5.1 — The Axe: Item Pickups & Inventory Bools

Compare against your own file rather than copying it. Two differences are worth naming, because neither is a mistake. The shape: this file returns early out of each branch and the walkthrough chains else if — both ask every object exactly one question. The helper: here the swap lives in a method called PickUpAxe(), and the walkthrough writes the same two lines inline, so that "becoming an axe-wielder" has a name you can point at. What is NOT a difference is the gap itself: whichever way you wrote it, the line that changes the player is the assignment to the Animator's controller property, and that name is the one you had to go and read.

// ------------------------------------------------------------------
//  REFERENCE FILE — Assets/Scripts/PlayerController.cs
//  Written to be read, not pasted. Build it with the walkthrough
//  above, one step at a time, then open this and compare.
//  If it is sitting in your project unchanged, that is the thing
//  to go and do now — the walkthrough is still above you.
// ------------------------------------------------------------------
using UnityEngine;

// Your controller at the end of 5.1: movement and health from 2.2, animation
// from 1.6, the coin pickup from 2.1 — and the axe.
public class PlayerController : MonoBehaviour
{
    [SerializeField] private float moveSpeed = 5f;
    [SerializeField] private int health = 3;
    [SerializeField] private int coins;

    // The capability, and the controller that draws it. The starting value is
    // the design: false, until the player earns it.
    [SerializeField] private bool hasAxe = false;
    [SerializeField] private RuntimeAnimatorController axeController;

    private Rigidbody2D body;
    private Animator animator;
    private SpriteRenderer spriteRenderer;

    private float inputX;
    private float inputY;

    void Start()
    {
        // Looked up once, never inside Update() — the rules from 1.6 and 2.2.
        body = GetComponent<Rigidbody2D>();
        animator = GetComponentInChildren<Animator>();
        spriteRenderer = GetComponentInChildren<SpriteRenderer>();
    }

    void Update()
    {
        inputX = Input.GetAxis("Horizontal");
        inputY = Input.GetAxis("Vertical");

        Vector2 direction = new Vector2(inputX, inputY);

        // No Time.deltaTime: velocity is per second, not per frame.
        body.linearVelocity = direction * moveSpeed;

        UpdateAnimation();
        CheckAttack();
    }

    void UpdateAnimation()
    {
        bool isMoving = inputX != 0f || inputY != 0f;
        animator.SetBool("IsWalking", isMoving);

        if (Mathf.Abs(inputX) >= Mathf.Abs(inputY))
        {
            animator.SetInteger("WalkDir", 1);
            spriteRenderer.flipX = inputX < 0f;
        }
        else if (inputY > 0f)
        {
            animator.SetInteger("WalkDir", 0);
        }
        else
        {
            animator.SetInteger("WalkDir", 2);
        }
    }

    void CheckAttack()
    {
        if (Input.GetMouseButtonDown(0))
        {
            animator.SetTrigger("Attack");
        }
    }

    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.gameObject.CompareTag("Spikes"))
        {
            TakeDamage(1);
        }
    }

    // Every pickup in the game arrives here. The axe is one more question.
    // Your potion branch from 2.3 lives in this same callback, under its own
    // tag — it is left out here only because the tag is the one you invented.
    private void OnTriggerEnter2D(Collider2D other)
    {
        if (other.CompareTag("Coin"))
        {
            coins = coins + 1;
            Destroy(other.gameObject);
            return;
        }

        if (other.CompareTag("Axe"))
        {
            PickUpAxe();
            Destroy(other.gameObject);
        }
    }

    // The whole of "becoming an axe-wielder", and the only line in the game
    // that changes what the player IS. Setting a parameter picks a clip inside
    // one controller; this replaces the whole controller — every state, every
    // transition, every clip, in one assignment.
    private void PickUpAxe()
    {
        hasAxe = true;
        animator.runtimeAnimatorController = axeController;
    }

    private void TakeDamage(int amount)
    {
        if (health <= 0)
        {
            return;
        }

        health = health - amount;
        Debug.Log("Health: " + health);

        if (health <= 0)
        {
            Debug.Log("Player died.");
        }
    }
}

// The Inspector half of this lesson is the editor block at the top of the page:
// a trigger collider on Assets/Prefabs/AxeItem, one axe instance standing in the
// Overworld, and the Axe Controller slot on Assets/Prefabs/Player.