BoundingBox.cs

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

[RequireComponent(typeof(LineRenderer))]
public class BoundingBox : MonoBehaviour {

    public float size = 10.0f;

    private LineRenderer lineRenderer; 

    // Use this for initialization
    void Awake () {
        lineRenderer = GetComponent<LineRenderer>();

        // use cube
        Vector3[] corners = { 
            new Vector3(0.5f,0.5f,0.5f), 
            new Vector3(0.5f,-0.5f,0.5f), 
            new Vector3(-0.5f,-0.5f,0.5f), 
            new Vector3(-0.5f,0.5f,0.5f), 
            new Vector3(0.5f,0.5f,0.5f),    // end of top face
            new Vector3(0.5f,0.5f,-0.5f),   // down to bottom face
            new Vector3(0.5f,-0.5f,-0.5f), 
            new Vector3(-0.5f,-0.5f,-0.5f), 
            new Vector3(-0.5f,0.5f,-0.5f), 
            new Vector3(0.5f,0.5f,-0.5f),   // end of bottom face
            new Vector3(0.5f,-0.5f,-0.5f),  // over to next corner
            new Vector3(0.5f,-0.5f,0.5f),   // up 
            new Vector3(-0.5f,-0.5f,0.5f),  // over
            new Vector3(-0.5f,-0.5f,-0.5f),  // down
            new Vector3(-0.5f,0.5f,-0.5f),  // over
            new Vector3(-0.5f,0.5f,0.5f),   // up

        };
        lineRenderer.positionCount = corners.Length;

        for (int i=0; i < corners.Length; i++) {
            corners[i] *= size;
        }
        lineRenderer.SetPositions(corners);

    }
    

}