Blueprint Reference

A reference for the main blueprints you'll touch as a designer — what each one is, its most important instance-editable properties, and the functions worth knowing. It deliberately skips internal helpers; for why the pieces fit together see How It Works.

Every variable has a tooltip

This page covers the headline properties. In-editor, hover any variable for its full description and tuning guidance — the tooltips are the exhaustive reference.

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Navigation

BP_DroneNavManager

Actor — place exactly one per level. Owns the navigation graph and answers path queries.

Key Properties

Property	Type	Description
TraceRadius	Float (105)	Clearance an edge needs to be valid = drone radius + ~30 corner margin. Keep equal to the volume's NodeClearanceRadius.
ObstacleTraceChannel	Trace Channel (Visibility)	The channel used for all clearance/LOS traces. The drone must be transparent to it — see Collision Setup.
UsePathSimplification? / UsePathSmoothing?	Boolean	Post-process the raw A* path (string-pull + corner-cut). On by default.
DrawCalculatedPath?	Boolean	Runtime: draw every computed path (yellow line, green start, red goal). See Debugging.
DrawNearestNodeSearch?	Boolean	Visualise the start/goal node snap — useful for edge-of-volume "Path Not Found".
DrawDebug	Boolean	Draw node locations at runtime. Off for shipping.

Key Functions

Function	When	Description
Bake Navigation	Editor button	Builds the graph from your volumes and writes it into the data asset. Run after any geometry/volume/clearance change.
Show / Hide Nav Graph	Editor button	Draws the baked graph in the viewport (green = connected, red = isolated, blue = links).
FindPath	Runtime	The A* query. Called for you by the follower — you won't call it directly.

Connection distance lives on the volumes, not here. The manager no longer has a global MaxConnectionDistance — each volume derives its own from GridSpacing (see below), and the manager links each node at its source volume's reach. So dense and sparse volumes mix in one graph.

BP_DroneNavVolume

Actor — place one or many. Defines a region of airspace and fills it with candidate nodes at bake time.

Key Properties

Property	Type	Description
GenerationBounds	Box Component (root)	The sampled region. Resize it with the Box Extent; place/rotate the actor to position it. It's the actor's root, so the box can't be moved out of alignment with the actor.
GridSpacing	Float (200)	Distance between candidate nodes — the density knob. Smaller = denser graph (better routes, slower bake).
ConnectionDistanceRatio	Float (1.9)	Multiplier from GridSpacing to the linking distance. Clamped to ≥ 1.732 (the √3 floor), so the graph can't fragment. Rarely changed.
MaxConnectionDistance	Float (derived, read-only)	GridSpacing × max(ConnectionDistanceRatio, 1.732) × actor scale. Computed in the Construction Script — don't edit it; it updates live as you change GridSpacing.
NodeClearanceRadius	Float (105)	Empty space a node needs to survive. Match the manager's TraceRadius.
MaxGeneratedNodes	Int (500)	Safety cap on nodes per volume.
ShowFitPreview? / AgentRadius	Bool / Float	Editor preview of where the agent fits inside the volume.
DrawDebug / DrawDebugDuration	Bool / Float	Draw generated node positions.

Volumes never run on their own — the manager samples them during Bake Navigation. Place big sparse volumes (large GridSpacing) over open areas, smaller denser ones near complex geometry; they can overlap/abut and the graph stitches across them. Tuning is inline on the volume — there's no separate config asset. See Tuning.

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Movement

BP_DronePathFollowerComponent

Actor Component — the reusable movement engine. Lives on BP_AIDrone; attach to any pawn to make it fly paths.

Key Properties

Property	Type	Description
MoveSpeedChase	Float (450)	Cruise speed while pursuing a target.
MoveSpeedPatrol	Float (250)	Cruise speed while patrolling.
MaxAcceleration	Float (500)	How fast velocity can change. Lower = heavier/more inertial; higher = snappier. The only corner-rounding in the pipeline.
AcceptanceRadius	Float (100)	How close counts as "arrived." Set ≈ the drone's body bounds — too small and it wedges in gaps narrower than itself.
MaxSearchDistance	Float (2000)	How far the start/goal may be from the graph before a query fails.
UseLocalAvoidance?	Boolean	Reactive steering around obstacles between waypoints.
AvoidanceProbeDistance / AvoidanceProbeRadius	Float (200 / 80)	The forward probe that detects obstacles. Lower the distance for thin obstacles so it doesn't over-react.
AvoidanceStrength	Float (0.3)	0 = ignore obstacles, 1 = steer fully sideways, ~0.5 = arc around.

Key Functions & Events

Member	Kind	Description
RequestPathToLocation	Function	Asks the manager for a path and starts following it. Driven by the brain via the interface — not called directly.
FollowWaypoints	Function	Follows an exact waypoint list without pathfinding (used by patrol).
OnPathCompleted	Event (dispatcher)	Fires on arrival. The pawn relays it as OnReachedDestination (the patrol heartbeat).

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Drone pawn & brain

BP_AIDrone

Pawn — the drone body. Implements BPI_ControllableDrone; owns movement, facing, visual banking, and rotor audio.

Key Properties

Property	Type	Description
PatrolPath	BP_PatrolPath ref	The one you'll set most. Assign a patrol path and the drone patrols it when no target is in sight. Leave empty for chase-only.
TurnSpeed	Float	How quickly the drone rotates toward its facing target (≈4–6). Never 0 (= instant snap).
MaxBankAngle	Float (40)	Max visual roll/pitch lean into acceleration.
BankInterpSpeed	Float (2.0)	How smoothly the body eases into a bank.
AccelSmoothSpeed	Float (8)	Low-pass on the acceleration estimate that drives banking — higher = snappier, lower = smoother (anti-wobble knob).
Idle/Max Pitch & Volume Multipliers	Float	Rotor-audio pitch + volume at hover vs top speed; the hum lerps between them by current speed.

Components & Events

• Hierarchy: SphereCollision (root) → BodyMount (the banking pivot) → mesh + RotorAudio.
• OnReachedDestination — event dispatcher the brain (patrol) listens to; relayed from the follower's OnPathCompleted.

Collision is preconfigured

The root SphereCollision already ignores the nav trace channel (required for pathfinding) — you don't need to set it up for the included drone. Revisit it only if you build a custom pawn or resize the sphere, in which case keep TraceRadius / NodeClearanceRadius matched to it. See Collision Setup.

BP_AIDroneController

AIController — the brain. Senses the target, owns target memory, and runs BT_AIDrone. Commands the pawn only through the interface.

Key Properties

Property	Type	Description
FriendlyTag	Name (Team A)	Actors carrying this tag are treated as friendly and never chased. Give your player, allied NPCs, or anything the drone should ignore this tag.
CanSpotEnemies?	Boolean (true)	Master detection switch. Set to false and the drone goes blind — it ignores every actor and just patrols. Toggle it at runtime to enable/disable hunting.
MemoryDuration	Float	How long a lost target is remembered before giving up and returning to patrol.
SearchStartDelay	Float	Grace period after losing sight before it leaves the hover spot to actively investigate.
DesiredHoverHeight / DesiredApproachDistance	Float	Where the chase hover spot sits relative to the target (above + offset toward the drone's side).
RepathInterval / MoveGoalUpdateThreshold	Float	Re-path throttle — minimum time + goal-movement before requesting a new path (prevents jitter).
Scan: ScanYawRange / ScanYawSpeed / ScanLookDistance / ScanArriveRadius	Float	The left-right facing sweep while searching a last-known location.
DrawDebug?	Boolean	Controller-side debug draws.

Who counts as an enemy: an actor is hostile only when it is a Character (or subclass) and does not carry FriendlyTag. Non-Character actors (props, pickups, other drones) are never targeted, so you don't need to tag the whole level — just tag the Characters you want spared.

The controller runs BT_AIDrone (a priority selector: Chase → Search → Patrol → Idle) with BB_AIDrone as its blackboard. You normally won't edit the tree; tune behaviour through the properties above. See How It Works.

BPI_ControllableDrone

Interface — the only vocabulary the brain uses to command the body. Implement it to drive a custom drone pawn.

Message	Description
MoveToLocation	Path to a world location (chase/search) via the nav graph.
FollowWaypointPath	Follow an exact waypoint list (patrol), bypassing the graph.
SetMovementMode	Switch between Patrol / Chase speed modes.
SetFocusLocation / ClearFocus	Face a world point / return to facing travel direction.
Stop	Halt and clear the current path.

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Combat (optional)

BP_DroneWeaponComponent

Actor Component — the reusable weapon. Add it to a drone to let it shoot; a drone without it never fires. See Combat.

Key Properties

Property	Type	Description
Damage	Float (10)	Damage dealt per landed shot, via Unreal's Apply Point Damage.
DamageTypeClass	Class (DamageType)	Tags the damage so your health system can branch per type.
FiringRange	Float	How close the drone must be to open fire.
FireInterval	Float	Seconds between shots (rate of fire).
FireAimTolerance	Float	How tightly aimed the body must be before firing (wider = harder to juke out of).
MuzzleSocketPrefix	Name	Resolves the gun's muzzle sockets on the mesh at BeginPlay (multi-barrel).
WeaponObjectTypes	Array of Object Type	What a shot can hit. Default WorldStatic / WorldDynamic / Pawn — enemies (Pawns/Characters) are hit with no collision setup; world geometry blocks (cover).
ProjectileFX	Niagara (NS_projectile)	The projectile/tracer visual spawned per barrel. Multicast to all clients.
ProjectileSpeed	Float	Travel speed of the tracer.
MuzzleFX / ImpactFX / FireSound	Niagara / Sound	Per-shot effects you assign.
DrawDebug?	Boolean	Draw the shot traces. Off for shipping.

Key Functions & Events

Member	Kind	Description
OnHitTarget	Event (dispatcher)	Broadcast on the server each shot that lands: (HitActor, DamageAmount, Hit, HitDirection). Bind it to hook hits into your own systems.
StartFiring / StopFiring	Function	Begin/stop the firing timer. Driven by the brain — you won't call them directly.
IsInFiringRange / IsAimedAt	Function	The engage gates (range; body-forward aim).

Two ways to take damage. On your target, implement Event AnyDamage / OnTakePointDamage (engine-standard, works with any actor) or bind OnHitTarget on the drone's weapon. Both fire on the server — reduce a replicated health value there.

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Patrol authoring

BP_PatrolPath

Actor — a spline route with optional hold markers.

Property	Type	Description
Markers	Array of BP_PatrolHoldMarker	Optional pause points; the path snaps each onto the spline.
SampleSpacing	Float (25–50)	How finely the spline is sampled into waypoints — the live corner-smoothness lever (smaller = smoother).
SnapMarkersInEditor?	Boolean	Re-snaps markers onto the spline in the editor. Keep on.
ShowFitPreview? / AgentRadius	Bool / Float	Draws a clearance preview along the spline (green = fits, red = clips). Set AgentRadius to the drone's radius.
ShowPathDebug	Boolean	Draw the spline + markers at runtime.

BP_PatrolHoldMarker

Actor — a point on a patrol path where the drone pauses.

Property	Type	Description
HoldDuration	Float (3.0)	Seconds to pause (0 = fly through).
UseLookDirection?	Boolean	While paused, face the marker's own facing — rotate the marker actor to aim it (the arrow shows the direction). Otherwise the drone keeps facing its travel direction.
SplineDistance	Float	Auto-filled by the path's Construction Script — do not hand-edit.

See Patrol for the authoring workflow.

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Editor tools

BakeDroneNav (Editor Utility Widget)

Right-click → Run Editor Utility Widget. Buttons: Bake Navigation and Show / Hide Nav Graph. This is the main authoring surface for the nav graph — see Quick Start.