Collision and rebound of objects in unity (learning)

unity Object collision rebound related code ：

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

public class BallControl : MonoBehaviour
{
    
    // Ignore the first collision between the ball and the player 
    private bool isStart; 
    // Rigid body components 
    private Rigidbody2D rbody;
    // The location of the last collision 
    private Vector3 point;
    void Start()
    {
    
        rbody = GetComponent<Rigidbody2D>();
    }
    // Start moving 
    public void StartMove()
    {
    
        // Give the ball a speed   Direction  *  Speed  new Vector2(1,1).normalized（ Unit vector ）
        rbody.velocity = new Vector2(1,1).normalized * 1;
        isStart = true;
        // At the beginning 
        point = transform.position;
    }

    // When colliding with walls and players 
    private void OnCollisionEnter2D(Collision2D collision)
    {
    
        if (isStart == false)
        {
    
            return;
        }

        if (transform.position == point)
        {
    
            return;
        }
        // Destroy bricks 
        if (collision.collider.tag == "brick")
        {
    
            Destroy(collision.collider.gameObject);
        }
        
        // Reflection 
        Vector2 inVec = transform.position - point;
        point = transform.position;
        Vector2 outVec = Vector2.Reflect(inVec,collision.contacts[0].normal);
        rbody.velocity = outVec.normalized * 1;

    }

notes 1：

collision.contacts[0]:
public ContactPoint[] contacts
Physical engine generated touchpoints . Touchpoints are stored in Collision In structure , Each contact contains a contact point 、 Normal and collision of two collision bodies

to update ： It should be avoided , Because it will generate memory garbage . change to the use of sth. GetContact or GetContacts.

Variable	effect
normal	Normal of contact point .
otherCollider	Other colliding bodies in contact at this point
point	contact point
separation	The distance between the collision bodies at this contact point
thisCollider	The first collision body contacted at this point .

notes 2：

public static Vector2 Reflect (Vector2 inDirection, Vector2 inNormal);
effect ： Reflect a vector from the vector defined by the normal .