CameraScript

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

public class CameraScript : MonoBehaviour
{
	Transform lastWall;


	public float distFromPlayer = 5;
	public float speed = 20;
	public LayerMask wallMask;
	public Transform player;

	void Start ()
	{

	}

	void FixedUpdate ()
	{
		Vector3 targetPos = player.position - player.forward * distFromPlayer;
		targetPos.y = player.position.y + 3;
		transform.position = Vector3.Lerp(transform.position, targetPos, speed * Time.fixedDeltaTime);
		transform.LookAt(player.position);

		RaycastHit hit;
		Physics.Linecast(transform.position, player.position, out hit, wallMask);
		Debug.DrawLine(transform.position, player.position);

		if (lastWall != null && lastWall != hit.transform)
		{
			SetAlphaOnObj(lastWall, 1f);
		}

		if(hit.transform != null)
		{
			SetAlphaOnObj(hit.transform, 0.5f);

			lastWall = hit.transform;
		}
	}

	void SetAlphaOnObj(transform trans, float alpha)
	{
		Material mat = trans.GetComponent<MeshRenderer>().materials[0];
		Color c = mat.color;
		c.a = alpha;
		mat.color = c;
	}
}