Unity中拖拽逻辑仅生效一次的问题求助

可能原因及对应方案 #

1. 新输入系统与OnMouse事件的兼容性问题 #

Unity 6默认启用新输入系统，OnMouseDown/OnMouseUp这类旧输入事件可能出现注册异常，可通过两种方式解决：

方案A：启用旧输入系统兼容

• 打开Edit > Project Settings > Player
• 在Active Input Handling下拉菜单中选择Both或Old Input System
• 重启Unity后测试

方案B：改用新输入系统实现拖拽

替换原有代码为新输入系统逻辑，彻底避免兼容性问题：

using UnityEngine;
using UnityEngine.InputSystem;

public class DragObject : MonoBehaviour
{
    private Camera _camera;
    private bool _dragging;
    private Vector2 _mouseStartPos;
    private Vector3 _objectStartPos;

    private void Awake()
    {
        _camera = Camera.main;
    }

    private void OnEnable()
    {
        Mouse.current.leftButton.started += OnDragStart;
        Mouse.current.leftButton.canceled += OnDragEnd;
    }

    private void OnDisable()
    {
        Mouse.current.leftButton.started -= OnDragStart;
        Mouse.current.leftButton.canceled -= OnDragEnd;
    }

    private void Update()
    {
        if (_dragging)
        {
            Vector2 mouseWorldPos = _camera.ScreenToWorldPoint(Mouse.current.position.ReadValue());
            transform.position = _objectStartPos + (Vector3)(mouseWorldPos - _mouseStartPos);
        }
    }

    private void OnDragStart(InputAction.CallbackContext context)
    {
        RaycastHit2D hit = Physics2D.Raycast(_camera.ScreenToWorldPoint(Mouse.current.position.ReadValue()), Vector2.zero);
        if (hit.collider != null && hit.collider.gameObject == gameObject)
        {
            _dragging = true;
            _mouseStartPos = Mouse.current.position.ReadValue();
            _objectStartPos = transform.position;
        }
    }

    private void OnDragEnd(InputAction.CallbackContext context)
    {
        _dragging = false;
    }
}

2. Collider2D状态异常 #

拖拽后Collider2D可能因物体位置变化丢失事件注册，可在拖拽结束时强制刷新：

private void OnMouseUp()
{
    _dragging = false;
    // 强制重置Collider2D状态
    var collider = GetComponent<Collider2D>();
    collider.enabled = false;
    collider.enabled = true;
}

注：此为临时修复方案，优先推荐输入系统相关解决路径。

3. Physics2D.autoSimulation设置位置 #

Unity 6中该选项路径为：Edit > Project Settings > Physics 2D，在Simulation分组下找到Auto Simulation，确保其处于勾选状态。若未勾选，物理系统会停止自动模拟，导致碰撞事件完全失效。

内容的提问来源于stack exchange，提问作者SoggyEyeball