Betrayal
DANE SHERMAN
March 31, 2020
My primary goals with this project was to learn more about creating Autonomous Agents using state machines in Unity. The solution I landed on involved using an enum Property that would switch out Coroutine behaviors.
Animation
Using Pyxel Edit I made some simple animations for the all the characters in the game. I especially focused on making the dog as friendly and expressive as possible to give it personality and keep the player attached.
State Machines and Coroutines
All of the characters types in the game use state machines and coroutines to drive multiple behaviors. Below is a sample form the Person class that runs away from Grim but not when the friendly dog is nearby
public PersonState State
{
get { return state; }
set
{
state = value;
StopAllCoroutines();
switch (state)
{
case PersonState.IDLE:
StartCoroutine(Idle());
break;
case PersonState.FLEE:
StartCoroutine(Flee());
StartCoroutine(StayInFrame());
break;
case PersonState.DEATH:
StartCoroutine(Death());
break;
}
}
}
/// <summary>
/// Idle while player is far away or dog is close
/// </summary>
/// <returns></returns>
private IEnumerator Idle()
{
Vector2 diffPlayer;
Vector2 diffDog = Vector2.zero;
do
{
yield return new WaitForEndOfFrame();
//get difference to player
diffPlayer = transform.position - Characters.player.transform.position;
//get difference to dog
if(Characters.dog != null)
diffDog = transform.position - Characters.dog.transform.position;
//loop while player is far away OR dog is close
} while (diffPlayer.sqrMagnitude > FLEE_DIST * FLEE_DIST ||
(Characters.dog != null && diffDog.sqrMagnitude < Dog.CLOSE_DIST * Dog.CLOSE_DIST));
//player is close AND dog is not close
State = PersonState.FLEE;
}Flock of Chickens
Working on a short game about the Grim reaper and a dog to practice writing autonomous agents and drawing pixel chickens#gamedev #pixelart #madewithunity #screenshotsaturday pic.twitter.com/qXghEfCK7F
— Dane Sherman (@dazyn9) February 22, 2020
Getting the chickens to flock together while keeping them autonomous was one of the biggest challenges I had to tackle. What I ended up on is this Coroutine that Seek chickens that are far away and transitions to FLEE when the player or dog gets close. This keeps each of the chicken independent so that some can flock and regroup while others flee
/// <summary>
/// Flock while the dog and player are far away and not near a chicken
/// </summary>
/// <returns></returns>
protected virtual IEnumerator Flock()
{
Vector2 diffPlayer;
Vector2 diffDog;
do
{
yield return new WaitForEndOfFrame();
movement.Input = Vector2.zero;
//loop over all the other chicken
Vector2 diffChicken;
foreach(Chicken chicken in Characters.chicken)
{
if (chicken.Equals(this)) continue; //skip self
//check if the chicken is close
diffChicken = transform.position - chicken.transform.position;
if(diffChicken.sqrMagnitude < CLOSE_DIST * CLOSE_DIST)
{
//Enter IDLE state
movement.Input = Vector2.zero;
animator.SetFloat("Speed", 0);
State = ChickenState.IDLE;
break;
}
//check if the chicken is within flee distance
if (diffChicken.sqrMagnitude < FLEE_DIST * FLEE_DIST)
{
continue; //skip close-ish
}
//chicken is far away
movement.Seek(chicken.movement);
}
animator.SetFloat("Speed", movement.Speed);
diffPlayer = transform.position - Characters.player.transform.position;
diffDog = transform.position - Characters.dog.transform.position;
} while (diffPlayer.sqrMagnitude > FLEE_DIST * FLEE_DIST &&
diffDog.sqrMagnitude > FLEE_DIST * FLEE_DIST);
//Enter the FLEE state
movement.Input = Vector2.zero;
animator.SetFloat("Speed", 0);
State = ChickenState.FLEE;
}
