8bc731e5ae
- Updated Master Blueprint Index to include Multiplayer Networking support. - Added detailed Multiplayer Networking sections across all developer documentation (01-11). - Introduced authority maps, key patterns, and RPC guidelines for each system. - Established a comprehensive multiplayer networking architecture document outlining core principles, replication strategies, and anti-cheat considerations. - Enhanced UI documentation to clarify local-only behavior and binding to replicated dispatchers. - Implemented client prediction strategies and RPC naming conventions for consistency across the framework.
148 lines
9.4 KiB
Markdown
148 lines
9.4 KiB
Markdown
# 09 — AI, Perception & Encounters Systems (Systems 80-88)
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**Category Purpose:** These 9 systems form the enemy AI layer — base enemy character, patrol paths, alert state management, AI state machine, controller with behavior tree, blackboard definition, memory/last-known-location tracking, perception (sight/hearing/damage), and behavior variant selection. The `AI_BaseAgentController` runs behavior trees; all AI logic is data-driven via blackboard keys and behavior variants.
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---
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## System Index
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| # | System | Asset Type | Role |
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|---|--------|-----------|------|
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| 80 | `BP_EnemyBase` | Actor (Character) | Enemy base character; health, combat, patrol, death |
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| 81 | `BP_PatrolPath` | Actor | Patrol path spline; waypoints, wait times, loop |
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| 82 | `BPC_AlertSystem` | Component | AI alert states: Suspicious → Alerted → Combat |
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| 83 | `BPC_AIStateMachine` | Component | AI state machine: Patrol/Search/Combat/Flee |
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| 84 | `AI_BaseAgentController` | Controller | Base AI controller; behavior tree runner, perception init |
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| 85 | `BB_AgentBoard` | Blackboard | AI blackboard definition; all keys for enemy AI |
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| 86 | `BPC_AIMemorySystem` | Component | AI memory; last known locations, threat history |
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| 87 | `BPC_AIPerceptionSystem` | Component | AI perception; sight, hearing, damage sense |
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| 88 | `BPC_BehaviourVariantSelector` | Component | Behavior variant selection; weighted random from dataset |
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---
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## AI Architecture
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```
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┌──────────────────────────────────────────────────────────────────┐
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│ AI PIPELINE │
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│ │
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│ AI_BaseAgentController (AIController) │
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│ │ Runs Behavior Tree defined in BB_AgentBoard │
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│ │ Initializes perception system │
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│ │ │
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│ ├─► BPC_AIPerceptionSystem (senses) │
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│ │ Sight: vision cone, distance, light level │
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│ │ Hearing: sound events (gunshots, footsteps) │
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│ │ Damage: takes damage → knows attacker location │
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│ │ Team awareness: allies share detection │
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│ │ │
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│ ├─► BPC_AIMemorySystem (memory) │
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│ │ Last known player location │
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│ │ Threat history (who damaged me?) │
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│ │ Investigation points (where to search) │
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│ │ Forgets old data after configurable time │
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│ │ │
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│ ├─► BPC_AlertSystem (alert level) │
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│ │ Suspicious → (investigate) → Alerted → (engage) │
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│ │ → Combat → (player lost) → Search → (timeout) → Patrol │
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│ │ Flee: low health threshold triggers retreat │
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│ │ │
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│ └─► BPC_AIStateMachine (behavior state) │
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│ Patrol → Search → Combat → Flee │
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│ State transitions driven by alert level + memory │
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│ │
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│ BPC_BehaviourVariantSelector │
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│ │ Selects behavior variant at spawn: │
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│ │ Attack patterns (aggressive, defensive, flanking) │
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│ │ Patrol style (predictable, random, stationary) │
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│ │ Aggression level (cautious, balanced, reckless) │
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│ └─► Weighted random from DA_BehaviourVariant dataset │
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│ │
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│ BP_PatrolPath │
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│ └─► Spline-based path with waypoints and wait times │
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└──────────────────────────────────────────────────────────────────┘
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```
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---
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## 82 — BPC_AlertSystem: Alert States
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**What It Does:** Manages the enemy's alert progression — how aware they are of the player's presence. Drives behavior tree transitions and audio/visual feedback.
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**Alert Levels:**
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- `None`: Unaware, patrolling normally
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- `Suspicious`: Heard something, saw a glimpse — investigates last known location
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- `Alerted`: Confirmed player presence — moves to engage
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- `Combat`: Actively fighting — shooting, chasing, flanking
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- `Search`: Lost sight of player — searches last known area
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- `Flee`: Health critical — retreats to safety
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**Escalation:** Suspicion meter fills based on perception events. Partial sight = slow fill, full sight = fast fill, loud noise = burst fill. De-escalation: meter decays over time when no stimuli.
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---
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## 87 — BPC_AIPerceptionSystem: AI Senses
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**What It Does:** Wraps UE5's AI Perception system with game-specific logic. Handles sight (vision cone + distance + light level), hearing (sound event radius + type priority), damage sense (instant alert on hit), and team awareness (nearby allies share detection).
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**Sight:** Vision cone angle, max distance, peripheral vision penalty, light level modifier (harder to see in darkness), obstruction (line of sight trace)
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**Hearing:** Gunshot > footstep > door creak. Louder sounds have larger radius. Running is louder than walking. Silenced weapons have reduced radius.
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**Team Awareness:** If one enemy in a group detects the player, all nearby allies are alerted to the player's approximate position.
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---
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## 80-88: Remaining Systems
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- **80 BP_EnemyBase:** Character with health component, combat capability, patrol behavior, and death handling. Implements `I_Damageable`.
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- **81 BP_PatrolPath:** Spline component with waypoints. Each waypoint has wait time, look direction, and optional animation.
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- **83 BPC_AIStateMachine:** Discrete state machine: Patrol→Search→Combat→Flee. Transitions driven by blackboard values set by AlertSystem and PerceptionSystem.
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- **84 AI_BaseAgentController:** Custom AIController that runs the behavior tree, initializes perception, and manages the blackboard.
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- **85 BB_AgentBoard:** Blackboard Data Asset defining all keys: TargetActor, LastKnownLocation, AlertLevel, CurrentState, PatrolPath, HomeLocation, etc.
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- **86 BPC_AIMemorySystem:** Stores last known player location, threat sources, investigation points. Data decays over configurable time. Behavior tree queries memory to decide search patterns.
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- **88 BPC_BehaviourVariantSelector:** At spawn, selects a behavior variant from `DA_BehaviourVariant` with weighted random. Determines attack patterns, patrol style, and aggression. Creates enemy variety without separate classes.
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---
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## Common Implementation Patterns in This Category
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1. **Behavior Tree + Blackboard:** All decision-making in behavior trees reading blackboard keys. Components write to blackboard; trees read and act.
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2. **Alert Cascade:** Suspicious → Alerted → Combat → Search → Patrol. Each state has different behavior tree branches.
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3. **Memory with Decay:** AI doesn't have infinite memory — last known locations are forgotten after time. Forces re-investigation.
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4. **Perception Sharing:** Team awareness prevents "why didn't his friend react?" — nearby allies share detection.
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5. **Behavior Variants for Variety:** Weighted random selection at spawn means enemies of the same class behave differently — no hardcoded enemy types.
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---
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## Multiplayer Networking
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### AI is Server-Only
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**All AI logic runs on the server.** Behavior trees, perception, memory, and state machines execute on the server only. Clients receive:
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- **Position/Rotation/Animation:** via standard Actor replication
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- **Alert level:** replicated for client awareness UI (detection meter, investigation icon)
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- **Health:** replicated for client health bars
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- **Perception events:** replicated for client awareness indicators only (cosmetic)
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### Category Authority Map
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| System | Runs On | Replicated To Clients |
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|--------|---------|----------------------|
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| `AI_BaseAgentController` | Server | Position, rotation, animation |
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| `BP_EnemyBase` | Server | Health, state, mesh |
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| `BPC_AlertSystem` | Server | Alert level enum for UI |
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| `BPC_AIStateMachine` | Server | Current state for animation |
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| `BPC_AIPerceptionSystem` | Server | Detection events → client awareness indicators |
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| `BPC_AIMemorySystem` | Server | LastKnownLocation → client investigation UI |
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| `BPC_BehaviourVariantSelector` | Server (at spawn) | Variant choice for client animation matching |
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| `BP_PatrolPath` | Read-only | Spline data is static; identical on all clients |
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### Client Awareness
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- Clients receive perception events (enemy detected player, heard sound) as **cosmetic indicators** — red detection bar, investigation icon, audio cue.
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- The actual AI behavior (investigate, engage, flee) runs on server only.
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- Clients never run behavior trees — they only display the results.
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---
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*Developer Reference v1.0 — 09 AI Systems. Companion to docs/blueprints/09-ai/ specs.*
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