scene: improve docs and some code cleanup

lyra-ecs/src/archetype.rs

@@ -1,6 +1,6 @@
 use std::{ptr::{NonNull, self}, alloc::{self, Layout, alloc, dealloc}, mem, collections::HashMap, cell::{RefCell, Ref, RefMut, BorrowError, BorrowMutError}, ops::DerefMut};
 
-use crate::{world::ArchetypeEntityId, bundle::Bundle, component_info::ComponentInfo, DynTypeId, Tick, Entity};
+use crate::{bundle::Bundle, component_info::ComponentInfo, world::ArchetypeEntityId, DynTypeId, Entity, Tick};
 
 #[derive(Clone)]
 pub struct ComponentColumn {
@@ -295,21 +295,32 @@ impl Archetype {
             self.capacity = new_cap;
         }
 
-        debug_assert_eq!(self.entity_ids.len(), self.entities.len(), "Somehow the Archetype's entity storage got unsynced");
+        self.ensure_synced();
         let entity_index = ArchetypeEntityId(self.entity_ids.len() as u64);
         self.entity_ids.insert(entity, entity_index);
         self.entities.push(entity);
 
-        bundle.take(|data, type_id, _size| {
+        bundle.take(|data, type_id, info| {
-            let col = self.get_column_mut(type_id).unwrap();
+            self.put_component_at(tick, data, type_id, info.layout().size(), entity_index.0 as _);
-            unsafe { col.insert_entity(entity_index.0 as usize, data, *tick); }
         });
         
         entity_index
     }
 
-    /// Removes an entity from the Archetype and frees its components. Returns the entity record
+    pub(crate) fn put_component_at(&mut self, tick: &Tick, ptr: NonNull<u8>, type_id: DynTypeId, size: usize, index: usize) {
-    /// that took its place in the component column.
+        let _ = size;
+
+        let col = self.get_column_mut(type_id).unwrap();
+        //unsafe { col.set_at(index, ptr, *tick) };
+        unsafe { col.insert_entity(index, ptr, *tick); }
+    }
+
+    /// Removes an entity from the Archetype and frees its components.
+    /// 
+    /// Inside the component columns, the entities are swap-removed. Meaning that the last
+    /// entity in the column is moved in the position of the entity that was removed.
+    /// If there was an entity that was swapped, this function returns the entity, and its
+    /// new index in the archetype that was put in place of the removed entity.
     pub(crate) fn remove_entity(&mut self, entity: Entity, tick: &Tick) -> Option<(Entity, ArchetypeEntityId)> {
         let entity_index = self.entity_ids.remove(&entity)
             .expect("The entity is not in this Archetype!");
@@ -389,6 +400,11 @@ impl Archetype {
         self.capacity = new_capacity;
     }
 
+    /// Attempts to find the column storing components of `type_id`
+    pub fn get_column_at(&self, idx: usize) -> Option<&ComponentColumn> {
+        self.columns.get(idx)
+    }
+
     /// Attempts to find the column storing components of `type_id`
     pub fn get_column<I: Into<DynTypeId>>(&self, type_id: I) -> Option<&ComponentColumn> {
         let type_id = type_id.into();
@@ -436,7 +452,7 @@ impl Archetype {
     /// The entity IS NOT removed from the old archetype. You must manually call [`Archetype::remove_entity`](crate::Archetype).
     /// It was done this way because I had some borrow check issues when writing [`World::insert`](crate::World)
     /// related to borrowing mutably from self more than once.
-    /* pub fn move_into<B>(&self, into_arch: &mut Archetype, entity: Entity, new_components: B)
+    /* pub fn move_into<B>(&mut self, entities: &mut Entities, tick: &Tick, into_arch: &mut Archetype, entity: Entity, new_components: B)
     where
         B: Bundle
     {
@@ -446,25 +462,40 @@ impl Archetype {
 
         // move the existing components into the new archetype
         for col in self.columns.iter() {
-            let into_col = into_arch.get_column_mut(col.info.type_id).unwrap();
+            let into_col = into_arch.get_column_mut(col.info.type_id()).unwrap();
             
             // copy from the old column into the new column, then remove it from the old one
             unsafe {
                 let ptr = col.borrow_ptr();
                 let ptr = NonNull::new_unchecked(ptr.as_ptr()
-                    .add(new_index.0 as usize * col.info.layout.size));
+                    .add(new_index.0 as usize * col.info.layout().size()));
-                into_col.set_at(new_index.0 as _, ptr);
+                into_col.set_at(new_index.0 as _, ptr, *tick);
+                    //into_col.set_at(new_index.0 as _, ptr);
             }
         }
 
         // now move the new components into the new archetype
         new_components.take(|data, type_id, _size| {
             let col = into_arch.get_column_mut(type_id).unwrap();
-            unsafe { col.set_at(new_index.0 as _, data); }
+            unsafe { col.set_at(new_index.0 as _, data, *tick); }
             col.len += 1;
         });
 
-        //self.remove_entity(entity);
+        if let Some((en, new_idx)) = self.remove_entity(entity, tick) {
+            let moved_rec = Record {
+                id: self.id,
+                index: new_idx,
+            };
+            entities.insert_entity_record(en, moved_rec);
+        }
+        let new_rec = Record {
+            id: into_arch.id,
+            index: new_index,
+        };
+        entities.insert_entity_record(entity, new_rec);
+
+        into_arch.ensure_synced();
+        self.ensure_synced();
     } */
 
     /// Returns a borrow to the map used to find the column indices of the entity.
@@ -700,7 +731,7 @@ mod tests {
     #[test]
     fn dynamic_archetype() {
         let layout = Layout::new::<u32>();
-        let info = ComponentInfo::new_unknown(DynTypeId::Unknown(100), "u32", layout);
+        let info = ComponentInfo::new_unknown(Some("u32".to_string()), DynTypeId::Unknown(100), layout);
         let infos = vec![info.clone()];
 
         let mut a = Archetype::from_bundle_info(super::ArchetypeId(0), infos);

lyra-ecs/src/bundle.rs

@@ -1,4 +1,4 @@
-use std::{ptr::NonNull, mem::size_of, alloc::Layout};
+use std::{ptr::NonNull, alloc::Layout};
 
 use crate::{component::Component, component_info::ComponentInfo, DynTypeId};
 
@@ -11,7 +11,7 @@ pub trait Bundle {
 
     /// Take the bundle by calling the closure with pointers to each component, its type and size.
     /// The closure is expected to take ownership of the pointer.
-    fn take(self, f: impl FnMut(NonNull<u8>, DynTypeId, usize));
+    fn take(self, f: impl FnMut(NonNull<u8>, DynTypeId, ComponentInfo));
 
     /// Returns a boolean indicating if this Bundle is dynamic. See [`DynamicBundle`]
     fn is_dynamic(&self) -> bool;
@@ -26,8 +26,8 @@ impl Bundle for () {
         vec![ComponentInfo::new::<()>()]
     }
 
-    fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, usize)) {
+    fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, ComponentInfo)) {
-        f(NonNull::from(&self).cast(), DynTypeId::of::<()>(), size_of::<()>());
+        f(NonNull::from(&self).cast(), DynTypeId::of::<()>(), ComponentInfo::new::<()>());
     }
 
     fn is_dynamic(&self) -> bool {
@@ -44,8 +44,8 @@ impl<C: Component> Bundle for C {
         vec![ComponentInfo::new::<C>()]
     }
 
-    fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, usize)) {
+    fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, ComponentInfo)) {
-        f(NonNull::from(&self).cast(), DynTypeId::of::<C>(), size_of::<C>());
+        f(NonNull::from(&self).cast(), DynTypeId::of::<C>(), ComponentInfo::new::<C>());
 
         // this must be done to avoid calling drop on heap memory that the component
         // may manage. So something like a Vec, or HashMap, etc.
@@ -70,12 +70,12 @@ macro_rules! impl_bundle_tuple {
                 vec![$(ComponentInfo::new::<$name>()),+]
             }
 
-            fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, usize)) {
+            fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, ComponentInfo)) {
                 // these names wont follow rust convention, but its a macro so deal with it
                 let ($($name,)+) = self;
 
                 $(
-                    f(NonNull::from(&$name).cast(), DynTypeId::of::<$name>(), size_of::<$name>());
+                    f(NonNull::from(&$name).cast(), DynTypeId::of::<$name>(), ComponentInfo::new::<$name>());
                     // this must be done to avoid calling drop on heap memory that the component
                     // may manage. So something like a Vec, or HashMap, etc.
                     std::mem::forget($name);
@@ -136,8 +136,6 @@ impl DynamicBundle {
     where
         C: Component
     {
-        let info = ComponentInfo::new::<C>();
-        
         // an owned pointer must be created from the provided component since comp would drop
         // out of scope and the data would become invalid
         let ptr = unsafe {
@@ -147,16 +145,42 @@ impl DynamicBundle {
             let alloc_ptr = NonNull::new_unchecked(std::alloc::alloc(layout)).cast::<C>();
             std::ptr::copy_nonoverlapping(data.as_ptr(), alloc_ptr.as_ptr(), 1);
             
+            // this must be done to avoid calling drop on heap memory that the component
+            // may manage. So something like a Vec, or HashMap, etc.
+            std::mem::forget(comp);
+
             alloc_ptr.cast()
         };
 
+        let info = ComponentInfo::new::<C>();
         self.bundle.push((ptr, info));
     }
 
-    /// Push an unknown type to the bundle
+    /// Push an unknown type to the end of the bundle.
     pub fn push_unknown(&mut self, data: NonNull<u8>, info: ComponentInfo) {
         self.bundle.push((data, info));
     }
+
+    /// Push a bundle to the end of this dynamic bundle.
+    pub fn push_bundle<B>(&mut self, bundle: B)
+    where
+        B: Bundle
+    {
+        bundle.take(|ptr, _, info| {
+            // unfortunately the components in the bundle must be copied since there is no guarantee that
+            // `bundle` lasts for as long as the `DynamicBundle`. If the data wasn't copied, the pointers
+            // could be invalid later.
+            let p = unsafe {
+                let alloc_ptr = NonNull::new_unchecked(std::alloc::alloc(info.layout()));
+                std::ptr::copy_nonoverlapping(ptr.as_ptr(), alloc_ptr.as_ptr(), info.layout().size());
+
+                alloc_ptr
+            };
+
+            self.push_unknown(p, info);
+
+        });
+    }
 }
 
 impl Bundle for DynamicBundle {
@@ -168,9 +192,9 @@ impl Bundle for DynamicBundle {
         self.bundle.iter().map(|b| b.1).collect()
     }
 
-    fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, usize)) {
+    fn take(self, mut f: impl FnMut(NonNull<u8>, DynTypeId, ComponentInfo)) {
-        for (data, info) in self.bundle.iter() {
+        for (data, info) in self.bundle.into_iter() {
-            f(*data, info.type_id(), info.layout().size());
+            f(data, info.type_id(), info);
         }
     }
 

lyra-ecs/src/component_info.rs

@@ -67,7 +67,7 @@ impl ComponentInfo {
     }
 
     /// Create ComponentInfo from a type that is not known to rust
-    pub fn new_unknown<D>(type_id: D, name: &str, layout: Layout) -> Self
+    pub fn new_unknown<D>(name: Option<String>, type_id: D, layout: Layout) -> Self
     where
         D: Into<DynTypeId>,
     {

lyra-ecs/src/entity.rs

@@ -11,6 +11,16 @@ pub struct Entity {
     pub(crate) generation: u64,
 }
 
+impl Entity {
+    pub fn id(&self) -> EntityId {
+        self.id
+    }
+
+    pub fn generation(&self) -> u64 {
+        self.generation
+    }
+}
+
 pub struct Entities {
     pub(crate) arch_index: HashMap<EntityId, Record>,
     dead: VecDeque<Entity>,

lyra-ecs/src/query/dynamic/view.rs

@@ -111,7 +111,7 @@ mod tests {
     #[test]
     fn single_dynamic_view() {
         let comp_layout = Layout::new::<u32>();
-        let comp_info = ComponentInfo::new_unknown(DynTypeId::Unknown(100), "u32", comp_layout);
+        let comp_info = ComponentInfo::new_unknown(Some("u32".to_string()), DynTypeId::Unknown(100), comp_layout);
 
         let mut dynamic_bundle = DynamicBundle::default();
         let comp = 50u32;

lyra-ecs/src/query/entities.rs

@@ -2,21 +2,20 @@ use crate::{archetype::Archetype, World, Entity};
 
 use super::{Fetch, Query, AsQuery};
 
-pub struct EntitiesFetch {
+pub struct EntitiesFetch<'a> {
-    entities: Vec<Entity>,
+    archetype_entities: Option<&'a [Entity]>,
 }
 
-impl<'a> Fetch<'a> for EntitiesFetch {
+impl<'a> Fetch<'a> for EntitiesFetch<'a> {
     type Item = Entity;
 
     unsafe fn get_item(&mut self, entity: crate::world::ArchetypeEntityId) -> Self::Item {
-        let e = *self.entities.get_unchecked(entity.0 as usize);
+        self.archetype_entities.unwrap()[entity.0 as usize]
-        e
     }
 
     fn dangling() -> Self {
         Self {
-            entities: vec![],
+            archetype_entities: None,
         }
     }
 }
@@ -27,7 +26,7 @@ pub struct Entities;
 impl Query for Entities {
     type Item<'a> = Entity;
     
-    type Fetch<'a> = EntitiesFetch;
+    type Fetch<'a> = EntitiesFetch<'a>;
 
     fn new() -> Self {
         Entities
@@ -41,7 +40,7 @@ impl Query for Entities {
     unsafe fn fetch<'a>(&self, _world: &'a World, archetype: &'a Archetype, tick: crate::Tick) -> Self::Fetch<'a> {
         let _ = tick; // ignore unused warnings
         EntitiesFetch {
-            entities: archetype.entity_ids.keys().cloned().collect::<Vec<Entity>>(),
+            archetype_entities: Some(&archetype.entities),
         }
     }
 }

lyra-ecs/src/query/filter/has.rs

@@ -2,6 +2,10 @@ use std::marker::PhantomData;
 
 use crate::{query::{AsQuery, Query}, Archetype, Component, DynTypeId, World};
 
+/// A filter query that fetches when the entity has the component `C`.
+/// 
+/// This does not return a reference to the component, it returns `()` if the entity has
+/// the component. This query is great when its used with [`Or`](super::Or).
 #[derive(Default)]
 pub struct Has<C: Component> {
     _marker: PhantomData<C>

lyra-ecs/src/query/filter/mod.rs

@@ -1,5 +1,8 @@
-pub mod has_component;
+mod has;
-pub use has_component::*;
+pub use has::*;
 
-pub mod or;
+mod or;
 pub use or::*;
+
+mod not;
+pub use not::*;

lyra-ecs/src/query/filter/not.rs

@@ -0,0 +1,44 @@
+use crate::{query::{AsQuery, Query}, Archetype, World};
+
+/// A filter query that fetches the inverse of `Q`.
+/// 
+/// This means that entities that `Q` fetches are skipped, and entities that
+/// `Q` does not fetch are not skipped.
+/// 
+/// ```rust,nobuild
+/// // Iterate over entities that has a transform, and are not the origin of a `ChildOf` relationship.
+/// for (en, pos, _) in world
+///     .view::<(Entities, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>()
+///     .iter()
+/// {
+///     // ...
+/// }
+/// ```
+#[derive(Default, Copy, Clone)]
+pub struct Not<Q: Query> {
+    query: Q,
+}
+
+impl<Q: Query> Query for Not<Q> {
+    type Item<'a> = ();
+    
+    type Fetch<'a> = ();
+
+    fn new() -> Self {
+        Not {
+            query: Q::new(),
+        }
+    }
+
+    fn can_visit_archetype(&self, archetype: &Archetype) -> bool {
+        !self.query.can_visit_archetype(archetype)
+    }
+
+    unsafe fn fetch<'a>(&self, _world: &'a World, _: &'a Archetype, _: crate::Tick) -> Self::Fetch<'a> {
+        ()
+    }
+}
+
+impl<Q: Query> AsQuery for Not<Q> {
+    type Query = Self;
+}

lyra-ecs/src/query/filter/or.rs

@@ -1,5 +1,26 @@
 use crate::{query::{AsQuery, Query}, Archetype, World};
 
+/// A filter query returning when either `Q1` or `Q2` returns.
+/// 
+/// This checks if `Q1` can fetch before checking `Q2`.
+/// 
+/// ```rust,nobuild
+/// for (en, pos, _) in world
+///     .view::<(Entities, &Transform, Or<Has<Mesh>, Has<Scene>>)>()
+///     .iter()
+/// {
+///     // do some things with the position of the entities
+/// 
+///     // now handle do things with the Mesh or Scene that the entity could have
+///     if let Some(mesh) = world.view_one::<&Mesh>(en).get() {
+///         // do mesh things
+///     }
+/// 
+///     if let Some(scene) = world.view_one::<&Scene>(en).get() {
+///         // do scene things
+///     }
+/// }
+/// ```
 #[derive(Default)]
 pub struct Or<Q1: AsQuery, Q2: AsQuery> {
     left: Q1::Query,

lyra-ecs/src/world.rs

@@ -2,7 +2,7 @@ use std::{any::TypeId, collections::HashMap, ptr::NonNull};
 
 use atomic_refcell::{AtomicRef, AtomicRefMut};
 
-use crate::{archetype::{Archetype, ArchetypeId}, bundle::Bundle, query::{dynamic::DynamicView, AsQuery, Query, ViewState, ViewIter, ViewOne}, resource::ResourceData, ComponentInfo, DynTypeId, Entities, Entity, ResourceObject, Tick, TickTracker};
+use crate::{archetype::{Archetype, ArchetypeId}, bundle::Bundle, query::{dynamic::DynamicView, AsQuery, Query, ViewIter, ViewOne, ViewState}, resource::ResourceData, ComponentInfo, DynTypeId, DynamicBundle, Entities, Entity, ResourceObject, Tick, TickTracker};
 
 /// The id of the entity for the Archetype.
 /// 
@@ -144,37 +144,32 @@ impl World {
         let current_arch = self.archetypes.get(&record.id).unwrap();
         let current_arch_len = current_arch.len();
 
-        let mut col_types: Vec<DynTypeId> = current_arch.columns.iter().map(|c| c.info.type_id()).collect();
+        // contains the type ids for the old component columns + the ids for the new components
-        let orig_col = col_types.clone();
+        let mut combined_column_types: Vec<DynTypeId> = current_arch.columns.iter().map(|c| c.info.type_id()).collect();
-        col_types.extend(bundle.type_ids());
+        combined_column_types.extend(bundle.type_ids());
         
-        let mut col_infos: Vec<ComponentInfo> = current_arch.columns.iter().map(|c| c.info).collect();
+        // contains the ComponentInfo for the old component columns + the info for the new components
-        col_infos.extend(bundle.info());
+        let mut combined_column_infos: Vec<ComponentInfo> = current_arch.columns.iter().map(|c| c.info).collect();
+        combined_column_infos.extend(bundle.info());
 
-        let col_ptrs: Vec<(NonNull<u8>, ComponentInfo)> = current_arch.columns.iter()
+        // pointers only for the old columns
+        let old_columns: Vec<(NonNull<u8>, ComponentInfo)> = current_arch.columns.iter()
             .map(|c| unsafe { (NonNull::new_unchecked(c.borrow_ptr().as_ptr()), c.info) })
             .collect();
 
-        if let Some(arch) = self.archetypes.values_mut().find(|a| a.is_archetype_for(&col_types)) {
+        if let Some(arch) = self.archetypes.values_mut().find(|a| a.is_archetype_for(&combined_column_types)) {
-            let res_index = arch.reserve_one(entity);
+            let mut dbun = DynamicBundle::new();
-
+            // move old entity components into new archetype columns
-            for (col_type, (col_ptr, col_info)) in orig_col.into_iter().zip(col_ptrs.into_iter()) {
+            for (col_ptr, col_info) in old_columns.into_iter() {
                 unsafe {
                     let ptr = NonNull::new_unchecked(col_ptr.as_ptr()
                         .add(record.index.0 as usize * col_info.layout().size()));
-                    let col = arch.get_column_mut(col_type).unwrap();
+                    dbun.push_unknown(ptr, col_info);
-                    // set_at is used since the entity was reserved
-                    col.set_at(res_index.0 as _, ptr, tick);
                 }
             }
+            dbun.push_bundle(bundle);
 
-            bundle.take(|data, type_id, _size| {
+            let res_index = arch.add_entity(entity, dbun, &tick);
-                let col = arch.get_column_mut(type_id).unwrap();
-                // set_at is used since the entity was reserved
-                unsafe { col.set_at(res_index.0 as _, data, tick); }
-            });
-
-            arch.entity_ids.insert(entity, res_index);
             arch.ensure_synced();
             
             let new_record = Record {
@@ -187,25 +182,24 @@ impl World {
                 // if this entity is the only entity for this archetype, add more columns to it
                 let current_arch = self.archetypes.get_mut(&record.id).unwrap();
                 current_arch.extend(&tick, vec![bundle]);
-
                 return;
             }
 
             let new_arch_id = self.next_archetype_id.increment();
-            let mut archetype = Archetype::from_bundle_info(new_arch_id, col_infos);
+            let mut archetype = Archetype::from_bundle_info(new_arch_id, combined_column_infos);
-            let entity_arch_id = archetype.add_entity(entity, bundle, &tick);
             
-            // move the old components into the new archetype
+            let mut dbun = DynamicBundle::new();
-            for (column_ptr, column_info) in col_ptrs.into_iter() {
+            for (column_ptr, column_info) in old_columns.into_iter() {
                 unsafe {
                     // ptr of component for the entity
                     let comp_ptr = NonNull::new_unchecked(column_ptr.as_ptr()
                         .add(record.index.0 as usize * column_info.layout().size()));
-                    
+                    dbun.push_unknown(comp_ptr, column_info);
-                    let col = archetype.get_column_mut(column_info.type_id()).unwrap();
-                    col.insert_entity(entity_arch_id.0 as _, comp_ptr, tick);
                 }
             }
+            dbun.push_bundle(bundle);
+
+            let entity_arch_id = archetype.add_entity(entity, dbun, &tick);
 
             self.archetypes.insert(new_arch_id, archetype);
 
@@ -219,12 +213,103 @@ impl World {
         }
 
         let current_arch = self.archetypes.get_mut(&record.id).unwrap();
-        if current_arch.len() > 1 {
+        if let Some((en, enar)) = current_arch.remove_entity(entity, &tick) {
-            current_arch.remove_entity(entity, &tick);
+            let rec = Record {
-        } else if current_arch.len() == 1 {
+                id: current_arch.id(),
-            // The old archetype will only be removed if there was another archetype that would
+                index: enar
-            // work for the entity's components, and the old archetype only had a single entity.
+            };
-            self.archetypes.remove(&record.id).unwrap();
+            self.entities.insert_entity_record(en, rec);
+        }   
+
+        current_arch.ensure_synced();
+    }
+
+    /// A method used for debugging implementation details of the ECS.
+    /// 
+    /// Here's an example of the output:
+    /// ```
+    /// Entities
+    ///   1 in archetype 0 at 0
+    ///   0 in archetype 1 at 0
+    ///   2 in archetype 0 at 1
+    ///   3 in archetype 2 at 0
+    /// Arch 1 -- 1 entities
+    ///   Col 175564825027445222460146453544114453753
+    ///     0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 78 86 0 0
+    ///   Col 162279302565774655543278578489329315472
+    ///     0: 0 0 32 65 0 0 32 65 0 0 32 65 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 0 0 0 0
+    ///   Col 24291284537013640759061027938209843602
+    ///     0: 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+    /// Arch 2 -- 1 entities
+    ///   Col 175564825027445222460146453544114453753
+    ///     0: 0 0 0 0 0 0 0 0 0 0 0 0 237 127 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 78 86 0 0
+    ///   Col 162279302565774655543278578489329315472
+    ///     0: 0 0 76 66 0 0 170 66 0 0 136 65 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 0 0 0 0
+    ///   Col 142862377085187052737282554588643015580
+    ///     0: 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+    /// Arch 0 -- 2 entities
+    ///   Col 175564825027445222460146453544114453753
+    ///     0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 0 0 0 0
+    ///     1: 0 0 0 0 0 0 0 0 0 0 0 0 237 127 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 78 86 0 0
+    ///   Col 162279302565774655543278578489329315472
+    ///     0: 0 0 112 65 0 0 112 65 0 0 112 65 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 0 0 0 0
+    ///     1: 0 0 27 67 0 0 184 65 0 0 192 64 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 128 63 0 0 128 63 0 0 128 63 0 0 128 63 0 0 0 0
+    ///   Col 142862377085187052737282554588643015580
+    ///     0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+    ///     1: 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+    ///   Col 24291284537013640759061027938209843602
+    ///     0: 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+    ///     1: 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+    /// Arch 3 -- 0 entities
+    ///   Col 175564825027445222460146453544114453753
+    ///   Col 162279302565774655543278578489329315472
+    /// ```
+    /// 
+    /// This output prints all Entity ids, the archetype they're in, and the index that they're
+    /// in inside of the archetype. Additionally, the archetypes are printing, including their
+    /// columns type ids, and the contents of the type ids. This output can be used to debug
+    /// the contents of entities inside the archetypes.
+    /// 
+    /// Below is a template of the output:
+    /// ```
+    /// Entities
+    ///   %ENTITY_ID% in archetype %ARCHETYPE_ID% at %INDEX%
+    /// Arch ID -- %ARCHETYPE_LEN% entities
+    ///   %FOR EACH COL%
+    ///   Col COLUMN_COMPONENT_TYPE_ID
+    ///     %FOR EACH ENTITY%
+    ///     %ENTITY_INDEX%: %COMPONENT_BYTES%
+    /// ```
+    /// If the template above doesn't help you in understanding the output, read the source code
+    /// of the function. The source code is pretty simple.
+    pub fn debug_print_world(&self) {
+        println!("Entities");
+        for (en, rec) in &self.entities.arch_index {
+            println!("  {} in archetype {} at {}", en.0, rec.id.0, rec.index.0);
+        }
+
+        for arch in self.archetypes.values() {
+            println!("Arch {} -- {} entities", arch.id().0, arch.len());
+
+            for col in &arch.columns {
+                // no clue if doing this is stable, but this is a debug function so :shrug:
+                let tyid: u128 = unsafe { std::mem::transmute(col.info.type_id().as_rust()) };
+                println!("  Col {}", tyid);
+
+                for en in 0..col.len {
+                    // get the ptr starting at the component
+                    let p = col.borrow_ptr();
+                    let p = unsafe { p.as_ptr().add(en * col.info.layout().size()) };
+
+                    print!("    {}: ", en);
+                    // print each byte of the component
+                    for i in 0..col.info.layout().size() {
+                        let d = unsafe { *p.add(i) };
+                        print!("{} ", d);
+                    }
+                    println!();
+                }
+            }
         }
     }
 
@@ -364,6 +449,10 @@ impl World {
         self.resources.get(&TypeId::of::<T>())
             .map(|d| unsafe { NonNull::new_unchecked(d.data.as_ptr() as *mut T) })
     }
+
+    pub fn archetype_count(&self) -> usize {
+        self.archetypes.len()
+    }
 }
 
 // TODO: Ensure that all non-send resources are only accessible on the main thread.

lyra-scene/Cargo.toml

@@ -6,5 +6,6 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+anyhow = "1.0.81"
 lyra-ecs = { path = "../lyra-ecs", features = [ "math" ] }
 lyra-math = { path = "../lyra-math" }

lyra-scene/src/lib.rs

@@ -1,6 +1,11 @@
-use std::collections::VecDeque;
+mod node;
+pub use node::*;
 
-use lyra_ecs::{query::Entities, relation::ChildOf, Bundle, Component, Entity, World};
+mod world_transform;
+pub use world_transform::*;
+
+use lyra_ecs::{query::{Entities, ViewOne}, relation::ChildOf, Bundle, Component, World};
+use lyra_math::Transform;
 
 // So we can use lyra_ecs::Component derive macro
 pub(crate) mod lyra_engine {
@@ -9,10 +14,6 @@ pub(crate) mod lyra_engine {
     }
 }
 
-mod node;
-use lyra_math::{Transform, Vec3};
-pub use node::*;
-
 /// A flag spawned on all scene node entities
 #[derive(Component)]
 pub struct SceneNodeFlag;
@@ -21,7 +22,7 @@ pub struct SceneNodeFlag;
 #[derive(Component)]
 pub struct SceneNodeRoot;
 
-/// A SceneGraph is a Graph of nodes that represents the hierarchy of a scene.
+/// 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.
@@ -41,7 +42,7 @@ impl SceneGraph {
 
     /// Create a new SceneGraph inside an existing ECS World.
     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_en = world.spawn((WorldTransform::default(), Transform::default(), SceneNodeRoot));
         let root = SceneNode::new(None, root_en);
 
         Self {
@@ -50,70 +51,21 @@ impl SceneGraph {
         }
     }
 
-    /// Consume the SceneGraph, inserting its internal world into the provided world.
-    /// 
-    /// The `into` World will contain all nodes of the SceneGraph. You could iterate through the
-    /// SceneGraph manually if you'd like. The root entity has a [`SceneNodeRoot`] flag component,
-    /// and a Transform component. The children nodes have a [`SceneNodeFlag`] component and a 
-    /// Transform component. The transforms of the children will be local, you must find its world
-    /// transform by traversing up the hierarchy of the scene manually with the `ChildOf` relation.
-    /// 
-    /// Returns: the Entity of the root node in the provided world.
-    pub fn into_world(mut self, into: &mut World) -> Entity {
-        // first insert the root entity into the World.
-        let v = self.world.view_one::<&Transform>(self.root_node.entity());
-        let pos = *v.get().unwrap();
-        let new_root = into.spawn((pos, SceneNodeRoot));
-
-        // now process the children of the root node.
-        Self::traverse_inserting_into(&mut self.world, self.root_node.entity(), new_root, into);
-        new_root
-    }
-
-    /// Recursively traverse the `from` world, starting at `node_en`, inserting the
-    /// children entity into the world.
-    /// 
-    /// Parameters:
-    /// * `scene_world` - The world that the SceneGraph exists in
-    /// * `scene_en` - The entity of the parent entity inside of the `scene_world`.
-    /// * `parent_en` - The entity of the parent entity inside of the `into` world.
-    /// * `into` - The world to insert the SceneGraph world into.
-    fn traverse_inserting_into(scene_world: &mut World, scene_en: Entity, parent_en: Entity, into: &mut World) {
-        let v = scene_world.view::<(Entities, &Transform)>()
-            .relates_to::<ChildOf>(scene_en);
-
-        // unfortunately, the borrow checker exists, and wasn't happy that `scene_world` was
-        // immutably borrowed with the view (v), and being mutably borrowed in the
-        // recursive call.
-        let mut child_entities = VecDeque::new();
-
-        for ((child_scene_en, pos), _rel) in v.iter() {
-            let into_en = into.spawn((*pos, SceneNodeFlag));
-            into.add_relation(into_en, ChildOf, parent_en);
-
-            child_entities.push_back((child_scene_en, into_en));
-        }
-
-        while let Some((child_scene_en, into_en)) = child_entities.pop_front() {
-            Self::traverse_inserting_into(scene_world, child_scene_en, into_en, into);
-        }
-    }
-
     /// Adds a node to the root node of the SceneGraph.
     /// 
     /// The spawned entity will have a `ChildOf` relation targeting the root node, the
     /// `SceneNodeFlag` component is also added to the entity.
-    pub fn add_node<B: Bundle>(&mut self, local_transform: Transform, bundle: B) -> SceneNode {
+    pub fn add_node<B: Bundle>(&mut self, bundle: B) -> SceneNode {
         let node = self.root_node.clone();
-        self.add_node_under(&node, local_transform, bundle)
+        self.add_node_under(&node, bundle)
     }
 
     /// Add a node under a parent node.
     /// 
     /// The spawned entity will have a `ChildOf` relation targeting the provided parent node,
     /// the `SceneNodeFlag` component is also added to the entity.
-    pub fn add_node_under<B: Bundle>(&mut self, parent: &SceneNode, local_transform: Transform, bundle: B) -> SceneNode {
+    pub fn add_node_under<B: Bundle>(&mut self, parent: &SceneNode, bundle: B) -> SceneNode {
-        world_add_child_node(&mut self.world, parent, local_transform, bundle)
+        world_add_child_node(&mut self.world, parent, bundle)
     }
 
     /// Insert a component bundle to a SceneNode.
@@ -133,29 +85,32 @@ impl SceneGraph {
     /// Traverses down the SceneGraph, calling `callback` with each SceneNode and its world transform.
     /// 
     /// The traversal does not include the root scene node.
-    pub fn traverse_down<F>(&self, mut callback: F)
+    pub fn traverse_down<F, Q>(&self, mut callback: F)
     where
-        F: FnMut(&World, &SceneNode, Transform),
+        F: FnMut(&World, &SceneNode, ViewOne<Q::Query>),
+        Q: lyra_ecs::query::AsQuery,
     {
-        self.traverse_down_from(self.root_node.clone(), &mut callback);
+        self.traverse_down_from::<F, Q>(self.root_node.clone(), &mut callback);
     }
 
     /// Recursively Traverses down the SceneGraph from a starting node, calling `callback` with each
     /// SceneNode and its world transform.
-    fn traverse_down_from<F>(&self, start: SceneNode, callback: &mut F)
+    fn traverse_down_from<F, Q>(&self, start: SceneNode, callback: &mut F)
     where
-        F: FnMut(&World, &SceneNode, Transform),
+        F: FnMut(&World, &SceneNode, ViewOne<Q::Query>),
+        Q: lyra_ecs::query::AsQuery,
     {
         let v = self.world
-            .view::<(Entities, &Transform)>()
+            .view::<Entities>()
             .relates_to::<ChildOf>(start.entity());
 
-        for ((e, _), _rel) in v.iter() {
+        for (e, _rel) in v.iter() {
             let node = SceneNode::new(Some(start.entity()), e);
-            let world_pos = node.world_transform(self);
+            //let world_pos = node.world_transform(self);
-            callback(&self.world, &node, world_pos);
+            let v = self.world.view_one::<Q>(e);
+            callback(&self.world, &node, v);
 
-            self.traverse_down_from(node, callback);
+            self.traverse_down_from::<F, Q>(node, callback);
         }
     }
 
@@ -173,9 +128,9 @@ impl SceneGraph {
 /// 
 /// The spawned entity will have a `ChildOf` relation targeting the provided parent node,
 /// the `SceneNodeFlag` component is also added to the entity.
-pub(crate) fn world_add_child_node<B: Bundle>(world: &mut World, parent: &SceneNode, local_transform: Transform, bundle: B) -> SceneNode {
+pub(crate) fn world_add_child_node<B: Bundle>(world: &mut World, parent: &SceneNode, bundle: B) -> SceneNode {
     let e = world.spawn(bundle);
-    world.insert(e, (SceneNodeFlag, local_transform));
+    world.insert(e, (SceneNodeFlag,));
     world.add_relation(e, ChildOf, parent.entity());
 
     SceneNode::new(Some(parent.entity()), e)
@@ -183,10 +138,10 @@ pub(crate) fn world_add_child_node<B: Bundle>(world: &mut World, parent: &SceneN
 
 #[cfg(test)]
 pub mod tests {
-    use lyra_ecs::Component;
+    use lyra_ecs::{query::{filter::{Has, Not}, Entities}, relation::{ChildOf, RelationOriginComponent}, Component};
     use lyra_math::{Transform, Vec3};
 
-    use crate::{lyra_engine, SceneGraph};
+    use crate::{lyra_engine, WorldTransform, SceneGraph};
 
     #[derive(Component)]
     pub struct FakeMesh;
@@ -195,7 +150,7 @@ pub mod tests {
     fn single_node_hierarchy() {
         let mut scene = SceneGraph::new();
 
-        let a = scene.add_node(Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh);
+        let a = scene.add_node((Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh));
         assert!(a.parent(&scene).unwrap() == scene.root_node);
     }
 
@@ -203,10 +158,10 @@ pub mod tests {
     fn double_node_hierarchy() {
         let mut scene = SceneGraph::new();
 
-        let a = scene.add_node(Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh);
+        let a = scene.add_node((Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh));
         assert!(a.parent(&scene).unwrap() == scene.root_node);
 
-        let b = a.add_node(&mut scene, Transform::from_translation(Vec3::new(50.0, 50.0, 50.0)), FakeMesh);
+        let b = a.add_node(&mut scene, (Transform::from_translation(Vec3::new(50.0, 50.0, 50.0)), FakeMesh));
         assert!(b.parent(&scene).unwrap() == a);
     }
 
@@ -216,68 +171,25 @@ pub mod tests {
 
         let mut scene = SceneGraph::new();
 
-        let a = scene.add_node(Transform::from_translation(v2s[0]), FakeMesh);
+        let a = scene.add_node((WorldTransform::default(), Transform::from_translation(v2s[0]), FakeMesh));
         assert!(a.parent(&scene).unwrap() == scene.root_node);
-        let b = a.add_node(&mut scene, Transform::from_translation(v2s[1]), FakeMesh);
+        let b = a.add_node(&mut scene, (WorldTransform::default(), Transform::from_translation(v2s[1]), FakeMesh));
         assert!(b.parent(&scene).unwrap() == a);
 
+        let view = scene.world.view::<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>();
+        crate::system_update_world_transforms(&scene.world, view).unwrap();
+
         let mut idx = 0;
-        scene.traverse_down(|_, _, pos| {
+        scene.traverse_down::<_, &WorldTransform>(|_, _, v| {
+            let pos = v.get().unwrap();
             if idx == 0 {
-                assert_eq!(pos, Transform::from_translation(v2s[idx]));
+                assert_eq!(**pos, Transform::from_translation(v2s[idx]));
             } else if idx == 1 {
                 let t = v2s.iter().sum();
-                assert_eq!(pos, Transform::from_translation(t));
+                assert_eq!(**pos, Transform::from_translation(t));
             }
 
             idx += 1;
         });
     }
-
-    /* #[test]
-    fn inserting_and_from_world() {
-        let v2s = vec![Vec3::new(10.0, 10.0, 10.0), Vec3::new(50.0, 50.0, 50.0)];
-
-        let mut scene = SceneGraph::new();
-
-        let a = scene.add_node(Transform::from_translation(v2s[0]), FakeMesh);
-        assert!(a.parent(&scene).unwrap() == scene.root_node);
-        let b = a.add_node(&mut scene, Transform::from_translation(v2s[1]), FakeMesh);
-        assert!(b.parent(&scene).unwrap() == a);
-
-        let mut other_world = World::new();
-        let root = scene.into_world(&mut other_world);
-        
-        // check all of the entities inside of the World
-        let (root_pos, _) = other_world.view_one::<(&Transform, &SceneNodeRoot)>(root).get().unwrap();
-        assert_eq!(*root_pos, Transform::from_xyz(0.0, 0.0, 0.0));
-
-        let ((child_en, child_pos), _)  = other_world.view::<(Entities, &Transform)>()
-            .relates_to::<ChildOf>(root).iter().next().unwrap();
-        assert_eq!(*child_pos, Transform::from_translation(v2s[0]));
-
-        let ((_, childchild_pos), _)  = other_world.view::<(Entities, &Transform)>()
-            .relates_to::<ChildOf>(child_en).iter().next().unwrap();
-        assert_eq!(*childchild_pos, Transform::from_translation(v2s[1]));
-        
-        drop(root_pos);
-        drop(child_pos);
-        drop(childchild_pos);
-
-        // Now get the SceneGraph inside the World and use the nice utility tools to traverse it.
-        let scene = SceneGraph::from_world(&mut other_world, root)
-            .expect("Failed to get SceneGraph from World!");
-
-        let mut idx = 0;
-        scene.traverse_down(|_e, pos| {
-            if idx == 0 {
-                assert_eq!(pos, Transform::from_translation(v2s[idx]));
-            } else if idx == 1 {
-                let t = v2s.iter().sum();
-                assert_eq!(pos, Transform::from_translation(t));
-            }
-
-            idx += 1;
-        });
-    } */
 }

lyra-scene/src/node.rs

@@ -1,11 +1,10 @@
 use lyra_ecs::{query::Entities, relation::{ChildOf, RelationOriginComponent}, Bundle, Entity};
-use lyra_math::Transform;
 
 use crate::SceneGraph;
 
+/// A node inside of the Scene
 #[derive(Clone, PartialEq, Eq)]
 pub struct SceneNode {
-    //world: WorldLock,
     parent: Option<Entity>,
     entity: Entity
 }
@@ -52,50 +51,33 @@ impl SceneNode {
     /// 
     /// The spawned entity backing the scene node will have a `ChildOf` relation targeting
     /// the provided parent node, the `SceneNodeFlag` component is also added to the entity.
-    pub fn add_node<B: Bundle>(&self, graph: &mut SceneGraph, local_transform: Transform, bundle: B) -> SceneNode {
+    pub fn add_node<B: Bundle>(&self, graph: &mut SceneGraph, bundle: B) -> SceneNode {
-        graph.add_node_under(self, local_transform, bundle)
+        graph.add_node_under(self, bundle)
-    }
-
-    pub fn local_transform(&self, graph: &SceneGraph) -> Transform {
-        let v = graph.world.view_one::<&Transform>(self.entity);
-
-        let t = v.get().expect("Somehow the SceneNode is missing its Transform!");
-        t.clone()
-    }
-
-    /// Retrieves the world transform of the Node.
-    /// 
-    /// This traverses up the SceneGraph from this node.
-    pub fn world_transform(&self, graph: &SceneGraph) -> Transform {
-        match self.parent(graph) {
-            Some(parent) => {
-                let pt = parent.world_transform(graph);
-                pt + self.local_transform(graph)
-            },
-            None => {
-                self.local_transform(graph)
-            }
-        }
     }
 }
 
 #[cfg(test)]
 mod tests {
+    use lyra_ecs::{query::{filter::{Has, Not}, Entities}, relation::{ChildOf, RelationOriginComponent}};
     use lyra_math::{Transform, Vec3};
     
-    use crate::{tests::FakeMesh, SceneGraph};
+    use crate::{tests::FakeMesh, WorldTransform, SceneGraph};
 
     #[test]
     fn node_world_transform() {
         let mut scene = SceneGraph::new();
 
-        let a = scene.add_node(Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh);
+        let a = scene.add_node((WorldTransform::default(), Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh));
         assert!(a.parent(&scene).unwrap() == scene.root_node);
         
-        let b = a.add_node(&mut scene, Transform::from_translation(Vec3::new(50.0, 50.0, 50.0)), FakeMesh);
+        let b = a.add_node(&mut scene, (WorldTransform::default(), Transform::from_translation(Vec3::new(50.0, 50.0, 50.0)), FakeMesh));
         assert!(b.parent(&scene).unwrap() == a);
 
-        let wrld_tran = b.world_transform(&scene);
+        // update global transforms
-        assert_eq!(wrld_tran, Transform::from_translation(Vec3::new(60.0, 60.0, 60.0)));
+        let view = scene.world.view::<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>();
+        crate::system_update_world_transforms(&scene.world, view).unwrap();
+
+        let tran = scene.world.view_one::<&WorldTransform>(b.entity).get().unwrap();
+        assert_eq!(**tran, Transform::from_translation(Vec3::new(60.0, 60.0, 60.0)));
     }
 }

lyra-scene/src/world_transform.rs

@@ -0,0 +1,171 @@
+use std::ops::Deref;
+
+use lyra_ecs::{query::{filter::{Has, Not}, Entities, View}, relation::{ChildOf, RelationOriginComponent}, Component, Entity, World};
+use lyra_math::Transform;
+use crate::lyra_engine;
+
+/// The world transform of an entity.
+/// 
+/// A Transform represents the relative position of the entity to its parent entity, while
+/// a world transform is the position relative to the World. When wanting to move an entity,
+/// you should use its [`Transform`]. You cannot mutate [`WorldTransform`] as its managed completey
+/// by the [`system_update_world_transforms`] system. For the WorldTransform to work properly, you
+/// must have both a [`Transform`] and [`WorldTransform`] on the entities in the scene.
+#[derive(Debug, Copy, Clone, PartialEq, Default, Component)]
+pub struct WorldTransform(pub(crate) Transform);
+
+impl Deref for WorldTransform {
+    type Target = Transform;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+/// A system that updates the [`WorldTransform`]'s for entities and their children.
+/// 
+/// For entities without parents, this will update world transform to match local transform.
+/// For any children entities, their [`WorldTransform`]s will be updated to reflect the changes
+/// of its parent entity.
+pub fn system_update_world_transforms(world: &World, view: View<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>) -> anyhow::Result<()> {    
+    for (en, mut world_tran, tran, _) in view.into_iter() {
+        world_tran.0 = *tran;
+        recurse_update_trans(world, &world_tran, en);
+    }
+
+    Ok(())
+}
+
+fn recurse_update_trans(world: &World, parent_transform: &WorldTransform, entity: Entity) {
+    // store entities and their world transform to process outside of the view.
+    // it must be done after to avoid attempts of multiple mutable borrows to the archetype column
+    // with WorldTransform.
+    let mut next_entities = vec![];
+
+    for ((en, mut world_tran, tran), _) in 
+        world.view::<(Entities, &mut WorldTransform, &Transform)>()
+            .relates_to::<ChildOf>(entity)
+            .into_iter()
+    {
+        world_tran.0 = parent_transform.0 + *tran;
+        next_entities.push((en, world_tran.0.clone()));
+    }
+
+    for (en, pos) in next_entities.into_iter() {
+        recurse_update_trans(world, &WorldTransform(pos), en);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use lyra_ecs::{query::{filter::{Has, Not}, Entities}, relation::{ChildOf, RelationOriginComponent}, World};
+    use lyra_math::Transform;
+
+    use crate::{system_update_world_transforms, WorldTransform};
+
+    #[test]
+    fn test_system() {
+        let mut world = World::new();
+
+        let parent = world.spawn((WorldTransform::default(), Transform::from_xyz(10.0, 10.0, 10.0)));
+        let child = world.spawn((WorldTransform::default(), Transform::from_xyz(15.0, 15.0, 15.0)));
+        world.add_relation(child, ChildOf, parent);
+
+        let view = world.view::<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>();
+        system_update_world_transforms(&world, view).unwrap();
+
+        let g = world.view_one::<&WorldTransform>(child).get().unwrap();
+        assert_eq!(**g, Transform::from_xyz(25.0, 25.0, 25.0));
+    }
+
+    #[test]
+    fn test_system_many_entities() {
+        let mut world = World::new();
+
+        let parent = world.spawn((WorldTransform::default(), Transform::from_xyz(10.0, 10.0, 10.0)));
+        
+        let mut children = vec![];
+        let mut base_offset = 15.0;
+        for _ in 0..10 {
+            let en = world.spawn((WorldTransform::default(), Transform::from_xyz(base_offset, base_offset, base_offset)));  
+            world.add_relation(en, ChildOf, parent);
+            base_offset += 10.0;
+            children.push(en);
+        }
+
+        let second_child = world.spawn((WorldTransform::default(), Transform::from_xyz(5.0, 3.0, 8.0)));
+        world.add_relation(second_child, ChildOf, parent);
+
+        let view = world.view::<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>();
+        system_update_world_transforms(&world, view).unwrap();
+
+        let mut base_offset = 25.0;
+        for child in children.into_iter() {
+            let g = world.view_one::<&WorldTransform>(child).get().unwrap();
+            println!("Child {:?} at {:?}", child, g.translation);
+            assert_eq!(**g, Transform::from_xyz(base_offset, base_offset, base_offset));
+
+            base_offset += 10.0;
+        }
+    }
+
+    #[test]
+    fn test_system_many_children() {
+        let mut world = World::new();
+
+        let parent = world.spawn((WorldTransform::default(), Transform::from_xyz(10.0, 10.0, 10.0)));
+        let first_child = world.spawn((WorldTransform::default(), Transform::from_xyz(15.0, 15.0, 15.0)));
+        world.add_relation(first_child, ChildOf, parent);
+
+        let sec_chi = world.spawn((WorldTransform::default(), Transform::from_xyz(155.0, 23.0, 6.0)));
+        world.add_relation(sec_chi, ChildOf, first_child);
+
+        let thir_chi = world.spawn((WorldTransform::default(), Transform::from_xyz(51.0, 85.0, 17.0)));
+        world.add_relation(thir_chi, ChildOf, sec_chi);
+
+        let four_child = world.spawn((WorldTransform::default(), Transform::from_xyz(24.0, 61.0, 65.0)));
+        world.add_relation(four_child, ChildOf, thir_chi);
+
+        let five_child = world.spawn((WorldTransform::default(), Transform::from_xyz(356.0, 54.0, 786.0)));
+        world.add_relation(five_child, ChildOf, four_child);
+
+        let view = world.view::<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>();
+        system_update_world_transforms(&world, view).unwrap();
+
+        let g = world.view_one::<&WorldTransform>(five_child).get().unwrap();
+        assert_eq!(**g, Transform::from_xyz(611.0, 248.0, 899.0));
+    }
+
+    #[test]
+    fn test_system_branched_children() {
+        let mut world = World::new();
+
+        let parent = world.spawn((WorldTransform::default(), Transform::from_xyz(10.0, 10.0, 10.0)));
+        let first_child = world.spawn((WorldTransform::default(), Transform::from_xyz(15.0, 15.0, 15.0)));
+        world.add_relation(first_child, ChildOf, parent);
+
+        let sec_chi = world.spawn((WorldTransform::default(), Transform::from_xyz(155.0, 23.0, 6.0)));
+        world.add_relation(sec_chi, ChildOf, first_child);
+
+        let thir_chi = world.spawn((WorldTransform::default(), Transform::from_xyz(51.0, 85.0, 17.0)));
+        world.add_relation(thir_chi, ChildOf, first_child);
+
+        let four_child = world.spawn((WorldTransform::default(), Transform::from_xyz(24.0, 61.0, 65.0)));
+        world.add_relation(four_child, ChildOf, thir_chi);
+
+        let five_child = world.spawn((WorldTransform::default(), Transform::from_xyz(356.0, 54.0, 786.0)));
+        world.add_relation(five_child, ChildOf, sec_chi);
+
+        let view = world.view::<(Entities, &mut WorldTransform, &Transform, Not<Has<RelationOriginComponent<ChildOf>>>)>();
+        system_update_world_transforms(&world, view).unwrap();
+
+        let g = world.view_one::<&WorldTransform>(five_child).get().unwrap();
+        assert_eq!(**g, Transform::from_xyz(536.0, 102.0, 817.0));
+
+        let g = world.view_one::<&WorldTransform>(thir_chi).get().unwrap();
+        assert_eq!(**g, Transform::from_xyz(76.0, 110.0, 42.0));
+
+        let g = world.view_one::<&WorldTransform>(four_child).get().unwrap();
+        assert_eq!(**g, Transform::from_xyz(100.0, 171.0, 107.0));
+    }
+}