Function AircraftGetEntryPoint

src/aircraft_cmd.cpp:824–853

* Find the entry point to an airport depending on direction which * the airport is being approached from. Each airport can have up to * four entry points for its approach system so that approaching * aircraft do not fly through each other or are forced to do 180 * degree turns during the approach. The arrivals are grouped into * four sectors dependent on the DiagDirection from which the airpo

 * @return   The index of the entry point
 */
static uint8_t AircraftGetEntryPoint(const Aircraft *v, const AirportFTAClass *apc, Direction rotation)
{
	assert(v != nullptr);
	assert(apc != nullptr);

	/* In the case the station doesn't exit anymore, set target tile 0.
	 * It doesn't hurt much, aircraft will go to next order, nearest hangar
	 * or it will simply crash in next tick */
	TileIndex tile{};

	const Station *st = Station::GetIfValid(v->targetairport);
	if (st != nullptr) {
		/* Make sure we don't go to INVALID_TILE if the airport has been removed. */
		tile = (st->airport.tile != INVALID_TILE) ? st->airport.tile : st->xy;
	}

	int delta_x = v->x_pos - TileX(tile) * TILE_SIZE;
	int delta_y = v->y_pos - TileY(tile) * TILE_SIZE;

	DiagDirection dir;
	if (abs(delta_y) < abs(delta_x)) {
		/* We are northeast or southwest of the airport */
		dir = delta_x < 0 ? DIAGDIR_NE : DIAGDIR_SW;
	} else {
		/* We are northwest or southeast of the airport */
		dir = delta_y < 0 ? DIAGDIR_NW : DIAGDIR_SE;
	}
	dir = ChangeDiagDir(dir, DiagDirDifference(DIAGDIR_NE, DirToDiagDir(rotation)));
	return apc->entry_points[dir];
}


static void MaybeCrashAirplane(Aircraft *v);