> 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` 当你的游戏中三个内置目标选择模式都不适用时——比如 UI 列表中已选中的角色、当前任务所围绕的角色，或者站在触发体积中的角色。请使用此页面，而不是退回到 `手动` 并重建那些已经正常工作的目标选择部分。

### 前提条件

* 熟悉其中的模型 [对话定位的工作原理](/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/how-conversation-targeting-works.md)
* 一种三个内置模式无法表达的目标选择规则

### 实现该接口

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

```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);
}
```

`候选角色` 会按稳定顺序列出房间中当前的每个角色，并且在 `ResolveTarget` 被调用。 `当前角色` 是当前正在掌控对话的角色，或者 `null` 当没有任何角色时。

返回玩家应当对话的角色。返回 `null` 以保持对话停留在原处。返回一个不在 `候选角色` 中的角色，也会使对话停留在原处。

### 注册该提供程序

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

传入 `null` 移动到 `SetConversationTargetProvider` 以移除自定义提供程序，并恢复由 `ConversationTargeting.Mode`.

{% hint style="info" %}
已注册的提供程序会完全取代内置模式，包括 `LookAt` 和 `Proximity`。该 `ConversationTargeting` 上的设置 `ConvaiManager` 在提供程序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

提供程序只负责选择要对话的角色。所有让这个选择更自然的机制仍然会叠加在提供程序返回值之上：对话仍然不会在句中途切换，仍然不会在某个目标第一次成为有效选择的那一帧就确定到新目标，也仍然不会让玩家无人可对话。有关这三条规则，请参见 [对话定位的工作原理](/api-docs/zh/cha-jian-yu-ji-cheng/convai-unity-sdk/features/conversation-targeting/how-conversation-targeting-works.md) ，了解这在实践中的含义。

如果 `ResolveTarget` 抛出异常，SDK 会捕获该异常、记录日志，并让对话保持原处，而不是让一个有问题的提供程序拖垮整个对话。

### 验证提供程序是否已激活

进入 Play 模式，并确认对话遵循你的自定义规则，而不是玩家的视角或位置。检查该 Live 部分的 `ConvaiManager` 检查器——它会报告被指向的角色以及上一次目标选择决策背后的判定，无论该结果是由内置模式还是自定义提供程序产生的。

### 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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