How to make spawn canvas with render camera? - unity3d

Question

UNITY 2D C#
I have a Canvas object.
My Canvas is image (ARROW) that indicates target (STAR).
When a STAR hit the PLAYER,it is destroyed.
Unfortunately, I can not turn off the ARROW and (when STAR respawn) turn on it again, because after appearing ARROW indicates the previous target.
That's why I must to destroy the canvas.
I added a script to the STAR :
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class DestroyTest : MonoBehaviour {
public SpawnStar other;
public GameObject Spawner;
public GameObject ToDestroy;
void Awake (){
GameObject Spawner = GameObject.Find ("Spawner");
other = Spawner.GetComponent<SpawnStar>();
}
void OnCollisionEnter2D (Collision2D coll){
if (coll.gameObject.tag == "Player") {
Destroy (gameObject);
Debug.Log("DestroyedStar");
GameObject ToDestroy = GameObject.Find ("Window_QuestPointer");
Destroy (ToDestroy);
Debug.Log("DestroyedOptionOne");
other.Start ();
}
}
}
I added a script to the CANVAS:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using CodeMonkey.Utils;
public class Window_QuestPointer : MonoBehaviour {
[SerializeField] private Camera uiCamera;
public SpawnStar other;
public GameObject Spawner;
private Vector3 targetPosition;
private RectTransform pointerRectTransform;
void Awake (){
GameObject Spawner = GameObject.Find ("Spawner");
other = Spawner.GetComponent<SpawnStar>();
other.Start ();
}
private void Start ()
{
targetPosition = GameObject.FindWithTag("Star").transform.position;
pointerRectTransform = transform.Find ("Pointer").GetComponent<RectTransform> ();
}
private void Update (){
Vector3 toPosition = targetPosition;
Vector3 fromPosition = Camera.main.transform.position;
fromPosition.z = 0f;
Vector3 dir = (toPosition - fromPosition).normalized;
float angle = UtilsClass.GetAngleFromVectorFloat(dir);
pointerRectTransform.localEulerAngles = new Vector3 (0, 0, angle);
float borderSize = 40f;
Vector3 targetPositionScreenPoint = Camera.main.WorldToScreenPoint (targetPosition);
bool isOffscreen = targetPositionScreenPoint.x <= borderSize || targetPositionScreenPoint.x >= Screen.width - borderSize || targetPositionScreenPoint.y <= borderSize || targetPositionScreenPoint.y >= Screen.height - borderSize;
Debug.Log (isOffscreen + " " + targetPositionScreenPoint);
if(isOffscreen){
Vector3 cappedTargetScreenPosition = targetPositionScreenPoint;
cappedTargetScreenPosition.x = Mathf.Clamp (cappedTargetScreenPosition.x, borderSize, Screen.width - borderSize);
cappedTargetScreenPosition.y = Mathf.Clamp (cappedTargetScreenPosition.y, borderSize, Screen.height - borderSize);
Vector3 pointerWorldPosition = uiCamera.ScreenToWorldPoint (cappedTargetScreenPosition);
pointerRectTransform.position = pointerWorldPosition;
pointerRectTransform.localPosition = new Vector3 (pointerRectTransform.localPosition.x, pointerRectTransform.localPosition.y, 0f);
}
else{
Vector3 pointerWorldPosition = uiCamera.ScreenToWorldPoint (targetPositionScreenPoint);
pointerRectTransform.position = pointerWorldPosition;
pointerRectTransform.localPosition = new Vector3 (pointerRectTransform.localPosition.x, pointerRectTransform.localPosition.y, 0f);
}
}
}
I added a script to the SPAWNER object:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class SpawnStar : MonoBehaviour {
private int waveNumber = 0;
public int enemiesAmount = 0;
public GameObject star;
public GameObject option;
public Camera cam;
public GameObject objectToEnable;
// Use this for initialization
public void Start () {
StartCoroutine (StarEnable());
cam = Camera.main;
enemiesAmount = 0;
objectToEnable.SetActive (false);
}
// Update is called once per frame
public IEnumerator StarEnable () {
yield return new WaitForSeconds (10f);
float height = cam.orthographicSize + 1; // now they spawn just outside
float width = cam.orthographicSize * cam.aspect + 1;
if (enemiesAmount==0) {
Instantiate(star, new Vector3(cam.transform.position.x + Random.Range(-width, width),3,cam.transform.position.z+height+Random.Range(10,30)),Quaternion.identity);
enemiesAmount++;
Instantiate (option, transform.position, transform.rotation);
objectToEnable.SetActive (true);
}
}
}
In addition, the ARROW must respawn in the screen and the STAR off the screen.

Answer 1

you shouldn't destroy a canvas or any GameObject during runtime, answering your question, when you Instantiate the canvas prefab, set the renderer camera with
canvas.worldCamera, but you can, instead of destroying your canvas, create a container inside of it put all the GameObjects inside of this GameObject container, and activate and deactivate it when needed.

Answer 2

If you have one camera U can attach simple script which finds Canvas commonent and attach camera to it in Start() for example:
public class AttachCamera: MonoBehavour
{
private void Start()
{
gameObject.GetComponent<Canvas>().worldCamera = Camera.main;
}
}
If there are more than one camera U have to remember attached camera and set it mannualy after Canvas was spawned.

Answer 3

Can you please show your code that is responsible for destroying the Canvas?
I would use another GameObject that handles this gameplay logic.
First, I would use cameraObj.SetActive(false); to disable the camera, and not destroy it. Destroying and Creating objects can cause memory issues sometimes, and it's just not good practice unless absolutely necessary.
Then, use a Coroutine and WaitForSeconds() or something to that effect to wait, and then call cameraObj.SetActive(true) to re-enable your Camera's main GameObject.