UnityCameraZoom.cs

/* Note:
Attach this script to the player or object you want to zoom in on.
You can go into the inspector and change the camera zoom to a different numerical value if you like.
Left click is to zoom in, then left click again to zoom out.
*/
using UnityEngine;

public class UnityCameraZoom : MonoBehaviour {

    // We made a public int that will set the new field of view for the camera.
    public int cameraZoom = 20;
    // We made a public int that is the current field of view for the camera.
    private int cameraNormal = 60;
    // How fast the camera will zoom in and out.
    private float cameraSmooth = 5f;

    // A bool to declare if the camera is zoomed.
    private bool cameraZoomed = false;

    // Declareing the camera
    private Camera playerCamera;

    private void Start() {
        // on start we get the componenet camera.
        playerCamera = GetComponent<Camera>();
    }

    private void Update() {
        // If the player presses left mouse button
        if (Input.GetMouseButtonDown(0))
        {
            // then flip the boolean, so if its true set false, if false then set it to true..
            cameraZoomed = !cameraZoomed;
        }
        // if the camera zoom is set to true
        if (cameraZoomed) {
            // set the players camera field of view equal to:
            // the camera fov value, then get the value of the zoom, and find the difference and change it slowly.
            // The speed at which we change it, is called cameraSmooth.
            // We use Time.DeltaTime so the zoom doesn't happen instantly. If you was to remove it, it would do it in 1 frame.
            // instead of multiple frames which would remove the smooth like feature when zooming in..
            playerCamera.fieldOfView = Mathf.Lerp(playerCamera.fieldOfView, cameraZoom, Time.deltaTime * cameraSmooth);
        } else /*else if its not true*/ {
            // players camera fov is equal to:
            // the current fov of the players camera, then we set it back to noraml which is 60, then change the difference slowly
            // with cameraSmooth again.
            playerCamera.fieldOfView = Mathf.Lerp(playerCamera.fieldOfView, cameraNormal, Time.deltaTime * cameraSmooth);
        }
    }
}