PortalCamera

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

public class PortalCamera : MonoBehaviour
{
    public Transform playerCamera;
    public Transform portal;
    public Transform otherPortal;

    private float myAngle;

    private void Update()
    {
        PortalCameraController();
    }

    private void PortalCameraController()
    {
        Vector3 playerOffsetFromPortal = playerCamera.position - otherPortal.position;

        float angularDiff = Quaternion.Angle(portal.rotation, otherPortal.rotation);

        if (myAngle == 90 || myAngle == 270)
        {
            angularDiff -= 90;
        }

        Quaternion portalRotationDiff = Quaternion.AngleAxis(angularDiff, Vector3.up);
        Vector3 newCameraDirection = portalRotationDiff * playerCamera.forward;

        if (myAngle == 90 || myAngle == 270)
        {
            newCameraDirection = new Vector3(newCameraDirection.z * -1, newCameraDirection.y,
                newCameraDirection.x);
        }
        else
        {
            newCameraDirection = new Vector3(newCameraDirection.x * -1, newCameraDirection.y,
                newCameraDirection.z * -1);
        }

        transform.rotation = Quaternion.LookRotation(newCameraDirection, Vector3.up);
    }

    public void SetMyAngle(float angle)
    {
        myAngle = angle;
    }
}