typedef enum SWARM_DISTANCE {
    SWARM_DISTANCE_LINEAR,
    SWARM_DISTANCE_INVERSE_LINEAR,
    SWARM_DISTANCE_QUADRATIC,
    SWARM_DISTANCE_INVERSE_QUADRATIC
} SWARM_DISTANCE;

#define boid(...) C_CAST(boid_t, __VA_ARGS__)

typedef struct boid_t {
    vec3 position;
    vec3 velocity;
    vec3 acceleration;
    vec3 prev_position;
} boid_t;

typedef struct swarm_t {
    array(boid_t) boids;

    float perception_radius; // determines the vision radius of each boid. Only boids within this distance influence each other.

    float separation_weight; // how much boids repel each other
    SWARM_DISTANCE separation_type;

    float alignment_weight; // how much boids want go in the same direction
    float cohesion_weight; // how much boids want to be in the center of the swarm

    float steering_weight;
    array(vec3) steering_targets;
    SWARM_DISTANCE steering_target_type;

    float blindspot_angledeg;
    float max_acceleration; // how fast each boid can change its direction
    float max_velocity; // how fast each boid can move

    // private:
    map(vec3*, array(boid_t*)) voxel_cache_;
    float blindspot_angledeg_compare_value_;
} swarm_t;

API swarm_t swarm();
API void    swarm_update(swarm_t *self, float delta); // acc,vel,pos
API void    swarm_update_acceleration_only(swarm_t *self); // acc
API void    swarm_update_acceleration_and_velocity_only(swarm_t *self, float delta); // acc,vel

API int     ui_swarm(swarm_t *self);