低帧率下Rigidbody2D角色跳跃过高的问题修复咨询

问题根源 #

你的跳跃逻辑用帧计数（_jumpTime）控制持续跳跃的时长，低帧率时每帧的时间间隔大幅变长（比如5FPS下每帧0.2秒，60FPS下仅0.016秒），同样的_maxJumpTime=40，实际持续的物理时间会从正常的~0.67秒变成8秒——相当于持续给角色施加向上速度的时间被强行拉长，自然跳得极高。

修复步骤 #

1. 把帧计数改成时间计数：用基于秒的时长替代帧数量，确保不管帧率高低，跳跃持续的物理时间一致。
2. 将物理相关逻辑移到FixedUpdate：FixedUpdate的调用间隔是固定的（默认0.02秒），不受帧率波动影响，物理操作在这里执行更稳定。
3. 分离输入与物理逻辑：Update只处理输入状态判断，把实际的物理操作交给FixedUpdate，避免帧率波动干扰物理计算。

修改后的代码示例 #

using UnityEngine.InputSystem;
using UnityEngine;

[RequireComponent(typeof(Rigidbody2D))]
public class PlayerMove : MonoBehaviour
{
    private PlayerMovement _playerMovement;
    private Rigidbody2D _rb;
    
    [SerializeField] private LayerMask groundLayer;

    [SerializeField] private float speed = 5.0f;
    [SerializeField] private float jumpHeight = 8.0f;
    // 改成基于秒的跳跃持续时长，比如0.2秒，可根据手感调整
    [SerializeField] private float maxJumpDuration = 0.2f;

    private bool _isJumping;
    private float _currentJumpTimer;

    private void Awake() {
        _playerMovement = new PlayerMovement();
    }

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

    private void OnEnable() {
        _playerMovement.Enable();
    }

    private void OnDisable() {
        _playerMovement.Disable();
        _playerMovement.Dispose();
    }

    private bool isGrounded() => Physics2D.Raycast(transform.position, Vector3.down, 0.6f, groundLayer) 
                              || Physics2D.Raycast(new Vector2(transform.position.x - 0.5f, transform.position.y), Vector3.down, 0.6f, groundLayer) 
                              || Physics2D.Raycast(new Vector2(transform.position.x + 0.5f, transform.position.y), Vector3.down, 0.6f, groundLayer);

    private void Update() {
        // 仅处理输入状态，不碰物理逻辑
        if(_playerMovement.Movement.Jumping.WasPerformedThisFrame() && isGrounded())
        {
            _isJumping = true;
            _currentJumpTimer = maxJumpDuration;
        }

        if (_playerMovement.Movement.Jumping.WasReleasedThisFrame()) 
        {
            _isJumping = false;
        }

        if (isGrounded()) 
        {
            _currentJumpTimer = maxJumpDuration;
            if (!_playerMovement.Movement.Jumping.IsPressed())
                _isJumping = false;
        }
    }

    private void FixedUpdate() {
        // 移动逻辑保持不变
        Vector2 inp = _playerMovement.Movement.Move.ReadValue<Vector2>();
        _rb.velocity = new Vector2(inp.x * speed , _rb.velocity.y);

        // 跳跃逻辑移到FixedUpdate，用固定时间步长更新计时器
        if(_playerMovement.Movement.Jumping.IsPressed() && _isJumping && _currentJumpTimer > 0)
        {
            _rb.velocity = new Vector2(_rb.velocity.x, jumpHeight);
            // 用fixedDeltaTime确保时间计算不受帧率影响
            _currentJumpTimer -= Time.fixedDeltaTime;
        }
        else if (_currentJumpTimer <= 0)
        {
            _isJumping = false;
        }
    }
}

额外优化建议 #

• 给Rigidbody2D开启Interpolate选项，让低帧率下角色移动更平滑；
• 地面检测可以改用Physics2D.OverlapBox替代多道射线，性能和稳定性更优。

内容的提问来源于stack exchange，提问作者x8c8r