scene: spawning

crates/bevy_legion/legion_core/src/guid_entity_allocator.rs

@@ -20,13 +20,17 @@ impl GuidEntityAllocator {
         let entity = if !self.next_ids.read().is_empty() {
             self.next_ids.write().pop_front().unwrap()
         } else {
-            Entity::new(rand::random::<u32>(), Wrapping(1))
+            Entity::new(Self::new_entity_id(), Wrapping(1))
         };
 
         self.entities.write().insert(entity.index());
         entity
     }
 
+    pub fn new_entity_id() -> u32 {
+        rand::random::<u32>()
+    }
+
     /// Creates an iterator which allocates new `Entity` IDs.
     pub fn create_entities(&self) -> GuidCreateEntityIter {
         GuidCreateEntityIter { allocator: self }

crates/bevy_scene/Cargo.toml

@@ -9,8 +9,10 @@ bevy_app = { path = "../bevy_app" }
 bevy_asset = { path = "../bevy_asset" }
 bevy_type_registry = { path = "../bevy_type_registry" }
 bevy_property = { path = "../bevy_property" }
+
 legion = { path = "../bevy_legion", features = ["serialize"] }
 serde = { version = "1.0", features = ["derive"]}
 ron = { git = "https://github.com/ron-rs/ron", rev = "b43c1074d517131fd0cfc1deb96e11f95d6f42d8" }
+uuid = { version = "0.8", features = ["v4", "serde"] }
 anyhow = "1.0"
 thiserror = "1.0"

crates/bevy_scene/src/scene.rs

@@ -1,10 +1,9 @@
-use anyhow::Result;
-use bevy_type_registry::ComponentRegistry;
-use bevy_property::{PropertyTypeRegistry, DynamicProperties};
-use legion::prelude::{Resources, World};
-use serde::Serialize;
-use std::num::Wrapping;
 use crate::serde::SceneSerializer;
+use anyhow::Result;
+use bevy_property::{DynamicProperties, PropertyTypeRegistry};
+use bevy_type_registry::ComponentRegistry;
+use legion::{entity::EntityIndex, prelude::World};
+use serde::Serialize;
 
 #[derive(Default)]
 pub struct Scene {
@@ -12,7 +11,7 @@ pub struct Scene {
 }
 
 pub struct Entity {
-    pub entity: u32,
+    pub entity: EntityIndex,
     pub components: Vec<DynamicProperties>,
 }
 
@@ -38,10 +37,8 @@ impl Scene {
                                     })
                                 }
 
-                                let properties = component_registration.get_component_properties(
-                                    &component_resource_set,
-                                    index,
-                                );
+                                let properties = component_registration
+                                    .get_component_properties(&component_resource_set, index);
 
                                 entities[index].components.push(properties.to_dynamic());
                             }

crates/bevy_scene/src/scene_spawner.rs

@@ -2,14 +2,34 @@ use crate::Scene;
 use bevy_app::{EventReader, Events, FromResources, GetEventReader};
 use bevy_asset::{AssetEvent, Assets, Handle};
 use bevy_type_registry::TypeRegistry;
-use legion::prelude::{Entity, Resources, World};
+use legion::{
+    entity::EntityIndex,
+    guid_entity_allocator::GuidEntityAllocator,
+    prelude::{Entity, Resources, World},
+};
 use std::{
     collections::{HashMap, HashSet},
     num::Wrapping,
 };
 use thiserror::Error;
+use uuid::Uuid;
+
+struct InstanceInfo {
+    entity_map: HashMap<EntityIndex, EntityIndex>,
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+struct InstanceId(Uuid);
+
+impl InstanceId {
+    pub fn new() -> Self {
+        InstanceId(Uuid::new_v4())
+    }
+}
 pub struct SceneSpawner {
-    loaded_scene_entities: HashMap<Handle<Scene>, Vec<Entity>>,
+    loaded_scenes: HashSet<Handle<Scene>>,
+    spawned_scenes: HashMap<Handle<Scene>, Vec<InstanceId>>,
+    spawned_instances: HashMap<InstanceId, InstanceInfo>,
     scene_asset_event_reader: EventReader<AssetEvent<Scene>>,
     scenes_to_spawn: Vec<Handle<Scene>>,
     scenes_to_load: Vec<Handle<Scene>>,
@@ -19,7 +39,9 @@ impl FromResources for SceneSpawner {
     fn from_resources(resources: &Resources) -> Self {
         SceneSpawner {
             scene_asset_event_reader: resources.get_event_reader::<AssetEvent<Scene>>(),
-            loaded_scene_entities: Default::default(),
+            spawned_scenes: Default::default(),
+            spawned_instances: Default::default(),
+            loaded_scenes: Default::default(),
             scenes_to_spawn: Default::default(),
             scenes_to_load: Default::default(),
         }
@@ -35,12 +57,12 @@ pub enum SceneSpawnError {
 }
 
 impl SceneSpawner {
-    pub fn spawn(&mut self, scene: Handle<Scene>) {
-        self.scenes_to_spawn.push(scene);
+    pub fn spawn(&mut self, scene_handle: Handle<Scene>) {
+        self.scenes_to_spawn.push(scene_handle);
     }
 
-    pub fn load(&mut self, scene: Handle<Scene>) {
-        self.scenes_to_load.push(scene);
+    pub fn load(&mut self, scene_handle: Handle<Scene>) {
+        self.scenes_to_load.push(scene_handle);
     }
 
     pub fn load_sync(
@@ -48,6 +70,34 @@ impl SceneSpawner {
         world: &mut World,
         resources: &Resources,
         scene_handle: Handle<Scene>,
+    ) -> Result<(), SceneSpawnError> {
+        Self::load_internal(world, resources, scene_handle, None)?;
+        self.loaded_scenes.insert(scene_handle);
+        Ok(())
+    }
+
+    pub fn spawn_sync(
+        &mut self,
+        world: &mut World,
+        resources: &Resources,
+        scene_handle: Handle<Scene>,
+    ) -> Result<(), SceneSpawnError> {
+        let instance_id = InstanceId::new();
+        let mut instance_info = InstanceInfo {
+            entity_map: HashMap::default(),
+        };
+        Self::load_internal(world, resources, scene_handle, Some(&mut instance_info))?;
+        self.spawned_instances.insert(instance_id, instance_info);
+        let spawned = self.spawned_scenes.entry(scene_handle).or_insert_with(|| Vec::new());
+        spawned.push(instance_id);
+        Ok(())
+    }
+
+    fn load_internal(
+        world: &mut World,
+        resources: &Resources,
+        scene_handle: Handle<Scene>,
+        mut instance_info: Option<&mut InstanceInfo>,
     ) -> Result<(), SceneSpawnError> {
         let type_registry = resources.get::<TypeRegistry>().unwrap();
         let component_registry = type_registry.component.read().unwrap();
@@ -58,16 +108,23 @@ impl SceneSpawner {
                 handle: scene_handle,
             })?;
 
-        // TODO: this vec might not be needed
-        let mut entity_ids = Vec::with_capacity(scene.entities.len());
         for scene_entity in scene.entities.iter() {
+            let entity_id = if let Some(ref mut instance_info) = instance_info {
+                *instance_info
+                    .entity_map
+                    .entry(scene_entity.entity)
+                    .or_insert_with(|| GuidEntityAllocator::new_entity_id())
+            } else {
+                scene_entity.entity
+            };
+            let mut entity = Entity::new(entity_id, Wrapping(1));
             // TODO: use EntityEntry when legion refactor is finished
-            let mut entity = Entity::new(scene_entity.entity, Wrapping(1));
             if world.get_entity_location(entity).is_none() {
-                world.entity_allocator.push_next_ids((&[entity]).iter().cloned());
+                world
+                    .entity_allocator
+                    .push_next_ids((&[entity]).iter().cloned());
                 entity = world.insert((), vec![()])[0];
             }
-            entity_ids.push(entity);
             for component in scene_entity.components.iter() {
                 let component_registration = component_registry
                     .get_with_name(&component.type_name)
@@ -77,12 +134,23 @@ impl SceneSpawner {
                 component_registration.add_component_to_entity(world, resources, entity, component);
             }
         }
-
-        self.loaded_scene_entities.insert(scene_handle, entity_ids);
         Ok(())
     }
 
-    pub fn load_queued_scenes(&mut self, world: &mut World, resources: &Resources) {
+    pub fn update_spawned_scenes(&mut self, world: &mut World, resources: &Resources, scene_handles: &[Handle<Scene>]) -> Result<(), SceneSpawnError> {
+        for scene_handle in scene_handles {
+            if let Some(spawned_instances) = self.spawned_scenes.get(scene_handle) {
+                for instance_id in spawned_instances.iter() {
+                    if let Some(instance_info) = self.spawned_instances.get_mut(instance_id) {
+                        Self::load_internal(world, resources, *scene_handle, Some(instance_info))?;
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+
+    pub fn load_queued_scenes(&mut self, world: &mut World, resources: &Resources) -> Result<(), SceneSpawnError> {
         let scenes_to_load = self.scenes_to_load.drain(..).collect::<Vec<_>>();
         let mut non_existent_scenes = Vec::new();
         for scene_handle in scenes_to_load {
@@ -91,11 +159,29 @@ impl SceneSpawner {
                 Err(SceneSpawnError::NonExistentScene { .. }) => {
                     non_existent_scenes.push(scene_handle)
                 }
-                Err(err) => panic!("{:?}", err),
+                Err(err) => return Err(err),
             }
         }
 
         self.scenes_to_load = non_existent_scenes;
+        Ok(())
+    }
+
+    pub fn spawn_queued_scenes(&mut self, world: &mut World, resources: &Resources) -> Result<(), SceneSpawnError> {
+        let scenes_to_spawn = self.scenes_to_spawn.drain(..).collect::<Vec<_>>();
+        let mut non_existent_scenes = Vec::new();
+        for scene_handle in scenes_to_spawn {
+            match self.spawn_sync(world, resources, scene_handle) {
+                Ok(_) => {}
+                Err(SceneSpawnError::NonExistentScene { .. }) => {
+                    non_existent_scenes.push(scene_handle)
+                }
+                Err(err) => return Err(err),
+            }
+        }
+
+        self.scenes_to_spawn = non_existent_scenes;
+        Ok(())
     }
 }
 
@@ -103,16 +189,22 @@ pub fn scene_spawner_system(world: &mut World, resources: &mut Resources) {
     let mut scene_spawner = resources.get_mut::<SceneSpawner>().unwrap();
     let scene_asset_events = resources.get::<Events<AssetEvent<Scene>>>().unwrap();
 
+    let mut updated_spawned_scenes = Vec::new();
     for event in scene_spawner
         .scene_asset_event_reader
         .iter(&scene_asset_events)
     {
         if let AssetEvent::Modified { handle } = event {
-            if scene_spawner.loaded_scene_entities.contains_key(handle) {
+            if scene_spawner.loaded_scenes.contains(handle) {
                 scene_spawner.load(*handle);
             }
+            if scene_spawner.spawned_scenes.contains_key(handle) {
+                updated_spawned_scenes.push(*handle);      
+            }
         }
     }
 
-    scene_spawner.load_queued_scenes(world, resources);
+    scene_spawner.load_queued_scenes(world, resources).unwrap();
+    scene_spawner.spawn_queued_scenes(world, resources).unwrap();
+    scene_spawner.update_spawned_scenes(world, resources, &updated_spawned_scenes).unwrap();
 }

examples/scene/load_scene.rs

@@ -56,13 +56,15 @@ fn load_scene_system(asset_server: Res<AssetServer>, mut scene_spawner: ResMut<S
 
     // SceneSpawner can "spawn" scenes. "spawning" a scene creates a new instance of the scene in the World with new entity ids.
     // This guarantees that it will not overwrite existing entities.
-    // scene_spawner.spawn(scene_handle);
+    scene_spawner.spawn(scene_handle);
 
     // SceneSpawner can also "load" scenes. "loading" a scene preserves the entity ids in the scene.
     // In general, you should "spawn" scenes when you are dynamically composing your World and "load" scenes for things like game saves.
-
     scene_spawner.load(scene_handle);
 
+    // we have now loaded `scene_handle` AND spawned it, which means our World now has one set of entities with the Scene's ids and
+    // one set of entities with new ids
+
     // This tells the AssetServer to watch for changes to assets.
     // It enables our scenes to automatically reload in game when we modify their files
     asset_server.watch_for_changes().unwrap();