public static WorldGraph GetWorldGraph()
{
if (worldGraphSingleton == null)
{
worldGraphSingleton = new WorldGraph();
}
return(worldGraphSingleton);
}
public float GetHeuristic(Physics.Vector2D destination)
{
//Apply a simple euclidean distance heuristic
//Intended to give nodes a higher cost the further they are from the final goal
//If a different destination node is used as an argument then this heuristic may work better or worse
WorldGraph mainGraph = WorldGraph.GetWorldGraph();
Physics.Vector2D currentPosition = mainGraph.topLevelNode.GetNodePosition(index);
return((currentPosition - destination).Length() * 10);
}
public AIEngine(Physics.Player thePlayer)
{
physEng = Physics.PhysicsEngine.GetPhysicsEngine();
mainGraph = WorldGraph.GetWorldGraph();
AIPlayer = thePlayer;
actionPlan = new List <act_dur>();
currentState = STATES.WAITING;
currentStateCooldown = 0.0f;
walkingSpeed = 500f;
destinationNode = null;
currentlyJumping = false;
}
//The following method assumes the nodes provided are rigidbodies with leaf nodes attached to them
private static CONNECTION_TYPE GetConnectionBetweenRigidBodies(Node rigidBody1, Node rigidBody2)
{
WorldGraph mainGraph = WorldGraph.GetWorldGraph();
CONNECTION_TYPE toReturn = CONNECTION_TYPE.NONE;
List <Physics.Vector2D> nodePositions1, nodePositions2;
//compare each node from rigidbody 1 to each node in rigidbody 2
foreach (Node node1 in rigidBody1.internalNodes)
{
foreach (Node node2 in rigidBody2.internalNodes)
{
//Due to the presence of moving platforms, create lists of the different possible positions of each node
nodePositions1 = new List <Physics.Vector2D>();
nodePositions2 = new List <Physics.Vector2D>();
//add the node's default positions
nodePositions1.Add(mainGraph.topLevelNode.GetNodePosition(node1));
nodePositions2.Add(mainGraph.topLevelNode.GetNodePosition(node2));
//if rigidbody 1 moves between two points, add the position of node1 at BOTH those points to the list
if (rigidBody1 is NodeOnRails)
{
nodePositions1.Add(
mainGraph.topLevelNode.GetNodePosition(rigidBody1.index.GetParentIndex()) + ((NodeOnRails)rigidBody1).railPoint1 + node1.position);
nodePositions1.Add(
mainGraph.topLevelNode.GetNodePosition(rigidBody1.index.GetParentIndex()) + ((NodeOnRails)rigidBody1).railPoint2 + node1.position);
}
//if rigidbody 2 moves between two points, add the position of node2 when at BOTH those points to the list
if (rigidBody2 is NodeOnRails)
{
nodePositions2.Add(
mainGraph.topLevelNode.GetNodePosition(rigidBody2.index.GetParentIndex()) + ((NodeOnRails)rigidBody2).railPoint1 + node2.position);
nodePositions2.Add(
mainGraph.topLevelNode.GetNodePosition(rigidBody2.index.GetParentIndex()) + ((NodeOnRails)rigidBody2).railPoint2 + node2.position);
}
//at this point two lists have been created containing all the positions each node could occupy
//loop through both lists to determine if any position combinations should be connected
CONNECTION_TYPE temp;
//loop through both lists, adding all possible connections to node1
foreach (Physics.Vector2D pos1 in nodePositions1)
{
foreach (Physics.Vector2D pos2 in nodePositions2)
{
//find out if the two nodes can be connected
temp = GetConnectionBetween(node1.type, node2.type, pos1, pos2);
if (temp != CONNECTION_TYPE.NONE)
{
float cost = (pos1 - pos2).Length();
//modify cost based on the type of connection
switch (temp)
{
case CONNECTION_TYPE.JUMP:
cost += 20;
break;
case CONNECTION_TYPE.FALL:
cost += 5;
break;
default:
cost += 2;
break;
}
node1.addConnection(new Connection(node2.index, cost, temp));
//change the return value to reflect the presence of a connection
toReturn = CONNECTION_TYPE.HIGH_LEVEL;
}
}
}
}
}
return(toReturn);
}
public static List <NodeIndex> AstarPathfind(Node startNode, Node endNode, List <Node> nodesToSearch)
{
//ASSUMPTIONS:
// Start Node is on the same layer as the set of nodes to search
// End Node is on the same layer as the start Node, or one level above!
//reset the path of all nodes
foreach (Node n in nodesToSearch)
{
n.ResetPath();
}
WorldGraph fullAIGraph = WorldGraph.GetWorldGraph();
//create the open and closed lists
List <NodeIndex> openList = new List <NodeIndex>();
List <NodeIndex> closedList = new List <NodeIndex>();
//find the current layer being searched through
int nodeListDepth = startNode.index.GetMaxDepth();
bool endNodeOnSameLayer = nodeListDepth == endNode.index.GetMaxDepth();
//currentNode is the node being examined
NodeIndex currentNode;
NodeIndex nextNode;
openList.Add(startNode.index);
while (openList.Count() > 0)
{
//Get the cheapest node in the open list
currentNode = GetCheapestNode(openList, nodesToSearch, endNode.internalNodes);
//if the goal has been found then retrace the path and return it
if (currentNode.EqualAtDepth(endNode.index, endNode.index.GetMaxDepth()))
{
if (endNodeOnSameLayer)
{
//retrace the path from the end node
return(RetracePath(endNode, nodesToSearch));
}
else
{
return(RetracePath(endNode.GetNode(currentNode), nodesToSearch));
}
}
//if the goal has not been found then add the nodes at the end of all connections to the open list, and close the current node
foreach (Connection edge in nodesToSearch[currentNode.GetLowestIndex()].connections)
{
nextNode = edge.destination;
//ignore if the node has already been closed
if (!closedList.Contains(nextNode))
{
//calculate the cost by looking at the accumulated cost, the connection cost, and the heuristic
float totalCost = Math.Abs(nodesToSearch[currentNode.GetLowestIndex()].accumulatedCost + edge.traversalCost + fullAIGraph.topLevelNode.GetNode(nextNode).GetHeuristic(fullAIGraph.goalCoords));
Node tempNode = GetNodeFromLists(nextNode, nodesToSearch, endNode.internalNodes);
if (tempNode != null)
{
//if the node is not currently in the open list then add it to the open list
if (!openList.Contains(nextNode))
{
openList.Add(nextNode);
//set the parent Id and the current cost
tempNode.previousNode = currentNode;
tempNode.accumulatedCost = totalCost;
}
//update the node in the list if the new path is faster
else if (tempNode.accumulatedCost > totalCost)
{
//set the parent Id and the current cost
tempNode.previousNode = currentNode;
tempNode.accumulatedCost = totalCost;
}
}
}
}
closedList.Add(currentNode);
openList.Remove(currentNode);
}
return(null); // If the goal is not found, return null
}
