simple lines

Lines.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Lines : MonoBehaviour
{

    [SerializeField] private MeshFilter _meshFilter;
    private Vector3[] _positions;
    private Mesh _mesh;

    // Start is called before the first frame update
    void Start()
    {
        _mesh = new Mesh();

        _positions = new Vector3[100];
        int[] indices = new int[100];
        for(int i=0;i<100;i++){
            _positions[i] = new Vector3(
                10f * (Random.value-0.5f),
                10f * (Random.value-0.5f),
                10f * (Random.value-0.5f)
            );
            indices[i] = i;
        }

        _mesh.vertices = _positions;
        _meshFilter.mesh = _mesh;       
         
        _mesh.SetIndices(indices, MeshTopology.Lines, 0);
        
    }

    // Update is called once per frame
    void Update()
    {

        for(int i=0;i<_positions.Length;i++){

            if(i%2==0){
                _positions[i]=Vector3.zero;

            }else{
                _positions[i] = new Vector3(
                    10f * (Random.value-0.5f),
                    10f * (Random.value-0.5f),
                    10f * (Random.value-0.5f)
                );
            }

        }
        _mesh.vertices = _positions;

    }
}