andrew-raphael-lukasik / Simpletons

Simpletons

A basic state machine for programmers to prototype Unity AI nav agents in C#.

Goal of this repo is to make fsm-based ai creation processs relatively easy and quick so it can be used to prototype ai behaviours.

Implementation

Samples to show you how to use Simpletons:

Zombies and survivors following/avoiding each other

https://github.com/andrew-raphael-lukasik/Simpletons/tree/main/Samples/Zombies

pedestrians moving across the street and reacting to traffic lights

https://github.com/andrew-raphael-lukasik/Simpletons/tree/main/Samples/TrafficLights

Key implementation points:

• MonoBehaviour updates it's state machine ai brain by calling Tick(time) method

public class WalkerController : MonoBehaviour
{
    [SerializeField] WalkerAI _brain = new WalkerAI( owner:this );
    void FixedUpdate ()
    {
        _brain.Tick( time:Time.time );
    }
}

• custom SimpletonStateMachine is a place where you design your fsm ai

public WalkerAI ( WalkerController owner )
{
    _owner = owner;

    // create states:
    var start   = new WalkerIdleState( _owner );
    var idle    = new WalkerIdleState( _owner );
    var wander  = new WalkerWanderState( _owner );
    var agro    = new WalkerAgroState( _owner );
    var attack  = new WalkerAttackState( _owner );
    var dead    = new WalkerDeadState( _owner );

    // create transitions:
    SimpletonStateTransition start_to_idle, idle_to_wander, wander_to_idle, any_to_agro, agro_to_idle, agro_to_attack, attack_to_agro, any_to_dead;
    start_to_idle = new SimpletonStateTransition(
        predicate:      (state,time) => true ,
        destination:    idle ,
        label:          nameof(start_to_idle)
    );
    idle_to_wander = new SimpletonStateTransition(
        predicate:      (state,time) => Random.Range(1,6)==1 ,// 20% chance
        destination:    wander ,
        label:          nameof(idle_to_wander)
    );
    wander_to_idle = new SimpletonStateTransition(
        predicate:      (state,time) => state.completed || time>state.timeExpectedEnd || _owner.navMeshAgent.remainingDistance<1f ,
        destination:    idle ,
        label:          nameof(wander_to_idle)
    );
    any_to_agro = new SimpletonStateTransition(
        predicate:      (state,time) => _owner.survivorsAround.Count!=0 ,
        destination:    agro ,
        label:          nameof(any_to_agro)
    );
    any_to_dead = new SimpletonStateTransition(
        predicate:      (state,time) => _owner.Health<=0 ,
        destination:    idle ,
        label:          nameof(any_to_dead)
    );
    /* more transition definitions */

    // assign transitions to states:
    start.transitions = new SimpletonStateTransition[]{
        start_to_idle
    };
    idle.transitions = new SimpletonStateTransition[]{
        any_to_dead ,
        idle_to_wander ,
        any_to_agro ,
    };
    /* more transitions assigned to states */

    // assign initial state
    _initial = start;
    Reset();
    ConstructorAssertions();
}

To help you understand and debug it, Simpletons come with an inspector window:

Installation

Open Package Manager->Add package from git URL:

https://github.com/andrew-raphael-lukasik/Simpletons.git#upm

Add this line to the dependencies in manifest.json:

"dependencies": {
    "com.andrewraphaellukasik.simpletons": "https://github.com/andrew-raphael-lukasik/Simpletons.git#upm",
    ...
}

Games that use this package:

• https://andrew-raphael-lukasik.itch.io/non-human-society