steering behaviors

Vector2 arrive(Vector2 target) const noexcept {
    Vector2 toTarget = target - position;
    float distance = Vector2Length(toTarget);

    if (distance < 0.1f) return ZERO; // If already at target, no force needed

    float speed = globalConfig.max_speed;

    // Apply gradual deceleration within the arrive radius
    if (distance < globalConfig.arrive_radius) {
        speed = globalConfig.max_speed * (distance / globalConfig.arrive_radius);
    }

    Vector2 desiredVelocity = Vector2Normalize(toTarget) * speed;
    return (desiredVelocity - velocity) * globalConfig.arrive_weight;
}

Vector2 pursuit(const Boid& target) const noexcept {
    Vector2 toTarget = target.position - position;
    float distance = Vector2Length(toTarget);

    // Estimate time to intercept based on distance and relative speed
    float lookAheadTime = distance / (globalConfig.max_speed + Vector2Length(target.velocity));

    // Predict future target position
    Vector2 futurePosition = target.position + (target.velocity * lookAheadTime);

    // Seek the predicted position instead of current position
    return seek(futurePosition);
}

Vector2 evade(const Boid& pursuer) const noexcept {
    Vector2 toPursuer = pursuer.position - position;
    float distance = Vector2Length(toPursuer);

    // Compute lookahead time based on both speeds
    float lookAheadTime = distance / (globalConfig.max_speed + Vector2Length(pursuer.velocity));

    // Predict future position of the pursuer
    Vector2 futurePosition = pursuer.position + (pursuer.velocity * lookAheadTime);

    // Steer away from the predicted position
    return flee(futurePosition);
}

struct Config {
    float wander_distance = 50.0f; // Distance ahead of the boid to project the wander circle
    float wander_radius = 25.0f;    // Size of the wander circle
    float wander_jitter = 0.2f;     // How much the wander angle changes each frame
    float wander_weight = 0.5f;     // Steering force weight for wander behavior
};
float wanderAngle = 0.0f; // Persistent wandering angle

Vector2 wander() noexcept {
    // Step 1: Project the wander circle ahead of the boid
    Vector2 circleCenter = Vector2Normalize(velocity) * globalConfig.wander_distance;

    // Step 2: Adjust the wander angle slightly
    wanderAngle += unit_range() * globalConfig.wander_jitter; // Small random variation

    // Step 3: Compute displacement on the wander circle (ensuring uniform distribution)
    Vector2 displacement = {
        cos(wanderAngle) * globalConfig.wander_radius,
        sin(wanderAngle) * globalConfig.wander_radius
    };

    // Step 4: Calculate the final wander target
    Vector2 wanderTarget = position + circleCenter + displacement;

    // Step 5: Seek the wander target
    return seek(wanderTarget) * globalConfig.wander_weight;
}