Files are now in a src directory and I'm using a src/meson.build and tests/meson.build to specify what to build.

src/spatialmap.cpp

@@ -0,0 +1,138 @@
+#include "spatialmap.hpp"
+#include <fmt/core.h>
+
+using namespace fmt;
+
+using DinkyECS::Entity;
+
+void SpatialMap::insert(Point pos, Entity ent, bool has_collision) {
+  if(has_collision) {
+    dbc::check(!occupied(pos), "attempt to insert an entity with collision in space with collision");
+  }
+
+  $collision.emplace(pos, CollisionData{ent, has_collision});
+}
+
+CollisionData SpatialMap::remove(Point pos, Entity ent) {
+  auto [begin, end] = $collision.equal_range(pos);
+  for(auto it = begin; it != end; ++it) {
+    if(it->second.entity == ent) {
+      // does the it->second go invalid after erase?
+      auto copy = it->second;
+      $collision.erase(it);
+      return copy;
+    }
+  }
+
+  dbc::sentinel("failed to find entity to remove");
+}
+
+void SpatialMap::move(Point from, Point to, Entity ent) {
+  auto data = remove(from, ent);
+  insert(to, ent, data.collision);
+}
+
+Entity SpatialMap::occupied_by(Point at) const {
+  auto [begin, end] = $collision.equal_range(at);
+  for(auto it = begin; it != end; ++it) {
+    if(it->second.collision) {
+      return it->second.entity;
+    }
+  }
+
+  return DinkyECS::NONE;
+}
+
+bool SpatialMap::occupied(Point at) const {
+  return occupied_by(at) != DinkyECS::NONE;
+}
+
+bool SpatialMap::something_there(Point at) const {
+  return $collision.count(at) > 0;
+}
+
+Entity SpatialMap::get(Point at) const {
+  dbc::check($collision.contains(at), "attempt to get entity when none there");
+  auto [begin, end] = $collision.equal_range(at);
+  return begin->second.entity;
+}
+
+void SpatialMap::find_neighbor(EntityList &result, Point at, int dy, int dx) const {
+  // don't bother checking for cells out of bounds
+  if((dx < 0 && at.x <= 0) || (dy < 0 && at.y <= 0)) {
+    return;
+  }
+
+  Point cell = {at.x + dx, at.y + dy};
+
+  auto entity = find(cell, [&](auto data) {
+      return data.collision;
+  });
+
+  if(entity != DinkyECS::NONE) result.push_back(entity);
+}
+
+FoundEntities SpatialMap::neighbors(Point cell, bool diag) const {
+  EntityList result;
+
+  // just unroll the loop since we only check four directions
+  // this also solves the problem that it was detecting that the cell was automatically included as a "neighbor" but it's not
+  find_neighbor(result, cell, 0, 1); // north
+  find_neighbor(result, cell, 0, -1); // south
+  find_neighbor(result, cell, 1, 0); // east
+  find_neighbor(result, cell, -1, 0); // west
+
+  if(diag) {
+    find_neighbor(result, cell, 1, -1); // south east
+    find_neighbor(result, cell, -1, -1); // south west
+    find_neighbor(result, cell, 1, 1); // north east
+    find_neighbor(result, cell, -1, 1); // north west
+  }
+
+  return {!result.empty(), result};
+}
+
+inline void update_sorted(SortedEntities& sprite_distance, PointEntityMap& table, Point from, int max_dist) {
+  Point seen{0,0};
+  float wiggle = 0.0f;
+
+  for(const auto &rec : table) {
+    Point sprite = rec.first;
+
+    int inside = (from.x - sprite.x) * (from.x - sprite.x) +
+        (from.y - sprite.y) * (from.y - sprite.y);
+
+    if(from == sprite || rec.second.collision) {
+      wiggle = 0.0f;
+    } else if(sprite == seen) {
+      wiggle += 0.02f;
+    } else {
+      wiggle = 0.0f;
+      seen = sprite;
+    }
+
+    if(inside < max_dist) {
+      sprite_distance.push_back({inside, rec.second.entity, wiggle});
+    }
+  }
+}
+
+Entity SpatialMap::find(Point at, std::function<bool(CollisionData)> cb) const {
+  auto [begin, end] = $collision.equal_range(at);
+
+  for(auto it = begin; it != end; ++it) {
+    if(cb(it->second)) return it->second.entity;
+  }
+
+  return DinkyECS::NONE;
+}
+
+void SpatialMap::distance_sorted(SortedEntities& sprite_distance, Point from, int max_dist) {
+  sprite_distance.clear();
+
+  update_sorted(sprite_distance, $collision, from, max_dist);
+
+  std::sort(sprite_distance.begin(), sprite_distance.end(), [](auto &a, auto &b) {
+      return a.dist_square > b.dist_square;
+  });
+}