Implementing Basic State Machine Logic

Create a simple state machine to manage object behavior transitions using standard enumerations and conditional switch statements.

In this lesson, you will learn how to transition an object between distinct behaviors using a switch statement and a centralized enumeration.

The Logic of States

As your game grows, objects often need to behave differently depending on the context—for example, a guard might need to "Patrol," "Chase," or "Attack." Instead of writing a complex mess of nested if statements, a State Machine allows you to explicitly define these modes. By using an enum to categorize the state and a switch block inside your Update method, you ensure that only the logic relevant to the current state executes.

Implementation

First, define your states using an enum. Then, maintain a variable to track the current state and perform logic based on its value.

public enum GuardState { Patrol, Chase, Attack }

public class GuardController : MonoBehaviour
{
    public GuardState currentState = GuardState.Patrol;

    void Update()
    {
        switch (currentState)
        {
            case GuardState.Patrol:
                PerformPatrol();
                break;
            case GuardState.Chase:
                PerformChase();
                break;
            case GuardState.Attack:
                PerformAttack();
                break;
        }
    }

    void PerformPatrol() { /* Patrol logic */ }
    void PerformChase() { /* Chase logic */ }
    void PerformAttack() { /* Attack logic */ }
}

Why Use This?

This approach keeps your code readable and modular. When you need to trigger a transition—such as switching from Patrol to Chase when a player enters a trigger volume—you simply update the currentState variable. Because the Update method continuously checks this variable, the object immediately switches its behavior. This centralizes control, making it much easier to debug your game's AI or interaction logic.

While more complex projects might eventually require separate classes for each state to avoid massive switch statements, this enumeration-based approach is the industry-standard foundation for building clean, predictable object behaviors.

Key Takeaway: A State Machine uses an enumeration to categorize behaviors and a switch statement to ensure that an object only executes the logic appropriate for its current context.