> For the complete documentation index, see [llms.txt](https://docs.convai.com/api-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.convai.com/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/custom-targeting-rule.md).

# 编写自定义目标选择规则

当内置模式都不适合你的游戏如何选择对话对象时，用你自己的规则替换对话目标选择。

实现 `IConversationTargetProvider` 当三种内置目标模式都不适合你的游戏时——也就是 UI 列表选中的角色、当前任务所关联的角色，或站在触发体积中的角色。请使用此页面，而不要退回到 `手动` 并重建那些已经正常工作的目标部分。

### 前置条件

* 熟悉以下内容中的模型： [对话目标选择的工作方式](/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/how-conversation-targeting-works.md)
* 一种三种内置模式都无法表达的目标选择规则

### 实现该接口

`IConversationTargetProvider` 只有一个方法， `ResolveTarget`，会在每次目标评估时调用。

```csharp
using System.Collections.Generic;
using Convai.Runtime.Components;
using Convai.Runtime.Conversation;
using UnityEngine;

public sealed class QuestTargetProvider : MonoBehaviour, IConversationTargetProvider
{
    public ConvaiCharacter ResolveTarget(
        IReadOnlyList<ConvaiCharacter> candidates, ConvaiCharacter current) =>
        QuestState.CurrentSpeaker ?? current;

    private void Start() =>
        ConvaiManager.ActiveManager.SetConversationTargetProvider(this);
}
```

`candidates` 按稳定顺序列出当前房间中的每个角色，并且当 `ResolveTarget` 被调用。 `第二个触发。响应` 是当前正在进行对话的角色，或者 `null` 当没有任何角色符合时。

返回玩家应该交谈的角色。返回 `null` 以保持对话原状。返回一个不在 `candidates` 中的角色也会让对话保持原状。

### 注册提供者

```csharp
ConvaiManager manager = ConvaiManager.ActiveManager;
manager.SetConversationTargetProvider(new QuestTargetProvider());
```

直接传入 `null` 为 `SetConversationTargetProvider` 以移除自定义提供者，并恢复由以下项配置的行为： `ConversationTargeting.Mode`.

{% hint style="info" %}
已注册的提供者会完全取代内置模式，包括 `LookAt` 和 `Proximity`。 `ConversationTargeting` 上的设置 `ConvaiManager` 在提供者处于活动状态时不会生效。
{% endhint %}

### 你的规则之上仍然适用的内容

提供者只决定应该与哪个角色交谈。所有让这个选择保持自然的机制，仍会叠加在提供者返回的结果之上：对话仍然不会在句子中途切换，首次变成有效选择的那一帧仍然不会立刻确定新目标，而且仍然不会让玩家无人倾听。请参阅 [对话目标选择的工作方式](/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/how-conversation-targeting-works.md) 中的三条规则，了解这在实践中意味着什么。

如果 `ResolveTarget` 如果抛出异常，SDK 会捕获该异常、记录日志，并让对话保持原状，而不是让某个有问题的提供者拖垮整个对话。

### 验证提供者是否已激活

进入 Play 模式，确认对话遵循你的自定义规则，而不是玩家的视角或位置。查看 `ConvaiManager` Inspector 的 Live 部分——它会显示当前被交谈的角色，以及上一次目标选择决策背后的判断结果，无论该结果是由内置模式还是自定义提供者产生的。

### 下一步

{% content-ref url="/pages/f411a648fdc7e99258a645a2b4b897adb9e6a570" %}
[编写对话目标脚本](/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/script-the-conversation-target.md)
{% endcontent-ref %}

{% content-ref url="/pages/8ebdb90f75876aa6a33c36e080adab2e377b1140" %}
[对话目标选择参考](/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/targeting-reference.md)
{% endcontent-ref %}


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