Function PerformStationTileSlopeCheck

src/newgrf_station.cpp:676–695

* Check the slope of a tile of a new station. * @param north_tile Norther tile of the station rect. * @param cur_tile Tile to check. * @param statspec Station spec. * @param axis Axis of the new station. * @param plat_len Platform length. * @param numtracks Number of platforms. * @return Succeeded or failed command. */

 * @return Succeeded or failed command.
 */
CommandCost PerformStationTileSlopeCheck(TileIndex north_tile, TileIndex cur_tile, const StationSpec *statspec, Axis axis, uint8_t plat_len, uint8_t numtracks)
{
	TileIndex diff = cur_tile - north_tile;
	Slope slope = GetTileSlope(cur_tile);

	StationResolverObject object(statspec, nullptr, cur_tile, CBID_STATION_LAND_SLOPE_CHECK,
			(slope << 4) | (slope ^ (axis == AXIS_Y && HasBit(slope, CORNER_W) != HasBit(slope, CORNER_E) ? SLOPE_EW : 0)),
			(numtracks << 24) | (plat_len << 16) | (axis == AXIS_Y ? TileX(diff) << 8 | TileY(diff) : TileY(diff) << 8 | TileX(diff)));
	object.station_scope.axis = axis;

	std::array<int32_t, 16> regs100;
	uint16_t cb_res = object.ResolveCallback(regs100);

	/* Failed callback means success. */
	if (cb_res == CALLBACK_FAILED) return CommandCost();

	/* The meaning of bit 10 is inverted for a grf version < 8. */
	if (statspec->grf_prop.grffile->grf_version < 8) ToggleBit(cb_res, 10);
	return GetErrorMessageFromLocationCallbackResult(cb_res, regs100, statspec->grf_prop.grffile, STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
}


/**