Reference

Cheat sheet#

Everything you use daily, on one page.

Setup in five lines#

1. Content Browser › Miscellaneous › Data Asset › Perception Profile    DA_Profile_MyAI
2. The AI's Pawn › Add Component › APS Core                              assign the profile
3. APS Core › Details › Events › +                                      On AI Detect, On AI Lost
4. The player › Add Component › APS Target Component                     (optional: sample points, stance, light)
5. A footstep notify › Emit Sound (Self, DA_Sound_Footstep)              without it, hearing hears nothing

Ten words#

Word	Meaning
Confidence	0 to 1: how sure the AI is that a target is there. Every sense gives one per target each time it runs.
Fused, Smoothed	Fused is this update's combination of the senses. Smoothed drives everything: it rises while a sense reports, holds, and fades only once every sense is silent.
States	Undetected, Suspected, Detected, Tracked, Lost, Remembered, Expired: per target, with an event for each
Awareness	The AI's overall alert level, from its top target: Unaware, Peripheral, Suspicious, Alerted, Fully Aware
Attention target	The one target it focuses on, among those it has noticed. Sticky, so it doesn't flick between two. It may only be suspected: check the state before acting on it
Loss Reason	Why it lost you: OutOfRange, Occluded, SoundFaded, ScentLost, SensorDropout, TargetDestroyed. It decides how to search.
Belief Record	Everything it holds about one target; Get Belief Data returns it
Profile	The data asset with every perception setting for one kind of AI
Evidence	A scripted floor, ceiling, reduction or reset on belief: a disguise, an alibi, a cutscene
Place belief	A belief about a location, not an actor: a noise nobody made

Ten nodes#

Node (APS Core)	Gives	For
Get Attention Target	Actor	Its focus among the targets it has noticed. Chase it only at Suspicious or more (Get Awareness Level for Target)
Get Last Known Position	Vector	Where to search
Get Loss Reason	ELossReason	How to search: branch on it
Get Uncertainty Radius	Float	The search radius; grows while you hide
Get Awareness Level	EAwarenessLevel	Music, weapon poses, the HUD
Get Belief Data	Belief Record	Everything about one target (a meter: its Smoothed Confidence)
Get Sense Contributions	Each sense's share	Did it see me or only hear me?
Emit Sound		A noise the AI can hear (any Blueprint)
Set Target Confidence		Raise belief from script (it never lowers it)
Set Profile		Swap the whole perception setup

Eight events#

Event	Fires when	Typical response
On AI Telegraph	It's about to notice you	A "Hm?", a head turn
On AI Suspect	Something is there	Look, walk over
On AI Detect	It's sure	Alert, take cover, call it in
On AI Track	Locked on	Chase, shoot
On AI Lost	Contact broken	Read Get Loss Reason, then search
On AI Forget	It gave up (Expired), or a target fell back to Undetected	Back to patrol
On Attention Changed	A new focus (maybe one it only suspects)	Re-plan between targets you know are Detected
On AI Damaged	It was hit	React to an unseen attacker

Also: On AI See, On AI Hear, On AI Smell, On AI Feel (touch) and On AI Sense Vibration each time a sense reports; On AI Remember; On AI All Clear when it believes in nobody any more; On AI Awareness Changed; On AI Think Threat when a target's threat level changes, and On Threat Identified when one rises to High or Critical; On Target State Changed for every state change. All events: Events.

More queries#

Node (APS Core)	Gives
Get Top Target, Get Top Target Belief	The best-scoring target it has noticed, this update (it can change often)
Get Targets Sorted by Score	Every actor it holds a belief about, best first
Get Threat Level (Target), Get Highest Threat Level, Has Threat at or Above (Level)	Threat, per target or overall
Get Stimulus Source (Target)	The sense that first made the belief (the current one is the events' Stimulus)
Has Any Detection, Get Active Target Count	Is it aware of anyone; how many actors it is Suspected to Lost about
Get Predicted Position, Get Estimated Velocity, Get Estimated Acceleration (Target)	Where it thinks you're going (Memory)
Get Recent Episodes (Target)	Its last five encounters with you (Memory)
Get Perceived Objects	Beliefs about things (bodies, forced locks), not someone
Get Location Beliefs, Get Strongest Location Belief, Report Location Belief, Clear Location Belief	Beliefs about places: read them, add one, drop one (How APS thinks)

On the APS Subsystem: Get Agent Count (how many APS Cores are running), Is Perceived as Object (Actor). On an APS Target Component: Get Effective Stance.

Loss reason → search#

Loss reason	Meaning	The tree should
Occluded	It went behind something	Go to the last known position, search that cover
OutOfRange	Walked out of range or the cone	Go there, then on along Get Loss Direction
SoundFaded	The noise stopped	Look around there: don't chase
ScentLost	The trail went cold	Follow Get Loss Direction like a trail
SensorDropout	Too dark, cloaked, blinded, or a sense just stopped	A short look, then patrol
TargetDestroyed	The actor is gone	Clear the target

What feeds each sense#

Sense	Needs from you	Through walls?
Vision	Nothing	No (glass and leaves partly, by surface)
Hearing	Emit Sound: required	Muffled per wall
Smell	Nothing	Partly (seeps under doors)
Touch	Nothing: wired automatically	n/a
Vibration	Nothing for walking; Report Vibration Event for blasts	Yes
Damage	Nothing: wired automatically	Yes, any range
Pain	Report Pain from Definition	n/a
Echolocation	Nothing	Yes

Default thresholds#

Confidence	State	Awareness
0.85 and up	Tracked	Fully Aware
0.60 and up	Tracked	Alerted
0.35 and up	Detected	Suspicious
0.25	On AI Telegraph fires
0.15 and up	Suspected	Peripheral
below 0.15	Undetected	Unaware

Steps down need a 0.04 margin below the line. Tracked also needs Min Track Duration (0.5 s) in Detected first.

Difficulty dial#

Setting	Easy	Normal	Hard
`Suspect Threshold`, `Detect Threshold`, `Track Threshold`	0.25, 0.50, 0.75	0.15, 0.35, 0.60	0.10, 0.25, 0.45
`Confidence Rise Rate`	3	5	7
`First Spot Reaction Time`	0.8	0.4	0.1
`Min Time in Lost`	3	8	15

Keep cone angles and occlusion the same on every difficulty. Ready-made AI

Performance dial#

Lever	Effect
`Base Update Interval` 0.1 → 0.2	Halves the perception cost
The Target Component's `Visibility Samples` 5 → 3	40% fewer vision traces
`Max Tracked Targets` 16 → 4	Less memory, less sorting
One occlusion channel instead of three	A third of the traces
An APS Quality Profile	Slower updates, fewer samples, nothing reset
`Enable Statistical Tier`	Distant AI stop tracing (and see through walls: keep the threshold at 3)
Tier 4	Suspended by itself, beyond about 225 m for an idle AI

Performance & crowds

See what it perceives#

APS Core › Details › APS › View › Show Visualizer      tick it
console: aps.Visualizer 0 | 1 | 2      nothing · everything · status only
         aps.VisualizerPage 0..6       Senses · Memory · Brain · Squad · Events · Player Model · Environment
         aps.Tune VisionMaxRange 5000  a setting on every AI, live

The Senses page answers most "why doesn't it see me": each sense shows what it reads, or why it reads nothing. A sense draws only if it is in Sense Classes: no smell ring means no Smell Sense. Visualizer & debugging

Quick fixes#

Symptom	Fix
Detects nothing at all	No profile assigned, `Sense Classes` empty, or the APS Core is on the controller (it must be on the Pawn)
Hears nothing	Nothing calls Emit Sound
Sees through doors	Add their channel to `Vision Occlusion Channels` (the list replaces Visibility: keep it in)
Sees you the instant you step out	`First Spot Reaction Time` 0.3 to 0.5
Sees you before it has turned	`Eye Turn Rate Deg Per Sec` about 200
Forgets instantly	`Vision Loss` Grace Time 0.8 to 1.5
Never forgets	Raise `Default Decay Exponent`
Searches in a dumb circle	Branch on Get Loss Reason
The whole squad knows at once	`Auto Share on Detect` off
A client sees nothing	Get Replicated Perception State (Multiplayer)
The cone points at the sky	`Eye Socket Alignment` Automatic
Crouching doesn't hide you	`Min Visible Points Crouched` 2, and an APS Target Component on the player
"Why can't it see me?"	Print Explain Perception (Target)
A thrown can is ignored	Noises nobody made arrive on On Location Belief Changed, not On AI Hear
A setting seems to do nothing	Some do nothing in APS 3.0: the reference marks them (Troubleshooting)

Things that surprise people#

Confidence never falls while a sense reports you. It rises or holds; fading starts only when every sense is silent.
**Vision Sample Count is ignored for a target with an APS Target Component**: the component brings its own five points.
Never-search zones are advice. Your search asks Is Location in Never Search Zone; nothing is blocked for you.
Pain Sense reads your health by itself and dulls every sense with it: at half health, half strength.
Noises nobody made never fire On AI Hear. Emit Sound at Location makes a belief about a place.
An idle AI never reaches tier 0: it updates at half rate at best until it is Suspicious.
An explosion shakes the ground for vibration only if its sound type's Sound Name is exactly Explosion.
100 damage from one attacker is full confidence. Scale to your damage numbers.
Set Target Confidence only raises. To lower or clear belief, use Add Target Evidence.
Allies count. Guards perceive each other: they take target slots and count toward fear ("more than 2 targets").