Automatic Injection

8_RuntimeVariables

In this scene, we demonstrate an example of automatic injection. Instead of manually passing the runtime variables to other components, we will use the Runtime Injector. Select enemy_runtime_autoInjection in the scene.

You can see that this component will create and inject two variables: hp and speed. For the hp variable, it will create a deep copy of the example variable example_float_enemyHealthTemplate. This is useful because we can predefine a max value.

Next, it will inject the hp variable into both the RuntimeHealthInjected component and the HealthBarSpriteAutoInjection component.

For the speed variable, it will create a brand-new variable (without a template) and inject it into EnemyMovementInjected.cs.

If we look at the code, the fields to be injected are simply marked with the [RuntimeInjectable] attribute. Here is what RuntimeHealthInjected.cs looks like:

public class RuntimeInjectedHealth : MonoBehaviour
{
    [Tooltip("This field will be injected at runtime")] 
    [SerializeField]
    [RuntimeInjectable("hp")] 
    private FloatVariable _runtimeHpVariable;

    [SerializeField] private FloatReference _maxHealth;
    
    private void Start()
    {
        _runtimeHpVariable.Value = _maxHealth.Value;
        _runtimeHpVariable.OnValueChanged += OnHealthChanged;
    }

    private void OnDisable()
    {
        _runtimeHpVariable.OnValueChanged -= OnHealthChanged;
    }

    private void OnHealthChanged(float newValue)
    {
        if (newValue <= 0f)
            gameObject.SetActive(false);
    }

    //In this example, this is called when the enemy collides with the Player.
    public void TakeDamage(int amount) => _runtimeHpVariable.Add(-amount);
}

As you can see, this approach eliminates much of the manual work previously required, such as creating and injecting the variables.

Note: The RuntimeInjector calls its Awake method before the default components. This means that other components can directly access the injected variables in their Awake methods (as shown in RuntimeHealthInjected.cs).