Shoot raycast on reflect direction

Question

I'm creating a pool game. And I want to shoot Raycast on the reflect direction so I can draw LineRenderer on it.

Main Cue Ball Script:

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    
    public class DrawCueBallTrajectory : MonoBehaviour
    {
        private RaycastHit hit;
    
        private LineRenderer lineRender;
    
        private float cueBallRadius;
         
        private void Awake()
        {
            lineRender = GetComponent<LineRenderer>();
    
            cueBallRadius = GetComponent<SphereCollider>().radius;
        }
    
        void Update()
        {
            Vector3 reduceTransPos = new Vector3(transform.position.x, transform.position.y - 2f, transform.position.z);
    
            Ray ray = new Ray(transform.position, -transform.forward);
    
            if (Physics.SphereCast(ray, cueBallRadius, out hit))
            {
                if (hit.collider != null)
                {
                    lineRender.enabled = true;
    
                    lineRender.SetPosition(0, transform.position);
                    lineRender.SetPosition(1, -transform.forward + new Vector3(hit.point.x, hit.point.y + 1f, hit.point.z));
    
                    if (hit.collider.gameObject.CompareTag("OtherCueBall"))
                    {
    
                        Vector3 newDirection = Vector3.Reflect(hit.transform.position, hit.normal);
    
                        hit.collider.gameObject.GetComponent<OtherCueBallTrajectory>().DrawPredictionLine(newDirection);
                    }
                }
            }
        }
    
    }

Other Ball Script

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    
    public class OtherCueBallTrajectory : MonoBehaviour
    {
        private RaycastHit hit;
    
        private LineRenderer lineRender;
    
        private float cueBallRadius;
    
        private void Awake()
        {
            lineRender = GetComponent<LineRenderer>();
    
            cueBallRadius = GetComponent<SphereCollider>().radius;
        }
    
        public void DrawPredictionLine(Vector3 targetDestination)
        {
    
        Ray ray = new Ray(transform.position); // what to put here

        }
    }

Answer 1

You must emit another sphere cast along the point of impact. Also adjust the lineRender points count according to the number of fractures. I made these changes to the script main cue ball and do not see the need to refer the second sphere cast to the other ball.

    if (Physics.SphereCast(ray, cueBallRadius, out hit))
    {
        if (hit.collider != null)
        {
            lineRender.enabled = true;
    
            lineRender.positionCount = 2; // here I set lineRender position count

            lineRender.SetPosition(0, transform.position);
            lineRender.SetPosition(1, -transform.forward + new Vector3(hit.point.x, hit.point.y + 1f, hit.point.z));
    
            if (hit.collider.gameObject.CompareTag("OtherCueBall"))
            {
                Vector3 newDirection = Vector3.Reflect(hit.transform.position, hit.normal);
    
                lineRender.positionCount = 3; // we need 1 more break point
                
                // second sphere cast begin from hit.point along reflectDirection
                if (Physics.SphereCast(hit.point, cueBallRadius, newDirection, out var secondHit))
                {
                    lineRender.SetPosition(2, secondHit.point); // stop when hit wall or anything
                }
                else
                {
                    lineRender.SetPosition(2, hit.point + newDirection * 10f); // point along direction for maximum of 10f length for e.g..
                }
            }
        }
    }