The HUD

Part of the Game Architecture in Unity section of Coddy's Unity journey. Lesson 46 of 50.

Challenge

Medium

A HUD that only listens. Keep everything from the earlier lessons. The canvas, named HUD, has a health bar (HealthFill, a Filled image), HealthText and WaveText, and your HUD script, with hero, spawner, healthBar, healthText and waveText set in the Inspector. The HUD never asks the hero or the spawner anything: they announce their changes with C# events, and the HUD shows what it hears.

Hero gets public event Action<int, int> HealthChanged, raised with the health and maxHealth in Start, and whenever a hit or a heal changes the health.
WaveSpawner gets public event Action<int> WaveStarted, raised with the wave's number when a wave starts.
HUD subscribes to both in OnEnable and unsubscribes in OnDisable. On HealthChanged it fills the bar to the share of health left and shows the health as HP 3/5. On WaveStarted it shows Wave 2. It has no Update.

Raise HealthChanged in Start, not in Awake: every object's OnEnable runs before any Start, so by then the HUD is listening. Press Play and watch the HUD while you fight, then Check.

Try it yourself

using UnityEngine;

public class HUD : MonoBehaviour
{
    // A later lesson fills this in: health and wave on screen.
}

All lessons in Game Architecture in Unity

1Components, Not Hierarchies

Small Components A Base Enemy Script Abstract Components Components Working Together Recap: Modular Turret

4Serialized Data

Serializable Classes Lists in the Inspector Enums in the Inspector Recap: Loot Table

7State Machines

States as Classes A State Machine Transitions Enemy Brains Recap: Door States

10Project: Arena Survivor

The HUD

2Interfaces in Unity

IDamageable Interfaces and TryGetComponent GetComponents Recap: Interact Key

5ScriptableObjects

Data Assets Weapon Stats Shared Settings Waves as Data Recap: Item Database

8Reusable Code

Extension Methods A Generic Singleton Generic Helpers Recap: FindNearest

11Final Challenges

Tower Defense Lite Crafting Bench Boss Fight

3Events

C# Events in Unity Subscribe in OnEnable UnityEvent Fields Events Drive the UI Recap: Achievement Popup

6Saving with JSON

JsonUtility Save the Game Load and Defaults Recap: Save Slots

9Object Pooling

Why Pool Objects A Pool with a Queue Unity's ObjectPool Recap: Bullet Pool