FCommandMeta

基本信息

类型: USTRUCT(BlueprintType)
父类: (none)
源文件: Plugins/CharacterControl/Source/CharacterControl/Public/CommandEndpoint.h
模块: CharacterControl

功能概述

Metadata header for every command packet. Carries CommandID (int32, from UInputAction), HopLimit (uint8, mutable, decremented per router hop), bIsContinuous (bool, routing strategy selector), bIsUpward (bool, upward propagation flag).

设计用意

Routing envelope - decouples "what the command is" (payload) from "how it travels" (hop limit, direction). HopLimit prevents broadcast storms in router graphs. Upward flag supports parent-child router topologies.

职责范围

Carries routing metadata for one command packet. Embedded in FCommandPacket::Meta. Decremented at each router hop.

项目内依赖

依赖项	关系	源文件
(none)

对外接口

FCommandMeta 是嵌入在 FCommandPacket::Meta 中的数据容器，所有字段通过 UPROPERTY(BlueprintReadOnly) 暴露给蓝图。调用者不直接构造 FCommandMeta，而是由 UCommandInputComponent::BuildPacket 在输入事件触发时自动填充。路由过程中 UCommandRouter::ReceiveCommand 会递减 HopLimit。

CommandID (int32, BlueprintReadOnly): 由 BuildPacket 从 UInputAction::GetUniqueID() 填充，标识命令来源
HopLimit (uint8, mutable, BlueprintReadOnly): 每经过一层路由递减 1，耗尽则丢包。BuildPacket 对连续命令设为 3、离散命令设为 5
bIsContinuous (bool, BlueprintReadOnly): 决定路由分发策略（连续走 RouteContinuousCommand，离散走 RouteDiscreteCommand）
bIsUpward (bool, BlueprintReadOnly): 上行传播标志，在上级路由器中决定是否同时投递本地和向上转发

使用方法

FCommandMeta 作为 FCommandPacket 的成员由 BuildPacket 构建，在 CommandRouter 中消费：

构建: Plugins/CharacterControl/Source/CharacterControl/Private/CommandInputComponent.cpp:70-72 -- BuildPacket 设置 CommandID、bIsContinuous、HopLimit（连续 3、离散 5）
跳数递减: Plugins/CharacterControl/Source/CharacterControl/Private/CommandRouter.cpp:16-21 -- ReceiveCommand 检查 HopLimit 并在 >0 时递减
上行传播跳数递减: Plugins/CharacterControl/Source/CharacterControl/Private/CommandRouter.cpp:155 -- 上行命令在路由器层面再递减一次
路由策略选择: Plugins/CharacterControl/Source/CharacterControl/Private/CommandRouter.cpp:23-30 -- 根据 bIsContinuous 选择 RouteContinuousCommand 或 RouteDiscreteCommand

用例

BuildPacket 构建: Plugins/CharacterControl/Source/CharacterControl/Private/CommandInputComponent.cpp:70-72 -- 输入触发时根据 FInputCommand::bIsContinuous 设置 Meta 各字段，连续命令 HopLimit=3，离散命令 HopLimit=5
HopLimit 防护: Plugins/CharacterControl/Source/CharacterControl/Private/CommandRouter.cpp:16-18 -- ReceiveCommand 入口处首先检查 HopLimit，<=0 直接丢包，防止广播风暴
逐跳递减: Plugins/CharacterControl/Source/CharacterControl/Private/CommandRouter.cpp:21 -- 每经过一个路由器，mutable 的 HopLimit 减 1，确保命令不会无限传播
上行转发: Plugins/CharacterControl/Source/CharacterControl/Private/CommandRouter.cpp:148-155 -- 当 bIsUpward 为 true 时，先投递本地（清除上行标志），再向上级路由器转发

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