I seem to have an issue that several others have had but each situation seems to be somewhat unique in it’s solving and thus, as of yet I have been unable to ascertain the issue. Basically, when I run my P2P_guide.cs script, it kicks out this error in the debug console:
NullReferenceException: Object reference not set to an instance of an object
Grid_Manager.NodeFromWorldPoint (Vector3 worldPosition) (at Assets/Pathfinding_Resources/Grid_Manager.cs:65)
Pathfinding.FindPath (Vector3 startPos, Vector3 targetPos) (at Assets/Pathfinding_Resources/Pathfinding.cs:21)
P2P_guide.amble () (at Assets/Pathfinding_Resources/P2P_guide.cs:25)
P2P_guide.Start () (at Assets/Pathfinding_Resources/P2P_guide.cs:20)
As you can see, this is quite a complex error and seeing as I have not been programming in c# for too long and thus am relatively inexperienced I have spent ages trying to find the problem but no luck and so I was wondering if a fresh set of eyes could shed some light on the situation? Here are the scripts I am running:
This one is attached to a player object:
P2P_guide
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class P2P_guide : MonoBehaviour {
GameObject pathobj;
Grid_Manager grid;
public List<Node_Manager> path;
Pathfinding pathfinder;
public Transform Destination;
public List<Vector3> pathcoords;
public Transform Player;
void Start() {
pathobj = GameObject.Find ("A*");
grid = pathobj.GetComponent<Grid_Manager> ();
pathfinder = pathobj.GetComponent<Pathfinding> ();
amble ();
}
void amble() {
pathfinder.FindPath (Player.position, Destination.position);
path = grid.path;
pathcoords = new List<Vector3>();
foreach (Node_Manager node in path) {
pathcoords.Add (grid.WorldPointFromNode (node));
}
transform.LookAt (pathcoords [1]);
}
}
and then these three are attached to a game object called “A*” in the middle of the map:
Pathfinding
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class Pathfinding : MonoBehaviour {
public Transform seeker, target;
Grid_Manager grid;
void Awake() {
grid = GetComponent<Grid_Manager> ();
}
/* void Update() {
FindPath (seeker.position, target.position);
}
*/
public void FindPath(Vector3 startPos, Vector3 targetPos) {
Node_Manager startNode = grid.NodeFromWorldPoint (startPos);
Node_Manager targetNode = grid.NodeFromWorldPoint (targetPos);
List<Node_Manager> openSet = new List<Node_Manager> ();
HashSet<Node_Manager> closedSet = new HashSet<Node_Manager> ();
openSet.Add (startNode);
while (openSet.Count > 0) {
Node_Manager currentNode = openSet [0];
for (int i = 1; i < openSet.Count; i ++) {
if (openSet <em>.fCost < currentNode.fCost || openSet_.fCost == currentNode.fCost && openSet*.hCost < currentNode.hCost) {*_</em>
_ currentNode = openSet ;
* }*_
* }*
* openSet.Remove (currentNode);*
* closedSet.Add (currentNode);*
* if (currentNode == targetNode) {*
* RetracePath (startNode, targetNode);*
* return;*
* }*
* foreach (Node_Manager neighbour in grid.GetNeighbours(currentNode)) {
_ if (!neighbour.walkable || closedSet.Contains (neighbour)) {
continue;
}*_
* int newMovementCostToNeighbour = currentNode.gCost + GetDistance (currentNode, neighbour);*
* if (newMovementCostToNeighbour < neighbour.gCost || !openSet.Contains (neighbour)) {*
* neighbour.gCost = newMovementCostToNeighbour;*
* neighbour.hCost = GetDistance (neighbour, targetNode);*
* neighbour.parent = currentNode;*
* if (!openSet.Contains (neighbour)) {*
* openSet.Add (neighbour);*
* }*
* }*
* }*
* }*
* }*
* void RetracePath (Node_Manager startNode, Node_Manager endNode) {
List<Node_Manager> path = new List<Node_Manager> ();
Node_Manager currentNode = endNode;*
* while (currentNode != startNode) {*
* path.Add (currentNode);*
* currentNode = currentNode.parent;*
* }*
* path.Reverse ();*
* grid.path = path;*
* }*
* int GetDistance(Node_Manager nodeA, Node_Manager nodeB) {
_ int distX = Mathf.Abs (nodeA.gridX - nodeB.gridX);
int distY = Mathf.Abs (nodeA.gridY - nodeB.gridY);*_
* if (distX > distY) {*
_ return 14 * distY + 10 * (distX - distY);
* }*_
* else {*
_ return 14 * distX + 10 * (distY - distX);
* }
}
}*_
Grid_Manager
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class Grid_Manager : MonoBehaviour {
* public Transform player;*
* public LayerMask unwalkableMask;*
* public Vector2 gridWorldSize;*
* public float nodeRadius;*
* Node_Manager[,] grid;
_ public Vector3 worldBottomLeft;*_
* float nodeDiameter;*
* int gridSizeX, gridSizeY;*
* void Start() {*
_ nodeDiameter = nodeRadius * 2;
* gridSizeX = Mathf.RoundToInt (gridWorldSize.x / nodeDiameter);
gridSizeY = Mathf.RoundToInt (gridWorldSize.y / nodeDiameter);
CreateGrid ();
}*_
* void CreateGrid() {*
* grid = new Node_Manager[gridSizeX,gridSizeY];*
_ worldBottomLeft = transform.position - Vector3.right * gridWorldSize.x/2 - Vector3.forward * gridWorldSize.y/2;_
* for (int x = 0; x < gridSizeX; x ++) {*
* for (int y = 0; y < gridSizeY; y ++) {*
_ Vector3 worldPoint = worldBottomLeft + Vector3.right * (x * nodeDiameter + nodeRadius) + Vector3.forward * (y * nodeDiameter + nodeRadius);
* bool walkable = !(Physics.CheckSphere(worldPoint,nodeRadius,unwalkableMask));_
grid[x,y] = new Node_Manager(walkable,worldPoint,x,y);
_ }
}
}*_
* public List<Node_Manager> GetNeighbours(Node_Manager node) {
List<Node_Manager> neighbours = new List<Node_Manager> ();*
* for (int x = -1; x <= 1; x++) {*
* for (int y = -1; y <= 1; y++) {*
* if (x == 0 && y == 0) {*
* continue;*
* }*
* int checkX = node.gridX + x;*
* int checkY = node.gridY + y;*
* if (checkX >= 0 && checkX < gridSizeX && checkY >= 0 && checkY < gridSizeY) {*
* neighbours.Add (grid [checkX, checkY]);*
* }*
* }*
* }*
* return neighbours;*
* }*
* public Node_Manager NodeFromWorldPoint(Vector3 worldPosition) {
_ float percentX = (worldPosition.x + gridWorldSize.x / 2) / gridWorldSize.x;
float percentY = (worldPosition.z + gridWorldSize.y / 2) / gridWorldSize.y;
percentX = Mathf.Clamp01 (percentX);
percentY = Mathf.Clamp01 (percentY);*_
_ int x = Mathf.RoundToInt((gridSizeX - 1) * percentX);
int y = Mathf.RoundToInt((gridSizeY - 1) * percentY);
* return grid [x, y];
}*_
* public Vector3 WorldPointFromNode(Node_Manager node) {
Node_Manager Node = node;
_ int x = Node.gridX;
int y = Node.gridY;
int roundrad = Mathf.RoundToInt (nodeRadius);
int posx = Mathf.RoundToInt (worldBottomLeft.x) + (xroundrad);
int posy = Mathf.RoundToInt (worldBottomLeft.y) + (yroundrad);
Vector3 pos = new Vector3(posx,0,posy);
return pos;
}*_
* public List<Node_Manager> path;*
* void OnDrawGizmos() {*
* Gizmos.DrawWireCube (transform.position, new Vector3 (gridWorldSize.x, 1, gridWorldSize.y));*
* if (grid != null) {*
* Node_Manager playerNode = NodeFromWorldPoint (player.position);
foreach (Node_Manager n in grid) {*
* Gizmos.color = (n.walkable) ? Color.white : Color.red;*
* if (playerNode == n) {*
* Gizmos.color = Color.blue;*
* }*
* if (path != null)*
* if (path.Contains (n))*
* Gizmos.color = Color.black;*
_ Gizmos.DrawCube (n.worldPosition, Vector3.one * (nodeDiameter - .1f));
* }
}
}
}*_
Node_Manager
using UnityEngine;
using System.Collections;
public class Node_Manager {
* public bool walkable;*
* public Vector3 worldPosition;*
* public int gridX;*
* public int gridY;*
* public int gCost;*
* public int hCost;*
* public Node_Manager parent;*
* public Node_Manager(bool _walkable, Vector3 _worldPos, int _gridX, int _gridY) {
walkable = _walkable;
worldPosition = _worldPos;
gridX = gridX;
gridY = gridY;*
* }*
* public int fCost {*
* get {*
* return gCost + hCost;*
* }*
* }*
}
Anyway, thanks in advance and I hope to hear from someone soon!
