Node tree structure

examples/ui.rs

@@ -17,6 +17,7 @@ fn setup(world: &mut World) {
         mesh_storage.add(cube)
     };
 
+    // cube
     world.insert(
         (),
         vec![(
@@ -26,6 +27,7 @@ fn setup(world: &mut World) {
         )],
     );
 
+    // light
     world.insert(
         (),
         vec![(
@@ -46,6 +48,7 @@ fn setup(world: &mut World) {
         )],
     );
 
+    // 3d camera
     world.insert(
         (),
         vec![
@@ -67,26 +70,23 @@ fn setup(world: &mut World) {
         ],
     );
 
+    // 2d camera
     world.insert(
         (),
-        vec![
-            // camera
-            (
-                Camera::new(CameraType::Orthographic {
-                    left: 0.0,
-                    right: 0.0,
-                    bottom: 0.0,
-                    top: 0.0,
-                    near: 0.0,
-                    far: 1.0,
-                }),
-                ActiveCamera2d,
-            ),
-        ],
+        vec![(
+            Camera::new(CameraType::Orthographic {
+                left: 0.0,
+                right: 0.0,
+                bottom: 0.0,
+                top: 0.0,
+                near: 0.0,
+                far: 1.0,
+            }),
+            ActiveCamera2d,
+        )],
     );
 
     // bottom left anchor with vertical fill
-
     world.insert(
         (),
         vec![(Node::new(
@@ -98,7 +98,6 @@ fn setup(world: &mut World) {
     );
 
     // top right anchor with vertical fill
-
     world.insert(
         (),
         vec![(Node::new(
@@ -110,7 +109,6 @@ fn setup(world: &mut World) {
     );
 
     // render order test: reddest in the back, whitest in the front
-
     world.insert(
         (),
         vec![(Node::new(
@@ -150,4 +148,31 @@ fn setup(world: &mut World) {
             math::vec4(1.0, 0.7, 0.7, 1.0),
         ),)],
     );
+
+    // parenting
+    let parent = *world
+        .insert(
+            (),
+            vec![(Node::new(
+                math::vec2(300.0, 300.0),
+                Anchors::new(0.0, 0.0, 0.0, 0.0),
+                Margins::new(0.0, 200.0, 0.0, 200.0),
+                math::vec4(0.1, 0.1, 1.0, 1.0),
+            ),)],
+        )
+        .first()
+        .unwrap();
+
+    world.insert(
+        (),
+        vec![(
+            Node::new(
+                math::vec2(0.0, 0.0),
+                Anchors::new(0.0, 1.0, 0.0, 1.0),
+                Margins::new(20.0, 20.0, 20.0, 20.0),
+                math::vec4(0.6, 0.6, 1.0, 1.0),
+            ),
+            Parent(parent),
+        )],
+    );
 }

src/ecs/mod.rs

@@ -0,0 +1,60 @@
+use crate::{legion::system::SubWorld, Children, Entity, World};
+pub fn run_on_hierarchy<T>(
+    world: &mut World,
+    entity: Entity,
+    input: T,
+    func: &mut dyn FnMut(&mut World, Entity, T) -> Option<T>,
+) where
+    T: Copy,
+{
+    // TODO: not a huge fan of this pattern. are there ways to do recursive updates in legion without allocactions?
+    let children = match world.get_component::<Children>(entity) {
+        Some(children) => Some(
+            children
+                .iter()
+                .map(|entity| *entity)
+                .collect::<Vec<Entity>>(),
+        ),
+        None => None,
+    };
+
+    let result = func(world, entity, input);
+
+    if let Some(result) = result {
+        if let Some(children) = children {
+            for child in children {
+                run_on_hierarchy(world, child, result, func);
+            }
+        }
+    }
+}
+
+pub fn run_on_hierarchy_subworld<T>(
+    world: &mut legion::system::SubWorld,
+    entity: Entity,
+    input: T,
+    func: &dyn Fn(&mut SubWorld, Entity, T) -> Option<T>,
+) where
+    T: Copy,
+{
+    // TODO: not a huge fan of this pattern. are there ways to do recursive updates in legion without allocactions?
+    let children = match world.get_component::<Children>(entity) {
+        Some(children) => Some(
+            children
+                .iter()
+                .map(|entity| *entity)
+                .collect::<Vec<Entity>>(),
+        ),
+        None => None,
+    };
+
+    let result = func(world, entity, input);
+
+    if let Some(result) = result {
+        if let Some(children) = children {
+            for child in children {
+                run_on_hierarchy_subworld(world, child, result, func);
+            }
+        }
+    }
+}

src/lib.rs

@@ -1,12 +1,14 @@
 mod app;
 pub mod asset;
 mod core;
+pub mod ecs;
 pub mod render;
 pub mod ui;
 
 pub use crate::core::*;
 pub use app::{App, AppBuilder};
 
+pub use ecs::*;
 pub use glam as math;
 pub use legion;
 pub use legion::prelude::*;

src/render/passes/ui/mod.rs

@@ -1,9 +1,10 @@
 use crate::{
     asset::*,
-    math,
+    ecs, math,
     render::mesh::*,
     render::{instancing::InstanceBufferInfo, *},
     ui::Node,
+    Parent,
 };
 use legion::prelude::*;
 use wgpu::SwapChainOutput;
@@ -13,7 +14,7 @@ use zerocopy::{AsBytes, FromBytes};
 #[derive(Clone, Copy, AsBytes, FromBytes)]
 pub struct RectData {
     pub position: [f32; 2],
-    pub dimensions: [f32; 2],
+    pub size: [f32; 2],
     pub color: [f32; 4],
     pub z_index: f32,
 }
@@ -38,27 +39,39 @@ impl UiPipeline {
     pub fn create_rect_buffers(
         &self,
         device: &wgpu::Device,
-        world: &World,
+        world: &mut World,
     ) -> Vec<InstanceBufferInfo> {
-        let node_query = <Read<Node>>::query();
-        let node_count = node_query.iter(world).count();
+        let node_query = <Read<Node>>::query().filter(!component::<Parent>());
 
-        if node_count == 0 {
+        if node_query.iter(world).count() == 0 {
             return Vec::new();
         }
 
-        let mut data = Vec::with_capacity(node_count);
+        let mut data = Vec::new();
         // TODO: this probably isn't the best way to handle z-ordering
         let mut z = 0.9999;
-        for node in node_query.iter(world) {
-            data.push(RectData {
-                position: node.global_position.into(),
-                dimensions: node.dimensions.into(),
-                color: node.color.into(),
-                z_index: z,
-            });
+        {
+            let mut add_data: Box<dyn FnMut(&mut World, Entity, ()) -> Option<()>> =
+                Box::new(|world, entity, _| {
+                    let node = world.get_component::<Node>(entity).unwrap();
+                    data.push(RectData {
+                        position: node.global_position.into(),
+                        size: node.size.into(),
+                        color: node.color.into(),
+                        z_index: z,
+                    });
 
-            z -= 0.0001;
+                    z -= 0.0001;
+                    Some(())
+                });
+
+            for entity in node_query
+                .iter_entities(world)
+                .map(|(entity, _)| entity)
+                .collect::<Vec<Entity>>()
+            {
+                ecs::run_on_hierarchy(world, entity, (), &mut add_data);
+            }
         }
 
         let buffer = device.create_buffer_with_data(
@@ -72,7 +85,7 @@ impl UiPipeline {
         instance_buffer_infos.push(InstanceBufferInfo {
             mesh_id: mesh_id,
             buffer: buffer,
-            instance_count: node_count,
+            instance_count: data.len(),
         });
 
         instance_buffer_infos

src/render/passes/ui/ui.vert

@@ -6,7 +6,7 @@ layout(location = 1) in vec4 a_Normal;
 
 // instanced attributes (RectData)
 layout (location = 2) in vec2 a_RectPosition;
-layout (location = 3) in vec2 a_RectDimensions;
+layout (location = 3) in vec2 a_RectSize;
 layout (location = 4) in vec4 a_RectColor;
 layout (location = 5) in float a_RectZIndex;
 
@@ -18,7 +18,7 @@ layout(set = 0, binding = 0) uniform Globals {
 
 void main() {
     v_Color = a_RectColor;
-    vec4 position = a_Pos * vec4(a_RectDimensions, 0.0, 1.0);
-    position = position + vec4(a_RectPosition, -a_RectZIndex, 0.0);
+    vec4 position = a_Pos * vec4(a_RectSize, 0.0, 1.0);
+    position = position + vec4(a_RectPosition + a_RectSize / 2.0, -a_RectZIndex, 0.0);
     gl_Position = u_ViewProj * position;
 }

src/transform/src/hierarchy_maintenance_system.rs

@@ -7,9 +7,7 @@ pub fn build(_: &mut World) -> Vec<Box<dyn Schedulable>> {
     let missing_previous_parent_system = SystemBuilder::<()>::new("MissingPreviousParentSystem")
         // Entities with missing `PreviousParent`
         .with_query(<Read<Parent>>::query().filter(
-            component::<LocalToParent>()
-                & component::<LocalToWorld>()
-                & !component::<PreviousParent>(),
+            !component::<PreviousParent>(),
         ))
         .build(move |commands, world, _resource, query| {
             // Add missing `PreviousParent` components
@@ -24,10 +22,9 @@ pub fn build(_: &mut World) -> Vec<Box<dyn Schedulable>> {
         .with_query(<Read<PreviousParent>>::query().filter(!component::<Parent>()))
         // Entities with a changed `Parent`
         .with_query(<(Read<Parent>, Write<PreviousParent>)>::query().filter(
-            component::<LocalToParent>() & component::<LocalToWorld>() & changed::<Parent>(),
+            changed::<Parent>(),
         ))
         // Deleted Parents (ie Entities with `Children` and without a `LocalToWorld`).
-        .with_query(<Read<Children>>::query().filter(!component::<LocalToWorld>()))
         .write_component::<Children>()
         .build(move |commands, world, _resource, queries| {
             // Entities with a missing `Parent` (ie. ones that have a `PreviousParent`), remove
@@ -96,22 +93,6 @@ pub fn build(_: &mut World) -> Vec<Box<dyn Schedulable>> {
                 }
             }
 
-            // Deleted `Parents` (ie. Entities with a `Children` but no `LocalToWorld`).
-            for (entity, children) in queries.2.iter_entities(world) {
-                log::trace!("The entity {} doesn't have a LocalToWorld", entity);
-                if children_additions.remove(&entity).is_none() {
-                    log::trace!(" > It needs to be remove from the ECS.");
-                    for child_entity in children.0.iter() {
-                        commands.remove_component::<Parent>(*child_entity);
-                        commands.remove_component::<PreviousParent>(*child_entity);
-                        commands.remove_component::<LocalToParent>(*child_entity);
-                    }
-                    commands.remove_component::<Children>(entity);
-                } else {
-                    log::trace!(" > It was a new addition, removing it from additions map");
-                }
-            }
-
             // Flush the `children_additions` to the command buffer. It is stored separate to
             // collect multiple new children that point to the same parent into the same
             // SmallVec, and to prevent redundant add+remove operations.

src/ui/node.rs

@@ -12,7 +12,7 @@ enum GrowDirection {
 pub struct Node {
     pub position: Vec2,
     pub global_position: Vec2,
-    pub dimensions: Vec2,
+    pub size: Vec2,
     pub parent_dimensions: Vec2,
     pub anchors: Anchors,
     pub margins: Margins,
@@ -24,7 +24,7 @@ impl Default for Node {
         Node {
             position: Vec2::default(),
             global_position: Vec2::default(),
-            dimensions: Vec2::default(),
+            size: Vec2::default(),
             parent_dimensions: Vec2::default(),
             anchors: Anchors::default(),
             margins: Margins::default(),
@@ -38,7 +38,7 @@ impl Node {
         Node {
             position,
             global_position: Vec2::default(),
-            dimensions: Vec2::default(),
+            size: Vec2::default(),
             parent_dimensions: Vec2::default(),
             anchors,
             margins,
@@ -46,7 +46,7 @@ impl Node {
         }
     }
 
-    pub fn update(&mut self, parent_dimensions: Vec2) {
+    pub fn update(&mut self, parent_dimensions: Vec2, parent_position: Vec2) {
         let (rect_x, rect_width) = Self::compute_dimension_properties(
             self.position.x(),
             self.margins.left,
@@ -64,8 +64,8 @@ impl Node {
             parent_dimensions.y(),
         );
 
-        self.global_position = math::vec2(rect_x, rect_y);
-        self.dimensions = math::vec2(rect_width, rect_height);
+        self.size = math::vec2(rect_width, rect_height);
+        self.global_position = math::vec2(rect_x, rect_y) + parent_position;
     }
 
     fn compute_dimension_properties(
@@ -93,8 +93,11 @@ impl Node {
         let p0 = Self::compute_rect_position(offset, margin0, anchor_p0, p0_grow_direction);
         let p1 = Self::compute_rect_position(offset, margin1, anchor_p1, p1_grow_direction);
 
-        let p = (p0 + p1) / 2.0;
         let final_width = p1 - p0;
+        let mut p = (p0 + p1) / 2.0;
+
+        // move position to "origin" in bottom left hand corner
+        p = p - final_width / 2.0;
 
         (p, final_width)
     }

src/ui/ui_update_system.rs

@@ -1,15 +1,37 @@
-use crate::{ui::Node, *};
+use crate::{legion::system::SubWorld, math::Vec2, ui::Node, *};
 use winit::window::Window;
 
 pub fn build_ui_update_system() -> Box<dyn Schedulable> {
     SystemBuilder::new("ui_update_system")
         .read_resource::<Window>()
-        .with_query(<(Write<Node>,)>::query().filter(!component::<Children>()))
+        .with_query(<(Write<Node>,)>::query().filter(!component::<Parent>()))
+        .write_component::<Node>()
+        .read_component::<Children>()
         .build(move |_, world, window, node_query| {
             let window_size = window.inner_size();
-            let parent_dimensions = math::vec2(window_size.width as f32, window_size.height as f32);
-            for (mut node,) in node_query.iter_mut(world) {
-                node.update(parent_dimensions);
+            let parent_size = math::vec2(window_size.width as f32, window_size.height as f32);
+            let parent_position = math::vec2(0.0, 0.0);
+            for (entity, _) in node_query.iter_entities_mut(world) {
+                ecs::run_on_hierarchy_subworld(
+                    world,
+                    entity,
+                    (parent_size, parent_position),
+                    &update_node_entity,
+                );
             }
         })
 }
+
+fn update_node_entity(
+    world: &mut SubWorld,
+    entity: Entity,
+    parent_properties: (Vec2, Vec2),
+) -> Option<(Vec2, Vec2)> {
+    let (parent_size, parent_position) = parent_properties;
+    if let Some(mut node) = world.get_component_mut::<Node>(entity) {
+        node.update(parent_size, parent_position);
+        return Some((node.size, node.global_position));
+    }
+
+    None
+}