navex

Composable steering behaviors, flocking, flow fields, and formations for games.

no_std compatible | MIT / Apache-2.0

Live Demo

Overview

navex provides Craig Reynolds-style autonomous agent movement as pure functions. Each behavior takes an agent and context, returning a steering force. Compose behaviors via weighted blending or priority selection.

• Pure functional API: behaviors are stateless functions returning SteeringOutput
• Compose any combination of behaviors with weighted blend or priority select
• no_std + no allocations in core behaviors (users provide neighbor data)
• Works in embedded, WASM, and native environments

Quick Start

use navex::*;

// Create an agent
let agent = Agent::new(
    Vec2::new(0.0, 0.0),   // position
    Vec2::new(1.0, 0.0),   // velocity
    1.0,                     // mass
    100.0,                   // max_speed
    200.0,                   // max_force
);

// Seek a target
let steering = seek(&agent, Vec2::new(100.0, 50.0));
let updated = apply_steering(&agent, &steering, 0.016);

// Flock with neighbors
let weights = FlockWeights::default_reynolds();
let flock_steering = flock(&agent, &neighbor_positions, &neighbor_velocities, &weights);

// Blend multiple behaviors
let blended = weighted_blend(&[
    WeightedBehavior::new(seek_force, 0.6),
    WeightedBehavior::new(avoid_force, 2.0),
]);

Features

• Individual behaviors: Seek, flee, arrive, pursue, evade, wander (2D/3D)
• Group behaviors: Separation, alignment, cohesion, Reynolds flocking
• Obstacle avoidance: Circles, AABBs, walls (single-feeler and 3-feeler 2D)
• Flow fields: BFS-generated direction grids with blocked cell support
• Formations: Circle, V (chevron), grid, column, leader-follow patterns
• Composition: Weighted blend, priority select, behavior pipeline
• Spatial queries: SpatialQuery trait with brute-force implementation
• Configuration: FlockConfig for tunable flock parameters
• Observable: SteeringObserver trait to monitor steering decisions

API Overview

Type	Role
Agent<V>	Position, velocity, mass, and movement limits
SteeringOutput<V>	Linear force returned by all behaviors
FlockWeights<F>	Separation, alignment, cohesion weights
FlockConfig<F>	Full flock configuration (weights + radii)
Circle<V> / Aabb<V> / Wall<V>	Obstacle types for avoidance
FlowField<F>	Grid of direction vectors
Formation<V>	Computed slot positions around a leader
FormationPattern<V>	Trait for circle, V, grid, column patterns
WeightedBehavior<V>	Behavior + weight for blending
BehaviorPipeline<V>	Priority-ordered behavior composition
SpatialQuery<V>	Trait for neighbor lookups
SteeringObserver<V>	Trait for monitoring steering events

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.