2-scriptable-objects.md

title	Unity advanced 2. Scriptable objects
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Scriptable objects

Scriptable object class

• A special class for storing data that GameObjects can use
• Usually used as an asset template
• Can be made accessible from the Create Asset menu!
• Very handy if a GameObject needs easily-swappable data
  • Brackeys tutorial has an example of creating different Hearthstone cards
• Scriptable Object in Unity Docs

Creating a scriptable object

1. Create new class that inherits from ScriptableObject instead of MonoBehaviour
   • This will be the data structure of the variables you want to store

   •   using UnityEngine;
     
       [CreateAssetMenu(fileName = "New Mana Card", menuName = "Cards/ManaCard")]
       public class Card : ScriptableObject
       {
           public new string name;
           public string description;
           public int amountOfMana;
           public ManaEnum manaType;
       }

   • Note: The name field exists already, so we use the new keyword to override it.
2. Create a new data container based on the Scriptable object from the Asset menu
   • In this case, choose Cards > ManaCard
   • Set values for the created asset
3. Create a few more data containers with different data!

Using the scriptable object

1. Create a new script inside the GameObject for using the data from the Scriptable object.
2. In the script, create a new variable with the type of the Scriptable Object:

   [SerializeField] Card card

3. Drag the card template of your choice to the serialized field in Inspector
4. The data from Card is now available! Access its values with card.amountOfMana, card.name, etc.

Extra: Spawn manager: The manager class

using UnityEngine;

[CreateAssetMenu(fileName = "Spawn Manager", menuName = "ScriptableObjects/SpawnManagerScriptableObject", order = 1)]
public class SpawnManagerScriptableObject : ScriptableObject
{
    public string prefabName;
    public int numberOfPrefabsToCreate;
    public Vector3[] spawnPoints;
}

Spawn manager: Usage

using UnityEngine;

public class Spawner : MonoBehaviour
{
    // The GameObject to instantiate.
    public GameObject entityToSpawn;
    // An instance of the ScriptableObject defined above.
    public SpawnManagerScriptableObject spawnManagerValues;
    // This will be appended to the name of the created entities and increment when each is created.
    int instanceNumber = 1;

    void Start()
    {
        SpawnEntities();
    }

    void SpawnEntities()
    {
        int currentSpawnPointIndex = 0;
        for (int i = 0; i < spawnManagerValues.numberOfPrefabsToCreate; i++)
        {
            // Creates an instance of the prefab at the current spawn point.
            GameObject currentEntity = Instantiate(
                entityToSpawn, spawnManagerValues.spawnPoints[currentSpawnPointIndex], Quaternion.identity
            );
            // Sets the name of the instantiated entity to be the string defined in the ScriptableObject + a unique number. 
            currentEntity.name = spawnManagerValues.prefabName + instanceNumber;
            // Moves to the next spawn point index. If it goes out of range, it wraps back to the start.
            currentSpawnPointIndex = (currentSpawnPointIndex + 1) % spawnManagerValues.spawnPoints.Length;
            instanceNumber++;
        }
    }
}