Merge pull request #12 from DerLando/implement-quadtree-lookup

Implements first draft of quadtree lookup implemented via *BoundingBox*

Author: Michael-F-Bryan

arcs/Cargo.toml

@@ -26,6 +26,8 @@ kurbo = "0.5"
 shred = "0.9"
 cgmath = "0.17.0"
 lazy_static = "1"
+aabb-quadtree = "0.2.0"
+quadtree_euclid = { package = "euclid", version = "0.19.8" }
 euclid = "0.20.7"
 
 [dev-dependencies]

arcs/src/components/bounding_box.rs

@@ -1,16 +1,30 @@
 use crate::{algorithms::Bounded, DrawingSpace, Length, Point, Vector};
 use euclid::{num::Zero, Size2D};
 use specs::prelude::*;
-use specs_derive::Component;
+use aabb_quadtree::{Spatial};
+use quadtree_euclid::{TypedRect, TypedPoint2D, TypedSize2D};
 
 /// An axis-aligned bounding box.
-#[derive(Debug, Copy, Clone, PartialEq, Component)]
-#[storage(DenseVecStorage)]
+#[derive(Debug, Copy, Clone, PartialEq)]
 pub struct BoundingBox {
     bottom_left: Point,
     top_right: Point,
 }
 
+impl Component for BoundingBox {
+    type Storage = FlaggedStorage<Self, DenseVecStorage<Self>>;
+}
+
+impl Spatial<f64> for BoundingBox {
+    fn aabb(&self) -> TypedRect<f32, f64> {
+        let bb = self;
+        TypedRect::<f32, f64>::new(
+            // TypedRects have their origin at the bottom left corner (this is undocumented!)
+            TypedPoint2D::new(bb.bottom_left().x as f32, bb.bottom_left().y as f32),
+            TypedSize2D::new(bb.width().0 as f32, bb.height().0 as f32))
+    }
+}
+
 impl BoundingBox {
     /// Create a new [`BoundingBox`] around two points.
     pub fn new(first: Point, second: Point) -> Self {

arcs/src/components/mod.rs

@@ -8,6 +8,7 @@ mod name;
 mod styles;
 mod viewport;
 mod vtable;
+mod spatial_entity;
 
 pub use bounding_box::BoundingBox;
 pub use dimension::Dimension;
@@ -17,6 +18,7 @@ pub use name::{Name, NameTable};
 pub use styles::{LineStyle, PointStyle, WindowStyle};
 pub use viewport::Viewport;
 pub(crate) use vtable::ComponentVtable;
+pub use spatial_entity::{SpatialEntity, Space};
 
 use specs::World;
 

arcs/src/components/spatial_entity.rs

@@ -0,0 +1,247 @@
+use crate::{
+    components::BoundingBox,
+    {Point, Arc},
+    algorithms::{Bounded},
+};
+use specs::{Entity, world::Index};
+use aabb_quadtree::{QuadTree, Spatial, ItemId};
+use quadtree_euclid::{TypedRect, TypedPoint2D, TypedSize2D};
+use std::collections::HashMap;
+use euclid::Angle;
+
+pub(crate) type SpatialTree = QuadTree<SpatialEntity, f64, [(ItemId, TypedRect<f32, f64>); 0]>;
+
+/// A intermediate struct that maps an [`Entity`] to its [`BoundingBox`]
+/// 
+/// This is used to populate an efficient spatial lookup structure like a `QuadTree`
+#[derive(Debug, Copy, Clone)]
+pub struct SpatialEntity {
+    pub bounds: BoundingBox,
+    pub entity: Entity
+}
+
+impl Spatial<f64> for SpatialEntity {
+    fn aabb(&self) -> TypedRect<f32, f64> {
+        let bb = self.bounds;
+        TypedRect::<f32, f64>::new(
+            // TypedRects have their origin at the bottom left corner (this is undocumented!)
+            TypedPoint2D::new(bb.bottom_left().x as f32, bb.bottom_left().y as f32),
+            TypedSize2D::new(bb.width().0 as f32, bb.height().0 as f32))
+    }
+}
+
+impl SpatialEntity {
+    pub fn new(bounds: BoundingBox, entity: Entity) -> SpatialEntity {
+        SpatialEntity {
+            bounds,
+            entity
+        }
+    }
+}
+
+/// A global [`Resource`] for looking up which [`Entity`]s inhabit
+/// a given spatial point or region
+#[derive(Debug)]
+pub struct Space {
+    quadtree: SpatialTree,
+    ids: HashMap<Entity, ItemId>
+}
+
+impl Default for Space {
+    fn default() -> Self {
+        Space {
+            quadtree: Self::default_tree(),
+            ids: HashMap::new()
+        }
+    }
+}
+
+impl Space {
+    // FIXME: Hard-code is bad-bad
+    pub const WORLD_RADIUS: f64 = 1_000_000.0;
+    const TREE_ALLOW_DUPLICATES: bool = true;
+    const TREE_MIN_CHILDREN: usize = 4;
+    const TREE_MAX_CHILDREN: usize = 16;
+    const TREE_MAX_DEPTH: usize = 8;
+    const TREE_SIZE_HINT: usize = 4;
+
+    fn default_tree() -> SpatialTree{
+        // Initialize quadtree
+        let size = BoundingBox::new(
+            Point::new(-Self::WORLD_RADIUS, -Self::WORLD_RADIUS),
+            Point::new(Self::WORLD_RADIUS, Self::WORLD_RADIUS)
+            ).aabb();
+        let quadtree: SpatialTree = QuadTree::new(
+            size,
+            Self::TREE_ALLOW_DUPLICATES,
+            Self::TREE_MIN_CHILDREN,
+            Self::TREE_MAX_CHILDREN,
+            Self::TREE_MAX_DEPTH,
+            Self::TREE_SIZE_HINT,
+        );
+
+        quadtree
+    }
+
+    fn tree_with_world_size(size: impl Spatial<f64>) -> SpatialTree {
+        let quadtree: SpatialTree = QuadTree::new(
+            size.aabb(),
+            Self::TREE_ALLOW_DUPLICATES,
+            Self::TREE_MIN_CHILDREN,
+            Self::TREE_MAX_CHILDREN,
+            Self::TREE_MAX_DEPTH,
+            Self::TREE_SIZE_HINT,
+        );
+
+        quadtree
+    }
+
+    /// Modifies the spatial position of the given [`SpatialEntity`] inside of [`Space`]
+    /// If the [`SpatialEntity`] is not already inside of [`Space`] it will be inserted.
+    pub fn modify(&mut self, spatial: SpatialEntity) {
+        if !self.quadtree.bounding_box().contains_rect(&spatial.bounds.aabb()) {
+            self.resize(spatial.bounds);
+        }
+        let id = if self.ids.contains_key(&spatial.entity) {
+            self.modify_entity(spatial)
+        }
+        else {
+            self.insert_entity(spatial)
+        };
+        // Update hashmap
+        self.ids.entry(spatial.entity).or_insert(id);
+    }
+
+    fn insert_entity(&mut self, spatial: SpatialEntity) -> ItemId {
+        if let Some(id) = self.quadtree.insert(spatial) {
+            id
+        }
+        else {
+            panic!("ERROR: Failed to insert {:?} into Space!", self)
+        }
+    }
+
+    fn modify_entity(&mut self, spatial: SpatialEntity) -> ItemId {
+        let item_id = self.ids[&spatial.entity];
+        // remove old item
+        self.quadtree.remove(item_id);
+
+        // Add modified
+        self.insert_entity(spatial)
+    }
+
+    /// Removes the given [`Entity`] from this [`Space`]
+    pub fn remove(&mut self, entity: Entity) {
+        if self.ids.contains_key(&entity) {
+            let item_id = self.ids[&entity];
+
+            // remove old item
+            self.quadtree.remove(item_id);
+            self.ids.remove(&entity);
+        }
+    }
+
+    /// Removes an [`Entity`] from this [`Space`] given its [`Index`]
+    pub fn remove_by_id(&mut self, id: Index) {
+        let filter = move |(ent, _item_id): (&Entity, &ItemId)| {
+            if ent.id() == id {
+                Some(*ent)
+            } else {
+                None
+            }
+        };
+
+        if let Some(ent) = self.ids.iter().filter_map(filter).next() {
+            self.remove(ent);
+        }
+    }
+
+    /// Returns an iterator over all [`SpatialEntity`] in this [`Space`]
+    pub fn iter<'this>(
+        &'this self,
+    ) -> impl Iterator<Item = SpatialEntity> + 'this {
+        self.quadtree.iter().map(|(_, (ent, _))| *ent)
+    }
+
+    pub fn len(&self) -> usize {
+        self.quadtree.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.quadtree.is_empty()
+    }
+
+    // FIXME: radius in CanvasSpace in method signature
+    /// Performs a spatial query in an radius around a given [`Point`]
+    /// Returns an iterator with all [`SpatialEntity`] inhabiting the [`Space`]
+    /// close to the given point
+    /// The returned iterator can be empty
+    pub fn query_point<'this>(
+        &'this self, point: Point, radius: f64
+    ) -> impl Iterator<Item = SpatialEntity> + 'this {
+        let cursor_circle = Arc::from_centre_radius(
+            point,
+            radius,
+            Angle::radians(0.0),
+            Angle::radians(2.0 * std::f64::consts::PI)
+        );
+        self.query_region(cursor_circle.bounding_box())
+    }
+
+    /// Performs a spatial query for a given [`BoundingBox`]
+    /// Returns an iterator with all [`SpatialEntity`] inhabiting the [`Space`]
+    /// of the given BoundingBox
+    /// The returned iterator can be empty
+    pub fn query_region<'this>(
+        &'this self, region: BoundingBox
+    ) -> impl Iterator<Item = SpatialEntity> + 'this {
+        self.quadtree.query(region.aabb()).into_iter().map(|q| *q.0)
+    }
+
+    /// Clears the [`Space`] of all [`SpatialEntity`]
+    pub fn clear(&mut self) {
+        // Re-use old size
+        let size = self.quadtree.bounding_box();
+        self.quadtree = Self::tree_with_world_size(size);
+        self.ids.clear();
+    }
+
+    /// Resizes the inner quadtree to the given **bigger** size
+    /// 
+    /// # Panics
+    /// Panics if the size given is not bigger then the initial bounding_box of the [`Space`]
+    pub fn resize(&mut self, size: impl Spatial<f64>) {
+        if self.quadtree.bounding_box().contains_rect(&size.aabb()) {
+            panic!("Space.resize() ERROR: Size to resize to is smaller then the tree!")
+        }
+        let spatial_entities: Vec<_> = self.iter().collect();
+
+        self.clear();
+
+        self.quadtree = Self::tree_with_world_size(size);
+        for spatial_entity in spatial_entities {
+            let item_id = self.insert_entity(spatial_entity);
+            self.ids.insert(spatial_entity.entity, item_id);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        components::{BoundingBox, Space},
+        Point,
+    };
+
+    #[test]
+    fn space_should_resize() {
+        let mut space = Space::default();
+        assert_eq!(space.quadtree.bounding_box().max_x() as f64, Space::WORLD_RADIUS);
+        let new_radius = 2_000_000.0;
+        let new_size = BoundingBox::new(
+            Point::new(-new_radius, -new_radius),
+            Point::new(new_radius, new_radius));
+        space.resize(new_size);
+        assert_eq!(space.quadtree.bounding_box().max_x() as f64, new_radius);
+    }
+}

arcs/src/systems/bounds.rs

@@ -57,7 +57,7 @@ impl<'world> System<'world> for SyncBounds {
             bounds
                 .insert(ent, drawing_object.geometry.bounding_box())
                 .unwrap();
-        }
+            }
 
         for (ent, _) in (&entities, &self.removed).join() {
             bounds.remove(ent);

arcs/src/systems/mod.rs

@@ -2,9 +2,11 @@
 
 mod bounds;
 mod name_table_bookkeeping;
+mod spatial_relation;
 
 pub use bounds::SyncBounds;
 pub use name_table_bookkeeping::NameTableBookkeeping;
+pub use spatial_relation::SpatialRelation;
 
 use specs::{DispatcherBuilder, World};
 
@@ -20,4 +22,5 @@ pub fn register_background_tasks<'a, 'b>(
             &[],
         )
         .with(SyncBounds::new(world), SyncBounds::NAME, &[])
+        .with(SpatialRelation::new(world), SpatialRelation::NAME, &[SyncBounds::NAME])
 }