Variable Pre Change Transformers

Variable pre change transformers provide a way to modify the value of a Variable before it gets changed. These are used to introduce customized logic into the process of updating the value of an Variable. For example, a pre change transformer could be used to limit a player's health within certain boundaries, such as ensuring that it never drops below zero.

In this tutorial, we'll look at how to use a pre change transformer in UnityAtoms.

Step 1: Create a Pre Change Transformer

Firstly, we need to create a new class for our pre change transformer. Let's say we are going to create a transformer that ensures the health of our player never falls below 0.

Create a new C# script and name it MinHealthTransformer. This script should extend IntIntFunction and override the Call method:

using UnityAtoms.BaseAtoms;

[EditorIcon("atom-icon-sand")]
[CreateAssetMenu(menuName = "Unity Atoms/Functions/Transformers/MinHealth Int (int => int)", fileName = "MinHealth")]
public class MinHealthTransformer : IntIntFunction
{
    public override int Call(int value)
    {
        if (value < 0)
            return 0;
        else
            return value;
    }
}

In the Call method, we're checking if the new value of health is less than 0. If so, we're returning 0 instead of the new value. This ensures the player's health never drops below 0.

Step 2: Use the Pre Change Transformer

To use this transformer, we need to create a ScriptableObject of this type.

In the Unity Editor:

1. Right-click in the project window and choose Create > UnityAtoms > Functions > Transformers > MinHealth Int (int => int).
2. Name the Object MinHealthTransformer.
3. In the inspector window, set the Pre Change Transform to be MinHealthTransformer.

Now, whenever the PlayerHealth value is changed, the MinHealthTransformer's PreChangeCheck method will be called, ensuring the health never drops below 0.

Notes

As the name suggests, pre change transformers are executed before the change events are invoked.