Unity C#：特定Torso显示时生成对象异常的修复方案

教程使用的代码 #

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

public class Trial_Changer : MonoBehaviour
{
    [Header("Sprite To Change")]
    public SpriteRenderer bodyPart;

    [Header("Sprites to Cycle Through")]
    public List<Sprite> options = new List<Sprite>();

    public static int currentTorsoOption = 0;

    public void NextOption ()
    {
        currentTorsoOption++;
        if (currentTorsoOption >= options.Count)
        { currentTorsoOption = 0; }
        

        bodyPart.sprite = options[currentTorsoOption];

    }

    public void PreviousOption()
    {
        currentTorsoOption--;
        if (currentTorsoOption <= 0)
        { currentTorsoOption = options.Count - 1; }
        

        bodyPart.sprite = options[currentTorsoOption];

    }
}

尝试实现“Torso 2显示时生成对象”的代码 #

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

public class SpeechAppears : MonoBehaviour
{
    public GameObject speechBubbleTOSpawn;
    private int Torso = Trial_Changer.currentTorsoOption;

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

    }

    // Update is called once per frame
    void Update()
    {
        if (Torso == 2)
        {
            Instantiate(speechBubbleTOSpawn);
        }

    }
}

问题描述 #

当前对象始终显示，无法实现仅当Torso 2在屏幕上显示时才生成对象的需求，请问该如何修复？

错误原因及修复方法 #

错误原因 #

1. 静态变量未实时读取：你这里把Trial_Changer.currentTorsoOption的值存在了private int Torso里，但这个赋值只在脚本初始化时执行一次，后续currentTorsoOption变化时，Torso不会同步更新，导致判断逻辑完全失效。
2. 重复生成对象：就算判断逻辑正确，Update方法每帧都会执行，会无限生成气泡对象，既浪费资源又导致显示异常。

修复后的代码 #

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

public class SpeechAppears : MonoBehaviour
{
    public GameObject speechBubbleToSpawn;
    private GameObject spawnedBubble; // 记录已生成的气泡对象，避免重复创建

    void Update()
    {
        // 实时读取当前的Torso选项，不要缓存成固定变量
        int currentTorso = Trial_Changer.currentTorsoOption;

        if (currentTorso == 2)
        {
            // 只有当气泡还没生成的时候才创建
            if (spawnedBubble == null)
            {
                spawnedBubble = Instantiate(speechBubbleToSpawn, transform.position, Quaternion.identity);
                // 可选：把气泡设为当前物体的子对象，方便位置管理和销毁
                spawnedBubble.transform.SetParent(transform);
            }
        }
        else
        {
            // 切换到其他Torso时，销毁已生成的气泡
            if (spawnedBubble != null)
            {
                Destroy(spawnedBubble);
                spawnedBubble = null;
            }
        }
    }
}

额外优化建议 #

• 用事件替代每帧判断：可以在Trial_Changer里添加一个OnTorsoChanged事件，切换Torso时触发这个事件，SpeechAppears监听事件来处理生成/销毁逻辑，比每帧轮询更高效。
• 调整气泡生成位置：根据实际需求设置Instantiate的位置参数，避免气泡和Torso重叠。

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