bool CanTerraformFloodingTile(TileIndex tile, int z_new, Slope tileh_new)
{
    if (GetFloodingBehaviour(tile) != FLOOD_NONE) {
        if (tileh_new == SLOPE_FLAT || z_new == 1) {
            return false;
        }

        Slope tileh = GetTileSlope(tile);

        if (IsSlopeWithThreeCornersRaised(tileh)) {
            if (tileh_new == SLOPE_NS || tileh_new == SLOPE_EW) {
                return true;
            }

            if (IsSteepSlope(tileh_new) &&
                    OppositeCorner(GetHighestSlopeCorner(ComplementSlope(tileh))) == GetHighestSlopeCorner(tileh_new)) {
                return true;
            }
        }

        if (IsSteepSlope(tileh)) {
            if (IsSlopeWithThreeCornersRaised(tileh_new) &&
                    GetHighestSlopeCorner(tileh) == OppositeCorner(GetHighestSlopeCorner(ComplementSlope(tileh_new)))) {
                return true;
            }
        }

        return false;
    }

    return true;
}