Targeting Guide

Complete guide to implementing combat targeting using ElysPerceptionPlugin.

Overview

The targeting system builds on top of Perception via the UERPDomainComponent base class. UERPTargetingComponent provides eligibility validation using IERPTargetable interface and targeting rules, along with descriptor tracking.

Architecture:

• Perception: Evaluates candidates via configurable pipeline
• Domain (Targeting): UERPTargetingComponent extends UERPDomainComponent, validates eligibility
• Presentation: Your implementation (UI indicators, lock-on camera, etc.)

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Basic Setup

1. Configure Targeting Pipeline

On your PlayerController or Pawn, configure ERPPerceptionComponent:

Target Pipeline Settings:

• Channel Id: Target
• Default Sampling Range: 3000.0
• Sampler: ERPSphereOverlapSampler
  • Trace Channel: Visibility
  • Ignore Context Actor: check
• Filters: ERPTargetableFilter
• Scorers:
  • ERPDistanceScorer (normalize by range), Weight: 1.0
  • ERPConeScorer (optional, for camera-aware targeting), Weight: 0.5
• Resolver: ERPResolverBase (lowest score wins)

2. Add Targeting Component

Add ERPTargetingComponent to your PlayerController or Pawn:

• Channel Id: Target (must match pipeline)
• Rules: (optional instanced targeting rules)

3. Implement Targetable Interface

On target actors (enemies, NPCs, destructibles):

Blueprint:

1. Class Settings -> Interfaces -> Add ERPTargetable
2. Implement Can Be Targeted By -> return true (or custom logic)
3. Optionally implement Get Target Descriptor -> return a UERPTargetDescriptor data asset

C++:

class AYourEnemy : public ACharacter, public IERPTargetable
{
    GENERATED_BODY()

public:
    virtual bool CanBeTargetedBy_Implementation(AActor* TargetingActor) const override
    {
        return bIsAlive;
    }

    virtual UERPTargetDescriptor* GetTargetDescriptor_Implementation() const override
    {
        return TargetDescriptor; // Optional DataAsset
    }

protected:
    UPROPERTY(EditAnywhere) bool bIsAlive = true;
    UPROPERTY(EditAnywhere) UERPTargetDescriptor* TargetDescriptor = nullptr;
};

4. Bind Events

// In BeginPlay
TargetingComponent->OnDomainCandidateChanged.AddDynamic(this, &AMyPC::OnTargetChanged);
TargetingComponent->OnDescriptorChanged.AddDynamic(this, &AMyPC::OnTargetDescriptorChanged);

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Blueprint Example

Complete Targeting System

Components on PlayerController:

• ERPPerceptionComponent (target pipeline configured)
• ERPTargetingComponent (channel: "Target")

Event Graph:

// Handle target change
Event: OnDomainCandidateChanged (Previous, New, ChannelId)
  -> Set CurrentTarget = New
  -> Branch: IsValid(New)
    True:
      -> Show Target Indicator Widget
      -> Set Widget position to target actor
    False:
      -> Hide Target Indicator Widget

// Attack current target
Input Action: Attack
  -> TargetingComp -> GetCurrentCandidate
  -> IsValid?
    True: -> Execute attack on target
    False: -> Execute untargeted attack

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Targeting Rules

Add instanced UERPTargetRule objects for composable validation:

UCLASS(Blueprintable, EditInlineNew)
class UMyTeamRule : public UERPTargetRule
{
    GENERATED_BODY()
public:
    virtual bool CanTarget_Implementation(AActor* Instigator, AActor* Target, FName ChannelId) const override
    {
        // Only target enemies (different team)
        ITeamAgentInterface* InstigatorTeam = Cast<ITeamAgentInterface>(Instigator);
        ITeamAgentInterface* TargetTeam = Cast<ITeamAgentInterface>(Target);
        if (InstigatorTeam && TargetTeam)
        {
            return InstigatorTeam->GetGenericTeamId() != TargetTeam->GetGenericTeamId();
        }
        return true;
    }
};

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Pipeline Configurations

Distance-Only Targeting

Simple nearest-enemy targeting:

Sampler: ERPSphereOverlapSampler (range: 2000)
Filter: ERPTargetableFilter
Scorer: ERPDistanceScorer (weight: 1.0)
Resolver: ERPResolverBase

Camera-Aware Targeting

Prefers enemies near crosshair:

Sampler: ERPSphereOverlapSampler (range: 3000)
Filter: ERPTargetableFilter
Scorers:
  - ERPDistanceScorer (weight: 1.0)
  - ERPConeScorer (cone: 45 degrees, weight: 1.5)
Resolver: ERPResolverBase

Screen-Space Targeting

Lock-on to enemy nearest screen center:

Sampler: ERPSphereOverlapSampler
Filter: ERPTargetableFilter
Scorer: ERPViewportEllipseScorer (weight: 1.0)
  - Enable bProvideViewportInfoWhenAvailable on PerceptionComponent
Resolver: ERPResolverBase

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UERPTargetDescriptor

Target descriptors are UDataAsset-based objects that describe targeting properties:

UCLASS(BlueprintType)
class UERPTargetDescriptor : public UDataAsset
{
    GENERATED_BODY()
public:
    UPROPERTY(EditAnywhere, BlueprintReadOnly) FText DisplayName;
    UPROPERTY(EditAnywhere, BlueprintReadOnly) TSoftObjectPtr<UTexture2D> Icon;
    UPROPERTY(EditAnywhere, BlueprintReadOnly) FGameplayTagContainer TargetTags;
    UPROPERTY(EditAnywhere, BlueprintReadOnly) TMap<FName, TObjectPtr<UObject>> PresentationHints;
};

Use descriptors to drive UI without coupling to specific actor types.

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Widget Integration

The plugin provides UERPTargetingWidgetBase for targeting UI (reticles, lock-on indicators, info panels).

Pattern	Description	Key Hooks
Target Reticle	Lock-on marker positioned on target	OnTargetActiveChanged, tick for positioning
Target Info Panel	Nameplate with name, icon, health	OnDescriptorUpdated, OnTargetActorChanged

Quick wiring (presenter on your PlayerController):

Event: OnDomainCandidateChanged (Previous, New, ChannelId)
  -> TargetWidget -> SetTargetActor(New)
  -> TargetWidget -> SetTargetActive(IsValid(New))

Event: OnDescriptorChanged (Candidate, Descriptor, ChannelId)
  -> TargetWidget -> UpdateFromDescriptor(Descriptor)

For complete step-by-step walkthroughs including screen-space positioning, descriptor-driven styling, and health bar integration, see the Widget Guide.

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Compared to ChannelListenerComponent

Feature	ERPTargetingComponent	ERPChannelListenerComponent
Eligibility validation	IERPTargetable + Rules	None
Descriptor tracking	Yes	No
Base class	UERPDomainComponent	UActorComponent
Use case	Full targeting domain	Lightweight event mirror

Use ERPChannelListenerComponent when you only need raw perception events without eligibility checks.

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Next Steps

Build your targeting UI with Widget Guide.

Set up interactions with Interaction Guide.

Create custom domains with Custom Domains.

Check complete API in API Reference.