인터페이스 기반 유한 상태 머신(FSM)과 플레이어 액션 상태 전이 제어

public interface IState
{
    void Enter();
    void Execute();
    void FixedExecute();
    void Exit();
}

public class StateMachine
{
    public IState CurrentState { get; private set; }

    public void ChangeState(IState newState)
    {
        if (CurrentState == newState || newState == null) return;

        CurrentState?.Exit();
        CurrentState = newState;
        CurrentState.Enter();
    }

    public void Update() => CurrentState?.Execute();
    public void FixedUpdate() => CurrentState?.FixedExecute();
}

using UnityEngine;

public class PlayerIdleState : IState
{
    private readonly PlayerController _player;

    public PlayerIdleState(PlayerController player) => _player = player;

    public void Enter()
    {
        _player.Anim.Play("Idle");
        _player.Rb.linearVelocity = new Vector2(0f, _player.Rb.linearVelocity.y);
    }

    public void Execute()
    {
        if (Mathf.Abs(_player.MoveInput) > 0.01f)
        {
            _player.SM.ChangeState(_player.RunState);
        }
    }

    public void FixedExecute() { }
    public void Exit() { }
}

public class PlayerRunState : IState
{
    private readonly PlayerController _player;

    public PlayerRunState(PlayerController player) => _player = player;

    public void Enter() => _player.Anim.Play("Run");

    public void Execute()
    {
        if (Mathf.Abs(_player.MoveInput) <= 0.01f)
        {
            _player.SM.ChangeState(_player.IdleState);
        }
    }

    public void FixedExecute()
    {
        _player.Rb.linearVelocity = new Vector2(_player.MoveInput * _player.Speed, _player.Rb.linearVelocity.y);
    }

    public void Exit() { }
}