教程一 · 第 3 章：第一个完整游戏——Pong#

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using Godot;
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public partial class Paddle : CharacterBody2D
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{
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    [Export] public float Speed = 500f;
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    [Export] public string UpAction = "player1_up";
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    [Export] public string DownAction = "player1_down";
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    [Export] public float TopBound = 60f;    // 挡板中心能到达的最上/最下 y
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    [Export] public float BottomBound = 480f;
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    public override void _PhysicsProcess(double delta)
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    {
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        float dir = Input.GetAxis(UpAction, DownAction); // -1, 0, 1
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        Velocity = new Vector2(0f, dir * Speed);
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        MoveAndSlide(); // CharacterBody2D 的移动方式：自动按速度移动并处理碰撞滑动
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        // 夹在场地内
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        Position = new Vector2(
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            Position.X,
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            Mathf.Clamp(Position.Y, TopBound, BottomBound)
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        );
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    }
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}

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using Godot;
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public partial class Ball : CharacterBody2D
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{
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    [Signal] public delegate void ScoredEventHandler(StringName side); // "left" 或 "right"
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    [Export] public float StartSpeed = 400f;
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    [Export] public float SpeedGainPerHit = 30f;
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    [Export] public float MaxSpeed = 1100f;
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    [Export] public float BoundY = 530f;  // 撞到上下墙的 y 边界（球半径 10，场地高 540）
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    private float _speed;
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    private Vector2 _direction;
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    private RandomNumberGenerator _rng = new();
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    public override void _Ready()
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    {
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        _rng.Randomize(); // 不调用的话随机序列固定
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        ResetBall();
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    }
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    public void ResetBall()
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    {
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        Position = Vector2.Zero;
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        _speed = StartSpeed;
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        // 水平朝左或右，垂直给个随机角度（避免完全水平的无聊球路）
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        float angle = _rng.RandfRange(-Mathf.Pi / 4f, Mathf.Pi / 4f);
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        _direction = new Vector2(_rng.Randf() < 0.5f ? -1f : 1f, 0f)
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                     .Rotated(angle).Normalized();
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    }
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    public override void _PhysicsProcess(double delta)
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    {
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        Velocity = _direction * _speed;
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        var collision = MoveAndSlideCollide(); // 手动版移动，返回碰撞信息
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        for (int i = 0; i < collision.Count; i++)
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        {
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            var collisionInfo = collision[i];
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            var collider = collisionInfo.GetCollider();
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            if (collider is Paddle paddle)
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            {
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                BounceFromPaddle(paddle);
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            }
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            else
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            {
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                // 撞墙：竖直方向反弹
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                _direction.Y = -_direction.Y;
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            }
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        }
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        // 出左右边界 = 得分
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        if (Position.X < -20f)
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        {
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            EmitSignal(SignalName.Scored, "right"); // 球从左边出去，右边玩家得分
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            ResetBall();
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        }
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        else if (Position.X > 980f)
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        {
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            EmitSignal(SignalName.Scored, "left");
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            ResetBall();
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        }
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    }
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    private void BounceFromPaddle(Paddle paddle)
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    {
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        // 击球点偏离挡板中心越远，反弹角度越刁
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        float offset = (Position.Y - paddle.Position.Y) / 60f; // -1..1
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        offset = Mathf.Clamp(offset, -1f, 1f);
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        float dirX = paddle.Name == "Player1" ? 1f : -1f;
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        float angle = offset * Mathf.Pi / 3f; // 最大 60°
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        _direction = new Vector2(dirX, Mathf.Sin(angle)).Normalized();
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        _speed = Mathf.Min(_speed + SpeedGainPerHit, MaxSpeed);
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    }
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}

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// Paddle.cs 里加
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[Export] public int Side = 1; // 1 = 左侧挡板（把球向右打），-1 = 右侧

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using Godot;
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public partial class Main : Node2D
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{
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    private int _leftScore;
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    private int _rightScore;
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    private Label _scoreLeftLabel = null!;
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    private Label _scoreRightLabel = null!;
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    private Ball _ball = null!;
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    public override void _Ready()
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    {
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        _scoreLeftLabel = GetNode<Label>("CanvasLayer/ScoreLeft");
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        _scoreRightLabel = GetNode<Label>("CanvasLayer/ScoreRight");
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        _ball = GetNode<Ball>("Ball");
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        // 订阅球的得分信号
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        _ball.Scored += OnScored;
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        UpdateScore();
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    }
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    public override void _UnhandledInput(InputEvent @event)
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    {
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        if (Input.IsActionJustPressed("restart"))
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        {
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            _leftScore = 0;
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            _rightScore = 0;
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            _ball.ResetBall();
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            UpdateScore();
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        }
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    }
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    private void OnScored(StringName side)
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    {
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        if (side == "left") _leftScore++;
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        else _rightScore++;
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        UpdateScore();
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    }
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    private void UpdateScore()
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    {
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        _scoreLeftLabel.Text = _leftScore.ToString();
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        _scoreRightLabel.Text = _rightScore.ToString();
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    }
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}