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use super::scene_tree::SceneTreeRef;
use crate::interop::{GodotAccess, GodotNodeHandle};
use crate::plugins::assets::GodotResource;
use crate::plugins::signals::{
DeferredSignalConnectionTrait, DeferredSignalConnections, SignalConnectionSpec, SignalSender,
};
use crate::plugins::transforms::IntoGodotTransform;
use crate::plugins::transforms::IntoGodotTransform2D;
use bevy_app::{App, Plugin, PostUpdate};
use bevy_asset::{Assets, Handle};
use bevy_ecs::event::Event;
use bevy_ecs::prelude::Res;
use bevy_ecs::{
component::Component,
entity::Entity,
query::Without,
system::{Commands, Query, ResMut},
};
use bevy_transform::components::Transform;
use godot::obj::Gd;
use godot::prelude::Variant;
use godot::{
builtin::GString,
classes::{Node, Node2D, Node3D, PackedScene, ResourceLoader},
};
use std::collections::HashMap;
use std::str::FromStr;
use tracing::error;
#[derive(Default)]
pub struct GodotPackedScenePlugin;
impl Plugin for GodotPackedScenePlugin {
fn build(&self, app: &mut App) {
app.add_systems(PostUpdate, spawn_scene);
}
}
// silence warning about the following docs referring to private `spawn_scene`
#[allow(rustdoc::private_intra_doc_links)]
/// A to-be-instanced-and-spawned Godot scene.
///
/// [`GodotScene`]s that are spawned/inserted into the bevy world will be instanced from the provided
/// handle/path and the instance will be added as an [`GodotNodeHandle`] in the next PostUpdateFlush set.
/// (see [`spawn_scene`])
#[derive(Debug, Component)]
pub struct GodotScene {
resource: GodotSceneResource,
parent: Option<GodotNodeHandle>,
deferred_signal_connections: Vec<Box<dyn DeferredSignalConnectionTrait>>,
}
#[derive(Debug)]
enum GodotSceneResource {
Handle(Handle<GodotResource>),
Path(String),
}
impl GodotScene {
/// Instantiate the godot scene from a Bevy `Handle<GodotResource>` and add it to the
/// scene tree root. This is the preferred method when using Bevy's asset system.
pub fn from_handle(handle: Handle<GodotResource>) -> Self {
Self {
resource: GodotSceneResource::Handle(handle),
parent: None,
deferred_signal_connections: Vec::new(),
}
}
/// Instantiate the godot scene from the given path and add it to the scene tree root.
///
/// Note that this will call [`ResourceLoader`].load() - which is a blocking load.
/// If you want async loading, you should load your resources through Bevy's AssetServer
/// and use from_handle().
pub fn from_path(path: &str) -> Self {
Self {
resource: GodotSceneResource::Path(path.to_string()),
parent: None,
deferred_signal_connections: Vec::new(),
}
}
/// Set the parent node for this scene when spawned.
pub fn with_parent(mut self, parent: GodotNodeHandle) -> Self {
self.parent = Some(parent);
self
}
/// Connect a Godot signal from a child node to trigger a Bevy event.
/// The signal will be connected when the scene is spawned, and observers
/// will be triggered when the signal fires.
///
/// # Requirements
/// This method requires [`GodotSignalsPlugin<T>`] to be added to your app for the
/// event type `T` you're using. If the plugin is not added, the signal connections
/// will be ignored and an error will be logged at runtime.
///
/// # Arguments
/// * `node_path` - Path relative to the scene root (e.g., "VBox/MyButton" or "." for root node).
/// Argument supports the same syntax as [Node.get_node](https://docs.godotengine.org/en/stable/classes/class_node.html#class-node-method-get-node).
/// * `signal_name` - Name of the Godot signal to connect (e.g., "pressed").
/// * `mapper` - Closure that maps signal arguments to your event type.
/// * The closure receives three arguments: `args`, `node_handle`, and `entity`:
/// - `args: &[Variant]`: raw Godot arguments (clone if you need detailed parsing).
/// - `node_handle: GodotNodeHandle`: emitting node handle.
/// - `entity: Option<Entity>`: Bevy entity the GodotScene component is attached to (Always Some).
/// * The closure returns an optional event, or None to skip triggering.
///
/// # Example
/// ```ignore
/// let scene: Handle<GodotResource> = ...;
/// let entity = world.spawn_empty();
/// entity.insert(
/// GodotScene::from_handle(scene).with_signal_connection::<MyEvent>(
/// "VBox/MyButton",
/// "pressed",
/// |args, _node_id, _entity| {
/// Some(MyEvent::from_args(args))
/// }
/// )
/// );
/// ```
pub fn with_signal_connection<T, F>(
mut self,
node_path: &str,
signal_name: &str,
mapper: F,
) -> Self
where
T: Event + Clone + Send + std::fmt::Debug + 'static,
for<'a> T::Trigger<'a>: Default,
F: Fn(&[Variant], GodotNodeHandle, Option<Entity>) -> Option<T> + Send + Sync + 'static,
{
self.deferred_signal_connections
.push(Box::new(SignalConnectionSpec {
node_path: node_path.to_string(),
signal_name: signal_name.to_string(),
connections: DeferredSignalConnections::<T>::with_connection(signal_name, mapper),
}));
self
}
}
fn spawn_scene(
mut commands: Commands,
mut new_scenes: Query<(&mut GodotScene, Entity, Option<&Transform>), Without<GodotNodeHandle>>,
mut scene_tree: SceneTreeRef,
mut assets: ResMut<Assets<GodotResource>>,
signal_sender: Option<Res<SignalSender>>,
mut godot: GodotAccess,
) {
// Build a per-frame cache for path-based scene loading.
// This avoids repeated ResourceLoader.load() calls when spawning multiple
// instances of the same scene in a single frame (~22x faster).
let mut local_cache: HashMap<String, Gd<PackedScene>> = HashMap::new();
for (mut scene, ent, transform) in new_scenes.iter_mut() {
let packed_scene: Gd<PackedScene> = match &scene.resource {
GodotSceneResource::Handle(handle) => {
let resource = assets
.get_mut(handle)
.expect("packed scene to exist in assets")
.get()
.clone();
match resource.try_cast::<PackedScene>() {
Ok(ps) => ps,
Err(resource) => {
error!("Resource is not a PackedScene: {:?}", resource);
continue;
}
}
}
GodotSceneResource::Path(path) => {
// Use cached resource if available, otherwise load and cache
if let Some(cached) = local_cache.get(path) {
cached.clone()
} else {
let resource = godot
.singleton::<ResourceLoader>()
.load(
&GString::from_str(path.as_str()).expect("path to be a valid GString"),
)
.expect("packed scene to load");
match resource.try_cast::<PackedScene>() {
Ok(ps) => {
local_cache.insert(path.clone(), ps.clone());
ps
}
Err(resource) => {
error!("Resource is not a PackedScene: {:?}", resource);
continue;
}
}
}
}
};
let instance = match packed_scene.instantiate() {
Some(instance) => instance,
None => {
error!("Failed to instantiate PackedScene");
continue;
}
};
if let Some(transform) = transform {
if let Ok(mut node) = instance.clone().try_cast::<Node3D>() {
node.set_global_transform(transform.to_godot_transform());
} else if let Ok(mut node) = instance.clone().try_cast::<Node2D>() {
node.set_global_transform(transform.to_godot_transform_2d());
} else {
error!(
"attempted to spawn a scene with a transform on Node that did not inherit from Node, the transform was not set"
)
}
}
// Connect signals (only if typed signals plugin is available)
if !scene.deferred_signal_connections.is_empty() {
if let Some(ref sender) = signal_sender {
for deferred_connection in scene.deferred_signal_connections.drain(..) {
deferred_connection.connect(&instance, ent, sender);
}
} else {
error!(
"GodotScene has signal connections but GodotSignalsPlugin is not added. \
Add GodotSignalsPlugin<YourEventType> to enable signal connections."
);
scene.deferred_signal_connections.clear();
}
}
match scene.parent {
Some(parent_id) => {
let mut parent = godot.get::<Node>(parent_id);
parent.add_child(&instance);
}
None => {
scene_tree.get().get_root().unwrap().add_child(&instance);
}
}
commands.entity(ent).insert(GodotNodeHandle::new(instance));
}
}