Resource Pattern

Resource Pattern in Godot 4.3+

Resources are Godot's built-in data containers. Use them for configuration, item definitions, character stats, and any data that lives outside the scene tree. All examples target Godot 4.3+ with no deprecated APIs.

Related skills: inventory-system for Resource-based item definitions, save-load for Resource serialization, component-system for data-driven component configuration, ability-system for Resource-based ability definitions built on this pattern.

1. What Are Resources

A Resource is a reference-counted data object that:

• Is saved as a .tres (text) or .res (binary) file on disk
• Is editable directly in the Godot Inspector
• Is loaded once and shared by default — every node that loads the same path gets the same in-memory object
• Can be nested inside other Resources and PackedScenes
• Survives scene changes (unlike Node state, which is discarded on scene reload)

Because Resources are shared by default, they are ideal for read-only data (item definitions, audio settings, ability blueprints). For per-instance mutable state, call make_unique() or duplicate() — see section 8.

2. When to Use Resources

Use a custom Resource any time you want Inspector editing + typed data + sharing across scenes.

3. Basic Custom Resource

GDScript

gdscriptCopy code
# item_data.gd
class_name ItemData
extends Resource

enum ItemType { WEAPON, ARMOUR, CONSUMABLE, QUEST }

@export var name:        String   = ""
@export var description: String   = ""
@export var icon:        Texture2D
@export var value:       int      = 0
@export var item_type:   ItemType = ItemType.CONSUMABLE

Create an instance in the editor: right-click the FileSystem panel → New Resource → choose ItemData. Fill in the Inspector fields and save as res://data/items/health_potion.tres.

Load it at runtime:

gdscriptCopy code
var potion: ItemData = load("res://data/items/health_potion.tres")
print(potion.name)        # "Health Potion"
print(potion.value)       # 50

C#

csharpCopy code
// ItemData.cs
using Godot;

[GlobalClass]
public partial class ItemData : Resource
{
    public enum ItemType { Weapon, Armour, Consumable, Quest }

    [Export] public string   Name        { get; set; } = "";
    [Export] public string   Description { get; set; } = "";
    [Export] public Texture2D Icon       { get; set; }
    [Export] public int      Value       { get; set; } = 0;
    [Export] public ItemType Type        { get; set; } = ItemType.Consumable;
}

[GlobalClass] is required in C# so the editor recognizes the class and shows it in New Resource.

csharpCopy code
var potion = GD.Load<ItemData>("res://data/items/health_potion.tres");
GD.Print(potion.Name);   // "Health Potion"
GD.Print(potion.Value);  // 50

4. Editor Integration

Use class_name, @tool, and @icon to make custom Resources first-class in the Inspector — they appear in the Resource picker, can be created via right-click "New Resource", show a custom icon. @export_group and @export_subgroup organize properties.

See references/editor-integration.md for the full GDScript + C# pattern with class_name, @icon, @export_group.

5. Resource as Configuration

The strongest use case: data-driven game content. Loot tables, enemy stats, ability definitions, item catalogs all become custom Resources. Designers tweak .tres files in the Inspector; programmers wire the loader. Avoids JSON's loose schema and stringly-typed parsing.

See references/configuration-pattern.md for a worked LootTable + DropEntry example (GDScript + C#).

6. Resource Collections

@export var entries: Array[Entry] = [] exposes a typed array in the Inspector — drag and drop multiple Resource files. For startup-loaded sets, use ResourcePreloader. For asset-folder discovery at runtime, walk DirAccess.

See references/collections.md for typed-array exports (v1.6.0 C# parity preserved), ResourcePreloader setup, and the directory-walking loader pattern.

7. Resource vs Node

Rule of thumb: if it has no behavior and no need to exist in the scene tree, make it a Resource. If it needs to move, render, receive input, or run per-frame logic, make it a Node.

8. Sharing vs Unique

By default, Resources are shared by reference. Two scenes referencing res://items/sword.tres see the SAME instance — mutating one mutates both. Use .duplicate() (shallow) or .duplicate(true) (deep) for instance-local state.

See references/sharing-vs-unique.md for the full pattern (v1.6.0 C# parity preserved).

9. Saving Custom Resources

ResourceSaver.save(resource, path) writes to a .tres (text) or .res (binary) file. Use for save games (where the schema lives in code as a Resource subclass) instead of hand-rolled JSON when you want strong typing.

See references/saving-resources.md for the full save/load pattern (GDScript + C#) and security caveat (never load .tres from untrusted sources — they execute embedded GDScript).

10. Anti-patterns

Mutable shared Resources without duplicate() — accidental shared state

gdscriptCopy code
# BAD — all enemies share the same EnemyStats object.
# Damaging one enemy damages all of them.
class_name Enemy
extends CharacterBody2D

@export var stats: EnemyStats  # loaded from .tres, shared

func take_damage(amount: int) -> void:
    stats.health -= amount  # mutates the shared Resource!

gdscriptCopy code
# GOOD — each enemy owns its own copy.
func _ready() -> void:
    stats = stats.duplicate()  # now safe to mutate

Game logic inside Resources

gdscriptCopy code
# BAD — Resources have no scene tree access, no _process, no signals from nodes.
class_name EnemyStats
extends Resource

func update_health_regen(delta: float) -> void:
    # Can't call get_tree(), can't read Input, can't access nodes.
    # This logic belongs in a Node.
    health = min(health + regen_rate * delta, max_health)

gdscriptCopy code
# GOOD — keep logic in Nodes, data in Resources.
# enemy.gd
func _process(delta: float) -> void:
    _current_health = minf(_current_health + stats.regen_rate * delta, stats.max_health)

Giant monolithic Resources

gdscriptCopy code
# BAD — one Resource holds everything; impossible to reuse parts.
class_name GameConfig
extends Resource

@export var player_health: int
@export var player_speed: float
@export var enemy_goblin_health: int
@export var enemy_goblin_speed: float
@export var enemy_troll_health: int
# ... 200 more properties

gdscriptCopy code
# GOOD — small focused Resources, composed together.
class_name PlayerConfig
extends Resource

@export var health: int   = 100
@export var speed:  float = 200.0

gdscriptCopy code
class_name EnemyConfig
extends Resource

@export var health: int   = 50
@export var speed:  float = 80.0

csharpCopy code
// ❌ Anti-pattern: mutating a shared Resource — accidental shared state
// All enemies share the same EnemyStats object loaded from the .tres file.
// Damaging one enemy damages all of them.
[GlobalClass]
public partial class Enemy : CharacterBody2D
{
    [Export] public EnemyStats Stats;  // loaded from .tres, shared by default

    public void TakeDamage(int amount)
    {
        Stats.Health -= amount;  // mutates the shared Resource — affects every Enemy!
    }
}

// ✅ Correct: duplicate before mutating so each instance owns its own copy.
public partial class EnemyGood : CharacterBody2D
{
    [Export] public EnemyStats Stats;

    public override void _Ready()
    {
        Stats = (EnemyStats)Stats.Duplicate();  // now safe to mutate independently
    }

    public void TakeDamage(int amount)
    {
        Stats.Health -= amount;  // only affects this instance
    }
}

// ❌ Anti-pattern: game logic inside a Resource
// Resources have no scene-tree access, no _Process, and cannot call GetTree() or read Input.
[GlobalClass]
public partial class EnemyStatsBad : Resource
{
    [Export] public float Health    { get; set; }
    [Export] public float MaxHealth { get; set; }
    [Export] public float RegenRate { get; set; }

    // This logic belongs in a Node, not a Resource.
    public void UpdateHealthRegen(double delta)
    {
        // Cannot call GetTree(), cannot access nodes, cannot read Input.
        Health = Mathf.Min(Health + RegenRate * (float)delta, MaxHealth);
    }
}

// ✅ Correct: keep logic in Nodes, data in Resources.
public partial class EnemyCorrect : CharacterBody2D
{
    [Export] public EnemyStats Stats;
    private float _currentHealth;

    public override void _Ready()
    {
        Stats = (EnemyStats)Stats.Duplicate();
        _currentHealth = Stats.MaxHealth;
    }

    public override void _Process(double delta)
    {
        _currentHealth = Mathf.Min(_currentHealth + Stats.RegenRate * (float)delta, Stats.MaxHealth);
    }
}

// ❌ Anti-pattern: giant monolithic Resource
// One Resource holds everything; impossible to reuse individual pieces.
[GlobalClass]
public partial class GameConfigBad : Resource
{
    [Export] public int   PlayerHealth      { get; set; }
    [Export] public float PlayerSpeed       { get; set; }
    [Export] public int   EnemyGoblinHealth { get; set; }
    [Export] public float EnemyGoblinSpeed  { get; set; }
    [Export] public int   EnemyTrollHealth  { get; set; }
    // ... 200 more properties
}

// ✅ Correct: small focused Resources, composed together.
[GlobalClass]
public partial class PlayerConfig : Resource
{
    [Export] public int   Health { get; set; } = 100;
    [Export] public float Speed  { get; set; } = 200.0f;
}

[GlobalClass]
public partial class EnemyConfig : Resource
{
    [Export] public int   Health { get; set; } = 50;
    [Export] public float Speed  { get; set; } = 80.0f;
}

11. Checklist

• Resource subclass uses class_name so the editor can find it for New Resource
• C# classes have [GlobalClass] attribute
• All Inspector-editable fields use @export / [Export]
• @export_range used on numeric fields with designer-tunable bounds
• @export_group and @export_category used to organize Inspector layout for Resources with many fields
• Per-instance mutable Resources are duplicate()-d in _ready()
• Read-only shared Resources (definitions, blueprints) are not duplicated
• Game logic (per-frame updates, scene queries) lives in Nodes, not Resources
• Large data sets split into focused single-responsibility Resources
• .tres used during development; .res considered for shipped production data
• ResourceSaver.save() return value checked and errors reported with push_error()
• .tres / .res files never loaded from untrusted external sources