NPC Queue system

Spline-Driven Paths and Line Layouts

Organizing moving characters into orderly lines presents distinct spatial challenges in interactive environments. The NPC Queue system addresses this by utilizing splines as the foundational framework for queue geometry. Instead of forcing rigid, coordinate-bound paths, the blueprint setup allows developers to lay out lines directly in the level viewport by shaping spline curves to fit counters, ticket booths, theme park attractions, or transport hubs.

Using splines makes altering the footprint of a waiting line straightforward. Designers can bend, extend, or compress paths around architectural obstacles such as walls, stanchions, and service desks without breaking character awareness. AI agents assigned to the queue follow the spline trajectory naturally, maintaining consistent directional orientation as they advance through the designated path toward their destination.

Customizable Queue Entry: Start-Only versus Free-Entry

Crowd flow demands varied line rules depending on the simulated scenario. The system incorporates two explicit entry configurations to govern how AI pedestrians approach and join an active line:

• Start-Only Mode: Characters must approach and join the line strictly at its designated beginning point. This mode models strict, orderly environments such as security checkpoints, single-file ticket turnstiles, or structured bank queues where cutting into the middle of the formation is prohibited.
• Free-Entry Mode: Characters are permitted to slot into available spaces at any position along the line. This configuration suits casual gathering points, food markets, or dynamic crowd scenarios where pedestrians fill gaps as they appear along the spline.

Switching between these entry methods enables tailored behavior across different zones of a game. A store entrance can enforce single-point access to prevent crowding at the front, while a broad counter area can allow incoming NPCs to slip into gaps along the perimeter as spots open up.

Dynamic Queue Behavior and Departure Logic

Static lines rarely reflect realistic human movement. To handle variability within simulation loops, the system features dynamic queue behavior that lets AI agents make decisions while waiting. Characters advance along the spline step by step as preceding agents move forward, but they are not locked into remaining in line indefinitely.

NPCs possess the ability to leave the queue randomly at any point along the spline path. This mechanism simulates impatience, changing priorities, or distraction, preventing the line from behaving like a rigid conveyor belt. Alternatively, characters can follow standard queue discipline, holding their positions until they successfully reach the head of the line to complete their intended interaction. Because agents follow the spline naturally, departures and positional updates occur fluidly along the track without breaking navigation flow.

Managing Multiple Queues in Crowd and Tycoon Environments

Complex simulations often require several service points operating simultaneously. The system includes native support for multiple queues running in the same scene, allowing distinct spline paths to operate side by side without interference. This capability is directly applicable to two primary game production contexts:

In tycoon and management games, player progression often hinges on customer throughput. Having multiple independent lines allows developers to bind separate queues to individual cash registers, ride entrances, or service windows. As lines fill up or stall, the underlying queue logic keeps track of agent counts and position states across every active spline.

In broad pedestrian and crowd simulations, multiple queues help break massive groups into believable, localized interactions. Street vendors, bus stops, and building checkpoints can each run self-contained queue loops. Because characters can join or peel away dynamically, the surrounding environment maintains the illusion of an active, thinking crowd that responds to wait times and line availability.

Integration Workflow with Documentation Guidance

Designed around Blueprint architecture, the package incorporates the core logic needed to govern AI character registration, spline path advancement, and line departures. The included documentation provides reference steps to assist with integrating the logic into custom character blueprints and project level designs. By providing spline creation tools, distinct entry modes, dynamic dropout mechanics, and multi-line support, the system gives simulation projects a functional foundation for believable line management.

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