Make an aimable target

Targets must implement BPI_AutoAim so the player’s Get Auto Aim Interface call succeeds. This guide follows ThirdPersonCharacter_NPC from the demo map.

flowchart LR
  Trace["Start Trace box hit"]
  Hit["Hit Target actor"]
  BPI["BPI_AutoAim"]
  Mesh["Skeletal Mesh Component"]
  Socket["Get Socket / Socket Location"]
  Aim["Set Look At Target Location"]

  Trace --> Hit
  Hit --> BPI
  BPI --> Mesh
  Mesh --> Socket
  Socket --> Aim

Why the interface is required

Start Trace stores the hit actor as Hit Target. Each tick the player calls Get Auto Aim Interface — that only succeeds when the actor implements BPI_AutoAim.

Without it:

• The interface cast fails
• Set Look At Target Location never receives a valid socket point
• On Auto Aim Failed may fire with an error message

1. Add the interface

1. Open your enemy / NPC Character Blueprint (must have a Skeletal Mesh component).
2. Class Settings → Interfaces → Add → BPI_AutoAim (Blueprints/Main/BPI_AutoAim).
3. Compile — Unreal adds Get Skeletal Mesh Component to implement.

2. Implement Get Skeletal Mesh Component

In Get Skeletal Mesh Component:

1. Get Mesh (character skeletal mesh component).
2. Return it on the function output.

3. Sockets

With Override Socket Name = None on the player’s component, Get Socket picks the closest socket to the trace hit.

To force a bone every time, set Override Socket Name on the player’s Auto Aim Component (e.g. your head socket). If the name does not exist on the mesh, aiming fails.

4. Trace object types

Default Types To Trace is Pawn only. Targets must be Character / Pawn actors, or you must add their object type to Types To Trace.

5. Exclude actors from traces

Call Set Actors To Ignore at Begin Play on the player’s component with the player (and allies) so the trace does not lock onto yourself.

Worked example — ThirdPersonCharacter_NPC

The demo map spawns four NPC instances (ThirdPersonCharacter_NPC_2, ThirdPersonCharacter_NPC2, etc.). All use the same Blueprint.

1. Open the reference Blueprint

Path: Content/AutoAimComponent/Blueprints/ThirdPersonCharacter_NPC

• Parent class: Character
• Graphs include GetSkeletalMeshComponent (interface implementation)

2. Verify interface

1. Class Settings → Interfaces — BPI_AutoAim is listed.
2. Open Get Skeletal Mesh Component — returns Mesh component.

3. Place in your test map

1. Drag ThirdPersonCharacter_NPC into your level (or duplicate the setup from AutoAimComponentExampleMap).
2. Ensure your player has the lock-on wiring.

4. Playtest checklist

Step	Expected result
Hold Start Targeting on NPC at < 3000 units	On Auto Aim Started fires
Camera while held	Smooth rotation toward closest socket
Release Start Targeting	On Auto Aim Ended fires
Aim at floor, press Start Targeting	On Auto Aim Failed

5. Example — duplicate for a new enemy

1. Duplicate ThirdPersonCharacter_NPC → BP_MyShooterEnemy.
2. Keep BPI_AutoAim and Get Skeletal Mesh Component unchanged.
3. Swap mesh / animations as needed — sockets must exist on the new skeleton.
4. Place in level and test lock-on from your wired player.

Troubleshooting

Symptom	Check
No lock on NPC	BPI_AutoAim added? Mesh returned from interface?
Lock fails at range	Within Trace Distance?
Wrong body part	Set Override Socket Name or adjust trace aim point
Locks through walls	Enable Check Line Of Sight

Next

• Play the demo — run the reference map
• Use Distance Angle Check + CT_DistanceBasedAngle → Component reference