Classes, Entity, Resource and prefabs: the difference

How a C# type, an engine instance, configuration data and a saved hierarchy relate.

Four different concepts

Concept	Meaning	Example
C# class	A type with fields and methods; inheritance is defined in C#	HealthModel, DamageReceiver
Entity	A hierarchy object with a parent, children and lifecycle	A DamageReceiver instance
Resource	Engine data that can be saved and shared between objects	ActorSettings
.rprefab prefab	A saved composition of entities, properties and references	An enemy template

A C# script really declares a C# class. The engine also represents the script file as a Script resource; that is a different layer. A plain HealthModel does not inherit ReckfellObject, cannot be added with AddChild and receives no _Ready callback.

Inheritance and composition

DamageReceiver inherits Entity and implements IDamageable. Its HealthModel is a separate object containing health rules. ActorSettings supplies initial parameters. Two receivers can reference one ActorSettings while owning different HealthModel instances.

HealthModel.cs

C#
using System;

public interface IDamageable
{
    bool TryApplyDamage(int amount);
}

public sealed class HealthModel : IDamageable
{
    public int Maximum { get; }
    public int Current { get; private set; }

    public HealthModel(int maximum)
    {
        if (maximum <= 0) throw new ArgumentOutOfRangeException(nameof(maximum));
        Maximum = maximum;
        Current = maximum;
    }

    public bool TryApplyDamage(int amount)
    {
        if (amount <= 0 || Current == 0) return false;
        Current = amount >= Current ? 0 : Current - amount;
        return true;
    }
}

ActorSettings.cs

C#
using Reckfell;

[GlobalClass]
public partial class ActorSettings : Resource
{
    [Export(PropertyHint.Range, "1,10000,1")]
    public int MaximumHealth { get; set; } = 100;
}

DamageReceiver.cs

C#
using Reckfell;

public partial class DamageReceiver : Entity, IDamageable
{
    [Export] public ActorSettings? Settings { get; set; }
    [Signal] public delegate void HealthChangedEventHandler(int current, int maximum);

    private HealthModel? _health;
    public int CurrentHealth => _health?.Current ?? 0;
    public int MaximumHealth => _health?.Maximum ?? 0;

    public override void _Ready() => ResetFromSettings();

    public bool ResetFromSettings()
    {
        if (Settings is null || !ReckfellObject.IsInstanceValid(Settings) ||
            Settings.MaximumHealth <= 0) return false;
        _health = new HealthModel(Settings.MaximumHealth);
        EmitSignal(SignalName.HealthChanged, _health.Current, _health.Maximum);
        return true;
    }

    public bool TryApplyDamage(int amount)
    {
        if (_health is null || !_health.TryApplyDamage(amount)) return false;
        EmitSignal(SignalName.HealthChanged, _health.Current, _health.Maximum);
        return true;
    }
}

What a prefab changes

PackedEntity.Instantiate creates a hierarchy from stored data. It does not declare a new CLR type: the root script type remains DamageReceiver. .rscene denotes a level and .rprefab a reusable object; both use PackedEntity. These are file roles rather than two Entity subclasses.

Parent determines hierarchy and child deletion. Owner determines membership in the saved composition; it does not identify a gameplay score owner, team or network owner.

Run the complete example · Entity and hierarchy