Line of Sight in Unity

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

//MADE BY LSTHIMO
public class PlayerAI : Player {
    //Line of sight
    [Header ("Line of sight")]
    public Transform viewport;
    [Space (5)]

    public float viewAngle = 110;
    public float viewRadius = 10;
    public LayerMask detectable;
    public int detectableLayerIndex;
    Collider playerCollider;

    void Start () {
        playerCollider = GetComponent<Collider> ();
    }

    void Update () {
        GetObjectsInSight ();
    }

    List<Collider> detectedColliders = new List<Collider> ();

    void GetObjectsInSight () {

        //Check if there is a detectable object in the view radius
        if (Physics.CheckSphere (viewport.position, viewRadius, detectable)) {

            //Get the detectable objects that are in radius
            Collider[] detectableCollidersArray = Physics.OverlapSphere (viewport.position, viewRadius, detectable);

            //Put the detectable objects in a list
            detectedColliders.RemoveRange(0, detectedColliders.Count);

            foreach (Collider c in detectableCollidersArray) {
                if (c != playerCollider) {
                    detectedColliders.Add (c);
                }
            }


            //Check if objects are detectable
            for (int index = 0; index < detectedColliders.Count; index++) {

                //Get collider
                Collider collider = detectedColliders[index];

                //Get angle
                Vector3 selfPosV3 = viewport.position + viewport.forward * viewRadius;

                Vector2 selfPos = new Vector2 (selfPosV3.x, selfPosV3.z);
                Vector2 detectablePos = new Vector2 (collider.transform.position.x, collider.transform.position.z);

                float angle = Vector2.Angle (selfPos, detectablePos);

                //Check if angle is in LOS
                if (angle >= -viewAngle / 2 && angle <= viewAngle / 2) {

                    //Set layer to ignore
                    int detectableValue = detectable.value;
                    detectableValue = ~detectableValue;

                    //Check if an object is obstructing the view
                    if (Physics.Linecast (viewport.position, collider.bounds.center, detectableValue)) {
                        detectedColliders.RemoveAt (index);
                        index -= 1;
                    }
                } else {
                    detectedColliders.RemoveAt (index);
                    index -= 1;
                }
            }

            //Sort colliders by distance to viewpoint
            detectedColliders = detectedColliders.OrderBy (point => Vector3.Distance (viewport.transform.position, point.transform.position)).ToList ();

            print ("There are " + detectedColliders.Count + " objects in my LOS");
        }
    }

    float Positive (float input) {
        if (input < 0) {
            return input * -1;
        } else {
            return input;
        }
    }

}