Function TrainEngineCapacitySorter

src/build_vehicle_gui.cpp:320–332

* Determines order of train engines by capacity * @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 TrainEngineCapacitySorter(const GUIEngineListItem &a, const GUIEngineListItem &b)
{
	const RailVehicleInfo *rvi_a = RailVehInfo(a.engine_id);
	const RailVehicleInfo *rvi_b = RailVehInfo(b.engine_id);

	int va = GetTotalCapacityOfArticulatedParts(a.engine_id) * (rvi_a->railveh_type == RAILVEH_MULTIHEAD ? 2 : 1);
	int vb = GetTotalCapacityOfArticulatedParts(b.engine_id) * (rvi_b->railveh_type == RAILVEH_MULTIHEAD ? 2 : 1);
	int r = va - vb;

	/* Use EngineID to sort instead since we want consistent sorting */
	if (r == 0) return EngineNumberSorter(a, b);
	return _engine_sort_direction ? r > 0 : r < 0;
}

/**
 * Determines order of train engines by engine / wagon