std::sort(entities.begin(), entities.end(), ZCompare);
for (std::vector<Entity *>::iterator i(entities.begin()), end(entities.end()); i != end; ++i) {
(*i)->Render(screen, offset);
std::sort(entities.begin(), entities.end(), ZCompare);
for (std::vector<Entity *>::iterator i(entities.begin()), end(entities.end()); i != end; ++i) {
(*i)->Render(screen, offset);