roguish/collider.cpp

#include "collider.hpp"

using DinkyECS::Entity;

void SpatialHashTable::insert(Point pos, Entity ent) {
  table[pos] = ent;
}

void SpatialHashTable::remove(Point pos) {
  table.erase(pos);
}

void SpatialHashTable::move(Point from, Point to, Entity ent) {
  remove(from);
  insert(to, ent);
}

bool SpatialHashTable::occupied(Point at) {
  return table[at];
}

std::tuple<bool, FoundList> SpatialHashTable::neighbors(Point cell) {
  FoundList result;

  // Check the current cell and its 8 neighbors
  // BUG: this can sign underflow, assert it won't
  for (size_t x = cell.x - 1; x <= cell.x + 1; x++) {
    for (size_t 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);
      }
    }
  }

  return std::tuple(!result.empty(), result);
}