u3d-space-shooter/Assets/Scripts/Player.cs

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

public class Player : MonoBehaviour
{
    [SerializeField]
    private float speed = 1.0f;
    [SerializeField]
    private GameObject laserPrefab;
    [SerializeField]
    private float fireRate = 0.15f;
    private float nextFire = -1f;
    [SerializeField]
    private int lives = 3;

    private SpawnManager spawnManager;

    void Start()
    {
        transform.position = new Vector3(0, 0, 0);
        
        spawnManager = GameObject.Find("SpawnManager").GetComponent<SpawnManager>();
        if(spawnManager == null )
        {
            Debug.LogError("Spawn Manager is null");
        }
    }

    void Update()
    {
        CalculateMovement();
        if (Input.GetButton("Fire1") && Time.time > nextFire)
        {
            ShootLaser();
        }
    }

    private void ShootLaser()
    {
        nextFire = Time.time + fireRate;
        Instantiate(laserPrefab, transform.position + new Vector3(0, 1.05f, 0), Quaternion.identity);        
    }

    private void CalculateMovement()
    {
        float horizontalInput = Input.GetAxis("Horizontal");
        float verticalInput = Input.GetAxis("Vertical");

        transform.Translate(new Vector3(horizontalInput, verticalInput, 0) * speed * Time.deltaTime);

        /* Set boundaries on top and bottom
        if (transform.position.y >= 0)
        {
            transform.position = new Vector3(transform.position.x, 0, 0);
        }
        else if (transform.position.y < -3.8f)
        {
            transform.position = new Vector3(transform.position.x, -3.8f, 0);
        }
        */
        
        // Same as the if statement above but cleaner.
        transform.position = new Vector3(transform.position.x, Mathf.Clamp(transform.position.y, -3.8f, 0), 0);

        // Pass through on the left and right side
        if (transform.position.x >= 11.3f)
        {
            transform.position = new Vector3(-11.3f, transform.position.y, 0);
        }
        else if (transform.position.x < -11.3f)
        {
            transform.position = new Vector3(11.3f, transform.position.y, 0);
        }
    }

    public void Damage()
    {
        lives--;
        if (lives < 1)
        {
            spawnManager.OnPlayerDeath();
            Destroy(this.gameObject);
        }
    }
}