost. -1 is not passable, 0 no cost, 1,2,3 etc higher cost
int terraincost = GetTerrainCost(x, y);
if (terraincost == -1)
{
return(null);
}
//Check if item has been added to the grid already
RouteNode existing = (RouteNode)mGrid.Item(x, y);
if (existing != null)
{
if (!existing.Closed && newCost < existing.MovementCost)
{
existing.MovementCost = newCost;
existing.TotalCost = existing.MovementCost + existing.Heuristic;
existing.Parent = parent;
mOpenList.Update(existing);
}
return(existing);
}
//Create a new node
RouteNode node = new RouteNode();
node.Parent = parent;
node.X = x;
node.Y = y;
node.MovementCost = newCost; //Add the cost to the parent cost
node.Heuristic = GetHeuristic(node);
node.TotalCost = node.MovementCost + node.Heuristic;
//Add terrain cost
node.MovementCost += terraincost;
node.TotalCost += terraincost;
//Set generation
node.Generation = mGeneration;
mGeneration++;
//Add to the open list and the grid
mOpenList.Push(node);
mGrid.Add(node);
return(node);
}
//Check that a node can be created here
private int GetTerrainCost(int x, int y)
{
//Check the boundary
if (!mBoundary.Contains(x, y))
{
return(-1);
}
x = Convert.ToInt32(x / mGrain) * mGrain;
y = Convert.ToInt32(y / mGrain) * mGrain;
TerrainNode node = (TerrainNode)mTerrain.Item(x, y);
if (node == null)
{
return(0);
}
return(node.MovementCost);
}