Interest Spots

An interest spot is something passing agents may stop for: a shop window, a notice board, a street performer. An agent that walks past may break off, go and stand at the spot for a while, and then carry on with what it was doing.

Interest spots are built on Interrupts. Read that page first for interrupt kinds and how to author the reaction an agent plays.

The short version

1. Create an Interrupt Kind and a reaction for it in the Reactive tree.
2. Add the InterestSpot component to the object and set its Kind.
3. Add a child object with a Sphere Collider and the InterestSpotVolume component. Size the collider to cover the path agents walk.
4. For a crowd, set Shape to Gathering and assign a Mark Group to Audience Marks.

The Interest Spot component

Field	What it does
Kind	The interrupt kind offered to passing agents
Shape	Solo for one visitor at a time, Gathering for several
Activity Enabled	Whether the spot is offering. Off, nobody stops
Probability	The chance an agent stops, from 0 to 1. Rolled once each time the agent enters the volume
Spot Cooldown Seconds	How long after one agent accepts before the spot offers to another
Requirements	Optional. Only agents that meet these are offered. See Requirement System
Anchor	Solo only. The item the visitor stands at. Leave empty to use the Item on the same object
Audience Marks	Gathering only. The mark group the audience stands on

Solo

One agent at a time visits the spot, standing at the anchor item's use spot. The spot makes no offers while a visitor is there, or while the item is reserved or in use by an agent doing something else.

Gathering

Several agents visit at once, each on its own mark. The spot stops offering when every mark is taken.

A gathering fills gradually. Only one agent is taken at a time, and Spot Cooldown Seconds sets the wait before the next. Lower it for a crowd that builds quickly.

Probability

The roll happens once per visit to the volume. An agent that fails it is left alone until it walks out and comes back in, so 0.15 means roughly one passer-by in seven stops, however long each takes to walk through.

Turning a spot on and off

Activity Enabled can be set from your own code, so a performer only draws a crowd while performing:

csharp

interestSpot.ActivityEnabled = true;

Disabling the component, or the volume, sends every current visitor back to what it was doing.

The Interest Spot Volume component

The volume is the area in which passing agents are noticed. It needs a collider set as a trigger and a kinematic Rigidbody. Adding the component sets both up for you.

Field	What it does
Spot	The interest spot this volume belongs to. Leave empty to use one on the same object or a parent
Offer Tick Interval	Seconds between rounds of offers while agents are inside
Max Offers Per Tick	How many agents are considered each round. Agents are taken in turn, so a crowded volume stays cheap

note

The Rigidbody is there because agents have none of their own, and Unity only reports trigger overlaps when one side has a Rigidbody. Keep it kinematic.

Size the volume to the route agents take, not to the spot itself. An agent only gets its chance while it is inside, so a volume it clips the corner of gives it one round of offers at most.

An empty volume costs nothing. It does no work until an agent walks in.

How long a visitor stays

The spot does not set this. The length comes from the endpoint behaviour on the reaction's action, so every spot using the same kind holds its visitors for the same time. Create a second kind and reaction for a spot that should hold agents longer.

Which agents stop

An agent is offered the spot when all of these are true:

• Activity Enabled is on and the spot cooldown has run out
• the spot has room
• the agent is not already handling an interrupt
• the agent meets the Requirements
• the agent's roll against Probability passes

The agent can still turn it down. Passing agents are asked at the Polite tier, so an agent that has already arrived at its task and begun is left to finish. The kind's cooldown and weight apply as well. See When an agent says no.

Common problems

Symptom	Cause
Nobody ever stops	The volume's collider is not a trigger, agents do not pass through it, or Activity Enabled is off
Agents are offered but decline with NoHandlerForKind	There is no reaction for the kind, or Reactive is None in module settings
Agents stop once and never again	The kind's Agent Cooldown Seconds. An agent also only rolls again after leaving the volume
A gathering only ever has one or two watching	Spot Cooldown Seconds is long compared with how long each visitor stays
A solo spot is never visited	The anchor item is reserved or in use, or there is no Item on the object and Anchor is empty
Agents at work walk straight past	The kind's weight does not beat the work weight, 0.7 by default. See Weight
Visitors all face the same way	The reaction's Look is not FACE_INTERRUPT_TARGET, or the marks all point the same way
The Console reports the collider must be a trigger	Tick Is Trigger on the volume's collider, or agents will walk into it

Next step

Continue to Service Points, or open the Interrupt Scene from Example Scenes to see a solo spot and a gathering side by side.