for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
Chunk *chunk = chunks.Get(pos);
for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
Chunk *chunk = chunks.Get(pos);