scene: make scenes own its own world, no references

Cargo.lock

@@ -984,12 +984,6 @@ dependencies = [
  "percent-encoding",
 ]
 
-[[package]]
-name = "fps_counter"
-version = "2.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3aaba7ff514ee9d802b562927f80b1e94e93d8e74c31b134c9c3762dabf1a36b"
-
 [[package]]
 name = "fsevent-sys"
 version = "4.1.0"
@@ -3104,7 +3098,6 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "async-std",
- "fps_counter",
  "lyra-engine",
  "tracing",
 ]

lyra-scene/src/lib.rs

@@ -1,4 +1,4 @@
-use std::{collections::VecDeque, ops::{Deref, DerefMut}};
+use std::collections::VecDeque;
 
 use lyra_ecs::{query::Entities, relation::ChildOf, Bundle, Component, Entity, World};
 
@@ -21,77 +21,31 @@ pub struct SceneNodeFlag;
 #[derive(Component)]
 pub struct SceneNodeRoot;
 
-enum MutCow<'a, T> {
-    Mut(&'a mut T),
-    Owned(T),
-}
-
-impl<'a, T> Deref for MutCow<'a, T> {
-    type Target = T;
-
-    fn deref(&self) -> &Self::Target {
-        match self {
-            MutCow::Mut(t) => t,
-            MutCow::Owned(t) => t,
-        }
-    }
-}
-
-impl<'a, T> DerefMut for MutCow<'a, T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        match self {
-            MutCow::Mut(t) => t,
-            MutCow::Owned(t) => t,
-        }
-    }
-}
-
 /// A SceneGraph is a Graph of nodes that represents the hierarchy of a scene.
 /// 
 /// This SceneGraph is special in the sense that it is literally just an ECS world with methods
 /// implemented for it that make it easier to use for a SceneGraph.
 //#[derive(Default)]
-pub struct SceneGraph<'a>  {
+pub struct SceneGraph  {
-    pub(crate) world: MutCow<'a, World>,
+    pub(crate) world: World,
     root_node: SceneNode,
 }
 
-impl<'a> SceneGraph<'a> {
+impl SceneGraph {
     /// Create a new SceneGraph with its own ECS World.
     pub fn new() -> Self {
-        let mut world = World::new();
+        let world = World::new();
         
-        let e = world.spawn((Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)), SceneNodeRoot));
+        Self::from_world(world)
-        let root = SceneNode::new(None, e);
-
-        Self {
-            world: MutCow::Owned(world),
-            root_node: root
-        }
-    }
-
-    /// Retrieve a SceneGraph from an ECS World.
-    /// 
-    /// Returns `None` if the `root_entity` was not created from a `SceneGraph` that was later
-    /// inserted into another world with [`SceneGraph::into_world`].
-    pub fn from_world(world: &'a mut World, root_entity: Entity) -> Option<Self> {
-        if world.view_one::<(&SceneNodeRoot, &Transform)>(root_entity).get().is_none() {
-            None
-        } else {
-            Some(Self {
-                world: MutCow::Mut(world),
-                root_node: SceneNode::new(None, root_entity),
-            })
-        }
     }
 
     /// Create a new SceneGraph inside an existing ECS World.
-    pub fn new_from_world(world: &'a mut World) -> Self {
+    pub fn from_world(mut world: World) -> Self {
         let root_en = world.spawn((Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)), SceneNodeRoot));
         let root = SceneNode::new(None, root_en);
 
         Self {
-            world: MutCow::Mut(world),
+            world,
             root_node: root,
         }
     }
@@ -185,7 +139,8 @@ impl<'a> SceneGraph<'a> {
     where
         F: FnMut(&SceneNode, Transform),
     {
-        let v = self.world.view::<(Entities, &Transform)>()
+        let v = self.world
+            .view::<(Entities, &Transform)>()
             .relates_to::<ChildOf>(start.entity());
 
         for ((e, _), _rel) in v.iter() {