Architecture

This page summarizes systems and patterns used in the UE platformer.

The following content is sourced from Docs/architecture.md:

Guiding principles

Composition over inheritance; small focused components.
Data-driven design via Primary Data Assets (tuning); Blueprints for presentation.
Clear interfaces for capabilities (Interactable, Damageable, Talkable, etc.).
Event-driven updates; avoid Tick unless necessary.

Core modules/classes

Character & Camera
- APlatformCharacter (derived from ACharacter)
  - Components: USpringArmComponent, UCameraComponent, UStatsComponent, UInteractionComponent
  - Input: Enhanced Input (IMC_Player)
- UPlayerCameraSettings (Data Asset) for camera tuning
Interaction System
- UInteractionComponent: performs line/sphere traces; manages current focus target
- IInteractable: interface with GetInteractionVerb, CanInteract, Interact
- Widget prompt: UUserWidget (WBP_InteractPrompt)
Stats & Damage
- UStatsComponent: Health, Stamina, optional Shield; regen settings
- IDamageable: ApplyDamage, OnDeath delegate
- Damage types via UDamageType subclasses (e.g., Melee, Ranged)
NPCs
- ABaseNPC: pawn/character with UStatsComponent, UCapsuleComponent, UWidgetComponent for markers
- AFriendlyNPC: adds dialog capability (ITalkable)
- AEnemyNPC: AIController + Behavior Tree (BT_Enemy), Blackboard (BB_Enemy)
AI
- Perception via UAIPerceptionComponent (sight)
- BehaviorTree tasks/services for patrol, chase, attack
- EQS optional for smarter movement
World Interaction
- AInteractiveActor: base for levers, pickups, doors; exposes IInteractable
- ATriggerEventActor: fires gameplay events (delegates) when overlapped or interacted
- Gameplay effects/actions defined as data (UPlatformEffect definition)

Data assets (examples)

UCharacterTuningData: WalkSpeed, AirControl, JumpCount, GravityScale
UCameraTuningData: TargetArmLength, Lag, RotationLag, FOV
UEnemyTuningData: PerceptionRange, AttackRange, AttackCooldown, Damage
UInteractableData: DisplayName, Verb, Cooldown, UIIcon, SFX, VFX

Subsystems

UPlatformerGameInstanceSubsystem: global services (save/load, tag registry)
UPlatformerWorldSubsystem: world-level systems (spawners, registries)

Testing

Functional tests (Gauntlet or Automation Spec) for: movement, interaction prompt, enemy chase, damage/death.

Performance

Avoid per-frame allocations; reserve arrays; reuse timers.
Keep collision channels and queries lean; batch traces when possible.

Logging/Debug

Categories: LogPlatformer, LogAI, LogInteraction
Minimal on-screen debug via DrawDebug helpers, toggled via cvars.

Layers and responsibilities

Input Layer: Enhanced Input mapping context and actions; converts raw input to intent (Move, Look, Jump, Interact, Sprint).
Character Layer: Movement and camera; contains minimal state; delegates features to components.
Systems Layer (Components/Interfaces): Interaction, Stats/Damage, Dialogue, Effects.
AI Layer: Perception, Behavior Trees, Tasks/Services; interacts with Systems layer via interfaces.
Data Layer: Primary Data Assets for tuning; no logic.

Interfaces (contracts)

IInteractable
- GetInteractionVerb() -> FText
- CanInteract(AActor* Instigator) -> bool
- Interact(AActor* Instigator) -> void
IDamageable
- ApplyDamage(const FDamageData&) -> float (actual applied)
- OnDeath: Multicast delegate with killer/instigator
ITalkable (optional)
- BeginDialog(AActor* Instigator) -> void

Dependencies and coupling

Character depends on components via composition; systems accessed via interfaces (no hard cast to concrete types).
AI depends on Blackboard keys and interfaces; no direct references to player character class.
UI (prompts) depends on interfaces and data only; no heavy business logic.

Configuration and cvars (examples)

platformer.CameraLag=12.0
platformer.InteractionRadius=60.0
ai.EnemySightRadius=1800

Error handling

Use ensureMsgf for recoverable config mistakes; checkNoEntry for illegal paths.
Validate Data Assets at load (OnAssetCreated/EditorValidator optional) and at BeginPlay.

Diagrams

System flow (high level)

Input (Enhanced Input)
	└─ IMC_Player (Move, Look, Jump, Interact, Sprint)
				│
				▼
Character (APlatformCharacter)
	├─ MovementComponent
	├─ Camera (SpringArm + CameraComponent)
	├─ UInteractionComponent ──► IInteractable targets
	└─ UStatsComponent ──► IDamageable (apply damage)
				│
				▼
AI / NPCs
	├─ AEnemyNPC + AIController + BT/BB + Perception
	└─ AFriendlyNPC (ITalkable)

Interaction flow

Tick/Timer/Trigger → UInteractionComponent → SphereTrace
	→ Focus target found? → Update prompt (UI)
	→ On Interact Action → IInteractable::CanInteract → IInteractable::Interact
		→ Execute effects (data-driven) → UI feedback (SFX/VFX optional)

Architecture ​

Architecture