(Solved)Count AR Point Cloud number (AR Foundation 3.0.1)

(edited)
Problem Solved!
just properly assign ARSessionOrigin and it works



Hi all.
I have been trying to count the number of all ar point cloud collected in the AR session

I've tried the following code. But arPointCloud keeps throwing error message: Object reference not set to an instance of an object

I would be so happy if anyone can help me.

Thanks!

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.UI;
5. using UnityEngine.XR.ARFoundation;
6.  
7.  
8. public class PointNumberCount : MonoBehaviour
9. {
10.     ARSessionOrigin arSessionOrigin;
11.     ARPointCloud arPointCloud;
12.  
13.     int totalNumber;
14.     List<Vector3> featurePoints = new List<Vector3>();
15.  
16.     void Start()
17.     {
18.    
19.         arSessionOrigin = GetComponent<ARSessionOrigin>();
20.    
21.         arPointCloud = arSessionOrigin.trackablesParent.GetComponentInChildren<ARPointCloud>();
22.     }
23.     void Update()
24.     {
25.    
26.             arPointCloud = arSessionOrigin.trackablesParent.GetComponentInChildren<ARPointCloud>();
27.             featurePoints = new List<Vector3>(arPointCloud.positions);
28.             totalNumber = featurePoints.Count;
29.  
30.     }
31. }
32. }