Function EngineNumberSorter

src/build_vehicle_gui.cpp:116–121

* Determines order of engines by engineID * @param a first engine to compare * @param b second engine to compare * @return for descending order: returns true if a < b. Vice versa for ascending order */

 * @return for descending order: returns true if a < b. Vice versa for ascending order
 */
static bool EngineNumberSorter(const GUIEngineListItem &a, const GUIEngineListItem &b)
{
	int r = Engine::Get(a.engine_id)->list_position - Engine::Get(b.engine_id)->list_position;

	return _engine_sort_direction ? r > 0 : r < 0;
}

/**
 * Determines order of engines by introduction date