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

using UnityEngine;

public class HideWall : MonoBehaviour
{
    public float maxRayDistance;

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

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

    public GameObject prevObject;

    void Update()
    {
        Vector3 direction = (target.transform.position - origin.transform.position).normalized;

        RaycastHit hit;

        if (Physics.Raycast(origin.transform.position, direction, out hit, maxRayDistance))
        {
            if (hit.collider.CompareTag("Wall"))
            {
                if (prevObject != null)
                    if (prevObject == hit.collider.gameObject)
                    {
                        var renderer = hit.collider.GetComponent<Renderer>();
                        var originalMat = renderer.material;
                        var originalColor = originalMat.color;
                        originalMat.color = new Color(originalColor.r, originalColor.g, originalColor.b, originalColor.a *0f);
                        renderer.material = originalMat;
                    }
                    else
                    {
                        var renderer = prevObject.GetComponent<Collider>().GetComponent<Renderer>();
                        var originalMat = renderer.material;
                        var originalColor = originalMat.color;
                        originalMat.color = new Color(originalColor.r, originalColor.g, originalColor.b, originalColor.a + 1f);
                        renderer.material = originalMat;
                    }

                prevObject = hit.collider.gameObject;
            }
        }
    }

    private void OnDrawGizmos()
    {
        Gizmos.color = Color.red;
        Gizmos.DrawRay(origin.transform.position, (target.transform.position - origin.transform.position).normalized * maxRayDistance);
    }
}