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* Restructure tutorials and add two new tutorials - Non-generated documentation review and edit - Consistent terminology - Stylistic changes - Minor structure changes - Minor clarifications - Typo fixes - Split basic tutorial into two - Tutorials are easier to follow when they are short and to the point - Added event and variable instancer tutorials - Had to bump node version for the docker container to work * #189 - Fixing minor nitpicks Co-authored-by: Adam Ramberg <adam@mambojambostudios.com>
55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
---
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id: events
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title: Events
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hide_title: true
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sidebar_label: Events
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---
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# Events
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Events are things that happens in our game that other scripts or entities could listen and subscribe to. Events are (like Variables) also Scriptable Objects that live outside of a specific scene. In Unity Atoms Events can be of different types and thereby pass along data to listeners. Variables do by default have the possibility to raise two specific Events:
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- `Changed` — raised every time a Variable’s value is changed. The Event contains the new value.
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- `Changed With History` — also raised every time a Variable’s value is changed. However, this Event contains both the new and the old value.
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This makes it easier to make our game more data driven than just using Variables. Lets take a look at how that looks in our last example. We can create a new `IntEvent` as a `.asset` file by right clicking and go _Create / Unity Atoms / Event / Int_ and name it `HealthChangedEvent`:
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And then drop it on our `IntVariable` for the player’s health like this:
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We can then modify our `HealthBar.cs` script to look like this:
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```cs
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public class HealthBar : MonoBehaviour
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{
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[SerializeField]
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private IntEvent HealthChangedEvent;
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[SerializeField]
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private IntVariable MaxHealth;
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void Start()
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{
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HealthChangedEvent.Register(this.ChangeFillAmount);
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}
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void OnDestroy()
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{
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HealthChangedEvent.Unregister(this.ChangeFillAmount);
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}
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private void ChangeFillAmount(int health)
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{
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GetComponent<Image>().fillAmount = 1.0f * health / MaxHealth.Value;
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}
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}
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```
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And then inject the `HealthChangedEvent` to our `HealthBar` component:
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We now react to global state changes instead of checking the Variable value each Update tick. In other words we only update our `Image` component when we actually need to. That is pretty sweet!
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