Unity camera script.

using UnityEngine;
using System.Collections;

public class CameraController : MonoBehaviour
{
    public Transform lookAt;
    public Transform lookAtDead;

    public Transform camTransform;

    private Camera cam;

    public float distance = 10.0f;
    public float currentX = 0.0f;
    public float currentY = 0.0f;
    public float maxDistance;
    public float minDistance;
    public float maxY;
    public float minY;

    //private float sensivityX = 4.0f;
    //private float sensivityY = 1.0f;

    private void Start()
    {
        camTransform = transform;
        cam = Camera.main;
    }

    private void Update()
    {
        if (lookAt != null)
        {
            currentX += Input.GetAxis("Mouse X");
            currentY -= Input.GetAxis("Mouse Y");
            distance += Input.GetAxis("Mouse ScrollWheel");

            if (currentY < minY)
            {
                currentY = minY;
            }

            if (currentY > maxY)
            {
                currentY = maxY;
            }

            if (distance < 2)
            {
                distance = 2;
            }

            if (distance > 12)
            {
                distance = 12;
            }

        }

    }

    private void LateUpdate()
    {
        if ( lookAt != null )
        {
            Vector3 dir = new Vector3(0, 0, -distance);
            Quaternion rotation = Quaternion.Euler(currentY, currentX, 0);
            camTransform.position = lookAt.position + rotation * dir;
            camTransform.LookAt(lookAt.position);

        }


    }
}