3DTD/Assets/Scripts/Camera/HideWall.cs

using System.Collections.Generic;
using UnityEngine;

public class HideWall : MonoBehaviour
{

    [SerializeField] private GameObject target;
    [SerializeField] private GameObject origin;
    public GameObject prevObject;

    public Material defaultMaterial; // Material when not hitting "Wall"
    public Material hitMaterial; // Material when hitting "Wall"

    public float sphereRadius;
    float maxSphereRayDistance;
    public Vector3 maxSphereRayDistanceOffset;

    private List<GameObject> prevHitObjects = new List<GameObject>();

    private void Start()
    {
        maxSphereRayDistance = Vector3.Distance(origin.transform.position, target.transform.position) - (sphereRadius * 2 + 1);
    }

    void Update()
    {
        Vector3 direction = ((target.transform.position + maxSphereRayDistanceOffset) - origin.transform.position).normalized;
        RaycastHit[] hits = Physics.SphereCastAll(origin.transform.position, sphereRadius, direction, maxSphereRayDistance);

        List<GameObject> hitObjectsThisFrame = new List<GameObject>();

        // Change material of currently hit objects
        for (int i = 0; i < hits.Length; i++)
        {
            if (hits[i].collider.CompareTag("Wall"))
            {
                var hitGameObject = hits[i].collider.gameObject;
                hitObjectsThisFrame.Add(hitGameObject);

                // Change material only if this object wasn't hit last frame
                if (!prevHitObjects.Contains(hitGameObject))
                {
                    Renderer renderer = hits[i].collider.GetComponent<Renderer>();
                    if (renderer != null)
                    {
                        renderer.material = hitMaterial;
                    }
                }
            }
        }

        // Restore the material of objects that are not hit this frame but were hit in the previous frame
        for (int i = 0; i < prevHitObjects.Count; i++)
        {
            if (!hitObjectsThisFrame.Contains(prevHitObjects[i]))
            {
                Renderer renderer = prevHitObjects[i].GetComponent<Renderer>();
                if (renderer != null)
                {
                    renderer.material = defaultMaterial;
                }
            }
        }

        // Update the list of previously hit objects
        prevHitObjects = hitObjectsThisFrame;
    }


    private void OnDrawGizmos()
    {
        Gizmos.color = Color.red;
        Gizmos.DrawWireSphere(origin.transform.position, sphereRadius);
    }
}