From 98baa1326460f275dead577b9ed18eba092a9385 Mon Sep 17 00:00:00 2001
From: "Zed A. Shaw" <zed.shaw@gmail.com>
Date: Tue, 22 Oct 2024 01:52:15 -0400
Subject: [PATCH] Tried out Google's AI response to the question of a C++
 spatial hash and it kind of came close.  This took some massaging but it
 could work.

---
 meson.build             |  5 +++
 scratchpad/collider.cpp | 70 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)
 create mode 100644 scratchpad/collider.cpp

diff --git a/meson.build b/meson.build
index 89fb5aa..8e616fd 100644
--- a/meson.build
+++ b/meson.build
@@ -38,4 +38,9 @@ myecstest = executable('myecstest', [
   ],
   dependencies: dependencies)
 
+collider = executable('collider', [
+  './scratchpad/collider.cpp'
+  ],
+  dependencies: dependencies)
+
 test('tests', runtests)
diff --git a/scratchpad/collider.cpp b/scratchpad/collider.cpp
new file mode 100644
index 0000000..bd0d4f4
--- /dev/null
+++ b/scratchpad/collider.cpp
@@ -0,0 +1,70 @@
+#include <iostream>
+#include <vector>
+#include <unordered_map>
+
+struct Point {
+    int x, y;
+
+    bool operator==(const Point& other) const {
+      return other.x == x && other.y == y;
+    }
+};
+
+struct Object {
+    Point position;
+    // Add other object data as needed
+};
+
+struct PointHash {
+  size_t operator()(const Point& p) const {
+    return std::hash<int>()(p.x) ^ std::hash<int>()(p.y);
+  }
+};
+
+class SpatialHashTable {
+public:
+    SpatialHashTable() {}
+
+    void insert(Object* obj) {
+        table[obj->position].push_back(obj);
+    }
+
+    std::vector<Object*> getNearbyObjects(Point position) {
+        std::vector<Object*> result;
+        Point cell = position;
+
+        // Check the current cell and its 8 neighbors
+        for (int x = cell.x - 1; x <= cell.x + 1; x++) {
+            for (int y = cell.y - 1; y <= cell.y + 1; y++) {
+                Point neighborCell = {x, y};
+                auto it = table.find(neighborCell);
+                if (it != table.end()) {
+                    result.insert(result.end(), it->second.begin(), it->second.end());
+                }
+            }
+        }
+
+        return result;
+    }
+
+private:
+    std::unordered_map<Point, std::vector<Object*>, PointHash> table;
+};
+
+int main() {
+    SpatialHashTable hashTable;
+    Object obj1 = {{5, 5}};
+    Object obj2 = {{15, 15}};
+    Object bomb = {{25, 25}};
+
+    hashTable.insert(&obj1);
+    hashTable.insert(&obj2);
+    hashTable.insert(&bomb);
+
+    std::vector<Object*> nearby = hashTable.getNearbyObjects({24, 24});
+    for (Object* obj : nearby) {
+        std::cout << obj->position.x << ", " << obj->position.y << std::endl;
+    }
+
+    return 0;
+}