Method potentialBiomeItemsAt

source/game/StarWorldTemplate.cpp:491–523

WorldTemplate::PotentialBiomeItems WorldTemplate::potentialBiomeItemsAt(int x, int y) const {
  if (!m_layout || y <= 0 || y >= (int)m_geometry.height() - 1)
    return {};
  x = m_geometry.xwrap(x);

  auto blockBiome = [this](int x, int y) -> Biome const* {
    BiomeIndex index = blockBiomeIndex(m_geometry.xwrap(x), y);
    if (index == NullBiomeIndex)
      return nullptr;
    return m_layout->getBiome(index).get();
  };

  auto lowerBlockBiome = blockBiome(x, y - 1);
  auto upperBlockBiome = blockBiome(x, y + 1);
  auto thisBlockBiome = blockBiome(x, y);
  
  PotentialBiomeItems potentialBiomeItems;
  // surface floor, surface ocean
  if (lowerBlockBiome)
    addPotentialBiomeItems(x, y, potentialBiomeItems, lowerBlockBiome->surfacePlaceables.itemDistributions, BiomePlacementArea::Surface, BiomePlacementMode::Floor);
  if (thisBlockBiome)
    addPotentialBiomeItems(x, y, potentialBiomeItems, thisBlockBiome->surfacePlaceables.itemDistributions, BiomePlacementArea::Surface, BiomePlacementMode::Ocean);

  // underground floor, ceiling, background
  if (lowerBlockBiome)
    addPotentialBiomeItems(x, y, potentialBiomeItems, lowerBlockBiome->undergroundPlaceables.itemDistributions, BiomePlacementArea::Underground, BiomePlacementMode::Floor);
  if (upperBlockBiome)
    addPotentialBiomeItems(x, y, potentialBiomeItems, upperBlockBiome->undergroundPlaceables.itemDistributions, BiomePlacementArea::Underground, BiomePlacementMode::Ceiling);
  if (thisBlockBiome)
    addPotentialBiomeItems(x, y, potentialBiomeItems, thisBlockBiome->undergroundPlaceables.itemDistributions, BiomePlacementArea::Underground, BiomePlacementMode::Background);

  return potentialBiomeItems;
}

List<BiomeItemPlacement> WorldTemplate::validBiomeItems(int x, int y, PotentialBiomeItems potentialBiomeItems) const {
  if (y <= 0 || y >= (int)m_geometry.height() - 1)