From 13384e80b141b64feabfb88c896153ad2e405675 Mon Sep 17 00:00:00 2001
From: Isaac Clayton <slightknack@gmail.com>
Date: Fri, 7 Jan 2022 20:04:23 +0100
Subject: [PATCH] Sketch out basic quadtree

---
 Cargo.lock  |  7 +++++++
 src/main.rs |  2 ++
 src/quad.rs | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+)
 create mode 100644 Cargo.lock
 create mode 100644 src/quad.rs

diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..5713a61
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "spatio"
+version = "0.1.0"
diff --git a/src/main.rs b/src/main.rs
index e7a11a9..5abe13f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,5 @@
+mod quad;
+
 fn main() {
     println!("Hello, world!");
 }
diff --git a/src/quad.rs b/src/quad.rs
new file mode 100644
index 0000000..f6eaab3
--- /dev/null
+++ b/src/quad.rs
@@ -0,0 +1,46 @@
+/// Represents the data present in a quad-tree node.
+/// May be the base-level repr, or a node with 4 children.
+pub enum Quad<A: Default, B> {
+    /// Base cell in grid.
+    /// May actually be a chunk of cells for performance.
+    Base(A),
+    /// Node with 4 children.
+    Node(Box<[Node<A, B>;4]>),
+    /// Children may be generated from Node.
+    Cached,
+}
+
+/// Represends a node in a quadtree.
+/// Has a depth denoting the number of nodes below it.
+/// Nodes should only be siblings of nodes with the same depth.
+/// Data stored inside a quadtree node, including children, are in `data`.
+pub struct Node<A: Default, B> {
+    depth: usize,
+    compr: B,
+    data:  Quad<A, B>,
+}
+
+/// Represents a context with shared state.
+pub struct Ctx();
+
+impl<A: Default, B> Node<A, B> {
+    /// Creates a new tree from a single base node
+    pub fn new_base(base: A, ctx: &mut Ctx) -> Self {
+        Node {
+            depth: 0,
+            compr: ctx.compress(&base),
+            data:  Quad::Base(base),
+        }
+    }
+
+    /// Creates a new tree with a single empty base node
+    pub fn new_empty(ctx: &mut Ctx) -> Self {
+        Self::new_base(Default::default(), ctx)
+    }
+
+    /// Creates a new node double the size by centering the current node
+    /// on a node double the size.
+    pub fn pad_empty(self, ctx: &mut Ctx) -> Self {
+        todo!()
+    }
+}