createEntities method

List<EntityID> createEntities(List<List<Component>> entitiesComponents)

Implementation

List<EntityID> createEntities(List<List<Component>> entitiesComponents) {
  final newEntities = <EntityID>[];

  for (final components in entitiesComponents) {
    final entityID = createEntity();
    newEntities.add(entityID);

    final componentIDs =
        components.map((component) => _getOrCreateComponentID(component.runtimeType)).toList();

    final hash = SetHash(componentIDs);
    final archetype = _getOrCreateArchetype(hash);

    for (int i = 0; i < components.length; i++) {
      final component = components[i];
      component.entityID = entityID;

      // Add component to the appropriate archetype slot
      _componentIndex[componentIDs[i]] ??= {};
      if (_componentIndex[componentIDs[i]]![hash] == null) {
        _componentIndex[componentIDs[i]]![hash] = archetype.components.length;
        archetype.components.add([]);
      }
      final componentsList = archetype.components[_componentIndex[componentIDs[i]]![hash]!];
      componentsList.add(component);
    }

    _entityIndex[entityID] = Record(
      archetype: archetype,
      entityRow: archetype.components[0].length - 1,
    );
  }

  return newEntities;
}