koobas.hobune.stream
Null Ref Exception on a script that should have a reference in it?
I'm trying to create a game AI where it uses a tier-based system (that uses an array of lists of transforms) to support a pathfinding algorithm. Thus far, I'm around 99% the logic for the pathfinding algorithm works, though I've yet to test it because I get an NRE error when I test my pathfinding target acquisition. The error seems to occur in line 185 of the code (where it says drawnPath.Add(target.transform); in the Patrol function) no matter what I do. The debugs never occur and I am extremely frustrated because as far as I'm concerned, I have everything else assigned, not to mention the fact that I have an if target == null statement right in the Patrol function! Can anyone help?
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;
public class AIHovercraft : MonoBehaviour {
public float hoverHeight;
public float hoverForce;
private float hoverStandard;
public float speed;
private Rigidbody rb;
private bool onGround;
private bool falling;
[SerializeField]
private NavMeshAgent enemy;
public HoverVehicle player;
public GameObject[] hovercraft;
private int tier;
private float altitude;
private WaitForSeconds altCheckDelay = new WaitForSeconds(0.06f);
private bool canCheck;
public enum State
{
EVADE,
CHASE,
PATROL
}
public State state;
private bool alive;
public GameManagement gManager;
#region EVADE
private int wIndex;
private Vector3 eDirect;
private int eModifier;
private WaitForSeconds waitForDamage = new WaitForSeconds(2f);
private bool hasTakenDamage;
#endregion
#region CHASE
private GameObject target;
#endregion
#region PATROL
List<Transform>[] allWaypoints;
List<Transform> drawnPath = new List<Transform>();
private int pWIndex;
public float maxDistance;
public float threatDistance;
public float nearestDistance;
private float nearestStaticDistance;
private bool isMarked;
#endregion
private void Awake()
{
allWaypoints = new List<Transform>[gManager.tiers];
int i = 0;
foreach (List<Transform> tier in allWaypoints)
{
allWaypoints[i] = new List<Transform>();
i++;
}
}
private void Start()
{
rb = GetComponent<Rigidbody>();
enemy = GetComponent<NavMeshAgent>();
enemy.updatePosition = true;
enemy.updateRotation = false;
state = State.PATROL;
alive = true;
hasTakenDamage = false;
canCheck = true;
nearestStaticDistance = nearestDistance;
//Start FSM
StartCoroutine("FSM");
}
private void Update()
{
CheckTier();
}
int CheckTier()
{
int i = 1;
foreach (int height in gManager.tierThresholds)
{
if (transform.localPosition.y > height)
{
tier = i;
}
i++;
}
StartCoroutine("TierDelay");
return tier;
}
IEnumerator FSM()
{
while (alive)
{
switch (state)
{
case State.PATROL:
Patrol();
break;
case State.CHASE:
Chase();
break;
case State.EVADE:
Evade();
break;
}
yield return null;
}
}
IEnumerator TierDelay()
{
yield return altCheckDelay;
}
void Patrol()
{
foreach (GameObject hc in hovercraft)
{
float targetDistance = Vector3.Distance(hc.transform.position, transform.position);
float targetAngle = Vector3.Angle(transform.position, hc.transform.position);
var direction = hc.transform.position - transform.position;
if (targetDistance <= maxDistance && targetAngle <= 90 && targetDistance < threatDistance)
{
Ray ray = new Ray(transform.position, direction);
RaycastHit hit;
if (Physics.Raycast(ray, out hit))
{
if (hit.collider.CompareTag("Hovercraft"))
{
threatDistance = targetDistance;
target = hc;
state = State.CHASE;
return;
}
}
}
}
nearestDistance = nearestStaticDistance;
if (target == null)
{
pWIndex = 0;
foreach (Transform point in allWaypoints[0])
{
float targetDistance = Vector3.Distance(point.transform.position, transform.position);
float targetAngle = Vector3.Angle(transform.position, point.transform.position);
var direction = point.transform.position - transform.position;
if (targetDistance <= maxDistance && targetAngle <= 90 && targetDistance < nearestDistance)
{
nearestDistance = targetDistance;
target = point.gameObject;
}
}
drawnPath.Add(target.transform);
isMarked = false;
DrawPath();
foreach (Transform waypoint in drawnPath)
{
Debug.Log(waypoint);
}
}
}
private void DrawPath()
{
for (int i = 0; i < 4; i++)
{
Vector3 originPosition = drawnPath[i].position;
RaycastHit hit;
while (!isMarked)
{
eModifier = UnityEngine.Random.Range(-1, 2);
if (eModifier == -1)
{
Physics.Raycast(originPosition, -transform.right, out hit);
if (hit.collider.gameObject.layer == tier + 7)
{
target = hit.collider.gameObject;
}
}
else if (eModifier == 0)
{
Physics.Raycast(originPosition, transform.forward, out hit);
if (hit.collider.gameObject.layer == tier + 7)
{
target = hit.collider.gameObject;
}
}
else if (eModifier == -1)
{
Physics.Raycast(originPosition, transform.right, out hit);
if (hit.collider.gameObject.layer == tier + 7)
{
target = hit.collider.gameObject;
}
}
else if (eModifier == 2)
{
Physics.Raycast(originPosition, transform.forward, out hit);
if (hit.collider.gameObject.layer == tier + 7)
{
target = hit.collider.gameObject;
}
}
if (target != null)
{
isMarked = true;
}
}
drawnPath.Add(target.transform);
isMarked = false;
}
}
void Chase()
{
Debug.Log("Chasing " + target.name);
}
void Evade()
{
}
public void AccountWaypoints(Transform[] waypoints)
{
foreach (Transform waypoint in waypoints)
{
allWaypoints[waypoint.gameObject.layer - 8].Add(waypoint);
}
}
private void FixedUpdate()
{
Hover();
}
private void Hover()
{
RaycastHit hit;
Ray ray = new Ray(transform.position, -transform.up);
if (Physics.Raycast(ray, out hit, hoverHeight))
{
float proportionalHeight = (hoverHeight - hit.distance) / hoverHeight;
Vector3 appliedHoverForce = transform.up * proportionalHeight * hoverForce;
//ForceMode.Acceleration helps smooth out the hovering.
rb.AddForce(appliedHoverForce, ForceMode.Acceleration);
onGround = true;
falling = false;
}
else if (!Physics.Raycast(ray, out hit, hoverHeight + 1f))
{
onGround = false;
falling = true;
}
}
}
drawnPath.Add(target.transform)
You are adding the target.transform but you aren't checking it is still null.
You have a loop above this line that appears to assign target, but this is conditional. If the condition is not met, then target is STILL null and you are attempting to read it's transform.
Simply add:
if (target !=null) drawnPath.Add(target.transform);
Or ensure that target is always assigned within your foreach loop.
You are actually ONLY executing it if target is null, then trying to work on something to create target, but you don't check further if it's still null. In other words:
target == null, so run this if-statement. Then try to assign target if this other statement is also true. But regardless of the former, add it to drawnPath. That's not sound at all.
