66 lines
3.2 KiB
Markdown
66 lines
3.2 KiB
Markdown
---
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title: "GAS (Gameplay Ability System)"
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type: concept
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tags: [unreal-engine, networking, multiplayer, ue5, abilities]
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sources: ["unreal-multiplayer-architect", "unreal-systems-engineer"]
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last_updated: 2026-04-26
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## Additional Sources
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Gameplay Ability System（GAS）是 UE5 的可扩展技能与属性框架，通过 UGameplayAbility、UAttributeSet、UAbilitySystemComponent 实现网络就绪的技能系统。[[UnrealSystemsEngineer]] 补充：所有 Tick 逻辑必须 C++；FGameplayTag 优于字符串标识符；通过 UPROPERTY(ReplicatedUsing=OnRep_Health) + GAMEPLAYATTRIBUTE_REPNOTIFY 宏实现属性复制。
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## Core Components
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- **UAbilitySystemComponent**：GAS 核心组件，管理技能和属性，必须正确配置网络复制
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- **UGameplayAbility**：可激活的技能类，支持网络预测和复制
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- **FGameplayEffectContext**：技能效果上下文，携带命中结果、来源和自定义数据
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- **FPredictionKey**：预测键，标记可预测的能力和属性变更，支持服务器确认或回滚
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- **UAttributeSet**：属性集，包含可复制的游戏属性（生命值、能量等）
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## Network Integration (Dual Init Path)
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GAS 在多人游戏中必须实现双路径初始化：
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```cpp
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// 服务器路径 — PossessedBy 在 Actor 被 Controller 拥有时调用
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void AMyCharacter::PossessedBy(AController* NewController)
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{
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Super::PossessedBy(NewController);
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AbilitySystemComponent->InitAbilityActorInfo(GetPlayerState(), this);
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}
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// 客户端路径 — OnRep_PlayerState 在 PlayerState 复制到达时调用
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void AMyCharacter::OnRep_PlayerState()
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{
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Super::OnRep_PlayerState();
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AbilitySystemComponent->InitAbilityActorInfo(GetPlayerState(), this);
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}
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```
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## Network Prediction in GAS
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- `FPredictionKey`：标记所有预测变更，服务器确认后生效
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- 客户端预测技能激活和属性变更
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- 服务器验证并广播 `GameplayEffect` 到所有客户端
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- 验证失败时服务器回滚客户端预测
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## Best Practices
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- **双路径初始化**：必须在 `PossessedBy` 和 `OnRep_PlayerState` 两个入口点初始化 GAS
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- **AttributeSet 复制**：使用 `UPROPERTY(Replicated)` 让属性在服务器和客户端同步
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- **预测管理**：高频技能必须正确设置 `NetDeltaFrequency` 避免带宽爆炸
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- **预测键作用域**：`FPredictionKey` 必须在能力激活时生成并传递给所有子操作
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## Connection to Other Concepts
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- [[Actor Replication]] — GAS 依赖 Actor 复制机制同步属性和状态
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- [[Network Prediction]] — GAS 内置网络预测支持（FPredictionKey）
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- [[Server-Authoritative Model]] — 服务器权威验证技能激活请求
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## Relationship to Agent
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[[UnrealMultiplayerArchitect]] 强调：GAS 网络集成必须从双路径初始化开始，测试必须在 150ms 模拟延迟下验证技能激活，"Profile GAS replication overhead" 是网络优化的关键步骤。
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[[UnrealSystemsEngineer]] 补充：系统架构师负责 UGameplayAbility/UAttributeSet C++ 实现和 BlueprintCallable 暴露；Tick 依赖逻辑必须 C++（即使是技能冷却检查）；AttributeSet 使用 FGameplayAttributeData + GAMEPLAYATTRIBUTE_REPNOTIFY 宏保证复制安全。
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## Aliases
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- Gameplay Ability System
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- UE5 GAS
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- AbilitySystemComponent
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- FPredictionKey
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- GameplayEffect
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- AttributeSet
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