Add an AI to your level¶

Two AI characters ship with the template: a human and an infected. You put one in your level by dragging it in and picking a Data Asset in the Details panel. There is no controller to assign, no Behavior Tree to hook up, and no graph to open.

The human: Content/TheLastTemplate/Blueprints/AI/NPC/BP_NPCCharacter
The infected: Content/TheLastTemplate/Blueprints/AI/Zombie/BP_ZombieCharacter

The infected is not a child of the human. They are two separate characters built from the same components, so a change on one does not follow to the other.

Place a human enemy¶

Drag BP_NPCCharacter from the Content Browser into your level.
Select it. In the Details panel, set Data NPC to one of the presets in Content/TheLastTemplate/Blueprints/DataAssets/AI/Childs/.
Add a NavMeshBoundsVolume over the ground the AI should walk on, and scale it to cover the area. Press P in the viewport to draw the navigation in green.
Play.

That is the whole job. AI Controller Class is already BP_NPCController and Auto Possess AI is already Placed in World or Spawned, so the character takes control of itself when the level starts.

If you place the character on ground with no navigation under it, it will stand still forever and never chase anything. That is the single most common reason an AI looks broken.

Place an infected¶

Same four steps with BP_ZombieCharacter, plus one field.

Set Zombie Data on a placed infected

BP_ZombieCharacter has two Data Asset fields. Data NPC ships filled with DA_Zombie_Roaming, but Zombie Data ships empty. Set it to DA_Zombie_Roaming as well. That asset carries the melee fields the infected needs: Attack Damage, Strike Bone and Attack Montage.

The presets that ship¶

Five presets live in Content/TheLastTemplate/Blueprints/DataAssets/AI/Childs/.

Preset	What it does when nothing is hostile	Weapon	Faction
`DA_NPC_Roaming`	Wanders around where you placed it	`BP_Weapon_Pistol_01`	`DA_Faction_Hunters`
`DA_NPC_Melee_Roaming`	Wanders, fights with its fists	none	`DA_Faction_Hunters`
`DA_NPC_Path`	Walks a patrol path called `Path_01`	`BP_Weapon_Pistol_01`	`DA_Faction_Hunters`
`DA_NPC_Stand`	Goes to a stand point called `Stand_01` and holds it	`BP_Weapon_Pistol_01`	`DA_Faction_Hunters`
`DA_Zombie_Roaming`	Wanders, attacks bare handed	none	`DA_Faction_Infected`

DA_NPC_Stand is what a fresh BP_NPCCharacter starts with, so a character dropped in without any editing looks for a stand point named Stand_01.

An unarmed enemy is not a mode. It is a preset with Default Weapon Class left empty, which is exactly what DA_NPC_Melee_Roaming does.

The four NPC presets are the same asset with three or four fields moved. Duplicate the closest one and change those fields rather than starting from BP_NPCDataAsset. Every field is listed in The AI settings asset.

Which side it fights for¶

An AI's side is not set on the placed character. It is the Faction field inside its Data Asset. Pick a preset and you pick a side.

Three factions ship, and each one lists the other two in its Hostile Factions, so everything hostile fights everything else hostile. If your AI ignores you entirely, this is the first thing to check. See Factions and who fights who.

What it does when nothing is hostile nearby¶

The Idle Pattern field of the Data Asset picks one of four behaviours.

`Idle Pattern`	What happens	Field it reads
`None`	No idle behaviour at all	none
`Path`	Walks a list of waypoints in order	`Path Id`
`Roaming`	Picks points around itself and walks to them	`Roam Zone Id`, `Roam Min Radius`, `Roam Max Radius`
`StandPoint`	Walks to one marker and stays there	`Stand Point Id`

The three ids are plain text, matched against markers you place in the level. Nothing references anything, so you can add and move markers freely.

Marker	Field to fill	Use
`BP_AIPath`	`Path Id`, `Path Index`	One actor per waypoint. Same `Path Id`, ordered by `Path Index`
`BP_AIRoamZone`	`Zone Id`	A sphere the AI stays inside while roaming
`BP_AIStandPoint`	`Point Id`	A single spot to hold

All three are in Content/TheLastTemplate/Blueprints/Environments/AI/. Full detail in Patrol paths, roam zones and stand points.

An id is only read when Idle Pattern matches it. A Stand Point Id sitting in a preset set to Roaming does nothing.

What the character already carries¶

You do not add any of these. They are on both characters when you drag one in.

Component	What it gives you
`BP_AIBrain`	Reads the Data Asset, tracks the current target and decides idle, search, ranged or melee
`BP_FactionComponent`	Who this character is hostile to
`BP_CombatComponent`	Melee attacks, dodges and stealth finishers
`BP_VitalsSystem`	Health, and dying
`BP_HitReactionManager`	Physical reaction to being hit, and ragdoll
`BP_FallDamageComponent`	Damage from falling
`BP_NPCWeaponManager`	Holding, firing and reloading a gun. Human only

Use your own mesh¶

Make a child of BP_NPCCharacter or BP_ZombieCharacter, swap the Skeletal Mesh on the child, and place that instead. Keep the Animation Blueprint. If your mesh uses a different skeleton, you need to retarget the animations, which is the longer job covered in Add a new enemy type.

If nothing happens¶

Work down this list. One of them is almost always the answer.

No navigation. Press P. If there is no green under the AI, it cannot move a step.
Data NPC is empty. With no Data Asset there is no Behavior Tree, no faction and no ranges. The AI stands there.
Zombie Data is empty on a placed infected.
Nobody is hostile. An AI only reacts to factions listed in its faction's Hostile Factions.
Use Sight or Use Hearing is off in the Data Asset. Both ship on, but a preset you edited may have lost one.
Auto Possess AI was changed. It must stay on Placed in World or Spawned, or the character never gets a controller.
The AI has a gun but no ammunition. Starting Reserve Ammo at 0 gives you an enemy that draws a weapon and never fires.

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