Function TrainApproachingLineEnd

src/train_cmd.cpp:3794–3831

* Train is approaching line end, slow down and possibly reverse * * @param v front train engine * @param signal not line end, just a red signal * @param reverse Set to false to not execute the vehicle reversing. This does not change any other logic. * @return true iff we did NOT have to reverse */

 * @return true iff we did NOT have to reverse
 */
static bool TrainApproachingLineEnd(Train *v, bool signal, bool reverse)
{
	/* Calc position within the current tile */
	uint x = v->x_pos & 0xF;
	uint y = v->y_pos & 0xF;

	/* for diagonal directions, 'x' will be 0..15 -
	 * for other directions, it will be 1, 3, 5, ..., 15 */
	switch (v->direction) {
		case DIR_N : x = ~x + ~y + 25; break;
		case DIR_NW: x = y;            [[fallthrough]];
		case DIR_NE: x = ~x + 16;      break;
		case DIR_E : x = ~x + y + 9;   break;
		case DIR_SE: x = y;            break;
		case DIR_S : x = x + y - 7;    break;
		case DIR_W : x = ~y + x + 9;   break;
		default: break;
	}

	/* Do not reverse when approaching red signal. Make sure the vehicle's front
	 * does not cross the tile boundary when we do reverse, but as the vehicle's
	 * location is based on their center, use half a vehicle's length as offset.
	 * Multiply the half-length by two for straight directions to compensate that
	 * we only get odd x offsets there. */
	if (!signal && x + (v->gcache.cached_veh_length + 1) / 2 * (IsDiagonalDirection(v->direction) ? 1 : 2) >= TILE_SIZE) {
		/* we are too near the tile end, reverse now */
		v->cur_speed = 0;
		if (reverse) ReverseTrainDirection(v);
		return false;
	}

	/* slow down */
	v->vehstatus.Set(VehState::TrainSlowing);
	uint16_t break_speed = _breakdown_speeds[x & 0xF];
	if (break_speed < v->cur_speed) v->cur_speed = break_speed;

	return true;
}


/**