set_envmap_obj(p, is_terrain_known(p)? grd(p) : 0);

        set_envmap_obj(p, is_terrain_known(p)? grd(p) : DNGN_UNSEEN);

        set_envmap_obj(p, is_terrain_known(p)? grd(p) : 0);

        set_envmap_obj(p, is_terrain_known(p)? grd(p) : DNGN_UNSEEN);

    int num_lines = _get_number_of_lines_levelmap();
    if (num_lines > GYM)
        num_lines = GYM;
    int num_cols = get_number_of_cols();
    if (num_cols > GXM)
        num_cols = GXM;

    const int num_lines = std::min(_get_number_of_lines_levelmap(), GYM);
    const int num_cols  = std::min(get_number_of_cols(),            GXM);

    const dungeon_feature_type grid = grd[x][y];

    const bool seen = see_grid(x,y);
    const int grid = (seen ? grd[x][y] : get_envmap_obj(x,y));

    // Special-case secret doors so that we don't run into awkwardness when
    // a monster opens a secret door without the hero seeing it, but the travel
    // code paths through the secret door because it looks at the actual grid,
    // rather than the env overmap.
    if ((grid == DNGN_OPEN_DOOR || grid == DNGN_CLOSED_DOOR)
        && is_terrain_changed(x, y))

    // FIXME: this compares to the *real* monster at the square,
    // even if the one we've seen is different.
    if (!ignore_hostile
        && (seen || grid > DNGN_START_OF_MONSTERS)
        && _is_monster_blocked(x, y))

        const int c = get_envmap_obj(x, y);
        const int secret_door = grid_secret_door_appearance(coord_def(x, y));
        return (c != secret_door);
    }
    if (!ignore_hostile && _is_monster_blocked(x, y))

    }

    if (ignore_hostile && _is_reseedable(x, y))

    if (ignore_hostile
        && (seen || grid < NUM_REAL_FEATURES)
        && _is_reseedable(x, y))
    {

    }

    return (is_traversable(grid)

    if (grid >= NUM_REAL_FEATURES)
        return (true);
    return (is_traversable(static_cast<dungeon_feature_type>(grid))

    set_terrain_changed(pos1.x, pos1.y);
    set_terrain_changed(pos2.x, pos2.y);

    set_terrain_changed(pos1);
    set_terrain_changed(pos2);

            set_envmap_obj(*ri, 0);

            set_envmap_obj(*ri, DNGN_UNSEEN);