Flappy Bird Clone

Programming languages / engine used

• C#
• Unity

Background Move

I got two same background components, and they move right to left. When the backgrounds pass certain position, move back to right.

public class Background : MonoBehaviour
{
    [SerializeField] private float moveSpeed = 5f;

    void Update()
    {
         transform.position += Vector3.left * moveSpeed * Time.deltaTime;
        if (transform.position.x < 0.6f){
            transform.position = new Vector3(24.45f, -1.8f, 0);
            }
    }
}

Player

Jump

Player is simply when clicked, it jumps. Unity offers physics thing, so I just need to add Rigidbody 2D to player component and set.

public class Player : MonoBehaviour
{
    [SerializeField] private float jumpForce = 3f;
    private Rigidbody2D rb;

    void Start()
    {
        rb = GetComponent<Rigidbody2D>();
    }

    void Update()
    {
        if (Input.GetMouseButtonDown(0)) // mouse-left click
        {
            Jump();
        }
    }

    void Jump()
    {
        rb.velocity = Vector2.up * jumpForce;
    }
}

Collision

When player goes to out of the screen or collide pipe, it dies. Write code for triggerEnter that if it collides an object which has tag ‘Dead’, destroyed.

private void OnTriggerEnter2D(Collider2D other){

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

And I added two empty object which has collider and ‘Dead’ tag and place at the top and bottom of the screen.

Pipe

Spawn

Now need to handle pipe. There are two pipes and there is an empty objects which has ‘Score’ tag so when player pass between two pipes, user get a score.

And add edge collider for pipes and ‘Dead’ tag as well.

After, I added spawner to spawn pipes, and pipes will be spawned at random Y position at every 3 seconds.

public class Spawner : MonoBehaviour
{
    [SerializeField] private GameObject pipes;
    private float maxY = 3.3f;
    private float minY = -0.8f;

    void Start()
    {
        StartCoroutine(SpawnPipe());
    }

    private IEnumerator SpawnPipe(){
        while (true){
            float spawnY = Random.Range(minY, maxY);

            Instantiate(pipes, new Vector3(transform.position.x, spawnY, transform.position.z), Quaternion.identity);
            yield return new WaitForSeconds(3f);
        }
    }
}

Move

And pipe should move to left. Pretty same idea as background, but it should be destory if it goes to out of the screen. Otherwise, memory leak is occured.

public class Pipe : MonoBehaviour
{
    [SerializeField] private float moveSpeed = 5f;
    void Update()
    {
        transform.position += Vector3.left * moveSpeed * Time.deltaTime;
        if (transform.position.x < -7.5f){
            Destroy(gameObject);
        }
    }
}

Score

First I created GameManager script and I will handle score in this script.

using TMPro; // to handle text

public class GameManager : MonoBehaviour
{
    public int score;
    public TextMeshProUGUI scoreText;
    public static GameManager instance;
    void Awake()
        {
            if (instance == null)
            {
                instance = this;
                
            }
        }
    void Start()
    {
        score = 0;
    }
    void Update()
    {
        scoreText.text = score.ToString();
    }
    public void AddScore()
    {
        score++;

    }
}

And created Score script to check whether player pass between the pipes.

public class Score : MonoBehaviour
{
    void Update()
    {

    }

    private void OnTriggerEnter2D(Collider2D other){

        if (other.gameObject.CompareTag("Player")){
            GameManager.instance.AddScore();
        }
    }
}

Main Scene

I wanted to make a button to start the game.

Create a MainScene roughly with start button and when the button clicked, game is started. Code is really short.

using UnityEngine.SceneManagement; // need this to handle scene

public class SceneLoader : MonoBehaviour
{
public void LoadGameScene()
    {
        SceneManager.LoadScene("GameScene");
    }
}

Game Over

I created panel, score, best score and button and combine in a empty object named GameOver. This was deactivated and when player dies, it wil be activated and when button is clicked, load the gamescene so that you can re-start it.

Learned New

I found that ‘PlayerPrefs’ which is database offered by Unity so you can save data permanently.

I will handle best score with this method.

void Start()
{
    // read best score from database, 0 is default value
    bestScore = PlayerPrefs.GetInt("BestScore", 0);
}
.
.
.
// set best score
if (score > bestScore){
    bestScore = score;
    PlayerPrefs.SetInt("BestScore", bestScore);
}
bestScoreText.text = "Best Score: " + bestScore.ToString();
.
.
// this will be executed when user quit the game
void OnApplicationQuit(){
    PlayerPrefs.SetInt("BestScore", bestScore);
}