Some preliminary explorations of avoiding obstacles and finding paths by rays in unity

I learned the method of ray pathfinding a few days ago , By sending a ray forward , If the normal of the obstacle location point hit by the ray is on the right side of the ray , Turn to the right , If it's on the left , Turn left . As shown in the figure below ：

// The following method is to avoid obstacles by comparing the normals in the ray 
if (Physics.Raycast (transform.position + Vector3.up * 0.5f, transform.forward, out hit, 10f, lmBarrier)) { // Fire a line in front of the character who is half a meter higher 10 Meter ray , If there is an object hitting the obstacle level 
    float rotateDir = Vector3.Dot (transform.right, hit.normal); // Get the point multiplication result of the normal of the right direction of the character and the hit position , It is mainly used to judge the position of obstacles , Is it on the left or right side of the character 
    Debug.DrawRay (transform.position + Vector3.up * 0.5f, transform.forward * 7, Color.red); 
    Debug.DrawRay (hit.point, hit.normal, Color.blue);
    if (rotateDir >= 0) {  // If greater than or equal to 0
        transform.Rotate (transform.up * 90 * Time.deltaTime);  // In clockwise direction 90 Degrees per second 
        lookReTime = 0; // Avoid avoiding obstacles , It also faces the player , Prone to reverse steering 
    } else {
        transform.Rotate (transform.up * -90 * Time.deltaTime);  // Then turn counterclockwise to 90 Degrees per second 
	    lookReTime = 0; 
	}

It really can avoid some simple obstacles , But we will soon find out , There will be some problems ： When two obstacles form an included angle , It is likely to cause you to turn back and forth in this corner , I can't get out of this corner anymore

So I think of some ways to solve this problem , Added a judge whether to enter the dead end mode ：

1、 A preliminary and simple determination , When you encounter the obstacles you encountered before （ It doesn't include the one just met ）, Enter dead end mode ;

2、 After entering the dead end mode , Monsters have only one behavior , Is to try to follow the wall in one direction to escape the dead end ;

3、 It is necessary to confirm whether to leave the dead end , Restore the normal behavior of the monster after leaving the dead end

How to judge whether the monster has left the dead end , I use two conditions here , One is that there must be no more obstacles between the monster and the target , The angle between the monster's forward direction and the target direction must be less than 90 degree .

        RaycastHit hit;  // It is used to detect whether there are obstacles ahead 

        if (!Physics.Raycast(transform.position + Vector3.up * 0.5f, player.position - transform.position, out hit, Vector3.Distance(player.position, transform.position), lmBarrier))
        {// If the radiation from the target doesn't touch the obstacle 
            transform.LookAt(player);
            isDilemma = false;  // Dead end mode is off 
            lookReTime = 0;
            Debug.Log("haha, Look where you're going ");
        }
        else
        {
            if (!isDilemma)  // If you are not in dead end mode , entering 
            {
                if (Physics.Raycast(transform.position + Vector3.up * 0.5f, transform.forward, out hit, rayDis, lmBarrier))
                { // Fire a line in front of the character who is half a meter higher 10 Meter ray , If there is an object hitting the obstacle level 
                    barrier03 = barrier02;  //barrier01-03 These are all stated GameObject type 
                    barrier02 = barrier01;
                    barrier01 = hit.transform.gameObject;
                    
                    if (barrier01 == barrier02)
                    { // If the next one is the same 
                        rotateDir = Vector3.Dot(transform.right, hit.transform.position - transform.position);
                        
                        if (rotateDir >= 0)
                        {
                            transform.Rotate(transform.up * -180 * Time.deltaTime);
                            lookReTime = 0; // Avoid avoiding obstacles , It also faces the player , Prone to reverse steering 
                        }
                        else
                        {
                            transform.Rotate(transform.up * 180 * Time.deltaTime);
                            lookReTime = 0; // Avoid avoiding obstacles , It also faces the player , Prone to reverse steering 
                        }
                        Debug.Log(" I'll find you soon ");
                    }else if (barrier03 == barrier01)  // If the one you just met is the same as the one you met before , The dead end mode is triggered 
                    { // Enter dead end mode 
                        barrier04 = barrier01.transform;
                        rotateDir = Vector3.Dot(transform.right, barrier04.position - transform.position);
                        if (rotateDir >= 0)
                        {  // If the obstacle is on the right side of the forward direction 
                            for (int i = 0; i < 72; i++) // Quickly find the edge of the obstacle , Walk to its edge 
                            {
                                transform.Rotate(transform.up * 5);
                                if (!Physics.Raycast(transform.position + Vector3.up * 0.5f, transform.forward, out hit, rayDis, lmBarrier))
                                {
                                    break;
                                }
                            }
                        }
                        else
                        {
                            for (int i = 0; i < 72; i++)
                            {
                                transform.Rotate(transform.up * -5);
                                if (!Physics.Raycast(transform.position + Vector3.up * 0.5f, transform.forward, out hit, rayDis, lmBarrier))
                                {
                                    break;
                                }
                            }
                        }
                        isDilemma = true;  // Turn on dead end mode 
                        Debug.Log (" Enter the dead end mode ");
                    }
                }
            }
            else
            {
                rotateDir = Vector3.Dot(transform.forward, player.position - transform.position);
                if (Physics.Raycast(transform.position + Vector3.up * 0.5f, player.position - transform.position, out hit, rayDis, lmBarrier))
                {
                    //Debug.DrawRay(transform.position + Vector3.up * 0.5f, player.position - transform.position, Color.red);
                    if (hit.transform.gameObject != barrier04.transform.gameObject && rotateDir > 0)
                    {
                        isDilemma = false;
                        // Debug.Log(" The dead end mode is disabled ");
                        transform.LookAt(player);
                        lookReTime = 0;
                    }
                    if (Physics.Raycast(transform.position + Vector3.up * 0.5f, transform.forward, out hit, rayDis, lmBarrier))
                    {
                        if (hit.transform.gameObject != barrier01 && hit.transform.gameObject != barrier02)
                        {
                            isDilemma = false;
                            //Debug.Log(" Temporarily remove the dead end mode ");
                        }
                    }

                }
                else if (rotateDir > 0)
                {
                    isDilemma = false;
                    //Debug.Log(" The dead end mode is disabled ");
                    transform.LookAt(player);
                    lookReTime = 0;
                }
                else
                {
                    rotateDir = Vector3.Dot(transform.right, barrier04.position - transform.position);
                    if (rotateDir >= 0)
                    {
                        for (int i = 0; i < 72; i++)
                        {
                            transform.Rotate(transform.up * 5f);
                            if (Physics.Raycast(transform.position + Vector3.up * 0.5f, transform.forward, out hit, rayDis, lmBarrier))
                            {
                                transform.Rotate(transform.up * -5f);
                                break;
                            }
                        }
                    }
                    else
                    {
                        for (int i = 0; i < 72; i++)
                        {
                            transform.Rotate(transform.up * -5f);
                            if (Physics.Raycast(transform.position + Vector3.up * 0.5f, transform.forward, out hit, rayDis, lmBarrier))
                            {
                                transform.Rotate(transform.up * 5f);
                                break;
                            }
                        }
                    }
                    //Debug.Log(" When will there be a dead end ");
                }


            }		
        }

Although the problem of included angle is solved , But when faced with more complicated situations , Still very clumsy , So I'm going to learn something later AI Algorithm , Better to solve these problems . And the code is written in a mess , I have to work harder in the future .