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2022-04-13

Godot experiments

3:15pm

Playing around with ways to avoid the "editable children" pitfall in godot. Stay tuned.

6:30pm

Node tree for our custom node called "Thing":

Thing
├── Area2D
│   └── CollisionShape2D
└── Sprite

"Thing.gd":

tool
extends Node2D

export var sprite: Texture = null setget set_sprite
export var collision_shape: Shape2D = null setget set_collision_shape

onready var _sprite: Sprite = $Sprite
onready var _collision_shape: CollisionShape2D = $Area2D/CollisionShape2D

func _get_configuration_warning() -> String:
	var warnings = []

	if sprite == null:
		warnings.append("missing sprite")
	if collision_shape == null:
		warnings.append("missing collision_shape")

	return PoolStringArray(warnings).join("; ")

func set_sprite(value: Texture) -> void:
	sprite = value
	if not is_inside_tree():
		yield(self, "ready")
	if _sprite != null:
		_sprite.texture = sprite

func set_collision_shape(value: Shape2D) -> void:
	collision_shape = value
	if not is_inside_tree():
		yield(self, "ready")
	if _collision_shape != null:
		_collision_shape.shape = collision_shape

The idea here is to encapsulate all of the "wiring" by exposing the public attributes as exported variables. In this case, two elements: the sprite texture (`Sprite`), as well as a collision box (`Area2D`, which requires some kind of `CollisionShape`-esque child).

A brief tour:

tool

This is necessary for running the script in the editor (which allows for live updates).

Godot docs: running code in the editor

export var ...

This allows for assigning instance variables via the editor UI.

Godot docs: gdscript exports

func _get_configuration_warning(): -> String:

This allows for displaying a warning (in the editor and the console), basically I'm using it here to define required attrs.

Godot docs: _get_configuration_warning

The setter functions for the `sprite` and `collision_shape` attributes allows us to wire the custom nodes attributes into the private children, as necessary. One little "gotcha" here, the `yield` business is for handing the case when the setter is called during initial construction of the node, otherwise the wiring never actually happens. The `yield` lets us pause execution until the `ready` signal has fired, letting us know the base node has entered the editor tree.

Godot docs: coroutines

I've got a few places I want to get some real-world practice with this particular pattern, so stay tuned for more info.

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