Running code in the editor

What is tool?

tool is a powerful line of code that, when added at the top of your script, makes it execute in the editor. You can also decide which parts of the script execute in the editor, which in game, and which in both.

You can use it for doing many things, but it is mostly useful in level design for visually presenting things that are hard to predict ourselves. Here are some use cases:

• If you have a cannon that shoots cannonballs affected by physics (gravity), you can draw the cannonball’s trajectory in the editor, making level design a lot easier.
• If you have jumppads with varying jump heights, you can draw the maximum jump height a player would reach if it jumped on one, also making level design easier.
• If your player doesn’t use a sprite, but draws itself using code, you can make that drawing code execute in the editor to see your player.

Danger

tool scripts run inside the editor, and let you access the scene tree of the currently edited scene. This is a powerful feature which also comes with caveats, as the editor does not include protections for potential misuse of tool scripts. Be extremely cautious when manipulating the scene tree, especially via Node.queue_free, as it can cause crashes if you free a node while the editor runs logic involving it.

How to use it

To turn a script into a tool, add the keyword tool at the top of your code.

To check if you are currently in the editor, use: Engine.editor_hint.

For example, if you want to execute some code only in the editor, use:

GDScript

C#

if Engine.editor_hint:
    # Code to execute when in editor.

if (Engine.EditorHint)
{
    // Code to execute when in editor.
}

On the other hand, if you want to execute code only in game, simply negate the same statement:

GDScript

C#

if not Engine.editor_hint:
    # Code to execute when in game.

if (!Engine.EditorHint)
{
    // Code to execute when in game.
}

Pieces of code do not have either of the 2 conditions above will run both in-editor and in-game.

Here is how a _process() function might look for you:

GDScript

C#

func _process(delta):
    if Engine.editor_hint:
        # Code to execute in editor.
    if not Engine.editor_hint:
        # Code to execute in game.
    # Code to execute both in editor and in game.

public override void _Process(float delta)
{
    if (Engine.EditorHint)
    {
        // Code to execute in editor.
    }
    if (!Engine.EditorHint)
    {
        // Code to execute in game.
    }
    // Code to execute both in editor and in game.
}

Note

Modifications in editor are permanent. For example, in the following case, when we remove the script, the node will keep its rotation. Be careful to avoid making unwanted modifications.

Try it out

Add a Sprite node to your scene and set the texture to Godot icon. Attach and open a script, and change it to this:

GDScript

C#

tool
extends Sprite
func _process(delta):
    rotation_degrees += 180 * delta

using Godot;
using System;
[Tool]
public class MySprite : Sprite
{
    public override void _Process(float delta)
    {
        RotationDegrees += 180 * delta;
    }
}

Save the script and return to the editor. You should now see your object rotate. If you run the game, it will also rotate.

Note

If you don’t see the changes, reload the scene (close it and open it again).

Now let’s choose which code runs when. Modify your _process() function to look like this:

GDScript

C#

func _process(delta):
    if Engine.editor_hint:
        rotation_degrees += 180 * delta
    else:
        rotation_degrees -= 180 * delta

public override void _Process(float delta)
{
    if (Engine.EditorHint)
    {
        RotationDegrees += 180 * delta;
    }
    else
    {
        RotationDegrees -= 180 * delta;
    }
}

Save the script. Now the object will spin clockwise in the editor, but if you run the game, it will spin counter-clockwise.

Editing variables

Add and export a variable speed to the script. The function set_speed after “setget” is executed with your input to change the variable. Modify _process() to include the rotation speed.

GDScript

C#

tool
extends Sprite
export var speed = 1 setget set_speed
# Update speed and reset the rotation.
func set_speed(new_speed):
    speed = new_speed
    rotation_degrees = 0
func _process(delta):
    rotation_degrees += 180 * delta * speed

using Godot;
using System;
[Tool]
public class MySprite : Sprite
{
    private float speed = 1;
    [Export]
    public float Speed {
        get => speed;
        set => SetSpeed(value);
    }
    // Update speed and reset the rotation.
    private void SetSpeed(float newSpeed)
    {
        speed = newSpeed;
        RotationDegrees = 0;
    }
    public override void _Process(float delta)
    {
        RotationDegrees += 180 * delta * speed;
    }
}

Note

Code from other nodes doesn’t run in the editor. Your access to other nodes is limited. You can access the tree and nodes, and their default properties, but you can’t access user variables. If you want to do so, other nodes have to run in the editor too. AutoLoad nodes cannot be accessed in the editor at all.

Instancing scenes

You can instantiate packed scenes normally and add them to the scene currently opened in the editor. Be sure to set the scene root as the owner of all the nodes created this way or the nodes won’t be visible in the editor.

If you are using tool:

GDScript

C#

func _ready():
    var node = Spatial.new()
    add_child(node) # Parent could be any node in the scene
    node.set_owner(get_tree().edited_scene_root)

public override void _Ready()
{
    var node = new Spatial();
    AddChild(node); // Parent could be any node in the scene
    node.Owner = GetTree().EditedSceneRoot;
}

If you are using EditorScript:

GDScript

C#

func _run():
    var parent = get_scene().find_node("Parent") # Parent could be any node in the scene
    var node = Spatial.new()
    parent.add_child(node)
    node.set_owner(get_scene())

public override void _Run()
{
    var parent = GetScene().FindNode("Parent"); // Parent could be any node in the scene
    var node = new Spatial();
    parent.AddChild(node);
    node.Owner = GetScene();
}

Warning

Using tool improperly can yield many errors. It is advised to first write the code how you want it, and only then add the tool keyword to the top. Also, make sure to separate code that runs in-editor from code that runs in-game. This way, you can find bugs more easily.