#10 Make an Air Hockey Game in Unity – INTERFACES & CLEANUP (Code)

How can we group different classes (scripts) together based on their common functionality? Well, we can utilize interfaces. This will allow us to nicely reset the position of any game object!

This post contains all the code that’s been written in this YouTube video.

MenuManager.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class MenuManager : MonoBehaviour {

    public Toggle MultiplayerToggle;

    private void Start()
    {
        MultiplayerToggle.isOn = GameValues.IsMultiplayer;
    }

    public void PlayGame()
    {
        SceneManager.LoadScene("main");
    }

    public void SetMultiplayer(bool isOn)
    {
        GameValues.IsMultiplayer = isOn;
    }
}

IResetable.cs

public interface IResetable
{
    void ResetPosition();
}

PuckScript.cs

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

public class PuckScript : MonoBehaviour, IResetable {

    public ScoreScript ScoreScriptInstance;
    public static bool WasGoal { get; private set; }
    public float MaxSpeed;

    public AudioManager audioManager;

    private Rigidbody2D rb;

	// Use this for initialization
	void Start () {
        rb = GetComponent<Rigidbody2D>();
        WasGoal = false;
        UiManager.Instance.ResetableGameObjects.Add(this);
	}

    private void OnTriggerEnter2D(Collider2D other)
    {
        if (!WasGoal)
        {
            if (other.tag == "AiGoal")
            {
                ScoreScriptInstance.Increment(ScoreScript.Score.PlayerScore);
                WasGoal = true;
                audioManager.PlayGoal();
                StartCoroutine(ResetPuck(false));
            }
            else if (other.tag == "PlayerGoal")
            {
                ScoreScriptInstance.Increment(ScoreScript.Score.AiScore);
                WasGoal = true;
                audioManager.PlayGoal();
                StartCoroutine(ResetPuck(true));
            }
        }
    }

    private void OnCollisionEnter2D(Collision2D collision)
    {
        audioManager.PlayPuckCollision();
    }

    private IEnumerator ResetPuck(bool didAiScore)
    {
        yield return new WaitForSecondsRealtime(1);
        WasGoal = false;
        rb.velocity = rb.position = new Vector2(0, 0);

        if (didAiScore)
            rb.position = new Vector2(0, -1);
        else
            rb.position = new Vector2(0, 1);
    }

    public void ResetPosition()
    {
        rb.position = new Vector2(0, 0);
    }

    private void FixedUpdate()
    {
        rb.velocity = Vector2.ClampMagnitude(rb.velocity, MaxSpeed);
    }
}

AiScript.cs

using UnityEngine;

public class AiScript : MonoBehaviour, IResetable {

    public float MaxMovementSpeed;
    private Rigidbody2D rb;
    private Vector2 startingPosition;

    public Rigidbody2D Puck;

    public Transform PlayerBoundaryHolder;
    private Boundary playerBoundary;

    public Transform PuckBoundaryHolder;
    private Boundary puckBoundary;

    private Vector2 targetPosition;

    private bool isFirstTimeInOpponentsHalf = true;
    private float offsetXFromTarget;

    private void Start()
    {
        rb = GetComponent<Rigidbody2D>();
        startingPosition = rb.position;

        playerBoundary = new Boundary(PlayerBoundaryHolder.GetChild(0).position.y,
                              PlayerBoundaryHolder.GetChild(1).position.y,
                              PlayerBoundaryHolder.GetChild(2).position.x,
                              PlayerBoundaryHolder.GetChild(3).position.x);

        puckBoundary = new Boundary(PuckBoundaryHolder.GetChild(0).position.y,
                              PuckBoundaryHolder.GetChild(1).position.y,
                              PuckBoundaryHolder.GetChild(2).position.x,
                              PuckBoundaryHolder.GetChild(3).position.x);

        UiManager.Instance.ResetableGameObjects.Add(this);
    }

    private void FixedUpdate()
    {
        if (!PuckScript.WasGoal)
        {
            float movementSpeed;

            if (Puck.position.y < puckBoundary.Down)
            {
                if (isFirstTimeInOpponentsHalf)
                {
                    isFirstTimeInOpponentsHalf = false;
                    offsetXFromTarget = Random.Range(-1f, 1f);
                }

                movementSpeed = MaxMovementSpeed * Random.Range(0.1f, 0.3f);
                targetPosition = new Vector2(Mathf.Clamp(Puck.position.x + offsetXFromTarget, playerBoundary.Left,
                                                        playerBoundary.Right),
                                            startingPosition.y);
            }
            else
            {
                isFirstTimeInOpponentsHalf = true;

                movementSpeed = Random.Range(MaxMovementSpeed * 0.4f, MaxMovementSpeed);
                targetPosition = new Vector2(Mathf.Clamp(Puck.position.x, playerBoundary.Left,
                                            playerBoundary.Right),
                                            Mathf.Clamp(Puck.position.y, playerBoundary.Down,
                                            playerBoundary.Up));
            }

            rb.MovePosition(Vector2.MoveTowards(rb.position, targetPosition,
                    movementSpeed * Time.fixedDeltaTime));
        }
    }

    public void ResetPosition()
    {
        rb.position = startingPosition;
    }
}

PlayerMovement.cs

using UnityEngine;

public class PlayerMovement : MonoBehaviour, IResetable {

    Rigidbody2D rb;
    Vector2 startingPosition;

    public Transform BoundaryHolder;

    Boundary playerBoundary;

    public Collider2D PlayerCollider { get; private set; }

    public PlayerController Controller;

    public int? LockedFingerID { get; set; }

	// Use this for initialization
	void Start () {
        rb = GetComponent<Rigidbody2D>();
        startingPosition = rb.position;
        PlayerCollider = GetComponent<Collider2D>();

        playerBoundary = new Boundary(BoundaryHolder.GetChild(0).position.y,
                                      BoundaryHolder.GetChild(1).position.y,
                                      BoundaryHolder.GetChild(2).position.x,
                                      BoundaryHolder.GetChild(3).position.x);

    }

    private void OnEnable()
    {
        Controller.Players.Add(this);
        UiManager.Instance.ResetableGameObjects.Add(this);
    }
    private void OnDisable()
    {
        Controller.Players.Remove(this);
        UiManager.Instance.ResetableGameObjects.Remove(this);
    }

    public void MoveToPosition(Vector2 position)
    {
        Vector2 clampedMousePos = new Vector2(Mathf.Clamp(position.x, playerBoundary.Left,
                                                  playerBoundary.Right),
                                      Mathf.Clamp(position.y, playerBoundary.Down,
                                                  playerBoundary.Up));
        rb.MovePosition(clampedMousePos);
    }

    public void ResetPosition()
    {
        rb.position = startingPosition;
    }
}

UiManager.cs

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

public class UiManager : MonoBehaviour {

    #region Singleton
    public static UiManager Instance { get; private set; }
    private void Awake()
    {
        Instance = this;
    }
    #endregion

    [Header("Canvas")]
    public GameObject CanvasGame;
    public GameObject CanvasRestart;

    [Header("CanvasRestart")]
    public GameObject WinTxt;
    public GameObject LooseTxt;

    [Header("Other")]
    public AudioManager audioManager;

    public ScoreScript scoreScript;

    public List<IResetable> ResetableGameObjects = new List<IResetable>();

    public void ShowRestartCanvas(bool didAiWin)
    {
        Time.timeScale = 0;

        CanvasGame.SetActive(false);
        CanvasRestart.SetActive(true);

        if (didAiWin)
        {
            audioManager.PlayLostGame();
            WinTxt.SetActive(false);
            LooseTxt.SetActive(true);
        }
        else
        {
            audioManager.PlayWonGame();
            WinTxt.SetActive(true);
            LooseTxt.SetActive(false);
        }
    }

    public void RestartGame()
    {
        Time.timeScale = 1;

        CanvasGame.SetActive(true);
        CanvasRestart.SetActive(false);

        scoreScript.ResetScores();

        foreach (var obj in ResetableGameObjects)
            obj.ResetPosition();
    }

    public void ShowMenu()
    {
        Time.timeScale = 1;
        SceneManager.LoadScene("menu");
    }
}