Small Components

Part of the Game Architecture in Unity section of Coddy's Unity journey. Lesson 1 of 64.

A GameObject is a list of components, and each script you write is one more of them. Unity games are built by giving each script one job and putting several scripts on an object. A player's moving, shooting and hit points could all live in one PlayerController, but as three components, Mover, Shooter and Health, each one can go on other objects too:

public class Health : MonoBehaviour
{
    public int hp = 3;

    public void TakeDamage(int amount)
    {
        hp -= amount;
        if (hp <= 0)
        {
            Destroy(gameObject);
        }
    }
}

Player: Mover, Shooter, Health
Turret: Shooter, Health
Crate: Health

With plain C# classes you might build a tree instead: Character, then ShootingCharacter : Character, then Player : ShootingCharacter. A turret shoots but never walks and a crate only breaks, so every new kind of object means reshaping the tree. With components, a new kind of object is a new mix of scripts that already exist, put together in the Inspector, and each script can have its own values there: a slow Mover on one object, a fast one on another.

Components on one object share its Transform, so each should change only the part it owns. A Mover that adds to x and z with transform.position += leaves y alone, so a Jumper on the same object can still change the height. A Mover that set the whole position to new Vector3(x, 0.5f, z) would put y back every frame and cancel the jump.

Challenge

Easy

Split Boat.cs so each script does one job.

Move the bobbing into Bobber: startY set in Start(), the bobbing in Update(), using its own height and speed.
Move the blinking into Blinker, with its own timer.
Delete both jobs and their fields from Boat, so it only steers.

Press Play: the duck bobs, the buoy blinks, and the boat steers. Then Check.

Try it yourself

using UnityEngine;
using UnityEngine.InputSystem;

// One script, three jobs: steering, bobbing and blinking.
public class Boat : MonoBehaviour
{
    public float speed = 3f;
    public float bobHeight = 0.1f;
    public float bobSpeed = 2f;
    public Renderer lamp;
    public float blinkInterval = 0.5f;

    private InputAction moveAction;
    private float startY;
    private float blinkTimer;

    void Start()
    {
        moveAction = InputSystem.actions.FindAction("Move");
        startY = transform.position.y;
    }

    void Update()
    {
        // steering
        Vector2 input = moveAction.ReadValue<Vector2>();
        transform.position += new Vector3(input.x, 0f, input.y) * speed * Time.deltaTime;

        // bobbing
        Vector3 p = transform.position;
        p.y = startY + Mathf.Sin(Time.time * bobSpeed) * bobHeight;
        transform.position = p;

        // blinking
        blinkTimer += Time.deltaTime;
        if (blinkTimer >= blinkInterval)
        {
            blinkTimer -= blinkInterval;
            lamp.enabled = !lamp.enabled;
        }
    }
}