feat(nested_blueprints): added support for nested blueprints both in bevy_gltf_blueprints & in gltf_auto_export (#65)

* feat(bevy_gltf_blueprints): 
  * added support for nested blueprints
  * added example/test for nested blueprints with multiple levels of nesting
* feat(tools/gltf_auto_export): 
  * implemented functionality to export nested blueprints/collection instances
  * added add prefs to control nested blueprints export
  * experiments with nested blueprints merge modes
  * when exporting of nested blueprints is disabled, will not scan for nested blueprints
and thus no export them
* docs(): updated docs & added images for nested blueprints support

Cargo.lock

@@ -779,7 +779,7 @@ dependencies = [
 
 [[package]]
 name = "bevy_gltf_blueprints"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "bevy",
  "bevy_gltf_components 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -857,6 +857,18 @@ dependencies = [
  "rand",
 ]
 
+[[package]]
+name = "bevy_gltf_blueprints_nested_blueprints_example"
+version = "0.3.0"
+dependencies = [
+ "bevy",
+ "bevy_asset_loader",
+ "bevy_editor_pls",
+ "bevy_gltf_blueprints",
+ "bevy_rapier3d",
+ "rand",
+]
+
 [[package]]
 name = "bevy_gltf_components"
 version = "0.2.0"

Cargo.toml

@@ -6,6 +6,7 @@ members = [
     "examples/bevy_gltf_blueprints/basic/",
     "examples/bevy_gltf_blueprints/basic_scene_components/",
     "examples/bevy_gltf_blueprints/basic_xpbd_physics/",
+    "examples/bevy_gltf_blueprints/nested_blueprints/",
     "examples/bevy_gltf_blueprints/animation/",
     "examples/bevy_gltf_blueprints/multiple_levels/",
     "examples/bevy_gltf_blueprints/materials/"

crates/bevy_gltf_blueprints/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bevy_gltf_blueprints"
-version = "0.4.0"
+version = "0.5.0"
 authors = ["Mark 'kaosat-dev' Moissette"]
 description = "Adds the ability to define Blueprints/Prefabs for [Bevy](https://bevyengine.org/) inside gltf files and spawn them in Bevy."
 homepage = "https://github.com/kaosat-dev/Blender_bevy_components_workflow"

crates/bevy_gltf_blueprints/README.md

@@ -26,7 +26,7 @@ Here's a minimal usage example:
 # Cargo.toml
 [dependencies]
 bevy="0.12"
-bevy_gltf_blueprints = { version = "0.4"} 
+bevy_gltf_blueprints = { version = "0.5"} 
 
 ```
 
@@ -64,7 +64,7 @@ fn spawn_blueprint(
 Add the following to your `[dependencies]` section in `Cargo.toml`:
 
 ```toml
-bevy_gltf_blueprints = "0.4"
+bevy_gltf_blueprints = "0.5"
 ```
 
 Or use `cargo add`:
@@ -281,6 +281,8 @@ https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/example
 
 https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/materials
 
+https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/nested_blueprints
+
 
 ## Compatible Bevy versions
 
@@ -289,7 +291,7 @@ The main branch is compatible with the latest Bevy release, while the branch `be
 Compatibility of `bevy_gltf_blueprints` versions:
 | `bevy_gltf_blueprints` | `bevy` |
 | :--                 | :--    |
-| `0.3 - 0.4`         | `0.12` |
+| `0.3 - 0.5`         | `0.12` |
 | `0.1 - 0.2`         | `0.11` |
 | branch `main`       | `0.12` |
 | branch `bevy_main`  | `main` |

crates/bevy_gltf_blueprints/src/spawn_from_blueprints.rs

@@ -34,7 +34,7 @@ pub struct SpawnedRoot;
 /// * also takes into account the already exisiting "override" components, ie "override components" > components from blueprint
 pub(crate) fn spawn_from_blueprints(
     spawn_placeholders: Query<
-        (Entity, &Name, &BlueprintName, &Transform),
+        (Entity, &Name, &BlueprintName, &Transform, Option<&Parent>),
         (
             Added<BlueprintName>,
             Added<SpawnHere>,
@@ -49,9 +49,12 @@ pub(crate) fn spawn_from_blueprints(
     assets_gltf: Res<Assets<Gltf>>,
     asset_server: Res<AssetServer>,
     blueprints_config: Res<BluePrintsConfig>,
+
 ) {
-    for (entity, name, blupeprint_name, transform) in spawn_placeholders.iter() {
-        debug!("need to spawn {:?}", blupeprint_name.0);
+    for (entity, name, blupeprint_name, transform, original_parent) in spawn_placeholders.iter() {
+        debug!("need to spawn {:?}, id: {:?}", blupeprint_name.0, entity);
+
+
         let what = &blupeprint_name.0;
         let model_file_name = format!("{}.{}", &what, &blueprints_config.format);
         let model_path =
@@ -60,8 +63,7 @@ pub(crate) fn spawn_from_blueprints(
         debug!("attempting to spawn {:?}", model_path);
         let model_handle: Handle<Gltf> = asset_server.load(model_path);
 
-        let world = game_world.single_mut();
-        let world = world.1[0]; // FIXME: dangerous hack because our gltf data have a single child like this, but might not always be the case
+     
 
         let gltf = assets_gltf
             .get(&model_handle)
@@ -92,6 +94,15 @@ pub(crate) fn spawn_from_blueprints(
                 },
             ))
             .id();
-        commands.entity(world).add_child(child_scene);
+
+        let world = game_world.single_mut();
+        let mut parent = world.1[0]; // FIXME: dangerous hack because our gltf data have a single child like this, but might not always be the case
+    
+        // ideally, insert the newly created entity as a child of the original parent, if any, the world otherwise
+        if let Some(original_parent) = original_parent {
+            parent = original_parent.get();
+        }
+     
+        commands.entity(parent).add_child(child_scene);    
     }
 }

examples/bevy_gltf_blueprints/nested_blueprints/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "bevy_gltf_blueprints_nested_blueprints_example"
+version = "0.3.0"
+edition = "2021"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+bevy="0.12"
+bevy_gltf_blueprints = { path = "../../../crates/bevy_gltf_blueprints" }
+bevy_rapier3d = { version = "0.23.0", features = [ "serde-serialize", "debug-render-3d", "enhanced-determinism"] }
+bevy_asset_loader = { version = "0.18", features = ["standard_dynamic_assets" ]} 
+bevy_editor_pls = { version = "0.6" }
+rand = "0.8.5"

examples/bevy_gltf_blueprints/nested_blueprints/README.md

@@ -0,0 +1,14 @@
+
+# Nested blueprints example/demo
+
+Example of blueprints (and thus gltf) nested & reuse to avoid redundant data in blueprints gltfs that lead to asset & memory bloat
+- ideally, to be used together with ```gltf_auto_export``` version >0.8  with the "export nested blueprints" option for exports, as that will generate whole 
+gltf blueprints hierarchies, and minimise their size for you
+- It shows you how ou can configure```Bevy_gltf_blueprints``` to spawn nested blueprints
+
+
+## Running this example
+
+```
+cargo run --features bevy/dynamic_linking
+```

examples/bevy_gltf_blueprints/nested_blueprints/assets/assets_core.assets.ron

@@ -0,0 +1 @@
+({})

examples/bevy_gltf_blueprints/nested_blueprints/assets/assets_game.assets.ron

@@ -0,0 +1,6 @@
+({
+    "world":File (path: "models/World.glb"),
+    "models": Folder (
+        path: "models/library",
+    ),
+})

examples/bevy_gltf_blueprints/nested_blueprints/src/assets/assets_core.rs

@@ -0,0 +1,5 @@
+use bevy::prelude::*;
+use bevy_asset_loader::prelude::*;
+
+#[derive(AssetCollection, Resource)]
+pub struct CoreAssets {}

examples/bevy_gltf_blueprints/nested_blueprints/src/assets/assets_game.rs

@@ -0,0 +1,13 @@
+use bevy::gltf::Gltf;
+use bevy::prelude::*;
+use bevy::utils::HashMap;
+use bevy_asset_loader::prelude::*;
+
+#[derive(AssetCollection, Resource)]
+pub struct GameAssets {
+    #[asset(key = "world")]
+    pub world: Handle<Gltf>,
+
+    #[asset(key = "models", collection(typed, mapped))]
+    pub models: HashMap<String, Handle<Gltf>>,
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/assets/mod.rs

@@ -0,0 +1,35 @@
+pub mod assets_core;
+pub use assets_core::*;
+
+pub mod assets_game;
+pub use assets_game::*;
+
+use bevy::prelude::*;
+use bevy_asset_loader::prelude::*;
+
+use crate::state::AppState;
+
+pub struct AssetsPlugin;
+impl Plugin for AssetsPlugin {
+    fn build(&self, app: &mut App) {
+        app
+            // load core assets (ie assets needed in the main menu, and everywhere else before loading more assets in game)
+            .add_loading_state(
+                LoadingState::new(AppState::CoreLoading).continue_to_state(AppState::MenuRunning),
+            )
+            .add_dynamic_collection_to_loading_state::<_, StandardDynamicAssetCollection>(
+                AppState::CoreLoading,
+                "assets_core.assets.ron",
+            )
+            .add_collection_to_loading_state::<_, CoreAssets>(AppState::CoreLoading)
+            // load game assets
+            .add_loading_state(
+                LoadingState::new(AppState::AppLoading).continue_to_state(AppState::AppRunning),
+            )
+            .add_dynamic_collection_to_loading_state::<_, StandardDynamicAssetCollection>(
+                AppState::AppLoading,
+                "assets_game.assets.ron",
+            )
+            .add_collection_to_loading_state::<_, GameAssets>(AppState::AppLoading);
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/camera/camera_replace_proxies.rs

@@ -0,0 +1,24 @@
+use bevy::core_pipeline::bloom::{BloomCompositeMode, BloomSettings};
+use bevy::core_pipeline::tonemapping::{DebandDither, Tonemapping};
+use bevy::prelude::*;
+
+use super::CameraTrackingOffset;
+
+pub fn camera_replace_proxies(
+    mut commands: Commands,
+    mut added_cameras: Query<(Entity, &mut Camera), (Added<Camera>, With<CameraTrackingOffset>)>,
+) {
+    for (entity, mut camera) in added_cameras.iter_mut() {
+        info!("detected added camera, updating proxy");
+        camera.hdr = true;
+        commands
+            .entity(entity)
+            .insert(DebandDither::Enabled)
+            .insert(Tonemapping::BlenderFilmic)
+            .insert(BloomSettings {
+                intensity: 0.01,
+                composite_mode: BloomCompositeMode::Additive,
+                ..default()
+            });
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/camera/camera_tracking.rs

@@ -0,0 +1,58 @@
+use bevy::prelude::*;
+
+#[derive(Component, Reflect, Debug)]
+#[reflect(Component)]
+/// Component for cameras, with an offset from the Trackable target  
+///
+pub struct CameraTracking {
+    pub offset: Vec3,
+}
+impl Default for CameraTracking {
+    fn default() -> Self {
+        CameraTracking {
+            offset: Vec3::new(0.0, 6.0, 8.0),
+        }
+    }
+}
+
+#[derive(Component, Reflect, Debug, Deref, DerefMut)]
+#[reflect(Component)]
+/// Component for cameras, with an offset from the Trackable target  
+pub struct CameraTrackingOffset(Vec3);
+impl Default for CameraTrackingOffset {
+    fn default() -> Self {
+        CameraTrackingOffset(Vec3::new(0.0, 6.0, 8.0))
+    }
+}
+
+impl CameraTrackingOffset {
+    fn new(input: Vec3) -> Self {
+        CameraTrackingOffset(input)
+    }
+}
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+/// Add this component to an entity if you want it to be tracked by a Camera
+pub struct CameraTrackable;
+
+pub fn camera_track(
+    mut tracking_cameras: Query<
+        (&mut Transform, &CameraTrackingOffset),
+        (
+            With<Camera>,
+            With<CameraTrackingOffset>,
+            Without<CameraTrackable>,
+        ),
+    >,
+    camera_tracked: Query<&Transform, With<CameraTrackable>>,
+) {
+    for (mut camera_transform, tracking_offset) in tracking_cameras.iter_mut() {
+        for tracked_transform in camera_tracked.iter() {
+            let target_position = tracked_transform.translation + tracking_offset.0;
+            let eased_position = camera_transform.translation.lerp(target_position, 0.1);
+            camera_transform.translation = eased_position; // + tracking.offset;// tracked_transform.translation + tracking.offset;
+            *camera_transform = camera_transform.looking_at(tracked_transform.translation, Vec3::Y);
+        }
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/camera/mod.rs

@@ -0,0 +1,24 @@
+pub mod camera_tracking;
+pub use camera_tracking::*;
+
+pub mod camera_replace_proxies;
+pub use camera_replace_proxies::*;
+
+use bevy::prelude::*;
+use bevy_gltf_blueprints::GltfBlueprintsSet;
+
+pub struct CameraPlugin;
+impl Plugin for CameraPlugin {
+    fn build(&self, app: &mut App) {
+        app.register_type::<CameraTrackable>()
+            .register_type::<CameraTracking>()
+            .register_type::<CameraTrackingOffset>()
+            .add_systems(
+                Update,
+                (
+                    camera_replace_proxies.after(GltfBlueprintsSet::AfterSpawn),
+                    camera_track,
+                ),
+            );
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/lighting/lighting_replace_proxies.rs

@@ -0,0 +1,25 @@
+use bevy::prelude::*;
+
+use bevy::pbr::{CascadeShadowConfig, CascadeShadowConfigBuilder};
+
+// fixme might be too specific to might needs, should it be moved out ? also these are all for lights, not models
+pub fn lighting_replace_proxies(
+    mut added_dirights: Query<(Entity, &mut DirectionalLight), Added<DirectionalLight>>,
+    mut added_spotlights: Query<&mut SpotLight, Added<SpotLight>>,
+    mut commands: Commands,
+) {
+    for (entity, mut light) in added_dirights.iter_mut() {
+        light.illuminance *= 5.0;
+        light.shadows_enabled = true;
+        let shadow_config: CascadeShadowConfig = CascadeShadowConfigBuilder {
+            first_cascade_far_bound: 15.0,
+            maximum_distance: 135.0,
+            ..default()
+        }
+        .into();
+        commands.entity(entity).insert(shadow_config);
+    }
+    for mut light in added_spotlights.iter_mut() {
+        light.shadows_enabled = true;
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/lighting/mod.rs

@@ -0,0 +1,18 @@
+mod lighting_replace_proxies;
+use lighting_replace_proxies::*;
+
+use bevy::pbr::{DirectionalLightShadowMap, NotShadowCaster};
+use bevy::prelude::*;
+
+pub struct LightingPlugin;
+impl Plugin for LightingPlugin {
+    fn build(&self, app: &mut App) {
+        app
+        .insert_resource(DirectionalLightShadowMap { size: 4096 })
+         // FIXME: adding these since they are missing
+        .register_type::<NotShadowCaster>()
+
+        .add_systems(PreUpdate, lighting_replace_proxies) // FIXME: you should actually run this in a specific state most likely
+      ;
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/mod.rs

@@ -0,0 +1,35 @@
+pub mod camera;
+pub use camera::*;
+
+pub mod lighting;
+pub use lighting::*;
+
+pub mod relationships;
+pub use relationships::*;
+
+pub mod physics;
+pub use physics::*;
+
+// pub mod save_load;
+// pub use save_load::*;
+
+use bevy::prelude::*;
+use bevy_gltf_blueprints::*;
+
+pub struct CorePlugin;
+impl Plugin for CorePlugin {
+    fn build(&self, app: &mut App) {
+        app.add_plugins((
+            LightingPlugin,
+            CameraPlugin,
+            PhysicsPlugin,
+            // SaveLoadPlugin,
+            BlueprintsPlugin {
+                library_folder: "models/library".into(),
+                format: GltfFormat::GLB,
+                aabbs: true,
+                ..Default::default()
+            },
+        ));
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/physics/controls.rs

@@ -0,0 +1,12 @@
+use bevy::prelude::{info, ResMut};
+use bevy_rapier3d::prelude::RapierConfiguration;
+
+pub fn pause_physics(mut physics_config: ResMut<RapierConfiguration>) {
+    info!("pausing physics");
+    physics_config.physics_pipeline_active = false;
+}
+
+pub fn resume_physics(mut physics_config: ResMut<RapierConfiguration>) {
+    info!("unpausing physics");
+    physics_config.physics_pipeline_active = true;
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/physics/mod.rs

@@ -0,0 +1,37 @@
+pub mod physics_replace_proxies;
+use bevy_rapier3d::{
+    prelude::{NoUserData, RapierPhysicsPlugin},
+    render::RapierDebugRenderPlugin,
+};
+pub use physics_replace_proxies::*;
+
+pub mod utils;
+
+pub mod controls;
+pub use controls::*;
+
+use crate::state::GameState;
+use bevy::prelude::*;
+// use super::blueprints::GltfBlueprintsSet;
+use bevy_gltf_blueprints::GltfBlueprintsSet;
+// use crate::Collider;
+pub struct PhysicsPlugin;
+impl Plugin for PhysicsPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_plugins((
+            RapierPhysicsPlugin::<NoUserData>::default(),
+            RapierDebugRenderPlugin::default(),
+        ))
+        .register_type::<AutoAABBCollider>()
+        .register_type::<physics_replace_proxies::Collider>()
+        // find a way to make serde's stuff serializable
+        // .register_type::<bevy_rapier3d::dynamics::CoefficientCombineRule>()
+        //bevy_rapier3d::dynamics::CoefficientCombineRule
+        .add_systems(
+            Update,
+            physics_replace_proxies.after(GltfBlueprintsSet::AfterSpawn),
+        )
+        .add_systems(OnEnter(GameState::InGame), resume_physics)
+        .add_systems(OnExit(GameState::InGame), pause_physics);
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/physics/physics_replace_proxies.rs

@@ -0,0 +1,101 @@
+use bevy::prelude::*;
+// use bevy::render::primitives::Aabb;
+use bevy_rapier3d::geometry::Collider as RapierCollider;
+use bevy_rapier3d::prelude::{ActiveCollisionTypes, ActiveEvents, ComputedColliderShape};
+
+use super::utils::*;
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+pub enum Collider {
+    Ball(f32),
+    Cuboid(Vec3),
+    Capsule(Vec3, Vec3, f32),
+    #[default]
+    Mesh,
+}
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+pub enum AutoAABBCollider {
+    #[default]
+    Cuboid,
+    Ball,
+    Capsule,
+}
+
+// replaces all physics stand-ins with the actual rapier types
+pub fn physics_replace_proxies(
+    meshes: Res<Assets<Mesh>>,
+    mesh_handles: Query<&Handle<Mesh>>,
+    mut proxy_colliders: Query<
+        (Entity, &Collider, &Name, &mut Visibility),
+        (Without<RapierCollider>, Added<Collider>),
+    >,
+    // needed for tri meshes
+    children: Query<&Children>,
+
+    mut commands: Commands,
+) {
+    for proxy_colider in proxy_colliders.iter_mut() {
+        let (entity, collider_proxy, name, mut visibility) = proxy_colider;
+        // we hide the collider meshes: perhaps they should be removed altogether once processed ?
+        if name.ends_with("_collider") || name.ends_with("_sensor") {
+            *visibility = Visibility::Hidden;
+        }
+
+        let mut rapier_collider: RapierCollider;
+        match collider_proxy {
+            Collider::Ball(radius) => {
+                info!("generating collider from proxy: ball");
+                rapier_collider = RapierCollider::ball(*radius);
+                commands.entity(entity)
+                    .insert(rapier_collider)
+                    .insert(ActiveEvents::COLLISION_EVENTS)  // FIXME: this is just for demo purposes !!!
+                    ;
+            }
+            Collider::Cuboid(size) => {
+                info!("generating collider from proxy: cuboid");
+                rapier_collider = RapierCollider::cuboid(size.x, size.y, size.z);
+                commands.entity(entity)
+                    .insert(rapier_collider)
+                    .insert(ActiveEvents::COLLISION_EVENTS)  // FIXME: this is just for demo purposes !!!
+                    ;
+            }
+            Collider::Capsule(a, b, radius) => {
+                info!("generating collider from proxy: capsule");
+                rapier_collider = RapierCollider::capsule(*a, *b, *radius);
+                commands.entity(entity)
+                    .insert(rapier_collider)
+                    .insert(ActiveEvents::COLLISION_EVENTS)  // FIXME: this is just for demo purposes !!!
+                    ;
+            }
+            Collider::Mesh => {
+                info!("generating collider from proxy: mesh");
+                for (_, collider_mesh) in
+                    Mesh::search_in_children(entity, &children, &meshes, &mesh_handles)
+                {
+                    rapier_collider = RapierCollider::from_bevy_mesh(
+                        collider_mesh,
+                        &ComputedColliderShape::TriMesh,
+                    )
+                    .unwrap();
+                    commands
+                        .entity(entity)
+                        .insert(rapier_collider)
+                        // FIXME: this is just for demo purposes !!!
+                        .insert(
+                            ActiveCollisionTypes::default()
+                                | ActiveCollisionTypes::KINEMATIC_STATIC
+                                | ActiveCollisionTypes::STATIC_STATIC
+                                | ActiveCollisionTypes::DYNAMIC_STATIC,
+                        )
+                        .insert(ActiveEvents::COLLISION_EVENTS);
+                    //  .insert(ActiveEvents::COLLISION_EVENTS)
+                    // break;
+                    // RapierCollider::convex_hull(points)
+                }
+            }
+        }
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/physics/utils.rs

@@ -0,0 +1,175 @@
+use bevy::prelude::*;
+use bevy::render::mesh::{MeshVertexAttributeId, PrimitiveTopology, VertexAttributeValues};
+// TAKEN VERBATIB FROM https://github.com/janhohenheim/foxtrot/blob/src/util/trait_extension.rs
+
+pub(crate) trait Vec3Ext: Copy {
+    fn is_approx_zero(self) -> bool;
+    fn split(self, up: Vec3) -> SplitVec3;
+}
+impl Vec3Ext for Vec3 {
+    #[inline]
+    fn is_approx_zero(self) -> bool {
+        self.length_squared() < 1e-5
+    }
+
+    #[inline]
+    fn split(self, up: Vec3) -> SplitVec3 {
+        let vertical = up * self.dot(up);
+        let horizontal = self - vertical;
+        SplitVec3 {
+            vertical,
+            horizontal,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub(crate) struct SplitVec3 {
+    pub(crate) vertical: Vec3,
+    pub(crate) horizontal: Vec3,
+}
+
+pub(crate) trait Vec2Ext: Copy {
+    fn is_approx_zero(self) -> bool;
+    fn x0y(self) -> Vec3;
+}
+impl Vec2Ext for Vec2 {
+    #[inline]
+    fn is_approx_zero(self) -> bool {
+        self.length_squared() < 1e-5
+    }
+
+    #[inline]
+    fn x0y(self) -> Vec3 {
+        Vec3::new(self.x, 0., self.y)
+    }
+}
+
+pub(crate) trait MeshExt {
+    fn transform(&mut self, transform: Transform);
+    fn transformed(&self, transform: Transform) -> Mesh;
+    fn read_coords_mut(&mut self, id: impl Into<MeshVertexAttributeId>) -> &mut Vec<[f32; 3]>;
+    fn search_in_children<'a>(
+        parent: Entity,
+        children: &'a Query<&Children>,
+        meshes: &'a Assets<Mesh>,
+        mesh_handles: &'a Query<&Handle<Mesh>>,
+    ) -> Vec<(Entity, &'a Mesh)>;
+}
+
+impl MeshExt for Mesh {
+    fn transform(&mut self, transform: Transform) {
+        for coords in self.read_coords_mut(Mesh::ATTRIBUTE_POSITION.clone()) {
+            let vec3 = (*coords).into();
+            let transformed = transform.transform_point(vec3);
+            *coords = transformed.into();
+        }
+        for normal in self.read_coords_mut(Mesh::ATTRIBUTE_NORMAL.clone()) {
+            let vec3 = (*normal).into();
+            let transformed = transform.rotation.mul_vec3(vec3);
+            *normal = transformed.into();
+        }
+    }
+
+    fn transformed(&self, transform: Transform) -> Mesh {
+        let mut mesh = self.clone();
+        mesh.transform(transform);
+        mesh
+    }
+
+    fn read_coords_mut(&mut self, id: impl Into<MeshVertexAttributeId>) -> &mut Vec<[f32; 3]> {
+        // Guaranteed by Bevy for the current usage
+        match self
+            .attribute_mut(id)
+            .expect("Failed to read unknown mesh attribute")
+        {
+            VertexAttributeValues::Float32x3(values) => values,
+            // Guaranteed by Bevy for the current usage
+            _ => unreachable!(),
+        }
+    }
+
+    fn search_in_children<'a>(
+        parent: Entity,
+        children_query: &'a Query<&Children>,
+        meshes: &'a Assets<Mesh>,
+        mesh_handles: &'a Query<&Handle<Mesh>>,
+    ) -> Vec<(Entity, &'a Mesh)> {
+        if let Ok(children) = children_query.get(parent) {
+            let mut result: Vec<_> = children
+                .iter()
+                .filter_map(|entity| mesh_handles.get(*entity).ok().map(|mesh| (*entity, mesh)))
+                .map(|(entity, mesh_handle)| {
+                    (
+                        entity,
+                        meshes
+                            .get(mesh_handle)
+                            .expect("Failed to get mesh from handle"),
+                    )
+                })
+                .map(|(entity, mesh)| {
+                    assert_eq!(mesh.primitive_topology(), PrimitiveTopology::TriangleList);
+                    (entity, mesh)
+                })
+                .collect();
+            let mut inner_result = children
+                .iter()
+                .flat_map(|entity| {
+                    Self::search_in_children(*entity, children_query, meshes, mesh_handles)
+                })
+                .collect();
+            result.append(&mut inner_result);
+            result
+        } else {
+            Vec::new()
+        }
+    }
+}
+
+pub(crate) trait F32Ext: Copy {
+    fn is_approx_zero(self) -> bool;
+    fn squared(self) -> f32;
+    fn lerp(self, other: f32, ratio: f32) -> f32;
+}
+
+impl F32Ext for f32 {
+    #[inline]
+    fn is_approx_zero(self) -> bool {
+        self.abs() < 1e-5
+    }
+
+    #[inline]
+    fn squared(self) -> f32 {
+        self * self
+    }
+
+    #[inline]
+    fn lerp(self, other: f32, ratio: f32) -> f32 {
+        self.mul_add(1. - ratio, other * ratio)
+    }
+}
+
+pub(crate) trait TransformExt: Copy {
+    fn horizontally_looking_at(self, target: Vec3, up: Vec3) -> Transform;
+    fn lerp(self, other: Transform, ratio: f32) -> Transform;
+}
+
+impl TransformExt for Transform {
+    fn horizontally_looking_at(self, target: Vec3, up: Vec3) -> Transform {
+        let direction = target - self.translation;
+        let horizontal_direction = direction - up * direction.dot(up);
+        let look_target = self.translation + horizontal_direction;
+        self.looking_at(look_target, up)
+    }
+
+    fn lerp(self, other: Transform, ratio: f32) -> Transform {
+        let translation = self.translation.lerp(other.translation, ratio);
+        let rotation = self.rotation.slerp(other.rotation, ratio);
+        let scale = self.scale.lerp(other.scale, ratio);
+        Transform {
+            translation,
+            rotation,
+            scale,
+        }
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/physics/utils_old.rs

@@ -0,0 +1,75 @@
+use bevy::prelude::*;
+use bevy::render::mesh::{MeshVertexAttributeId, PrimitiveTopology, VertexAttributeValues};
+// TAKEN VERBATIB FROM https://github.com/janhohenheim/foxtrot/blob/6e31fc02652fc9d085a4adde0a73ab007dbbb0dc/src/util/trait_extension.rs
+
+pub trait Vec3Ext {
+    #[allow(clippy::wrong_self_convention)] // Because [`Vec3`] is [`Copy`]
+    fn is_approx_zero(self) -> bool;
+    fn x0z(self) -> Vec3;
+}
+impl Vec3Ext for Vec3 {
+    fn is_approx_zero(self) -> bool {
+        [self.x, self.y, self.z].iter().all(|&x| x.abs() < 1e-5)
+    }
+    fn x0z(self) -> Vec3 {
+        Vec3::new(self.x, 0., self.z)
+    }
+}
+
+pub trait MeshExt {
+    fn transform(&mut self, transform: Transform);
+    fn transformed(&self, transform: Transform) -> Mesh;
+    fn read_coords_mut(&mut self, id: impl Into<MeshVertexAttributeId>) -> &mut Vec<[f32; 3]>;
+    fn search_in_children<'a>(
+        children: &'a Children,
+        meshes: &'a Assets<Mesh>,
+        mesh_handles: &'a Query<&Handle<Mesh>>,
+    ) -> (Entity, &'a Mesh);
+}
+
+impl MeshExt for Mesh {
+    fn transform(&mut self, transform: Transform) {
+        for attribute in [Mesh::ATTRIBUTE_POSITION, Mesh::ATTRIBUTE_NORMAL] {
+            for coords in self.read_coords_mut(attribute.clone()) {
+                let vec3 = (*coords).into();
+                let transformed = transform.transform_point(vec3);
+                *coords = transformed.into();
+            }
+        }
+    }
+
+    fn transformed(&self, transform: Transform) -> Mesh {
+        let mut mesh = self.clone();
+        mesh.transform(transform);
+        mesh
+    }
+
+    fn read_coords_mut(&mut self, id: impl Into<MeshVertexAttributeId>) -> &mut Vec<[f32; 3]> {
+        match self.attribute_mut(id).unwrap() {
+            VertexAttributeValues::Float32x3(values) => values,
+            // Guaranteed by Bevy
+            _ => unreachable!(),
+        }
+    }
+
+    fn search_in_children<'a>(
+        children: &'a Children,
+        meshes: &'a Assets<Mesh>,
+        mesh_handles: &'a Query<&Handle<Mesh>>,
+    ) -> (Entity, &'a Mesh) {
+        let entity_handles: Vec<_> = children
+            .iter()
+            .filter_map(|entity| mesh_handles.get(*entity).ok().map(|mesh| (*entity, mesh)))
+            .collect();
+        assert_eq!(
+            entity_handles.len(),
+            1,
+            "Collider must contain exactly one mesh, but found {}",
+            entity_handles.len()
+        );
+        let (entity, mesh_handle) = entity_handles.first().unwrap();
+        let mesh = meshes.get(mesh_handle).unwrap();
+        assert_eq!(mesh.primitive_topology(), PrimitiveTopology::TriangleList);
+        (*entity, mesh)
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/relationships/mod.rs

@@ -0,0 +1,11 @@
+pub mod relationships_insert_dependant_components;
+pub use relationships_insert_dependant_components::*;
+
+use bevy::prelude::*;
+
+pub struct EcsRelationshipsPlugin;
+impl Plugin for EcsRelationshipsPlugin {
+    fn build(&self, app: &mut App) {
+        app;
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/relationships/relationships_insert_dependant_components.rs

@@ -0,0 +1,15 @@
+use bevy::prelude::*;
+
+pub fn insert_dependant_component<
+    Dependant: Component,
+    Dependency: Component + std::default::Default,
+>(
+    mut commands: Commands,
+    entities_without_depency: Query<(Entity, &Name), (With<Dependant>, Without<Dependency>)>,
+) {
+    for (entity, name) in entities_without_depency.iter() {
+        let name = name.clone().to_string();
+        commands.entity(entity).insert(Dependency::default());
+        warn!("found an entity called {} with a {} component but without an {}, please check your assets", name.clone(), std::any::type_name::<Dependant>(), std::any::type_name::<Dependency>());
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/save_load/loading.rs

@@ -0,0 +1,218 @@
+use bevy::prelude::*;
+use bevy_gltf_blueprints::{clone_entity::CloneEntity, GameWorldTag, SpawnHere};
+
+use crate::{
+    assets::GameAssets,
+    state::{AppState, GameState, InAppRunning},
+};
+
+use super::Saveable;
+
+const SCENE_FILE_PATH: &str = "scenes/save.scn.ron";
+
+#[derive(Component, Debug)]
+pub struct TempLoadedSceneMarker;
+
+#[derive(Component, Debug)]
+pub struct SaveablesToRemove(Vec<(Entity, Name)>);
+
+#[derive(Component, Event)]
+pub struct LoadRequest {
+    pub path: String,
+}
+
+pub fn should_load(save_requested_events: EventReader<LoadRequest>) -> bool {
+    return save_requested_events.len() > 0;
+}
+
+pub fn load_prepare(
+    mut next_app_state: ResMut<NextState<AppState>>,
+    mut next_game_state: ResMut<NextState<GameState>>,
+) {
+    next_app_state.set(AppState::LoadingGame);
+    next_game_state.set(GameState::None);
+    info!("--loading: prepare")
+}
+
+/// unload the level recursively
+pub fn _unload_world_old(world: &mut World) {
+    let entities: Vec<Entity> = world
+        // .query_filtered::<Entity, Or<(With<Save>, With<Unload>)>>()
+        .query_filtered::<Entity, With<GameWorldTag>>() // our level/world contains this component
+        .iter(world)
+        .collect();
+    for entity in entities {
+        // Check the entity again in case it was despawned recursively
+        if world.get_entity(entity).is_some() {
+            world.entity_mut(entity).despawn_recursive();
+        }
+    }
+}
+
+pub fn unload_world(mut commands: Commands, gameworlds: Query<Entity, With<GameWorldTag>>) {
+    for e in gameworlds.iter() {
+        info!("--loading: despawn old world/level");
+        commands.entity(e).despawn_recursive();
+    }
+}
+
+// almost identical to setup_game, !!??
+pub fn load_world(
+    mut commands: Commands,
+    game_assets: Res<GameAssets>,
+    // scenes: ResMut<Scene>,
+) {
+    info!("--loading: loading world/level");
+
+    commands.spawn((
+        SceneBundle {
+            scene: game_assets.world.clone(),
+            ..default()
+        },
+        bevy::prelude::Name::from("world"),
+        GameWorldTag,
+        InAppRunning,
+    ));
+}
+
+pub fn load_saved_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
+    commands.spawn((
+        DynamicSceneBundle {
+            // Scenes are loaded just like any other asset.
+            scene: asset_server.load(SCENE_FILE_PATH),
+            ..default()
+        },
+        TempLoadedSceneMarker,
+    ));
+    // commands.entity(world).add_child(child_scene);
+    info!("--loading: loaded saved scene");
+}
+
+pub fn process_loaded_scene(
+    loaded_scene: Query<(Entity, &Children), With<TempLoadedSceneMarker>>,
+    named_entities: Query<(Entity, &Name, &Parent)>, // FIXME: very inneficient
+    mut commands: Commands,
+
+    mut game_world: Query<(Entity, &Children), With<GameWorldTag>>,
+    saveables: Query<(Entity, &Name), With<Saveable>>,
+    asset_server: Res<AssetServer>,
+) {
+    for (loaded_scene, children) in loaded_scene.iter() {
+        info!("--loading: post processing loaded scene");
+
+        let mut entities_to_load: Vec<(Entity, Name)> = vec![];
+
+        for loaded_entity in children.iter() {
+            if let Ok((source, name, _)) = named_entities.get(*loaded_entity) {
+                entities_to_load.push((source, name.clone()));
+
+                let mut found = false;
+                for (e, n, p) in named_entities.iter() {
+                    // if we have an entity with the same name as in same file, overwrite
+                    if e != source && name.as_str() == n.as_str() {
+                        // println!("found entity with same name {} {} {:?} {:?}", name, n, source, e);
+                        // source is entity within the newly loaded scene (source), e is within the existing world (destination)
+                        info!("copying data from {:?} to {:?}", source, e);
+                        commands.add(CloneEntity {
+                            source: source,
+                            destination: e,
+                        });
+                        // FIXME: issue with hierarchy & parenting, would be nice to be able to filter out components from CloneEntity
+                        commands.entity(p.get()).add_child(e);
+                        commands.entity(source).despawn_recursive();
+                        found = true;
+                        break;
+                    }
+                }
+                // entity not found in the list of existing entities (ie entities that came as part of the level)
+                // so we spawn a new one
+                if !found {
+                    info!("generating new entity");
+                    let world = game_world.single_mut();
+                    let world = world.1[0];
+
+                    let new_entity = commands
+                        .spawn((bevy::prelude::Name::from(name.clone()), SpawnHere))
+                        .id();
+
+                    commands.add(CloneEntity {
+                        source: source,
+                        destination: new_entity,
+                    });
+
+                    commands.entity(world).add_child(new_entity);
+                    info!("copying data from {:?} to {:?}", source, new_entity);
+                }
+            }
+        }
+        commands.spawn(SaveablesToRemove(entities_to_load.clone()));
+
+        // if an entity is present in the world but NOT in the saved entities , it should be removed from the world
+        // ideally this should be run between spawning of the world/level AND spawn_placeholders
+
+        // remove the dynamic scene
+        info!("--loading: DESPAWNING LOADED SCENE");
+        commands.entity(loaded_scene).despawn_recursive();
+
+        asset_server.mark_unused_assets();
+        asset_server.free_unused_assets();
+    }
+    //for saveable in saveables.iter(){
+    //    println!("SAVEABLE BEFORE {:?}", saveable)
+    //}
+}
+
+pub fn final_cleanup(
+    saveables_to_remove: Query<(Entity, &SaveablesToRemove)>,
+    mut commands: Commands,
+    saveables: Query<(Entity, &Name), With<Saveable>>,
+    mut next_app_state: ResMut<NextState<AppState>>,
+    mut next_game_state: ResMut<NextState<GameState>>,
+) {
+    if let Ok((e, entities_to_load)) = saveables_to_remove.get_single() {
+        info!("saveables to remove {:?}", entities_to_load);
+        for (e, n) in saveables.iter() {
+            let mut found = false;
+            println!("SAVEABLE {}", n);
+
+            //let entities_to_load = saveables_to_remove.single();
+            for (en, na) in entities_to_load.0.iter() {
+                found = na.as_str() == n.as_str();
+                if found {
+                    break;
+                }
+            }
+            if !found {
+                println!("REMOVING THIS ONE {}", n);
+                commands.entity(e).despawn_recursive();
+            }
+        }
+        // if there is a saveable that is NOT in the list of entities to load, despawn it
+
+        // despawn list
+        commands.entity(e).despawn_recursive();
+
+        info!("--loading: done, move to InGame state");
+        // next_app_state.set(AppState::AppRunning);
+        next_game_state.set(GameState::InGame);
+    }
+}
+
+fn process_loaded_scene_load_alt(
+    entities: Query<(Entity, &Children), With<TempLoadedSceneMarker>>,
+    named_entities: Query<(Entity, &Name, &Parent)>, // FIXME: very inneficient
+    mut commands: Commands,
+) {
+    for (entity, children) in entities.iter() {
+        let mut entities_to_load: Vec<(Entity, Name)> = vec![];
+        for saved_source in children.iter() {
+            if let Ok((source, name, _)) = named_entities.get(*saved_source) {
+                println!("AAAAAAA {}", name);
+                entities_to_load.push((source, name.clone()));
+            }
+        }
+        println!("entities to load {:?}", entities_to_load);
+
+        commands.entity(entity).despawn_recursive();
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/save_load/mod.rs

@@ -0,0 +1,70 @@
+pub mod saveable;
+use bevy::asset::free_unused_assets_system;
+use bevy_gltf_components::GltfComponentsSet;
+pub use saveable::*;
+
+pub mod saving;
+pub use saving::*;
+
+pub mod loading;
+pub use loading::*;
+
+use bevy::prelude::*;
+use bevy::prelude::{App, IntoSystemConfigs, Plugin};
+use bevy::utils::Uuid;
+
+use bevy_gltf_blueprints::GltfBlueprintsSet;
+
+#[derive(SystemSet, Debug, Hash, PartialEq, Eq, Clone)]
+pub enum LoadingSet {
+    Load,
+    PostLoad,
+}
+
+pub struct SaveLoadPlugin;
+impl Plugin for SaveLoadPlugin {
+    fn build(&self, app: &mut App) {
+        app
+        .register_type::<Uuid>()
+        .register_type::<Saveable>()
+        .add_event::<SaveRequest>()
+        .add_event::<LoadRequest>()
+
+        .configure_sets(
+            Update,
+            (LoadingSet::Load, LoadingSet::PostLoad)
+            .chain()
+            .before(GltfBlueprintsSet::Spawn)
+            .before(GltfComponentsSet::Injection)
+        )
+
+        .add_systems(PreUpdate, save_game.run_if(should_save))
+
+        .add_systems(Update,
+            (
+                load_prepare,
+                unload_world,
+                load_world,
+                load_saved_scene,
+                // process_loaded_scene
+            )
+            .chain()
+            .run_if(should_load) // .run_if(in_state(AppState::AppRunning))
+            .in_set(LoadingSet::Load)
+        )
+        .add_systems(Update,
+            (
+                process_loaded_scene,
+                apply_deferred,
+                final_cleanup,
+                apply_deferred,
+                free_unused_assets_system
+            )
+                .chain()
+                .in_set(LoadingSet::PostLoad)
+            )
+
+        // .add_systems(Update, bla)
+      ;
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/save_load/old.rs

@@ -0,0 +1,137 @@
+const NEW_SCENE_FILE_PATH:&str="save.scn.ron";
+
+
+
+
+use bevy::ecs::component::Components;
+use bevy::ecs::entity::EntityMap;
+use serde::{Deserialize, Serialize};
+
+
+use std::io::Read;
+use bevy::scene::serde::SceneDeserializer;
+use ron::Deserializer;
+use serde::de::DeserializeSeed;
+
+
+
+
+#[derive(Debug, Deserialize)]
+struct Components2;
+
+#[derive(Debug, Deserialize)]
+struct Fake {
+    resources: HashMap<u32, String>,
+    entities: HashMap<u32, Components2>
+}
+
+fn ron_test(){
+    let full_path = "/home/ckaos/projects/grappling-boom-bot/assets/save.ron";
+    match File::open(full_path) {
+        Ok(mut file) => {
+            let mut serialized_scene = Vec::new();
+            if let Err(why) = file.read_to_end(&mut serialized_scene) {
+                error!("file read failed: {why:?}");
+            }
+            match Deserializer::from_bytes(&serialized_scene) {
+                Ok(mut deserializer) => {
+                    // deserializer.
+                    let bla:Fake = ron::from_str("(
+                        resources: {},
+                        entities: {}
+                    )").unwrap();
+                    info!("testing {:?}", bla);
+                    info!("YOYO DONE YO !")
+                }
+                Err(why) => {
+                    error!("deserializer creation failed: {why:?}");
+                }
+            }
+        }
+        Err(why) => {
+            error!("load failed: {why:?}");
+        }
+    }
+}
+
+fn inject_component_data(world: &mut World, scene: DynamicScene){
+    let mut entity_map = EntityMap::default();
+    if let Err(why) = scene.write_to_world(world, &mut entity_map) {
+        panic!("world write failed: {why:?}");
+    }
+    println!("entity map {:?}", entity_map);
+    // TODO: EntityMap doesn't implement `iter()`
+    for old_entity in entity_map.keys() {
+        let entity = entity_map.get(old_entity).unwrap();
+        info!("entity update required: {old_entity:?} -> {entity:?}");
+        let e_mut = world
+            .entity_mut(entity);           
+    }
+
+    info!("done loading scene");
+}
+
+fn post_load(world: &mut World){
+    let full_path = "/home/ckaos/projects/grappling-boom-bot/assets/save.ron";
+    match File::open(full_path) {
+        Ok(mut file) => {
+            let mut serialized_scene = Vec::new();
+            if let Err(why) = file.read_to_end(&mut serialized_scene) {
+                error!("file read failed: {why:?}");
+            }
+            match Deserializer::from_bytes(&serialized_scene) {
+                Ok(mut deserializer) => {
+                    let result = SceneDeserializer {
+                        type_registry: &world.resource::<AppTypeRegistry>().read(),
+                    }
+                    .deserialize(&mut deserializer);
+                    info!("deserialize done");
+                    match result {
+                        Ok(scene) => {
+                            info!("scene loaded");
+                            // scene.write_to_world(world, entity_map)
+                            //  println!("{:?}", scene.entities);
+                            inject_component_data(world, scene);
+                            /*for dyn_ent in scene.entities.iter(){
+                                // let mut query = scene.world.query::<(Entity, &Name, &GltfExtras, &Parent)>();
+                            }*/
+                        }
+                        Err(why) => {
+                            error!("deserialization failed: {why:?}");
+                        }
+                    }
+                }
+                Err(why) => {
+                    error!("deserializer creation failed: {why:?}");
+                }
+            }
+        }
+        Err(why) => {
+            error!("load failed: {why:?}");
+        }
+    }
+
+}
+
+
+
+#[derive(Component, Reflect, Debug, Default )]
+#[reflect(Component)]
+pub struct Hackish;
+
+
+
+/// unload saveables
+fn unload_saveables(world: &mut World) {
+    let entities: Vec<Entity> = world
+        .query_filtered::<Entity, With<Saveable>>()// our level/world contains this component
+        .iter(world)
+        .collect();
+    for entity in entities {
+        // Check the entity again in case it was despawned recursively
+        if world.get_entity(entity).is_some() {
+            info!("despawning");
+            world.entity_mut(entity).despawn_recursive();
+        }
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/save_load/saveable.rs

@@ -0,0 +1,14 @@
+use bevy::prelude::*;
+use bevy::utils::Uuid;
+
+#[derive(Component, Reflect, Debug)]
+#[reflect(Component)]
+pub struct Saveable {
+    id: Uuid,
+}
+
+impl Default for Saveable {
+    fn default() -> Self {
+        Saveable { id: Uuid::new_v4() }
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/core/save_load/saving.rs

@@ -0,0 +1,87 @@
+use bevy::pbr::{Clusters, VisiblePointLights};
+use bevy::render::camera::CameraRenderGraph;
+use bevy::render::view::VisibleEntities;
+use bevy::tasks::IoTaskPool;
+use bevy::{gltf::GltfExtras, prelude::*};
+use bevy_rapier3d::prelude::RigidBody;
+use std::fs::File;
+use std::io::Write;
+
+use crate::core::physics::Collider;
+use crate::game::{Pickable, Player};
+
+use super::Saveable;
+
+const NEW_SCENE_FILE_PATH: &str = "save.scn.ron";
+
+#[derive(Component, Event)]
+pub struct SaveRequest {
+    pub path: String,
+}
+
+pub fn should_save(
+    // keycode: Res<Input<KeyCode>>,
+    save_requested_events: EventReader<SaveRequest>,
+) -> bool {
+    return save_requested_events.len() > 0;
+
+    // return keycode.just_pressed(KeyCode::S)
+}
+
+pub fn save_game(
+    world: &mut World,
+    // save_requested_events: EventReader<SaveRequest>,
+) {
+    info!("saving");
+    // world.
+    /*for bli in save_requested_events.iter(){
+        println!("SAAAAVE TO THISSSSS {:?}", bli.path)
+    }*/
+
+    let saveable_entities: Vec<Entity> = world
+        .query_filtered::<Entity, With<Saveable>>()
+        .iter(world)
+        .collect();
+
+    /*let static_entities: Vec<Entity> = world
+    .query_filtered::<Entity, Without<Saveable>>()
+    .iter(world)
+    .collect();*/
+    println!("saveable entities {}", saveable_entities.len());
+
+    let mut scene_builder = DynamicSceneBuilder::from_world(world);
+    scene_builder
+        .deny::<Children>()
+        .deny::<Parent>()
+        .deny::<ComputedVisibility>()
+        .deny::<Visibility>()
+        .deny::<GltfExtras>()
+        .deny::<GlobalTransform>()
+        .deny::<Collider>()
+        .deny::<RigidBody>()
+        .deny::<Saveable>()
+        // camera stuff
+        .deny::<Camera>()
+        .deny::<CameraRenderGraph>()
+        .deny::<Camera3d>()
+        .deny::<Clusters>()
+        .deny::<VisibleEntities>()
+        .deny::<VisiblePointLights>()
+        //.deny::<HasGizmoMarker>()
+        .extract_entities(saveable_entities.into_iter());
+
+    let dyn_scene = scene_builder.build();
+    let serialized_scene = dyn_scene
+        .serialize_ron(world.resource::<AppTypeRegistry>())
+        .unwrap();
+
+    #[cfg(not(target_arch = "wasm32"))]
+    IoTaskPool::get()
+        .spawn(async move {
+            // Write the scene RON data to file
+            File::create(format!("assets/scenes/{NEW_SCENE_FILE_PATH}"))
+                .and_then(|mut file| file.write(serialized_scene.as_bytes()))
+                .expect("Error while writing scene to file");
+        })
+        .detach();
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/game/in_game.rs

@@ -0,0 +1,85 @@
+use bevy::prelude::*;
+
+use crate::{
+    assets::GameAssets,
+    state::{GameState, InAppRunning},
+};
+use bevy_gltf_blueprints::{BluePrintBundle, BlueprintName, GameWorldTag};
+
+use bevy_rapier3d::prelude::Velocity;
+use rand::Rng;
+
+pub fn setup_game(
+    mut commands: Commands,
+    game_assets: Res<GameAssets>,
+    models: Res<Assets<bevy::gltf::Gltf>>,
+    mut next_game_state: ResMut<NextState<GameState>>,
+) {
+    println!("setting up all stuff");
+    commands.insert_resource(AmbientLight {
+        color: Color::WHITE,
+        brightness: 0.2,
+    });
+    // here we actually spawn our game world/level
+
+    commands.spawn((
+        SceneBundle {
+            // note: because of this issue https://github.com/bevyengine/bevy/issues/10436, "world" is now a gltf file instead of a scene
+            scene: models
+                .get(game_assets.world.id())
+                .expect("main level should have been loaded")
+                .scenes[0]
+                .clone(),
+            ..default()
+        },
+        bevy::prelude::Name::from("world"),
+        GameWorldTag,
+        InAppRunning,
+    ));
+
+    next_game_state.set(GameState::InGame)
+}
+
+pub fn spawn_test(
+    keycode: Res<Input<KeyCode>>,
+    mut commands: Commands,
+
+    mut game_world: Query<(Entity, &Children), With<GameWorldTag>>,
+) {
+    if keycode.just_pressed(KeyCode::T) {
+        let world = game_world.single_mut();
+        let world = world.1[0];
+
+        let mut rng = rand::thread_rng();
+        let range = 5.5;
+        let x: f32 = rng.gen_range(-range..range);
+        let y: f32 = rng.gen_range(-range..range);
+
+        let mut rng = rand::thread_rng();
+        let range = 0.8;
+        let vel_x: f32 = rng.gen_range(-range..range);
+        let vel_y: f32 = rng.gen_range(2.0..2.5);
+        let vel_z: f32 = rng.gen_range(-range..range);
+
+        let name_index: u64 = rng.gen();
+
+        let new_entity = commands
+            .spawn((
+                BluePrintBundle {
+                    blueprint: BlueprintName("Health_Pickup".to_string()),
+                    transform: TransformBundle::from_transform(Transform::from_xyz(x, 2.0, y)),
+                    ..Default::default()
+                },
+                bevy::prelude::Name::from(format!("test{}", name_index)),
+                // BlueprintName("Health_Pickup".to_string()),
+                // SpawnHere,
+                // TransformBundle::from_transform(Transform::from_xyz(x, 2.0, y)),
+                Velocity {
+                    linvel: Vec3::new(vel_x, vel_y, vel_z),
+                    angvel: Vec3::new(0.0, 0.0, 0.0),
+                },
+            ))
+            .id();
+        commands.entity(world).add_child(new_entity);
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/game/in_main_menu.rs

@@ -0,0 +1,113 @@
+use bevy::prelude::*;
+
+use crate::state::{AppState, GameState, InMainMenu};
+
+pub fn setup_main_menu(mut commands: Commands) {
+    commands.spawn((Camera2dBundle::default(), InMainMenu));
+
+    commands.spawn((
+        TextBundle::from_section(
+            "SOME GAME TITLE !!",
+            TextStyle {
+                //font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+                font_size: 18.0,
+                color: Color::WHITE,
+                ..Default::default()
+            },
+        )
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            top: Val::Px(100.0),
+            left: Val::Px(200.0),
+            ..default()
+        }),
+        InMainMenu,
+    ));
+
+    commands.spawn((
+        TextBundle::from_section(
+            "New Game (press Enter to start, press T once the game is started for demo spawning)",
+            TextStyle {
+                //font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+                font_size: 18.0,
+                color: Color::WHITE,
+                ..Default::default()
+            },
+        )
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            top: Val::Px(200.0),
+            left: Val::Px(200.0),
+            ..default()
+        }),
+        InMainMenu,
+    ));
+
+    /*
+    commands.spawn((
+        TextBundle::from_section(
+            "Load Game",
+            TextStyle {
+                //font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+                font_size: 18.0,
+                color: Color::WHITE,
+                ..Default::default()
+            },
+        )
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            top: Val::Px(250.0),
+            left: Val::Px(200.0),
+            ..default()
+        }),
+        InMainMenu
+    ));
+
+    commands.spawn((
+        TextBundle::from_section(
+            "Exit Game",
+            TextStyle {
+                //font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+                font_size: 18.0,
+                color: Color::WHITE,
+                ..Default::default()
+            },
+        )
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            top: Val::Px(300.0),
+            left: Val::Px(200.0),
+            ..default()
+        }),
+        InMainMenu
+    ));*/
+}
+
+pub fn teardown_main_menu(bla: Query<Entity, With<InMainMenu>>, mut commands: Commands) {
+    for bli in bla.iter() {
+        commands.entity(bli).despawn_recursive();
+    }
+}
+
+pub fn main_menu(
+    keycode: Res<Input<KeyCode>>,
+
+    mut next_app_state: ResMut<NextState<AppState>>,
+    // mut next_game_state: ResMut<NextState<GameState>>,
+    // mut save_requested_events: EventWriter<SaveRequest>,
+    // mut load_requested_events: EventWriter<LoadRequest>,
+) {
+    if keycode.just_pressed(KeyCode::Return) {
+        next_app_state.set(AppState::AppLoading);
+        // next_game_state.set(GameState::None);
+    }
+
+    if keycode.just_pressed(KeyCode::L) {
+        next_app_state.set(AppState::AppLoading);
+        // load_requested_events.send(LoadRequest { path: "toto".into() })
+    }
+
+    if keycode.just_pressed(KeyCode::S) {
+        // save_requested_events.send(SaveRequest { path: "toto".into() })
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/game/mod.rs

@@ -0,0 +1,115 @@
+pub mod in_game;
+pub use in_game::*;
+
+pub mod in_main_menu;
+pub use in_main_menu::*;
+
+pub mod picking;
+pub use picking::*;
+
+use crate::{
+    insert_dependant_component,
+    state::{AppState, GameState},
+};
+use bevy::prelude::*;
+use bevy_rapier3d::prelude::*;
+
+// this file is just for demo purposes, contains various types of components, systems etc
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+pub enum SoundMaterial {
+    Metal,
+    Wood,
+    Rock,
+    Cloth,
+    Squishy,
+    #[default]
+    None,
+}
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+/// Demo marker component
+pub struct Player;
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+/// Demo component showing auto injection of components
+pub struct ShouldBeWithPlayer;
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+/// Demo marker component
+pub struct Interactible;
+
+fn player_move_demo(
+    keycode: Res<Input<KeyCode>>,
+    mut players: Query<&mut Transform, With<Player>>,
+) {
+    let speed = 0.2;
+    if let Ok(mut player) = players.get_single_mut() {
+        if keycode.pressed(KeyCode::Left) {
+            player.translation.x += speed;
+        }
+        if keycode.pressed(KeyCode::Right) {
+            player.translation.x -= speed;
+        }
+
+        if keycode.pressed(KeyCode::Up) {
+            player.translation.z += speed;
+        }
+        if keycode.pressed(KeyCode::Down) {
+            player.translation.z -= speed;
+        }
+    }
+}
+
+// collision tests/debug
+pub fn test_collision_events(
+    mut collision_events: EventReader<CollisionEvent>,
+    mut contact_force_events: EventReader<ContactForceEvent>,
+) {
+    for collision_event in collision_events.read() {
+        println!("collision");
+        match collision_event {
+            CollisionEvent::Started(_entity1, _entity2, _) => {
+                println!("collision started")
+            }
+            CollisionEvent::Stopped(_entity1, _entity2, _) => {
+                println!("collision ended")
+            }
+        }
+    }
+
+    for contact_force_event in contact_force_events.read() {
+        println!("Received contact force event: {:?}", contact_force_event);
+    }
+}
+
+pub struct GamePlugin;
+impl Plugin for GamePlugin {
+    fn build(&self, app: &mut App) {
+        app.add_plugins(PickingPlugin)
+            .register_type::<Interactible>()
+            .register_type::<SoundMaterial>()
+            .register_type::<Player>()
+            // little helper utility, to automatically inject components that are dependant on an other component
+            // ie, here an Entity with a Player component should also always have a ShouldBeWithPlayer component
+            // you get a warning if you use this, as I consider this to be stop-gap solution (usually you should have either a bundle, or directly define all needed components)
+            .add_systems(
+                Update,
+                (
+                    // insert_dependant_component::<Player, ShouldBeWithPlayer>,
+                    player_move_demo, //.run_if(in_state(AppState::Running)),
+                    // test_collision_events
+                    spawn_test,
+                )
+                    .run_if(in_state(GameState::InGame)),
+            )
+            .add_systems(OnEnter(AppState::MenuRunning), setup_main_menu)
+            .add_systems(OnExit(AppState::MenuRunning), teardown_main_menu)
+            .add_systems(Update, (main_menu))
+            .add_systems(OnEnter(AppState::AppRunning), setup_game);
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/game/picking.rs

@@ -0,0 +1,34 @@
+use super::Player;
+use bevy::prelude::*;
+use bevy_gltf_blueprints::GltfBlueprintsSet;
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+pub struct Pickable;
+
+// very simple, crude picking (as in picking up objects) implementation
+
+pub fn picking(
+    players: Query<&GlobalTransform, With<Player>>,
+    pickables: Query<(Entity, &GlobalTransform), With<Pickable>>,
+    mut commands: Commands,
+) {
+    for player_transforms in players.iter() {
+        for (pickable, pickable_transforms) in pickables.iter() {
+            let distance = player_transforms
+                .translation()
+                .distance(pickable_transforms.translation());
+            if distance < 2.5 {
+                commands.entity(pickable).despawn_recursive();
+            }
+        }
+    }
+}
+
+pub struct PickingPlugin;
+impl Plugin for PickingPlugin {
+    fn build(&self, app: &mut App) {
+        app.register_type::<Pickable>()
+            .add_systems(Update, (picking.after(GltfBlueprintsSet::AfterSpawn),));
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/main.rs

@@ -0,0 +1,33 @@
+use bevy::prelude::*;
+use bevy_editor_pls::prelude::*;
+
+mod core;
+use crate::core::*;
+
+pub mod assets;
+use assets::*;
+
+pub mod state;
+use state::*;
+
+mod game;
+use game::*;
+
+mod test_components;
+use test_components::*;
+
+fn main() {
+    App::new()
+        .add_plugins((
+            DefaultPlugins.set(AssetPlugin::default()),
+            // editor
+            EditorPlugin::default(),
+            // our custom plugins
+            StatePlugin,
+            AssetsPlugin,
+            CorePlugin,           // reusable plugins
+            GamePlugin,           // specific to our game
+            ComponentsTestPlugin, // Showcases different type of components /structs
+        ))
+        .run();
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/state.rs

@@ -0,0 +1,54 @@
+use bevy::app::AppExit;
+use bevy::prelude::*;
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash, Default, States)]
+pub enum AppState {
+    #[default]
+    CoreLoading,
+    MenuRunning,
+    AppLoading,
+    AppRunning,
+    AppEnding,
+
+    // FIXME: not sure
+    LoadingGame,
+}
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash, Default, States)]
+pub enum GameState {
+    #[default]
+    None,
+
+    InMenu,
+    InGame,
+
+    InGameOver,
+
+    InSaving,
+    InLoading,
+}
+
+// tag components for all entities within a certain state (for despawning them if needed) , FIXME: seems kinda hack-ish
+#[derive(Component)]
+pub struct InCoreLoading;
+#[derive(Component, Default)]
+pub struct InMenuRunning;
+#[derive(Component)]
+pub struct InAppLoading;
+#[derive(Component)]
+pub struct InAppRunning;
+
+// components for tagging in game vs in game menu stuff
+#[derive(Component, Default)]
+pub struct InMainMenu;
+#[derive(Component, Default)]
+pub struct InMenu;
+#[derive(Component, Default)]
+pub struct InGame;
+
+pub struct StatePlugin;
+impl Plugin for StatePlugin {
+    fn build(&self, app: &mut App) {
+        app.add_state::<AppState>().add_state::<GameState>();
+    }
+}

examples/bevy_gltf_blueprints/nested_blueprints/src/test_components.rs

@@ -0,0 +1,93 @@
+use bevy::prelude::*;
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct Marker;
+
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct Enemy;
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct NestingTest;
+
+
+#[derive(Component, Reflect, Default, Debug, Deref, DerefMut)]
+#[reflect(Component)]
+struct TuppleTestF32(f32);
+
+#[derive(Component, Reflect, Default, Debug, Deref, DerefMut)]
+#[reflect(Component)]
+struct TuppleTestU64(u64);
+
+#[derive(Component, Reflect, Default, Debug, Deref, DerefMut)]
+#[reflect(Component)]
+pub struct TuppleTestStr(String);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct TuppleTest2(f32, u64, String);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct TuppleTestBool(bool);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct TuppleVec2(Vec2);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct TuppleVec3(Vec3);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct TuppleVec(Vec<String>);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct TuppleTestColor(Color);
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+struct BasicTest {
+    a: f32,
+    b: u64,
+    c: String,
+}
+
+#[derive(Component, Reflect, Default, Debug)]
+#[reflect(Component)]
+pub enum EnumTest {
+    Metal,
+    Wood,
+    Rock,
+    Cloth,
+    Squishy,
+    #[default]
+    None,
+}
+
+pub struct ComponentsTestPlugin;
+impl Plugin for ComponentsTestPlugin {
+    fn build(&self, app: &mut App) {
+        app.register_type::<BasicTest>()
+            .register_type::<Marker>()
+            .register_type::<Enemy>()
+            .register_type::<NestingTest>()
+
+            .register_type::<TuppleTestF32>()
+            .register_type::<TuppleTestU64>()
+            .register_type::<TuppleTestStr>()
+            .register_type::<TuppleTestBool>()
+            .register_type::<TuppleTest2>()
+            .register_type::<TuppleVec2>()
+            .register_type::<TuppleVec3>()
+            .register_type::<EnumTest>()
+            .register_type::<TuppleTestColor>()
+            .register_type::<TuppleVec>()
+            .register_type::<Vec<String>>();
+    }
+}

tools/gltf_auto_export/README.md

@@ -62,6 +62,9 @@ This [Blender addon](./)
 
     - export blueprints: check this if you want to automatically export blueprints (default: True)
     - blueprints path: the path to export blueprints to , relative to the main **export folder** (default: library)
+    - export nested blueprints: check this if you want to automatically export nested blueprints (collection instances inside blueprint collections)
+    as seperate blueprints  (default: True)
+    please read dedicate section below for more information
 
     - export materials library: check this if you want to automatically export material libraries (default: False)
     please read the dedicated section below for more information
@@ -109,6 +112,40 @@ You can enable this option to automatically replace all the **collection instanc
 
     ![exported collections](./docs/exported_collections.png)
 
+
+#### Nested blueprints
+
+To maximise reuse of meshes/components etc, you can also nest ***collections instances*** inside collections (as normally in Blender), but also export each nested Blueprint as a seperate blueprints.
+
+> Don't forget to toggle the option in the exporter settings 
+
+- To make things clearer: 
+
+    ![nested-blueprints](./docs/nested_blueprints.png)
+
+    - **Player2** & **Enemy** both use the **Humanoid_cactus** nested collection/blueprint, so **Humanoid_cactus** gets exported as a Blueprint for re-use ...but
+    - **Humanoid_cactus** is also made up of a main mesh & two instances of **Hand** , so **Hand** gets exported as a Blueprint for re-use ...but
+    - **Hand** is also made up of a main mesh & three instances of **Finger**, so **Finger** gets exported as a Blueprint for re-use
+
+- The exported models in this case end up being:
+
+    ![nested_blueprints2](./docs/nested_blueprints2.png)
+
+    - Note how **Player2.glb** is tiny, because most of its data is actually sotred in **Humanoid_cactus.glb**
+    - **Enemy.glb** is slightly bigger because that blueprints contains additional meshes
+    - All the intermediary blueprints got exported automatically, and all instances have been replaced with "empties" (see explanation in the **Process section** ) to minimize file size
+
+- Compare this to the output **WITHOUT** the nested export option:
+
+    ![nested_blueprints3](./docs/nested_blueprints3.png)
+
+    - less blueprints as the sub collections that are not in use somewhere directly are not exported
+    - **Player2.glb** & **Enemy.glb** are significantly larger
+
+
+TLDR: smaller, more reuseable blueprints which can share sub-parts with other entities !
+
+
 ### Materials
 
 You can enable this option to automatically generate a **material library** file that combines all the materials in use in your blueprints.

tools/gltf_auto_export/__init__.py

@@ -1,7 +1,7 @@
 bl_info = {
     "name": "gltf_auto_export",
     "author": "kaosigh",
-    "version": (0, 7, 1),
+    "version": (0, 8, 0),
     "blender": (3, 4, 0),
     "location": "File > Import-Export",
     "description": "glTF/glb auto-export",
@@ -43,6 +43,7 @@ bpy.context.window_manager['changed_objects_per_scene'] = {}
 bpy.context.window_manager['previous_params'] = {}
 bpy.context.window_manager['__gltf_auto_export_initialized'] = False
 bpy.context.window_manager['__gltf_auto_export_gltf_params_changed'] = False
+bpy.context.window_manager['__gltf_auto_export_saving'] = False
 
 ######################################################
 """ there are two places where we load settings for auto_export from:
@@ -60,6 +61,9 @@ def deps_update_handler(scene, depsgraph):
         print("-------------")
         changed = scene.name or ""
 
+        # only deal with changes if we are no in the mids of saving/exporting
+        #if not bpy.context.window_manager['__gltf_auto_export_saving']:
+
         # depsgraph = bpy.context.evaluated_depsgraph_get()
         if not 'changed_objects_per_scene' in bpy.context.window_manager:
             bpy.context.window_manager['changed_objects_per_scene'] = {}
@@ -71,6 +75,7 @@ def deps_update_handler(scene, depsgraph):
             if isinstance(obj.id, bpy.types.Object):
                 # get the actual object
                 object = bpy.data.objects[obj.id.name]
+                print("changed object", obj.id.name)
                 bpy.context.window_manager['changed_objects_per_scene'][scene.name][obj.id.name] = object
         
         bpy.context.window_manager.changedScene = changed
@@ -79,10 +84,16 @@ def deps_update_handler(scene, depsgraph):
 def save_handler(dummy): 
     print("-------------")
     print("saved", bpy.data.filepath)
+    # mark saving as in progress, this is needed to ignore any changes from the depsgraph done during saving
+    # bpy.context.window_manager['__gltf_auto_export_saving'] = True
+
     if not 'changed_objects_per_scene' in bpy.context.window_manager:
         bpy.context.window_manager['changed_objects_per_scene'] = {}
     changes_per_scene =  bpy.context.window_manager['changed_objects_per_scene']
 
+    if not 'previous_params' in bpy.context.window_manager: 
+        bpy.context.window_manager['previous_params'] = {}
+    
     #determine changed parameters
     addon_prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
 
@@ -113,6 +124,11 @@ def save_handler(dummy):
     # reset whether there have been changed objects since the last save 
     bpy.context.window_manager['changed_objects_per_scene'] = {}
 
+    # all our logic is done, mark this as done
+    #bpy.context.window_manager['__gltf_auto_export_saving'] = False
+    print("EXPORT DONE")
+
+
 def get_changedScene(self):
     return self["changedScene"]
 
@@ -153,6 +169,7 @@ def register():
     bpy.app.handlers.depsgraph_update_post.append(deps_update_handler)
     bpy.app.handlers.save_post.append(save_handler)
 
+
     bpy.types.WindowManager.changedScene = bpy.props.StringProperty(get=get_changedScene, set=set_changedScene)
     bpy.types.WindowManager.exportedCollections = bpy.props.CollectionProperty(type=CollectionsToExport)
 

tools/gltf_auto_export/auto_export.py

@@ -48,8 +48,6 @@ def auto_export(changes_per_scene, changed_export_parameters):
                 print("error setting preferences from saved settings", error)
         bpy.context.window_manager['__gltf_auto_export_initialized'] = True
 
-
-
     # have the export parameters (not auto export, just gltf export) have changed: if yes (for example switch from glb to gltf, compression or not, animations or not etc), we need to re-export everything
     print ("changed_export_parameters", changed_export_parameters)
     try:
@@ -63,6 +61,7 @@ def auto_export(changes_per_scene, changed_export_parameters):
 
         export_materials_library = getattr(addon_prefs,"export_materials_library")
         export_scene_settings = getattr(addon_prefs,"export_scene_settings")
+        export_nested_blueprints = getattr(addon_prefs,"export_nested_blueprints")
 
 
         [main_scene_names, level_scenes, library_scene_names, library_scenes] = get_scenes(addon_prefs)
@@ -74,11 +73,12 @@ def auto_export(changes_per_scene, changed_export_parameters):
             # inject/ update scene components
             upsert_scene_components(bpy.context.scene, world = bpy.context.scene.world)
 
-        # export everything everytime
+        # export
         if export_blueprints:
             print("EXPORTING")
             # get a list of all collections actually in use
-            collections = get_exportable_collections(level_scenes, library_scenes)
+            scan_nested_collections = export_nested_blueprints
+            (collections, blueprint_hierarchy) = get_exportable_collections(level_scenes, library_scenes, scan_nested_collections)
             # first check if all collections have already been exported before (if this is the first time the exporter is run
             # in your current Blender session for example)
             export_blueprints_path = os.path.join(folder_path, export_output_folder, getattr(addon_prefs,"export_blueprints_path")) if getattr(addon_prefs,"export_blueprints_path") != '' else folder_path
@@ -96,10 +96,10 @@ def auto_export(changes_per_scene, changed_export_parameters):
                     object_collections = list(obj.users_collection)
                     object_collection_names = list(map(lambda collection: collection.name, object_collections))
                     if len(object_collection_names) > 1:
-                        print("ERRROR, objects in multiple collections not supported")
+                        print("ERRROR for",obj_name,"objects in multiple collections not supported")
                     else:
                         object_collection_name =  object_collection_names[0] if len(object_collection_names) > 0 else None
-                        print("      object ", obj, object_collection_name)
+                        #print("      object ", obj, object_collection_name)
                         if object_collection_name in collections:
                             changed_collections.append(object_collection_name)
 
@@ -111,6 +111,7 @@ def auto_export(changes_per_scene, changed_export_parameters):
 
           
             # collections that do not come from a library should not be exported as seperate blueprints
+            # FIMXE: logic is erroneous, needs to be changed
             library_collections = [name for sublist in collections_per_scene.values() for name in sublist]
             collections_to_export = list(set(collections_to_export).intersection(set(library_collections)))
 
@@ -151,7 +152,7 @@ def auto_export(changes_per_scene, changed_export_parameters):
                     print("     exporting collections from scene:", scene_name)
                     print("     collections to export", collections_to_export)
                     library_scene = bpy.data.scenes[scene_name]
-                    export_blueprints_from_collections(collections_to_export, library_scene, folder_path, addon_prefs)
+                    export_blueprints_from_collections(collections_to_export, library_scene, folder_path, addon_prefs, blueprint_hierarchy, collections)
 
             # reset current scene from backup
             bpy.context.window.scene = old_current_scene

tools/gltf_auto_export/blueprints.py

@@ -0,0 +1,113 @@
+import bpy
+from .helpers_collections import (find_layer_collection_recursive)
+from .helpers import (make_empty3, traverse_tree)
+
+
+def generate_blueprint_hollow_scene(blueprint_collection, library_collections):
+    temp_scene = bpy.data.scenes.new(name="temp_scene_"+blueprint_collection.name)
+    temp_scene_root_collection = temp_scene.collection
+
+    # we set our active scene to be this one : this is needed otherwise the stand-in empties get generated in the wrong scene
+    bpy.context.window.scene = temp_scene
+    found = find_layer_collection_recursive(temp_scene_root_collection, bpy.context.view_layer.layer_collection)
+    if found:
+        # once it's found, set the active layer collection to the one we found
+        bpy.context.view_layer.active_layer_collection = found
+
+    original_names = []
+
+    # TODO also add the handling for "template" flags, so that instead of creating empties we link the data from the sub collection INTO the parent collection
+    # copies the contents of a collection into another one while replacing blueprint instances with empties
+    def copy_hollowed_collection_into(source_collection, destination_collection):
+        for object in source_collection.objects:
+            #FIXME: enum would be better
+            """ combine mode can be 
+              - 'Split' (default): replace with an empty, creating links to sub blueprints 
+              - 'Embed' : treat it as an embeded object and do not replace it with an empty
+              - 'Inject': inject components from sub collection instances into the curent object
+            """
+            combineMode = 'Split' if not 'Combine' in object else object['Combine']
+            # TODO: implement
+            # print("COMBINE MODE", combineMode)
+            # embed = 'Embed' in object and object['Embed'] == True # if the object has the "embed" flag set to true, treat it as an embeded object and do not replace it with an empty
+            # merge = 'Merge' in object and object['Merge'] == True 
+            if object.instance_type == 'COLLECTION' and (object.instance_collection.name in library_collections):
+                # if we have combine_mode set to "merge", we take all the custom attributed of the nested (1 level only ! unless we use 'deepMerge') custom attributes and copy them to this level 
+                """TODO: implement later
+                if merge:
+                    foo = get_nested_components(object)
+                    print("nested components", foo)
+                    pass
+                else: 
+                """
+                collection_name = object.instance_collection.name
+
+                original_name = object.name
+                original_names.append(original_name)
+
+                object.name = original_name + "____bak"
+                empty_obj = make_empty3(original_name, object.location, object.rotation_euler, object.scale, destination_collection)
+                """we inject the collection/blueprint name, as a component called 'BlueprintName', but we only do this in the empty, not the original object"""
+                empty_obj['BlueprintName'] = '"'+collection_name+'"'
+                empty_obj['SpawnHere'] = ''
+
+                for k, v in object.items():
+                    empty_obj[k] = v
+            else:
+                destination_collection.objects.link(object)
+
+        # for every sub-collection of the source, copy its content into a new sub-collection of the destination
+        for collection in source_collection.children:
+            copy_collection = bpy.data.collections.new(collection.name + "____collection_export")
+            copy_hollowed_collection_into(collection, copy_collection)
+            destination_collection.children.link(copy_collection)
+
+    copy_hollowed_collection_into(blueprint_collection, temp_scene_root_collection)
+
+
+    return (temp_scene, original_names)
+
+
+
+
+# clear & remove "hollow scene"
+def clear_blueprint_hollow_scene(temp_scene, original_collection, original_names):
+
+    def restore_original_names(collection):
+        for object in collection.objects:
+            if object.instance_type == 'COLLECTION':
+                if object.name.endswith("____bak"):
+                    object.name = object.name.replace("____bak", "")
+        for child_collection in collection.children:
+            restore_original_names(child_collection)
+    
+    restore_original_names(original_collection)
+
+    # remove empties (only needed when we go via ops ????)
+    root_collection = temp_scene.collection 
+    scene_objects = [o for o in root_collection.objects]
+    for object in scene_objects:
+        if object.type == 'EMPTY':
+            if hasattr(object, "SpawnHere"):
+                bpy.data.objects.remove(object, do_unlink=True)
+            else: 
+                bpy.context.scene.collection.objects.unlink(object)
+            #bpy.data.objects.remove(object, do_unlink=True)
+
+    bpy.data.scenes.remove(temp_scene)
+
+# TODO : add a flag to also search of deeply nested components
+def get_nested_components(object):
+    if object.instance_type == 'COLLECTION':
+        collection_name = object.instance_collection.name
+        collection = bpy.data.collections[collection_name]
+        all_objects = collection.all_objects
+        result = []
+        for object in all_objects:
+            components = dict(object)
+            if len(components.keys()) > 0:
+                result += [(object, components)]
+        return result
+    return []
+        #for collection in traverse_tree(collection):
+        #    for object in collection.all_objects

tools/gltf_auto_export/helpers.py

@@ -37,7 +37,7 @@ def make_empty3(name, location, rotation, scale, collection):
     bpy.context.view_layer.objects.active = original_active_object
     return empty_obj
 
-
+# traverse all collections
 def traverse_tree(t):
     yield t
     for child in t.children:
@@ -48,7 +48,7 @@ def check_if_blueprints_exist(collections, folder_path, extension):
     not_found_blueprints = []
     for collection_name in collections:
         gltf_output_path = os.path.join(folder_path, collection_name + extension)
-        print("gltf_output_path", gltf_output_path)
+        # print("gltf_output_path", gltf_output_path)
         found = os.path.exists(gltf_output_path) and os.path.isfile(gltf_output_path)
         if not found:
             not_found_blueprints.append(collection_name)

tools/gltf_auto_export/helpers_collections.py

@@ -2,6 +2,7 @@ import bpy
 from .helpers import traverse_tree
 
 # returns the list of the collections in use for a given scene
+# FIXME: this should also look into sub collections
 def get_used_collections(scene): 
     root_collection = scene.collection 
 
@@ -11,13 +12,7 @@ def get_used_collections(scene):
     for object in scene_objects:
         #print("object ", object)
         if object.instance_type == 'COLLECTION':
-            #print("THIS OBJECT IS A COLLECTION")
-            # print("instance_type" ,object.instance_type)
             collection_name = object.instance_collection.name
-            #print("instance collection", object.instance_collection.name)
-            #object.instance_collection.users_scene
-            # del object['blueprint']
-            # object['BlueprintName'] = '"'+collection_name+'"'
             if not collection_name in collection_names: 
                 collection_names.add(collection_name)
                 used_collections.append(object.instance_collection)
@@ -37,16 +32,87 @@ def get_marked_collections(scene):
             collection_names.append(collection.name)
     return (collection_names, marked_collections)
 
+# gets all collections within collections that might also be relevant
+def get_sub_collections(collections, parent, children_per_collection):
+    collection_names = set()
+    used_collections = []
+    
+
+    for root_collection in collections:
+        node = Node(name=root_collection.name, parent=parent)
+        parent.children.append(node)
+
+      
+        #print("root collection", root_collection.name)
+        for collection in traverse_tree(root_collection): # TODO: filter out COLLECTIONS that have the flatten flag (unlike the flatten flag on colleciton instances themselves)
+            node_name = collection.name
+            children_per_collection[node_name] = []
+            #print("  scanning", collection.name)
+            for object in collection.objects:
+                #print("FLATTEN", object.name, 'Flatten' in object)
+                if object.instance_type == 'COLLECTION' : # and not 'Flatten' in object: 
+                    collection_name = object.instance_collection.name
+                    (sub_names, sub_collections) = get_sub_collections([object.instance_collection], node, children_per_collection)
+                    if len(list(sub_names)) > 0:
+                        children_per_collection[node_name]  += (list(sub_names))
+                    #print("   found sub collection in use", object.name, object.instance_collection)
+
+
+                    if not collection_name in collection_names: 
+                        collection_names.add(collection_name)
+                        used_collections.append(object.instance_collection)
+                        collection_names.update(sub_names)
+
+        #for sub in traverse_tree(root_collection):
+    return (collection_names, used_collections)
+
+# FIXME: get rid of this, ugh
+def flatten_collection_tree(node, children_per_collection):
+    children_per_collection[node.name] = []
+    for child in node.children:
+        if not node.name in children_per_collection[node.name]:
+            children_per_collection[node.name].append(child.name)
+        flatten_collection_tree(child, children_per_collection)
+    children_per_collection[node.name] = list(set( children_per_collection[node.name]))
+       
+
+class Node :
+    def __init__(self, name="", parent=None):
+      self.name = name
+      self.children = []
+      self.changed = False
+      self.parent = parent
+      return
+    def __str__(self):
+        children = list(map(lambda child: str(child), self.children))
+        return "name: " +self.name + ", children:" + str(children)
+    
 # get exportable collections from lists of mains scenes and lists of library scenes
-def get_exportable_collections(main_scenes, library_scenes): 
+def get_exportable_collections(main_scenes, library_scenes, scan_nested_collections): 
     all_collections = []
+    all_collection_names = []
+    root_node = Node()
+    root_node.name = "root"
+    children_per_collection = {}
+
+
     for main_scene in main_scenes:
-        (collection_names, _) = get_used_collections(main_scene)
-        all_collections = all_collections + list(collection_names)
+        (collection_names, collections) = get_used_collections(main_scene)
+        all_collection_names = all_collection_names + list(collection_names)
+        all_collections = all_collections + collections
     for library_scene in library_scenes:
         marked_collections = get_marked_collections(library_scene)
-        all_collections = all_collections + marked_collections[0]
-    return all_collections
+        all_collection_names = all_collection_names + marked_collections[0]
+        all_collections = all_collections + marked_collections[1]
+
+    if scan_nested_collections:
+        (collection_names, collections) = get_sub_collections(all_collections, root_node, children_per_collection)
+        all_collection_names = all_collection_names + list(collection_names)
+        children_per_collection = {}
+        flatten_collection_tree(root_node, children_per_collection)
+        #print("ROOT NODE", children_per_collection) #
+
+    return (all_collection_names, children_per_collection)
 
 def get_collections_per_scene(collection_names, library_scenes): 
     collections_per_scene = {}
@@ -84,7 +150,6 @@ def find_layer_collection_recursive(find, col):
             return c
     return None
 
-
 #Recursivly transverse layer_collection for a particular name
 def recurLayerCollection(layerColl, collName):
     found = None

tools/gltf_auto_export/helpers_export.py

@@ -1,9 +1,12 @@
 import os
 import bpy
+
 from .preferences import (AutoExportGltfPreferenceNames)
 from .helpers_scenes import (generate_hollow_scene, clear_hollow_scene)
 from .helpers_collections import (recurLayerCollection)
+from .blueprints import clear_blueprint_hollow_scene, generate_blueprint_hollow_scene
 from .helpers import (traverse_tree)
+
 ######################################################
 #### Export logic #####
 
@@ -66,11 +69,13 @@ def get_source_scene(collection_name, library_scenes):
     return match
 
 # export collections: all the collections that have an instance in the main scene AND any marked collections, even if they do not have instances
-def export_collections(collections, folder_path, library_scene, addon_prefs, gltf_export_preferences): 
+def export_collections(collections, folder_path, library_scene, addon_prefs, gltf_export_preferences, blueprint_hierarchy, library_collections): 
     # set active scene to be the library scene (hack for now)
     bpy.context.window.scene = library_scene
     # save current active collection
     active_collection =  bpy.context.view_layer.active_layer_collection
+    export_nested_blueprints = getattr(addon_prefs,"export_nested_blueprints")
+    export_materials_library = getattr(addon_prefs,"export_materials_library")
 
     for collection_name in collections:
         print("exporting collection", collection_name)
@@ -83,17 +88,32 @@ def export_collections(collections, folder_path, library_scene, addon_prefs, glt
         export_settings = { **gltf_export_preferences, 'use_active_scene': True, 'use_active_collection': True, 'use_active_collection_with_nested':True}
         
         # if we are using the material library option, do not export materials, use placeholder instead
-        export_materials_library = getattr(addon_prefs,"export_materials_library")
         if export_materials_library:
             export_settings['export_materials'] = 'PLACEHOLDER'
 
+
+        #if relevant we replace sub collections instances with placeholders too
+        # this is not needed if a collection/blueprint does not have sub blueprints
+        if collection_name in blueprint_hierarchy and len(blueprint_hierarchy[collection_name]) > 0 and export_nested_blueprints :
+            print("generate hollow scene for nested blueprints", library_collections)
+            backup = bpy.context.window.scene
+            collection = bpy.data.collections[collection_name]
+            (hollow_scene, object_names) = generate_blueprint_hollow_scene(collection, library_collections)
+
             export_gltf(gltf_output_path, export_settings)
 
+            clear_blueprint_hollow_scene(hollow_scene, collection, object_names)
+            bpy.context.window.scene = backup
+        else:
+            print("NORMAL")
+            export_gltf(gltf_output_path, export_settings)
+
+    
     # reset active collection to the one we save before
     bpy.context.view_layer.active_layer_collection = active_collection
 
 
-def export_blueprints_from_collections(collections, library_scene, folder_path, addon_prefs):
+def export_blueprints_from_collections(collections, library_scene, folder_path, addon_prefs, blueprint_hierarchy, library_collections):
     export_output_folder = getattr(addon_prefs,"export_output_folder")
     gltf_export_preferences = generate_gltf_export_preferences(addon_prefs)
     export_blueprints_path = os.path.join(folder_path, export_output_folder, getattr(addon_prefs,"export_blueprints_path")) if getattr(addon_prefs,"export_blueprints_path") != '' else folder_path
@@ -102,7 +122,7 @@ def export_blueprints_from_collections(collections, library_scene, folder_path,
     #print("LIBRARY EXPORT", export_blueprints_path )
 
     try:
-        export_collections(collections, export_blueprints_path, library_scene, addon_prefs, gltf_export_preferences)
+        export_collections(collections, export_blueprints_path, library_scene, addon_prefs, gltf_export_preferences, blueprint_hierarchy, library_collections)
     except Exception as error:
         print("failed to export collections to gltf: ", error)
         # TODO : rethrow

tools/gltf_auto_export/preferences.py

@@ -15,14 +15,15 @@ AutoExportGltfPreferenceNames = [
     'export_main_scene_name',
     'export_output_folder',
     'export_library_scene_name',
+
     'export_blueprints',
     'export_blueprints_path',
-
-    'export_scene_settings',
+    'export_nested_blueprints',
 
     'export_materials_library',
     'export_materials_path',
 
+    'export_scene_settings',
 
     'main_scenes',
     'library_scenes',
@@ -75,6 +76,12 @@ class AutoExportGltfAddonPreferences(AddonPreferences):
         default='library'
     )
 
+    export_nested_blueprints: BoolProperty(
+        name='Export nested Blueprints',
+        description='Collection instances within Collections are turned into blueprint instances',
+        default=True
+    )
+
     export_materials_library: BoolProperty(
         name='Export materials library',
         description='remove materials from blueprints and use the material library instead',

tools/gltf_auto_export/ui/main.py

@@ -130,7 +130,8 @@ class AutoExportGLTF(Operator, AutoExportGltfAddonPreferences, ExportHelper):
       
 
         [main_scene_names, level_scenes, library_scene_names, library_scenes]=get_scenes(addon_prefs)
-        collections = get_exportable_collections(level_scenes, library_scenes)
+        scan_nested_collections = bpy.context.preferences.addons["gltf_auto_export"].preferences.export_nested_blueprints
+        (collections, _) = get_exportable_collections(level_scenes, library_scenes, scan_nested_collections)
 
         try:
             # we save this list of collections in the context
@@ -275,6 +276,15 @@ class GLTF_PT_auto_export_blueprints(bpy.types.Panel):
 
         return operator.bl_idname == "EXPORT_SCENES_OT_auto_gltf" #"EXPORT_SCENE_OT_gltf"
 
+
+    def draw_header(self, context):
+        layout = self.layout
+        sfile = context.space_data
+        operator = sfile.active_operator
+        layout.prop(operator, "export_blueprints", text="")
+
+        #self.layout.prop(operator, "auto_export", text="")
+
     def draw(self, context):
         layout = self.layout
         layout.use_property_split = True
@@ -283,8 +293,10 @@ class GLTF_PT_auto_export_blueprints(bpy.types.Panel):
         sfile = context.space_data
         operator = sfile.active_operator
 
-        layout.prop(operator, "export_blueprints")
+        layout.active = operator.export_blueprints
+        
         layout.prop(operator, "export_blueprints_path")
+        layout.prop(operator, "export_nested_blueprints")
 
         # materials
         layout.prop(operator, "export_materials_library")