public override void Initialise(Percepts percepts)
{
Name = "Greedy-Best First Agent";
base.Initialise(percepts);
_frontierList.Add(AgentData.RootNode);
}
public virtual void Initialise(Percepts percepts)
{
_agentData = new AgentData();
_state = AgentState.Searching;
AgentData.RootNode = new Node <TileType>(TileType.Start, null, percepts.AgentPos);
AgentData.RootNode.IsOnPath = true;
AgentData.SearchedPos.Add(AgentData.RootNode.Pos);
}
public override int HeuristicFunction(Vector2i Pos, Percepts percepts)
{
int manhattanDistance = 0;
// Manhanttan Distance to the FIRST goal
manhattanDistance = Math.Abs(percepts.GoalPositions[0].X - Pos.X) +
Math.Abs(percepts.GoalPositions[0].Y - Pos.Y);
return(manhattanDistance);
}
public override int CostFunction(Vector2i Pos, Percepts percepts)
{
//Dijkstra's Algorithm is to determine the cost to get up to this node, using a distance function.
// In this case, it'll be the manhattan distance to this node location
int manhattanDistance = 0;
manhattanDistance = Math.Abs(Pos.X - AgentData.RootNode.Pos.X) +
Math.Abs(Pos.Y - Pos.X - AgentData.RootNode.Pos.Y);
return(manhattanDistance);
}
protected virtual bool WithinMap(Vector2i pos, Percepts percepts)
{
if ((0 <= pos.X) && (pos.X < percepts.MapMatrix.GetLength(0)))
{
if ((0 <= pos.Y) && (pos.Y < percepts.MapMatrix.GetLength(1)))
{
if (percepts.MapMatrix[pos.X, pos.Y] != TileType.Wall)
{
return(true);
}
}
}
return(false);
}
public override int CostFunction(Vector2i Pos, Percepts percepts)
{
// Get the current latest node
// GBFS should only expand one node at a time...
Node <TileType> currentNode = AgentData.SearchedNodes[AgentData.SearchedNodes.Count - 1];
// Determine layers of parents
// This gives us the "cost" to get up to this point
int nodeDistance = 0;
Node <TileType> parentNode = currentNode.Parent;
while (parentNode != null)
{
nodeDistance++;
parentNode = parentNode.Parent;
}
return(nodeDistance);
}
public override AgentActions next(Percepts percepts)
{
AgentDelay--;
if (AgentDelay < 0)
{
AgentDelay = AgentData.AgentDelay;
}
else
{
return(AgentActions.Search);
}
UpdateInternalHeap(_frontierList);
switch (State)
{
case AgentState.Searching:
if (_frontierList.Count > 0)
{
Node <TileType> currentNode = _frontierList[_frontierList.Count - 1];
int lowestCost = 5000;
// This is reversed such that it provides a DFS under all equal circumstances
// this implies in a worst-case scenario, A* behaves as GBFS
for (int i = _frontierList.Count - 1; i >= 0; i--)
{
Node <TileType> listNode = _frontierList[i];
if (listNode.Cost < lowestCost)
{
lowestCost = listNode.Cost;
currentNode = listNode;
}
}
_frontierList.Remove(currentNode);
if (IsGoalNode(currentNode))
{
State = AgentState.Moving;
AgentData.NodePath = DetermineAgentPath(AgentData.RootNode, currentNode);
AgentData.DeterminedMoveSet = DetermineMoveSet();
State = AgentState.Moving;
AgentData.PosToSearch.Clear();
break;
}
AgentData.PosToSearch = new List <Vector2i>();
AgentData.PosToSearch.Add(currentNode.Pos);
AgentData.SearchedNodes.Add(currentNode);
List <Node <TileType> > bestNodes = new List <Node <TileType> >();
List <Node <TileType> > surroundingNodes = SearchSurroundingNodes(currentNode, percepts);
for (int i = 0; i < surroundingNodes.Count; i++)
{
Node <TileType> subnode = surroundingNodes[i];
if (!AgentData.SearchedPos.Contains(subnode.Pos))
{
_frontierList.Add(subnode);
AgentData.SearchedPos.Add(subnode.Pos);
AgentData.SearchedNodes.Add(subnode);
}
}
}
else
{
State = AgentState.Lost;
return(AgentActions.Lost);
}
return(AgentActions.Search);
case AgentState.Moving:
AgentData.Path.Add(percepts.AgentPos);
if (AgentData.DeterminedMoveSet.Count > 0)
{
return(AgentData.DeterminedMoveSet.Dequeue());
}
State = AgentState.Finished;
break;
default:
break;
}
return(AgentActions.Search);
}
public override void Initialise(Percepts percepts)
{
base.Initialise(percepts);
Name = "Dijkstra's Algorithm Agent";
}
public override void Initialise(Percepts percepts)
{
base.Initialise(percepts);
Name = "A-Star Agent";
}
protected virtual List <Node <TileType> > SearchSurroundingNodes(Node <TileType> currentNode, Percepts percepts)
{
Vector2i[] searchNodes = new Vector2i[4]; // 4 surrounding nodes
List <Node <TileType> > foundNodes = new List <Node <TileType> >();
// Priorities: Goes UP before LEFT then DOWN then RIGHT
searchNodes[0] = new Vector2i(currentNode.Pos.X, currentNode.Pos.Y - 1);
searchNodes[1] = new Vector2i(currentNode.Pos.X - 1, currentNode.Pos.Y);
searchNodes[2] = new Vector2i(currentNode.Pos.X, currentNode.Pos.Y + 1);
searchNodes[3] = new Vector2i(currentNode.Pos.X + 1, currentNode.Pos.Y);
for (int i = 0; i < searchNodes.Length; i++)
{
Vector2i newPos = searchNodes[i];
if (WithinMap(newPos, percepts))
{
if (!AgentData.SearchedPos.Contains(newPos))
{
Node <TileType> newNode = new Node <TileType>(
percepts.MapMatrix[newPos.X, newPos.Y], currentNode, newPos);
newNode.Cost = HeuristicFunction(newPos, percepts) + CostFunction(newPos, percepts);
if (AgentData.DirectionalMovementCost.Count != 0)
{
newNode.Cost += AgentData.DirectionalMovementCost[newPos - currentNode.Pos];
}
foundNodes.Add(newNode);
currentNode.Children.Add(newNode);
}
}
}
return(foundNodes);
}
public virtual int CostFunction(Vector2i Pos, Percepts percepts)
{
return(0);
}
public virtual int HeuristicFunction(Vector2i Pos, Percepts percepts)
{
return(0);
}
public abstract AgentActions next(Percepts percepts);