Flappy Cube Game in Unity 3D

Flappy Cube Game in Unity 3D

by NSDG • Jul 26, 2019 • 0 Comments
191

This is a second article from a "One Script Game" series. (You can check the first one here).

As the name says, the whole game is generated from a script with a minimal amount of manual setup.

Today we will be making a game inspired by Flappy Bird using primitive shapes in Unity.

The game mechanics are simple: The player taps the button to make the character bounce up while approaching a sets of pillars. The Player must avoid the pillars and stay in between them and by passing each pillar, 1 point is added. The objective is to beat your highest score.

All of this will be generated from a script, without any manual work.

Try it yourself

Let's begin!

Unity version used in this tutorial: Unity 2018.3.0f2 (64-bit)

Step 1: Create all the necessary scripts

Due to nature of the game, it can't be done with just 1 script. At minimum it requires 3 scripts, to handle the collision and trigger collider detection.

SC_TriggerDetector.cs

//You are free to use this script in Free or Commercial projects
//sharpcoderblog.com @2019

using UnityEngine;

public class SC_TriggerDetector : MonoBehaviour
{
    //This script is assigned automatically to a Pillar Trigger Collider by SC_FlappyCubeGame and will be used to count the points 
    [HideInInspector]
    public SC_FlappyCubeGame fcg;

    void OnTriggerEnter(Collider other)
    {
        fcg.AddPoint();
    }
}

SC_CollisionDetector.cs

//You are free to use this script in Free or Commercial projects
//sharpcoderblog.com @2019

using UnityEngine;

public class SC_CollisionDetector : MonoBehaviour
{
    //This script is assigned automatically to Flappy Cube by SC_FlappyCubeGame and will be used to detect the collisions
    [HideInInspector]
    public SC_FlappyCubeGame fcg;

    void OnCollisionEnter(Collision collision)
    {
        //print("OnCollisionEnter");
        fcg.GameOver();
    }
}

SC_FlappyCubeGame.cs

//You are free to use this script in Free or Commercial projects
//sharpcoderblog.com @2019

using System.Collections;
using UnityEngine;

public class SC_FlappyCubeGame : MonoBehaviour
{
    //Public variables
    public Camera mainCamera;
    public float cameraDistance = 10f;
    public float pillarHeight = 10f;
    public float distanceBetweenPillars = 5f;
    public float heightDistance = 4.5f;
    public float speed = 1.25f;
    public Color flappyCubeColor = new Color(1, 0.5f, 0);
    public Color pillarColor = Color.green;

    //Player cube
    GameObject flappyCube; 
    Rigidbody flappyCubeRigidbody;

    //Pillars
    public class Pillar
    {
        public Transform pillarRoot;
        public GameObject topCube;
        public GameObject bottomCube;
        public BoxCollider middleCollider; //Trigger collider for points
        public float offsetX; //When pillar reaches the end of Camera view, bring it to front by adding the offset
    }
    public Pillar[] pillarCubes;

    Vector3 initialPoint;
    Vector3 endPoint;
    Vector3 topPoint;
    Vector3 bottomPoint;
    Vector3 flappyCubeInitialPosition;

    bool gameStarted = false;
    bool gameOver = false;
    bool canRestart = false;
    bool newBestScore = false;

    int totalPoints = 0;
    int highestScore = 0;

    // Start is called before the first frame update
    void Start()
    {
        //Define reference points relative to Main Camera
        initialPoint = mainCamera.ViewportToWorldPoint(new Vector3(1.1f, 0.5f, cameraDistance));
        endPoint = mainCamera.ViewportToWorldPoint(new Vector3(-0.1f, 0.5f, cameraDistance));
        topPoint = mainCamera.ViewportToWorldPoint(new Vector3(0.5f, 1f, cameraDistance));
        bottomPoint = mainCamera.ViewportToWorldPoint(new Vector3(0.5f, 0f, cameraDistance));

        //Create Flappy Cube
        flappyCube = GameObject.CreatePrimitive(PrimitiveType.Cube);
        flappyCubeInitialPosition = mainCamera.ViewportToWorldPoint(new Vector3(0.35f, 0.5f, cameraDistance));
        flappyCube.transform.position = flappyCubeInitialPosition;
        flappyCubeRigidbody = flappyCube.AddComponent<Rigidbody>();
        flappyCubeRigidbody.constraints = RigidbodyConstraints.FreezePositionX | RigidbodyConstraints.FreezePositionZ | RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY;
        MeshRenderer mr = flappyCube.GetComponent<MeshRenderer>();
        mr.sharedMaterial = new Material(Shader.Find("Legacy Shaders/Diffuse"));
        mr.sharedMaterial.color = flappyCubeColor;
        flappyCube.AddComponent<SC_CollisionDetector>().fcg = this;

        //Create Pillar cubes
        pillarCubes = new Pillar[7];
        Material pillarMaterial = new Material(flappyCube.GetComponent<MeshRenderer>().sharedMaterial);
        pillarMaterial.color = pillarColor;
        for (int i = 0; i < pillarCubes.Length; i++)
        {
            Vector3 initialPointTmp = initialPoint + new Vector3(distanceBetweenPillars * i, 0, 0);
            //Create new Pillar instance
            Pillar newPillar = new Pillar();
            //Create pillar Root Object
            newPillar.pillarRoot = (new GameObject("Pillar")).transform;
            newPillar.pillarRoot.position = initialPointTmp;
            //Middle collider 
            GameObject colliderObject = new GameObject("TriggerCollider");
            colliderObject.transform.position = initialPointTmp;
            colliderObject.transform.SetParent(newPillar.pillarRoot);
            newPillar.middleCollider = colliderObject.AddComponent<BoxCollider>();
            newPillar.middleCollider.size = new Vector3(0.5f, heightDistance, 1);
            newPillar.middleCollider.isTrigger = true;
            colliderObject.AddComponent<SC_TriggerDetector>().fcg = this;
            //Top Pillar
            newPillar.topCube = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
            newPillar.topCube.transform.SetParent(newPillar.pillarRoot);
            initialPointTmp.y += heightDistance / 2 + pillarHeight;
            newPillar.topCube.transform.position = initialPointTmp;
            newPillar.topCube.transform.localScale = new Vector3(1.5f, pillarHeight, 1.5f);
            newPillar.topCube.GetComponent<MeshRenderer>().sharedMaterial = pillarMaterial;
            Destroy(newPillar.topCube.GetComponent<CapsuleCollider>());
            newPillar.topCube.AddComponent<BoxCollider>();
            //Bottom pillar
            newPillar.bottomCube = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
            newPillar.bottomCube.transform.SetParent(newPillar.pillarRoot);
            initialPointTmp.y -= (heightDistance / 2 + pillarHeight) * 2;
            newPillar.bottomCube.transform.position = initialPointTmp;
            newPillar.bottomCube.transform.localScale = new Vector3(1.5f, pillarHeight, 1.5f);
            newPillar.bottomCube.GetComponent<MeshRenderer>().sharedMaterial = pillarMaterial;
            Destroy(newPillar.bottomCube.GetComponent<CapsuleCollider>());
            newPillar.bottomCube.AddComponent<BoxCollider>();
            //Randomize Y position
            float positionYOffset = Random.Range(-distanceBetweenPillars / 2, distanceBetweenPillars / 2);
            newPillar.pillarRoot.position += new Vector3(0, positionYOffset, 0);
            //Set Pillar parent 
            newPillar.pillarRoot.SetParent(transform);
            //Assign Pillar instance to array
            pillarCubes[i] = newPillar;
        }

        //Load highest score if there any
        if (PlayerPrefs.HasKey("SC_HightScore"))
        {
            highestScore = PlayerPrefs.GetInt("SC_HightScore");
        }
    }

    // Update is called once per frame
    void Update()
    {
        //Cube jump
        if (Input.GetKeyDown(KeyCode.Space))
        {
            if (!gameStarted)
            {
                gameStarted = true;
                flappyCubeRigidbody.isKinematic = false;
            }
            if (gameOver)
            {
                RestartGame();
            }
            else
            {
                flappyCubeRigidbody.velocity = new Vector3(0, 8.5f, 0);
            }
        }

        if (!gameStarted)
        {
            if (!flappyCubeRigidbody.isKinematic)
            {
                flappyCubeRigidbody.isKinematic = true;
            }
        }
        else
        {
            //Infinite loop movement (The first Pillar becomes last once it goes out of view and so on)
            for (int i = 0; i < pillarCubes.Length; i++)
            {
                pillarCubes[i].pillarRoot.localPosition = new Vector3(pillarCubes[i].pillarRoot.localPosition.x + pillarCubes[i].offsetX - Time.deltaTime * speed, pillarCubes[i].pillarRoot.localPosition.y, pillarCubes[i].pillarRoot.localPosition.z);

                if (pillarCubes[i].pillarRoot.localPosition.x < endPoint.x)
                {
                    //Shift this Pillar back to the beginning
                    int shiftAfter = -1;
                    for (int a = 0; a < pillarCubes.Length; a++)
                    {
                        if (shiftAfter < 0 || pillarCubes[a].pillarRoot.localPosition.x > pillarCubes[shiftAfter].pillarRoot.localPosition.x)
                        {
                            shiftAfter = a;
                        }
                    }

                    if (shiftAfter > -1)
                    {
                        pillarCubes[i].pillarRoot.localPosition = new Vector3(pillarCubes[shiftAfter].pillarRoot.localPosition.x + distanceBetweenPillars, initialPoint.y, initialPoint.z);
                        float positionYOffset = Random.Range(-distanceBetweenPillars / 2, distanceBetweenPillars / 2);
                        pillarCubes[i].pillarRoot.localPosition += new Vector3(0, positionYOffset, 0);
                    }
                }
            }
        }

        //Slightly increase fall speed
        flappyCubeRigidbody.velocity -= new Vector3(0, Time.deltaTime * 5, 0);
        //Slightly rotate the Cube according to rigidbody velocity
        flappyCube.transform.localEulerAngles = new Vector3(0, 0, Mathf.Clamp(flappyCubeRigidbody.velocity.y, -35, 35));

        //Came Over if the Cube goes outside of the camera view
        if ((flappyCube.transform.position.y > topPoint.y || flappyCube.transform.position.y < bottomPoint.y) && !gameOver && gameStarted)
        {
            GameOver();
        }
    }

    void RestartGame()
    {
        if (canRestart)
        {
            //Move pillars to original position
            for (int i = 0; i < pillarCubes.Length; i++)
            {
                Vector3 initialPointTmp = initialPoint + new Vector3(distanceBetweenPillars * i, 0, 0);
                //Randomize Y position
                float positionYOffset = Random.Range(-distanceBetweenPillars / 2, distanceBetweenPillars / 2);
                pillarCubes[i].pillarRoot.position = initialPointTmp + new Vector3(0, positionYOffset, 0);
            }

            flappyCube.transform.position = flappyCubeInitialPosition;
            flappyCube.transform.localEulerAngles = Vector3.zero;
            flappyCubeRigidbody.velocity = Vector3.zero;
            gameOver = false;
            gameStarted = false;
            totalPoints = 0;
            newBestScore = false;
        }
    }

    public void GameOver()
    {
        gameOver = true;
        if (totalPoints > highestScore)
        {
            //Save highest score
            PlayerPrefs.SetInt("SC_HightScore", totalPoints);
            highestScore = totalPoints;
            newBestScore = true;
        }
        StartCoroutine(CanRestart());
    }

    IEnumerator CanRestart()
    {
        canRestart = false;
        yield return new WaitForSeconds(1.5f);
        canRestart = true;
    }

    public void AddPoint()
    {
        totalPoints++;
    }

    void OnGUI()
    {
        if (gameOver)
        {
            GUI.color = Color.red;
            GUI.Box(new Rect(Screen.width / 2 - 90, Screen.height / 2 - 30, 180, 60), "GAME OVER\n" + (newBestScore ? "--New Best Score!--" : "") + "\nPress 'Space' to restart");
        }
        else
        {
            if (!gameStarted)
            {
                GUI.color = Color.green;
                GUI.Box(new Rect(Screen.width / 2 - 90, Screen.height / 2 - 40, 180, 80), "FLAPPY CUBE\n\nBest Score: " + highestScore + "\nPress 'Space' to start");
            }
        }

        //Show Score
        GUI.color = Color.cyan;
        GUI.Box(new Rect(Screen.width / 2 - 35, 10, 70, 24), totalPoints.ToString());
    }
}

Step 2: Setting Up The Game

  • Create new Scene
  • Create new GameObject (GameObject -> Create Empty) and name it "_GameGenerator"
  • Attach SC_FlappyCubeGame to _GameGenerator

The game is now ready, press Play to test it!