Unityで作った3D版Pongのソースコード部分だけ (https://unityroom.com/games/3dpongmodoki)

BallController.cs

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

public class BallController : MonoBehaviour
{
    public GameObject StampPrefab;
    public GameObject ParticlePrefab;

    private Rigidbody rb;
    private GameObject BallZLine;
    private GameObject BallZLineHorizontal;
    private GameObject BallZLineVertical;
    private Vector3 lastVelocity;
    private Vector3 lastPosition;
    private int counter = 0;

    public static  float Z_CONSTANT_VELOCITY = 2.5f;
    private const float Z_CONSTANT_HALF_VELOCITY = 1.25f;
    private const float Z_STRANGE_VELOCITY_THRESHOLD = 0.1f;
    private const float XY_VELOCITY_LATIO_UPPER = 1f;
    private const float XY_VELOCITY_LATIO_BOTTOM = 0.2f;

    private AudioSource audioSource;
    public AudioClip audioBound;

    private const int COUNTER_ADJUST_THRESHOLD = 5;

    private GameObject createdParticle = null;

    // Start is called before the first frame update
    void Start()
    {
        lastVelocity = new Vector3(0, 0, 0);
        rb = this.GetComponent<Rigidbody>();
        BallZLine = GameObject.Find("BallZLine");
        BallZLineHorizontal = GameObject.Find("BallZLineHorizontal");
        BallZLineVertical = GameObject.Find("BallZLineVertical");
        audioSource = gameObject.GetComponent<AudioSource>();
    }

    //一定秒数ごとに呼び出される. デフォルトは20ms間隔らしい
    void FixedUpdate()
    {
        if (counter > COUNTER_ADJUST_THRESHOLD)
        {
            //ボールのスピードをいい感じに調整する
            adjustBallSpeed();
        }

        //異様に速度が遅くなっている場合はその速度は採用しない
        if(Mathf.Abs(rb.velocity.z) >= Z_CONSTANT_HALF_VELOCITY || counter < COUNTER_ADJUST_THRESHOLD)
        {
            lastVelocity = rb.velocity;
        }

        //iTween.MoveTo(BallZLine, iTween.Hash("x", this.transform.position.x, "y", this.transform.position.y));
        BallZLine.transform.position = new Vector3(this.transform.position.x, this.transform.position.y, 0);
        BallZLineHorizontal.transform.position = new Vector3(0, this.transform.position.y, this.transform.position.z);
        BallZLineVertical.transform.position = new Vector3(this.transform.position.x, 0, this.transform.position.z);
    }

    private void resetBallZLine()
    {
        BallZLine.transform.position = new Vector3(0, 0, 0);
        BallZLineHorizontal.transform.position = new Vector3(0, 0, 0);
        BallZLineVertical.transform.position = new Vector3(0, 0, 0);
    }

    private void adjustBallSpeed()
    {
        float vx = rb.velocity.x;
        float vy = rb.velocity.y;
        float vz = rb.velocity.z;
        float vz_abs = Mathf.Abs(vz);


        if (vz_abs <= Z_STRANGE_VELOCITY_THRESHOLD && counter > COUNTER_ADJUST_THRESHOLD) {
            // 突き抜け等の可能性があるため必ず手前方向に移動させる
            vz_abs = Z_CONSTANT_VELOCITY;
            vz = -1 * Z_CONSTANT_VELOCITY;
        }

        if (vz_abs < Z_CONSTANT_VELOCITY){
            vz_abs = Z_CONSTANT_VELOCITY;
            vz = vz >= 0 ? Z_CONSTANT_VELOCITY : -1 * Z_CONSTANT_VELOCITY;
        }


        if(Mathf.Abs(vx) >= XY_VELOCITY_LATIO_UPPER * vz_abs)
        {
            vx = vx >= 0 ? XY_VELOCITY_LATIO_UPPER * vz_abs : -1 * XY_VELOCITY_LATIO_UPPER * vz_abs;
        }
        if(Mathf.Abs(vx) <= XY_VELOCITY_LATIO_BOTTOM * vz_abs)
        {
            vx = vx >= 0 ? XY_VELOCITY_LATIO_BOTTOM * vz_abs : -1 * XY_VELOCITY_LATIO_BOTTOM * vz_abs;
        }

        if(Mathf.Abs(vy) >= XY_VELOCITY_LATIO_UPPER * vz_abs)
        {
            vy = vy >= 0 ? XY_VELOCITY_LATIO_UPPER * vz_abs : -1 * XY_VELOCITY_LATIO_UPPER * vz_abs;
        }
        if(Mathf.Abs(vy) <= XY_VELOCITY_LATIO_BOTTOM * vz_abs)
        {
            vy = vy >= 0 ? XY_VELOCITY_LATIO_BOTTOM * vz_abs : -1 * XY_VELOCITY_LATIO_BOTTOM * vz_abs;
        }

        rb.velocity = new Vector3(vx, vy, vz);
    }

    // Update is called once per frame
    void Update()
    {
        if (transform.position.z < -3f)
        {
            resetBallZLine();
            Destroy(gameObject);
        }

        counter += 1;

        if((lastPosition == null || counter % 11 == 0))
        {
            lastPosition = gameObject.transform.position;
        }

        if (counter % 17 == 0 && lastPosition.x == gameObject.transform.position.x &&  lastPosition.y == gameObject.transform.position.y && lastPosition.z == gameObject.transform.position.z
            && rb.velocity.x == 0 && rb.velocity.x == 0 && rb.velocity.z == 0){
            resetBallZLine();
            Destroy(gameObject);
        }
    }

    void createStamp(Collision coll)
    {
        float x = gameObject.transform.position.x;
        float y = gameObject.transform.position.y;
        float z = gameObject.transform.position.z;

        //当たり判定が発生した座標
        Vector3 contactCood = coll.GetContact(0).point;
        float cx = contactCood.x;
        float cy = contactCood.y;
        float cz = contactCood.z;

        GameObject wall = coll.gameObject;
        float wx = wall.transform.position.x;
        float wy = wall.transform.position.y;
        float wz = wall.transform.position.z;        

        // 0.1fは差が明確にあることを判定するために適当に選んだ閾値

        if(createdParticle != null)
        {
            Destroy(createdParticle);
        }

        if(Mathf.Abs(cx) - Mathf.Abs(x) > 0.1f) //左右の壁
        {
            GameObject obj = Instantiate(StampPrefab, new Vector3(wx, y, z), Quaternion.identity);
            createdParticle = Instantiate(ParticlePrefab, new Vector3(cx, y, z), Quaternion.identity);
            obj.transform.rotation = Quaternion.Euler(0, 0, 90) * obj.transform.rotation;
            return;
        }

        if(Mathf.Abs(cy) - Mathf.Abs(y) > 0.1f) //上下の壁
        {
            GameObject obj = Instantiate(StampPrefab, new Vector3(x, wy, z), Quaternion.identity);
            createdParticle = Instantiate(ParticlePrefab, new Vector3(x, cy, z), Quaternion.identity);
            return;
        }

        if(Mathf.Abs(cz) - Mathf.Abs(z) > 0.1f) //奥の壁もしくはラケット
        {
            if(z > 0) //奥の壁
            {

                GameObject obj = Instantiate(StampPrefab, new Vector3(x, y, wz), Quaternion.identity);
                createdParticle = Instantiate(ParticlePrefab, new Vector3(x, y, cz), Quaternion.identity);
                obj.transform.rotation = Quaternion.Euler(90, 0, 0) * obj.transform.rotation;
                return;
            }
            else //ラケット
            {
                GameObject obj = Instantiate(StampPrefab, new Vector3(x, y, wz), Quaternion.identity);
                //薄くする
                obj.transform.localScale = new Vector3(0.3f, 0.001f, 0.3f);
                obj.transform.rotation = Quaternion.Euler(90, 0, 0) * obj.transform.rotation;
                
                return;
            }
        }
    }

    void OnCollisionEnter(Collision coll)
    {
        Vector3 refrectVec = Vector3.Reflect(this.lastVelocity, coll.contacts[0].normal);
        //Debug.Log(refrectVec);
        refrectVec.x *= 1.01f;
        refrectVec.y *= 1.01f;
        refrectVec.z *= 1.01f;
        rb.velocity = refrectVec;
        createStamp(coll);
        audioSource.PlayOneShot(audioBound);
    }

}

KeyCheckerController.cs

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

public class KeyCheckerControler : MonoBehaviour
{
    public GameObject BallPrefab;
    public GameObject RacketPrefab;
    private GameObject ScoreText;

    private GameObject createdBall = null;
    private GameObject createdRacket = null;
    private GameObject RacketZLineHorizontal = null;
    private GameObject RacketZLineVertical = null;

    private const float CHECK_INTERVAL = 0.01f;
    private const float MOVE_DISTANCE = 0.05f;
    private const float PIXCELS_OF_UNIT = 100f;

    // Start is called before the first frame update
    void Start()
    {
        createdRacket = Instantiate(RacketPrefab, new Vector3(0, 0, -2f), Quaternion.identity);
        
        ScoreText = GameObject.Find("ScoreMeshText");
        ScoreText.GetComponent<TextMesh>().text = "0 回";

        RacketZLineHorizontal = GameObject.Find("RacketZLineHorizontal");
        RacketZLineVertical = GameObject.Find("RacketZLineVertical");

        //createdRacket.GetComponent<Renderer>().material.color = Color.blue;
        InvokeRepeating("checkKeyPress", CHECK_INTERVAL, CHECK_INTERVAL);        
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    float getConvertedMouseCoodX()
    {
        return ((Input.mousePosition.x / Screen.width) * 5f - 2.5f) * 1.3f;
    }

    float getConvertedMouseCoodY()
    {
        return (Input.mousePosition.y / Screen.height) * 5f - 2.5f;
    }

    void checkKeyPress()
    {
        createdRacket.transform.position = new Vector3 (getConvertedMouseCoodX(), getConvertedMouseCoodY(), createdRacket.transform.position.z);

        if (Input.GetKeyDown(KeyCode.Space))
        {
            shotNewBall();
        }

        RacketZLineHorizontal.transform.position = new Vector3(0, createdRacket.transform.position.y, createdRacket.transform.position.z);
        RacketZLineVertical.transform.position = new Vector3(createdRacket.transform.position.x, 0, createdRacket.transform.position.z);
    }

    private void reCreateRacket()
    {
        if(createdRacket != null)
        {
            Destroy(createdRacket);
            createdRacket = null;            
        }
        createdRacket = Instantiate(RacketPrefab, new Vector3(0, 0, -2f), Quaternion.identity);
    }

    void shotNewBall()
    {
        if (createdBall != null)
        {
            return;
        }
        createdBall = Instantiate(BallPrefab, new Vector3(0, 0, -1.5f), Quaternion.identity);
        float shotVerocityFixedZ = BallController.Z_CONSTANT_VELOCITY;

        float shotAngle = Random.Range(0f, 360f);
        float x_speed = Mathf.Cos(2 * Mathf.PI * (shotAngle / 360f)) * shotVerocityFixedZ;
        float y_speed = Mathf.Sin(2 * Mathf.PI * (shotAngle / 360f)) * shotVerocityFixedZ;

        createdBall.GetComponent<Renderer>().material.color = Color.black;
        //createdBall.GetComponent<Rigidbody>().AddForce(new Vector3(x_power, y_power, shotVerocityFixedZ));
        createdBall.GetComponent<Rigidbody>().velocity = new Vector3(x_speed, y_speed, shotVerocityFixedZ);

        //createdBall.GetComponent<Rigidbody>().AddForce(new Vector3(0, 0, shotPowerFixedZ));

        ScoreText.GetComponent<TextMesh>().text = "0 回";
        //内部状態を初期化するために作り直す
        reCreateRacket();
    }
}

RacketController.cs

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

public class RacketController : MonoBehaviour
{
    private int BoundCount;
    // Start is called before the first frame update
    void Start()
    {
        BoundCount = 0;
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    void OnCollisionEnter(Collision collision)
    {
        BoundCount++;
        GameObject.Find("ScoreMeshText").GetComponent<TextMesh>().text =  BoundCount.ToString() +  " 回";
    }
}

StampController.cs

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

public class StampController : MonoBehaviour
{

    private int counter = 0;

    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        //if(counter > 50)
        if(counter > 15)
        {
            Destroy(gameObject);
            return;
        }
        counter++;
    }
}