[Refactor] #38995 world_type 構造体に turn を game_turn に改名して取り込む。 / Rename turn to game_t...

[hengband/hengband.git] / src / grid.c


 /*!
  * @file grid.c
  * @brief グリッドの実装 / low level dungeon routines -BEN-
  * @date 2013/12/30
  * @author
  * Copyright (c) 1997 Ben Harrison, James E. Wilson, Robert A. Koeneke\n
  *\n
  * This software may be copied and distributed for educational, research,\n
  * and not for profit purposes provided that this copyright and statement\n
  * are included in all such copies.  Other copyrights may also apply.\n
  * \n
  * Support for Adam Bolt's tileset, lighting and transparency effects\n
  * by Robert Ruehlmann (rr9@angband.org)\n
  * \n
  * 2013 Deskull Doxygen向けのコメント整理\n
  */


#include "angband.h"
#include "world.h"
#include "projection.h"
#include "object-hook.h"
#include "generate.h"
#include "grid.h"
#include "trap.h"
#include "rooms.h"
#include "monster.h"
#include "quest.h"
#include "feature.h"

static byte display_autopick; /*!< 自動拾い状態の設定フラグ */
static int match_autopick;
static object_type *autopick_obj; /*!< 各種自動拾い処理時に使うオブジェクトポインタ */
static int feat_priority; /*!< マップ縮小表示時に表示すべき地形の優先度を保管する */


/*!
 * @brief 新規フロアに入りたてのプレイヤーをランダムな場所に配置する / Returns random co-ordinates for player/monster/object
 * @return 配置に成功したらTRUEを返す
 */
bool new_player_spot(void)
{
        POSITION y = 0, x = 0;
        int max_attempts = 10000;

        grid_type *g_ptr;
        feature_type *f_ptr;

        /* Place the player */
        while (max_attempts--)
        {
                /* Pick a legal spot */
                y = (POSITION)rand_range(1, current_floor_ptr->height - 2);
                x = (POSITION)rand_range(1, current_floor_ptr->width - 2);

                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Must be a "naked" floor grid */
                if (g_ptr->m_idx) continue;
                if (current_floor_ptr->dun_level)
                {
                        f_ptr = &f_info[g_ptr->feat];

                        if (max_attempts > 5000) /* Rule 1 */
                        {
                                if (!have_flag(f_ptr->flags, FF_FLOOR)) continue;
                        }
                        else /* Rule 2 */
                        {
                                if (!have_flag(f_ptr->flags, FF_MOVE)) continue;
                                if (have_flag(f_ptr->flags, FF_HIT_TRAP)) continue;
                        }

                        /* Refuse to start on anti-teleport grids in dungeon */
                        if (!have_flag(f_ptr->flags, FF_TELEPORTABLE)) continue;
                }
                if (!player_can_enter(g_ptr->feat, 0)) continue;
                if (!in_bounds(y, x)) continue;

                /* Refuse to start on anti-teleport grids */
                if (g_ptr->info & (CAVE_ICKY)) continue;

                break;
        }

        if (max_attempts < 1) /* Should be -1, actually if we failed... */
                return FALSE;

        /* Save the new player grid */
        p_ptr->y = y;
        p_ptr->x = x;

        return TRUE;
}



/*!
 * @brief 所定の位置に上り階段か下り階段を配置する / Place an up/down staircase at given location
 * @param y 配置を試みたいマスのY座標
 * @param x 配置を試みたいマスのX座標
 * @return なし
 */
void place_random_stairs(POSITION y, POSITION x)
{
        bool up_stairs = TRUE;
        bool down_stairs = TRUE;
        grid_type *g_ptr;

        /* Paranoia */
        g_ptr = &current_floor_ptr->grid_array[y][x];
        if (!is_floor_grid(g_ptr) || g_ptr->o_idx) return;

        /* Town */
        if (!current_floor_ptr->dun_level) up_stairs = FALSE;

        /* Ironman */
        if (ironman_downward) up_stairs = FALSE;

        /* Bottom */
        if (current_floor_ptr->dun_level >= d_info[p_ptr->dungeon_idx].maxdepth) down_stairs = FALSE;

        /* Quest-level */
        if (quest_number(current_floor_ptr->dun_level) && (current_floor_ptr->dun_level > 1)) down_stairs = FALSE;

        /* We can't place both */
        if (down_stairs && up_stairs)
        {
                /* Choose a staircase randomly */
                if (randint0(100) < 50) up_stairs = FALSE;
                else down_stairs = FALSE;
        }

        /* Place the stairs */
        if (up_stairs) place_up_stairs(y, x);
        else if (down_stairs) place_down_stairs(y, x);
}

/*!
 * @brief 所定の位置にさまざまな状態や種類のドアを配置する / Place a random type of door at the given location
 * @param y ドアの配置を試みたいマスのY座標
 * @param x ドアの配置を試みたいマスのX座標
 * @param room 部屋に接している場合向けのドア生成か否か
 * @return なし
 */
void place_random_door(POSITION y, POSITION x, bool room)
{
        int tmp, type;
        FEAT_IDX feat = feat_none;
        grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];

        /* Initialize mimic info */
        g_ptr->mimic = 0;

        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_DOORS)
        {
                place_floor_bold(y, x);
                return;
        }

        type = ((d_info[p_ptr->dungeon_idx].flags1 & DF1_CURTAIN) &&
                one_in_((d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_CAVE) ? 16 : 256)) ? DOOR_CURTAIN :
                ((d_info[p_ptr->dungeon_idx].flags1 & DF1_GLASS_DOOR) ? DOOR_GLASS_DOOR : DOOR_DOOR);

        /* Choose an object */
        tmp = randint0(1000);

        /* Open doors (300/1000) */
        if (tmp < 300)
        {
                /* Create open door */
                feat = feat_door[type].open;
        }

        /* Broken doors (100/1000) */
        else if (tmp < 400)
        {
                /* Create broken door */
                feat = feat_door[type].broken;
        }

        /* Secret doors (200/1000) */
        else if (tmp < 600)
        {
                /* Create secret door */
                place_closed_door(y, x, type);

                if (type != DOOR_CURTAIN)
                {
                        /* Hide. If on the edge of room, use outer wall. */
                        g_ptr->mimic = room ? feat_wall_outer : feat_wall_type[randint0(100)];

                        /* Floor type terrain cannot hide a door */
                        if (feat_supports_los(g_ptr->mimic) && !feat_supports_los(g_ptr->feat))
                        {
                                if (have_flag(f_info[g_ptr->mimic].flags, FF_MOVE) || have_flag(f_info[g_ptr->mimic].flags, FF_CAN_FLY))
                                {
                                        g_ptr->feat = one_in_(2) ? g_ptr->mimic : feat_ground_type[randint0(100)];
                                }
                                g_ptr->mimic = 0;
                        }
                }
        }

        /* Closed, locked, or stuck doors (400/1000) */
        else place_closed_door(y, x, type);

        if (tmp < 400)
        {
                if (feat != feat_none)
                {
                        set_cave_feat(y, x, feat);
                }
                else
                {
                        place_floor_bold(y, x);
                }
        }

        delete_monster(y, x);
}

/*!
 * @brief 所定の位置に各種の閉じたドアを配置する / Place a random type of normal door at the given location.
 * @param y ドアの配置を試みたいマスのY座標
 * @param x ドアの配置を試みたいマスのX座標
 * @param type ドアの地形ID
 * @return なし
 */
void place_closed_door(POSITION y, POSITION x, int type)
{
        int tmp;
        FEAT_IDX feat = feat_none;

        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_DOORS)
        {
                place_floor_bold(y, x);
                return;
        }

        /* Choose an object */
        tmp = randint0(400);

        /* Closed doors (300/400) */
        if (tmp < 300)
        {
                /* Create closed door */
                feat = feat_door[type].closed;
        }

        /* Locked doors (99/400) */
        else if (tmp < 399)
        {
                /* Create locked door */
                feat = feat_locked_door_random(type);
        }

        /* Stuck doors (1/400) */
        else
        {
                /* Create jammed door */
                feat = feat_jammed_door_random(type);
        }

        if (feat != feat_none)
        {
                cave_set_feat(y, x, feat);

                /* Now it is not floor */
                current_floor_ptr->grid_array[y][x].info &= ~(CAVE_MASK);
        }
        else
        {
                place_floor_bold(y, x);
        }
}

/*!
* @brief 鍵のかかったドアを配置する
* @param y 配置したいフロアのY座標
* @param x 配置したいフロアのX座標
* @return なし
*/
void place_locked_door(POSITION y, POSITION x)
{
        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_DOORS)
        {
                place_floor_bold(y, x);
        }
        else
        {
                set_cave_feat(y, x, feat_locked_door_random((d_info[p_ptr->dungeon_idx].flags1 & DF1_GLASS_DOOR) ? DOOR_GLASS_DOOR : DOOR_DOOR));
                current_floor_ptr->grid_array[y][x].info &= ~(CAVE_FLOOR);
                delete_monster(y, x);
        }
}


/*!
* @brief 隠しドアを配置する
* @param y 配置したいフロアのY座標
* @param x 配置したいフロアのX座標
* @param type DOOR_DEFAULT / DOOR_DOOR / DOOR_GLASS_DOOR / DOOR_CURTAIN のいずれか
* @return なし
*/
void place_secret_door(POSITION y, POSITION x, int type)
{
        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_DOORS)
        {
                place_floor_bold(y, x);
        }
        else
        {
                grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];

                if (type == DOOR_DEFAULT)
                {
                        type = ((d_info[p_ptr->dungeon_idx].flags1 & DF1_CURTAIN) &&
                                one_in_((d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_CAVE) ? 16 : 256)) ? DOOR_CURTAIN :
                                ((d_info[p_ptr->dungeon_idx].flags1 & DF1_GLASS_DOOR) ? DOOR_GLASS_DOOR : DOOR_DOOR);
                }

                /* Create secret door */
                place_closed_door(y, x, type);

                if (type != DOOR_CURTAIN)
                {
                        /* Hide by inner wall because this is used in rooms only */
                        g_ptr->mimic = feat_wall_inner;

                        /* Floor type terrain cannot hide a door */
                        if (feat_supports_los(g_ptr->mimic) && !feat_supports_los(g_ptr->feat))
                        {
                                if (have_flag(f_info[g_ptr->mimic].flags, FF_MOVE) || have_flag(f_info[g_ptr->mimic].flags, FF_CAN_FLY))
                                {
                                        g_ptr->feat = one_in_(2) ? g_ptr->mimic : feat_ground_type[randint0(100)];
                                }
                                g_ptr->mimic = 0;
                        }
                }

                g_ptr->info &= ~(CAVE_FLOOR);
                delete_monster(y, x);
        }
}

/*
 * Routine used by the random vault creators to add a door to a location
 * Note that range checking has to be done in the calling routine.
 *
 * The doors must be INSIDE the allocated region.
 */
void add_door(POSITION x, POSITION y)
{
        /* Need to have a wall in the center square */
        if (!is_outer_bold(y, x)) return;

        /* look at:
        *  x#x
        *  .#.
        *  x#x
        *
        *  where x=don't care
        *  .=floor, #=wall
        */

        if (is_floor_bold(y - 1, x) && is_floor_bold(y + 1, x) &&
                (is_outer_bold(y, x - 1) && is_outer_bold(y, x + 1)))
        {
                /* secret door */
                place_secret_door(y, x, DOOR_DEFAULT);

                /* set boundarys so don't get wide doors */
                place_solid_bold(y, x - 1);
                place_solid_bold(y, x + 1);
        }


        /* look at:
        *  x#x
        *  .#.
        *  x#x
        *
        *  where x = don't care
        *  .=floor, #=wall
        */
        if (is_outer_bold(y - 1, x) && is_outer_bold(y + 1, x) &&
                is_floor_bold(y, x - 1) && is_floor_bold(y, x + 1))
        {
                /* secret door */
                place_secret_door(y, x, DOOR_DEFAULT);

                /* set boundarys so don't get wide doors */
                place_solid_bold(y - 1, x);
                place_solid_bold(y + 1, x);
        }
}

/*!
* @brief 隣接4マスに存在する通路の数を返す / Count the number of "corridor" grids adjacent to the given grid.
* @param y1 基準となるマスのY座標
* @param x1 基準となるマスのX座標
* @return 通路の数
* @note Assumes "in_bounds(y1, x1)"
* @details
* XXX XXX This routine currently only counts actual "empty floor"\n
* grids which are not in rooms.  We might want to also count stairs,\n
* open doors, closed doors, etc.
*/
static int next_to_corr(POSITION y1, POSITION x1)
{
        int i, k = 0;
        POSITION y, x;

        grid_type *g_ptr;

        /* Scan adjacent grids */
        for (i = 0; i < 4; i++)
        {
                /* Extract the location */
                y = y1 + ddy_ddd[i];
                x = x1 + ddx_ddd[i];
                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Skip non floors */
                if (cave_have_flag_grid(g_ptr, FF_WALL)) continue;

                /* Skip non "empty floor" grids */
                if (!is_floor_grid(g_ptr))
                        continue;

                /* Skip grids inside rooms */
                if (g_ptr->info & (CAVE_ROOM)) continue;

                /* Count these grids */
                k++;
        }

        /* Return the number of corridors */
        return (k);
}

/*!
* @brief ドアを設置可能な地形かを返す / Determine if the given location is "between" two walls, and "next to" two corridor spaces.
* @param y 判定を行いたいマスのY座標
* @param x 判定を行いたいマスのX座標
* @return ドアを設置可能ならばTRUEを返す
* @note Assumes "in_bounds(y1, x1)"
* @details
* \n
* Assumes "in_bounds(y, x)"\n
*/
static bool possible_doorway(POSITION y, POSITION x)
{
        /* Count the adjacent corridors */
        if (next_to_corr(y, x) >= 2)
        {
                /* Check Vertical */
                if (cave_have_flag_bold(y - 1, x, FF_WALL) &&
                        cave_have_flag_bold(y + 1, x, FF_WALL))
                {
                        return (TRUE);
                }

                /* Check Horizontal */
                if (cave_have_flag_bold(y, x - 1, FF_WALL) &&
                        cave_have_flag_bold(y, x + 1, FF_WALL))
                {
                        return (TRUE);
                }
        }

        /* No doorway */
        return (FALSE);
}

/*!
* @brief ドアの設置を試みる / Places door at y, x position if at least 2 walls found
* @param y 設置を行いたいマスのY座標
* @param x 設置を行いたいマスのX座標
* @return なし
*/
void try_door(POSITION y, POSITION x)
{
        /* Paranoia */
        if (!in_bounds(y, x)) return;

        /* Ignore walls */
        if (cave_have_flag_bold(y, x, FF_WALL)) return;

        /* Ignore room grids */
        if (current_floor_ptr->grid_array[y][x].info & (CAVE_ROOM)) return;

        /* Occasional door (if allowed) */
        if ((randint0(100) < dun_tun_jct) && possible_doorway(y, x) && !(d_info[p_ptr->dungeon_idx].flags1 & DF1_NO_DOORS))
        {
                /* Place a door */
                place_random_door(y, x, FALSE);
        }
}


/*!
 * @brief 長方形の空洞を生成する / Make an empty square floor, for the middle of rooms
 * @param x1 長方形の左端X座標(-1)
 * @param x2 長方形の右端X座標(+1)
 * @param y1 長方形の上端Y座標(-1)
 * @param y2 長方形の下端Y座標(+1)
 * @param light 照明の有無
 * @return なし
 */
void place_floor(POSITION x1, POSITION x2, POSITION y1, POSITION y2, bool light)
{
        POSITION x, y;

        /* Place a full floor under the room */
        for (y = y1 - 1; y <= y2 + 1; y++)
        {
                for (x = x1 - 1; x <= x2 + 1; x++)
                {
                        place_floor_bold(y, x);
                        add_cave_info(y, x, CAVE_ROOM);
                        if (light) add_cave_info(y, x, CAVE_GLOW);
                }
        }
}


/*!
 * @brief 長方形の部屋を生成する / Make an empty square room, only floor and wall grids
 * @param x1 長方形の左端X座標(-1)
 * @param x2 長方形の右端X座標(+1)
 * @param y1 長方形の上端Y座標(-1)
 * @param y2 長方形の下端Y座標(+1)
 * @param light 照明の有無
 * @return なし
 */
void place_room(POSITION x1, POSITION x2, POSITION y1, POSITION y2, bool light)
{
        POSITION y, x;

        place_floor(x1, x2, y1, y2, light);

        /* Walls around the room */
        for (y = y1 - 1; y <= y2 + 1; y++)
        {
                place_outer_bold(y, x1 - 1);
                place_outer_bold(y, x2 + 1);
        }
        for (x = x1 - 1; x <= x2 + 1; x++)
        {
                place_outer_bold(y1 - 1, x);
                place_outer_bold(y2 + 1, x);
        }
}


/*!
 * @brief 特殊な部屋向けに各種アイテムを配置する / Create up to "num" objects near the given coordinates
 * @param y 配置したい中心マスのY座標
 * @param x 配置したい中心マスのX座標
 * @param num 配置したい数
 * @return なし
 * @details
 * Only really called by some of the "vault" routines.
 */
void vault_objects(POSITION y, POSITION x, int num)
{
        int dummy = 0;
        int i = 0, j = y, k = x;

        grid_type *g_ptr;


        /* Attempt to place 'num' objects */
        for (; num > 0; --num)
        {
                /* Try up to 11 spots looking for empty space */
                for (i = 0; i < 11; ++i)
                {
                        /* Pick a random location */
                        while (dummy < SAFE_MAX_ATTEMPTS)
                        {
                                j = rand_spread(y, 2);
                                k = rand_spread(x, 3);
                                dummy++;
                                if (!in_bounds(j, k)) continue;
                                break;
                        }

                        if (dummy >= SAFE_MAX_ATTEMPTS && cheat_room)
                        {
                                msg_print(_("警告！地下室のアイテムを配置できません！", "Warning! Could not place vault object!"));
                        }

                        /* Require "clean" floor space */
                        g_ptr = &current_floor_ptr->grid_array[j][k];
                        if (!is_floor_grid(g_ptr) || g_ptr->o_idx) continue;

                        if (randint0(100) < 75)
                        {
                                place_object(j, k, 0L);
                        }
                        else
                        {
                                place_gold(j, k);
                        }

                        /* Placement accomplished */
                        break;
                }
        }
}

/*!
 * @brief 特殊な部屋向けに各種アイテムを配置する(vault_trapのサブセット) / Place a trap with a given displacement of point
 * @param y トラップを配置したいマスの中心Y座標
 * @param x トラップを配置したいマスの中心X座標
 * @param yd Y方向の配置分散マス数
 * @param xd X方向の配置分散マス数
 * @return なし
 * @details
 * Only really called by some of the "vault" routines.
 */
void vault_trap_aux(POSITION y, POSITION x, POSITION yd, POSITION xd)
{
        int count = 0, y1 = y, x1 = x;
        int dummy = 0;

        grid_type *g_ptr;

        /* Place traps */
        for (count = 0; count <= 5; count++)
        {
                /* Get a location */
                while (dummy < SAFE_MAX_ATTEMPTS)
                {
                        y1 = rand_spread(y, yd);
                        x1 = rand_spread(x, xd);
                        dummy++;
                        if (!in_bounds(y1, x1)) continue;
                        break;
                }

                if (dummy >= SAFE_MAX_ATTEMPTS && cheat_room)
                {
                        msg_print(_("警告！地下室のトラップを配置できません！", "Warning! Could not place vault trap!"));
                }

                /* Require "naked" floor grids */
                g_ptr = &current_floor_ptr->grid_array[y1][x1];
                if (!is_floor_grid(g_ptr) || g_ptr->o_idx || g_ptr->m_idx) continue;

                /* Place the trap */
                place_trap(y1, x1);

                break;
        }
}

/*!
 * @brief 特殊な部屋向けに各種アイテムを配置する(メインルーチン) / Place some traps with a given displacement of given location
 * @param y トラップを配置したいマスの中心Y座標
 * @param x トラップを配置したいマスの中心X座標
 * @param yd Y方向の配置分散マス数
 * @param xd X方向の配置分散マス数
 * @param num 配置したいトラップの数
 * @return なし
 * @details
 * Only really called by some of the "vault" routines.
 */
void vault_traps(POSITION y, POSITION x, POSITION yd, POSITION xd, int num)
{
        int i;

        for (i = 0; i < num; i++)
        {
                vault_trap_aux(y, x, yd, xd);
        }
}

/*!
 * @brief 特殊な部屋地形向けにモンスターを配置する / Hack -- Place some sleeping monsters near the given location
 * @param y1 モンスターを配置したいマスの中心Y座標
 * @param x1 モンスターを配置したいマスの中心X座標
 * @param num 配置したいモンスターの数
 * @return なし
 * @details
 * Only really called by some of the "vault" routines.
 */
void vault_monsters(POSITION y1, POSITION x1, int num)
{
        int k, i;
        POSITION y, x;
        grid_type *g_ptr;

        /* Try to summon "num" monsters "near" the given location */
        for (k = 0; k < num; k++)
        {
                /* Try nine locations */
                for (i = 0; i < 9; i++)
                {
                        int d = 1;

                        /* Pick a nearby location */
                        scatter(&y, &x, y1, x1, d, 0);

                        /* Require "empty" floor grids */
                        g_ptr = &current_floor_ptr->grid_array[y][x];
                        if (!cave_empty_grid(g_ptr)) continue;

                        /* Place the monster (allow groups) */
                        current_floor_ptr->monster_level = current_floor_ptr->base_level + 2;
                        (void)place_monster(y, x, (PM_ALLOW_SLEEP | PM_ALLOW_GROUP));
                        current_floor_ptr->monster_level = current_floor_ptr->base_level;
                }
        }
}

/*!
 * @brief 指定のマスが床系地形であるかを返す / Function that sees if a square is a floor.  (Includes range checking.)
 * @param x チェックするマスのX座標
 * @param y チェックするマスのY座標
 * @return 床系地形ならばTRUE
 */
bool get_is_floor(POSITION x, POSITION y)
{
        if (!in_bounds(y, x))
        {
                /* Out of bounds */
                return (FALSE);
        }

        /* Do the real check */
        if (is_floor_bold(y, x)) return (TRUE);

        return (FALSE);
}

/*!
 * @brief 指定のマスを床地形に変える / Set a square to be floor.  (Includes range checking.)
 * @param x 地形を変えたいマスのX座標
 * @param y 地形を変えたいマスのY座標
 * @return なし
 */
void set_floor(POSITION x, POSITION y)
{
        if (!in_bounds(y, x))
        {
                /* Out of bounds */
                return;
        }

        if (current_floor_ptr->grid_array[y][x].info & CAVE_ROOM)
        {
                /* A room border don't touch. */
                return;
        }

        /* Set to be floor if is a wall (don't touch lakes). */
        if (is_extra_bold(y, x))
                place_floor_bold(y, x);
}

/*!
 * @brief マスにフロア端用の永久壁を配置する / Set boundary mimic and add "solid" perma-wall
 * @param g_ptr 永久壁を配置したいマス構造体の参照ポインタ
 * @return なし
 */
void place_bound_perm_wall(grid_type *g_ptr)
{
        if (bound_walls_perm)
        {
                /* Clear boundary mimic */
                g_ptr->mimic = 0;
        }
        else
        {
                feature_type *f_ptr = &f_info[g_ptr->feat];

                /* Hack -- Decline boundary walls with known treasure  */
                if ((have_flag(f_ptr->flags, FF_HAS_GOLD) || have_flag(f_ptr->flags, FF_HAS_ITEM)) &&
                        !have_flag(f_ptr->flags, FF_SECRET))
                        g_ptr->feat = feat_state(g_ptr->feat, FF_ENSECRET);

                /* Set boundary mimic */
                g_ptr->mimic = g_ptr->feat;
        }

        /* Add "solid" perma-wall */
        place_solid_perm_grid(g_ptr);
}


/*!
 * @brief 2点間の距離をニュートン・ラプソン法で算出する / Distance between two points via Newton-Raphson technique
 * @param y1 1点目のy座標
 * @param x1 1点目のx座標
 * @param y2 2点目のy座標
 * @param x2 2点目のx座標
 * @return 2点間の距離
 */
POSITION distance(POSITION y1, POSITION x1, POSITION y2, POSITION x2)
{
        POSITION dy = (y1 > y2) ? (y1 - y2) : (y2 - y1);
        POSITION dx = (x1 > x2) ? (x1 - x2) : (x2 - x1);

        /* Squared distance */
        POSITION target = (dy * dy) + (dx * dx);

        /* Approximate distance: hypot(dy,dx) = max(dy,dx) + min(dy,dx) / 2 */
        POSITION d = (dy > dx) ? (dy + (dx >> 1)) : (dx + (dy >> 1));

        POSITION err;

        /* Simple case */
        if (!dy || !dx) return d;

        while (1)
        {
                /* Approximate error */
                err = (target - d * d) / (2 * d);

                /* No error - we are done */
                if (!err) break;

                /* Adjust distance */
                d += err;
        }

        return d;
}


/*!
 * @brief マスに看破済みの罠があるかの判定を行う。 / Return TRUE if the given grid is a known trap
 * @param g_ptr マス構造体の参照ポインタ
 * @return 看破済みの罠があるならTRUEを返す。
 */
bool is_known_trap(grid_type *g_ptr)
{
        if (!g_ptr->mimic && !cave_have_flag_grid(g_ptr, FF_SECRET) &&
                is_trap(g_ptr->feat)) return TRUE;
        else
                return FALSE;
}



/*!
 * @brief マスに隠されたドアがあるかの判定を行う。 / Return TRUE if the given grid is a hidden closed door
 * @param g_ptr マス構造体の参照ポインタ
 * @return 隠されたドアがあるならTRUEを返す。
 */
bool is_hidden_door(grid_type *g_ptr)
{
        if ((g_ptr->mimic || cave_have_flag_grid(g_ptr, FF_SECRET)) &&
                is_closed_door(g_ptr->feat))
                return TRUE;
        else
                return FALSE;
}

/*!
 * @brief LOS(Line Of Sight / 視線が通っているか)の判定を行う。
 * @param y1 始点のy座標
 * @param x1 始点のx座標
 * @param y2 終点のy座標
 * @param x2 終点のx座標
 * @return LOSが通っているならTRUEを返す。
 * @details
 * A simple, fast, integer-based line-of-sight algorithm.  By Joseph Hall,\n
 * 4116 Brewster Drive, Raleigh NC 27606.  Email to jnh@ecemwl.ncsu.edu.\n
 *\n
 * Returns TRUE if a line of sight can be traced from (x1,y1) to (x2,y2).\n
 *\n
 * The LOS begins at the center of the tile (x1,y1) and ends at the center of\n
 * the tile (x2,y2).  If los() is to return TRUE, all of the tiles this line\n
 * passes through must be floor tiles, except for (x1,y1) and (x2,y2).\n
 *\n
 * We assume that the "mathematical corner" of a non-floor tile does not\n
 * block line of sight.\n
 *\n
 * Because this function uses (short) ints for all calculations, overflow may\n
 * occur if dx and dy exceed 90.\n
 *\n
 * Once all the degenerate cases are eliminated, the values "qx", "qy", and\n
 * "m" are multiplied by a scale factor "f1 = abs(dx * dy * 2)", so that\n
 * we can use integer arithmetic.\n
 *\n
 * We travel from start to finish along the longer axis, starting at the border\n
 * between the first and second tiles, where the y offset = .5 * slope, taking\n
 * into account the scale factor.  See below.\n
 *\n
 * Also note that this function and the "move towards target" code do NOT\n
 * share the same properties.  Thus, you can see someone, target them, and\n
 * then fire a bolt at them, but the bolt may hit a wall, not them.  However\n,
 * by clever choice of target locations, you can sometimes throw a "curve".\n
 *\n
 * Note that "line of sight" is not "reflexive" in all cases.\n
 *\n
 * Use the "projectable()" routine to test "spell/missile line of sight".\n
 *\n
 * Use the "update_view()" function to determine player line-of-sight.\n
 */
bool los(POSITION y1, POSITION x1, POSITION y2, POSITION x2)
{
        /* Delta */
        POSITION dx, dy;

        /* Absolute */
        POSITION ax, ay;

        /* Signs */
        POSITION sx, sy;

        /* Fractions */
        POSITION qx, qy;

        /* Scanners */
        POSITION tx, ty;

        /* Scale factors */
        POSITION f1, f2;

        /* Slope, or 1/Slope, of LOS */
        POSITION m;


        /* Extract the offset */
        dy = y2 - y1;
        dx = x2 - x1;

        /* Extract the absolute offset */
        ay = ABS(dy);
        ax = ABS(dx);


        /* Handle adjacent (or identical) grids */
        if ((ax < 2) && (ay < 2)) return TRUE;


        /* Paranoia -- require "safe" origin */
        /* if (!in_bounds(y1, x1)) return FALSE; */
        /* if (!in_bounds(y2, x2)) return FALSE; */


        /* Directly South/North */
        if (!dx)
        {
                /* South -- check for walls */
                if (dy > 0)
                {
                        for (ty = y1 + 1; ty < y2; ty++)
                        {
                                if (!cave_los_bold(ty, x1)) return FALSE;
                        }
                }

                /* North -- check for walls */
                else
                {
                        for (ty = y1 - 1; ty > y2; ty--)
                        {
                                if (!cave_los_bold(ty, x1)) return FALSE;
                        }
                }

                /* Assume los */
                return TRUE;
        }

        /* Directly East/West */
        if (!dy)
        {
                /* East -- check for walls */
                if (dx > 0)
                {
                        for (tx = x1 + 1; tx < x2; tx++)
                        {
                                if (!cave_los_bold(y1, tx)) return FALSE;
                        }
                }

                /* West -- check for walls */
                else
                {
                        for (tx = x1 - 1; tx > x2; tx--)
                        {
                                if (!cave_los_bold(y1, tx)) return FALSE;
                        }
                }

                /* Assume los */
                return TRUE;
        }


        /* Extract some signs */
        sx = (dx < 0) ? -1 : 1;
        sy = (dy < 0) ? -1 : 1;


        /* Vertical "knights" */
        if (ax == 1)
        {
                if (ay == 2)
                {
                        if (cave_los_bold(y1 + sy, x1)) return TRUE;
                }
        }

        /* Horizontal "knights" */
        else if (ay == 1)
        {
                if (ax == 2)
                {
                        if (cave_los_bold(y1, x1 + sx)) return TRUE;
                }
        }


        /* Calculate scale factor div 2 */
        f2 = (ax * ay);

        /* Calculate scale factor */
        f1 = f2 << 1;


        /* Travel horizontally */
        if (ax >= ay)
        {
                /* Let m = dy / dx * 2 * (dy * dx) = 2 * dy * dy */
                qy = ay * ay;
                m = qy << 1;

                tx = x1 + sx;

                /* Consider the special case where slope == 1. */
                if (qy == f2)
                {
                        ty = y1 + sy;
                        qy -= f1;
                }
                else
                {
                        ty = y1;
                }

                /* Note (below) the case (qy == f2), where */
                /* the LOS exactly meets the corner of a tile. */
                while (x2 - tx)
                {
                        if (!cave_los_bold(ty, tx)) return FALSE;

                        qy += m;

                        if (qy < f2)
                        {
                                tx += sx;
                        }
                        else if (qy > f2)
                        {
                                ty += sy;
                                if (!cave_los_bold(ty, tx)) return FALSE;
                                qy -= f1;
                                tx += sx;
                        }
                        else
                        {
                                ty += sy;
                                qy -= f1;
                                tx += sx;
                        }
                }
        }

        /* Travel vertically */
        else
        {
                /* Let m = dx / dy * 2 * (dx * dy) = 2 * dx * dx */
                qx = ax * ax;
                m = qx << 1;

                ty = y1 + sy;

                if (qx == f2)
                {
                        tx = x1 + sx;
                        qx -= f1;
                }
                else
                {
                        tx = x1;
                }

                /* Note (below) the case (qx == f2), where */
                /* the LOS exactly meets the corner of a tile. */
                while (y2 - ty)
                {
                        if (!cave_los_bold(ty, tx)) return FALSE;

                        qx += m;

                        if (qx < f2)
                        {
                                ty += sy;
                        }
                        else if (qx > f2)
                        {
                                tx += sx;
                                if (!cave_los_bold(ty, tx)) return FALSE;
                                qx -= f1;
                                ty += sy;
                        }
                        else
                        {
                                tx += sx;
                                qx -= f1;
                                ty += sy;
                        }
                }
        }

        /* Assume los */
        return TRUE;
}

#define COMPLEX_WALL_ILLUMINATION /*!< 照明状態を壁により影響を受ける、より複雑な判定に切り替えるマクロ */


/*!
 * @brief 指定された座標のマスが現在照らされているかを返す。 / Check for "local" illumination
 * @param y y座標
 * @param x x座標
 * @return 指定された座標に照明がかかっているならTRUEを返す。。
 */
static bool check_local_illumination(POSITION y, POSITION x)
{
        /* Hack -- move towards player */
        POSITION yy = (y < p_ptr->y) ? (y + 1) : (y > p_ptr->y) ? (y - 1) : y;
        POSITION xx = (x < p_ptr->x) ? (x + 1) : (x > p_ptr->x) ? (x - 1) : x;

        /* Check for "local" illumination */

#ifdef COMPLEX_WALL_ILLUMINATION /* COMPLEX_WALL_ILLUMINATION */

        /* Check for "complex" illumination */
        if ((feat_supports_los(get_feat_mimic(&current_floor_ptr->grid_array[yy][xx])) &&
                (current_floor_ptr->grid_array[yy][xx].info & CAVE_GLOW)) ||
                (feat_supports_los(get_feat_mimic(&current_floor_ptr->grid_array[y][xx])) &&
                (current_floor_ptr->grid_array[y][xx].info & CAVE_GLOW)) ||
                        (feat_supports_los(get_feat_mimic(&current_floor_ptr->grid_array[yy][x])) &&
                (current_floor_ptr->grid_array[yy][x].info & CAVE_GLOW)))
        {
                return TRUE;
        }
        else return FALSE;

#else /* COMPLEX_WALL_ILLUMINATION */

        /* Check for "simple" illumination */
        return (current_floor_ptr->grid_array[yy][xx].info & CAVE_GLOW) ? TRUE : FALSE;

#endif /* COMPLEX_WALL_ILLUMINATION */
}


/*! 対象座標のマスの照明状態を更新する際の補助処理マクロ */
#define update_local_illumination_aux(Y, X) \
{ \
        if (player_has_los_bold((Y), (X))) \
        { \
                /* Update the monster */ \
                if (current_floor_ptr->grid_array[(Y)][(X)].m_idx) update_monster(current_floor_ptr->grid_array[(Y)][(X)].m_idx, FALSE); \
\
                /* Notice and redraw */ \
                note_spot((Y), (X)); \
                lite_spot((Y), (X)); \
        } \
}

/*!
 * @brief 指定された座標の照明状態を更新する / Update "local" illumination
 * @param y y座標
 * @param x x座標
 * @return なし
 */
void update_local_illumination(POSITION y, POSITION x)
{
        int i;
        POSITION yy, xx;

        if (!in_bounds(y, x)) return;

#ifdef COMPLEX_WALL_ILLUMINATION /* COMPLEX_WALL_ILLUMINATION */

        if ((y != p_ptr->y) && (x != p_ptr->x))
        {
                yy = (y < p_ptr->y) ? (y - 1) : (y + 1);
                xx = (x < p_ptr->x) ? (x - 1) : (x + 1);
                update_local_illumination_aux(yy, xx);
                update_local_illumination_aux(y, xx);
                update_local_illumination_aux(yy, x);
        }
        else if (x != p_ptr->x) /* y == p_ptr->y */
        {
                xx = (x < p_ptr->x) ? (x - 1) : (x + 1);
                for (i = -1; i <= 1; i++)
                {
                        yy = y + i;
                        update_local_illumination_aux(yy, xx);
                }
                yy = y - 1;
                update_local_illumination_aux(yy, x);
                yy = y + 1;
                update_local_illumination_aux(yy, x);
        }
        else if (y != p_ptr->y) /* x == p_ptr->x */
        {
                yy = (y < p_ptr->y) ? (y - 1) : (y + 1);
                for (i = -1; i <= 1; i++)
                {
                        xx = x + i;
                        update_local_illumination_aux(yy, xx);
                }
                xx = x - 1;
                update_local_illumination_aux(y, xx);
                xx = x + 1;
                update_local_illumination_aux(y, xx);
        }
        else /* Player's grid */
        {
                for (i = 0; i < 8; i++)
                {
                        yy = y + ddy_cdd[i];
                        xx = x + ddx_cdd[i];
                        update_local_illumination_aux(yy, xx);
                }
        }

#else /* COMPLEX_WALL_ILLUMINATION */

        if ((y != p_ptr->y) && (x != p_ptr->x))
        {
                yy = (y < p_ptr->y) ? (y - 1) : (y + 1);
                xx = (x < p_ptr->x) ? (x - 1) : (x + 1);
                update_local_illumination_aux(yy, xx);
        }
        else if (x != p_ptr->x) /* y == p_ptr->y */
        {
                xx = (x < p_ptr->x) ? (x - 1) : (x + 1);
                for (i = -1; i <= 1; i++)
                {
                        yy = y + i;
                        update_local_illumination_aux(yy, xx);
                }
        }
        else if (y != p_ptr->y) /* x == p_ptr->x */
        {
                yy = (y < p_ptr->y) ? (y - 1) : (y + 1);
                for (i = -1; i <= 1; i++)
                {
                        xx = x + i;
                        update_local_illumination_aux(yy, xx);
                }
        }
        else /* Player's grid */
        {
                for (i = 0; i < 8; i++)
                {
                        yy = y + ddy_cdd[i];
                        xx = x + ddx_cdd[i];
                        update_local_illumination_aux(yy, xx);
                }
        }

#endif /* COMPLEX_WALL_ILLUMINATION */
}


/*!
 * @brief 指定された座標をプレイヤーが視覚に収められるかを返す。 / Can the player "see" the given grid in detail?
 * @param y y座標
 * @param x x座標
 * @return 視覚に収められる状態ならTRUEを返す
 * @details
 * He must have vision, illumination, and line of sight.\n
 * \n
 * Note -- "CAVE_LITE" is only set if the "torch" has "los()".\n
 * So, given "CAVE_LITE", we know that the grid is "fully visible".\n
 *\n
 * Note that "CAVE_GLOW" makes little sense for a wall, since it would mean\n
 * that a wall is visible from any direction.  That would be odd.  Except\n
 * under wizard light, which might make sense.  Thus, for walls, we require\n
 * not only that they be "CAVE_GLOW", but also, that they be adjacent to a\n
 * grid which is not only "CAVE_GLOW", but which is a non-wall, and which is\n
 * in line of sight of the player.\n
 *\n
 * This extra check is expensive, but it provides a more "correct" semantics.\n
 *\n
 * Note that we should not run this check on walls which are "outer walls" of\n
 * the dungeon, or we will induce a memory fault, but actually verifying all\n
 * of the locations would be extremely expensive.\n
 *\n
 * Thus, to speed up the function, we assume that all "perma-walls" which are\n
 * "CAVE_GLOW" are "illuminated" from all sides.  This is correct for all cases\n
 * except "vaults" and the "buildings" in town.  But the town is a hack anyway,\n
 * and the player has more important things on his mind when he is attacking a\n
 * monster vault.  It is annoying, but an extremely important optimization.\n
 *\n
 * Note that "glowing walls" are only considered to be "illuminated" if the\n
 * grid which is next to the wall in the direction of the player is also a\n
 * "glowing" grid.  This prevents the player from being able to "see" the\n
 * walls of illuminated rooms from a corridor outside the room.\n
 */
bool player_can_see_bold(POSITION y, POSITION x)
{
        grid_type *g_ptr;

        /* Blind players see nothing */
        if (p_ptr->blind) return FALSE;

        g_ptr = &current_floor_ptr->grid_array[y][x];

        /* Note that "torch-lite" yields "illumination" */
        if (g_ptr->info & (CAVE_LITE | CAVE_MNLT)) return TRUE;

        /* Require line of sight to the grid */
        if (!player_has_los_bold(y, x)) return FALSE;

        /* Noctovision of Ninja */
        if (p_ptr->see_nocto) return TRUE;

        /* Require "perma-lite" of the grid */
        if ((g_ptr->info & (CAVE_GLOW | CAVE_MNDK)) != CAVE_GLOW) return FALSE;

        /* Feature code (applying "mimic" field) */
        /* Floors are simple */
        if (feat_supports_los(get_feat_mimic(g_ptr))) return TRUE;

        /* Check for "local" illumination */
        return check_local_illumination(y, x);
}

/*!
 * @brief 指定された座標をプレイヤー収められていない状態かどうか / Returns true if the player's grid is dark
 * @return 視覚に収められていないならTRUEを返す
 * @details player_can_see_bold()関数の返り値の否定を返している。
 */
bool no_lite(void)
{
        return (!player_can_see_bold(p_ptr->y, p_ptr->x));
}


/*!
 * @brief 指定された座標が地震や階段生成の対象となるマスかを返す。 / Determine if a given location may be "destroyed"
 * @param y y座標
 * @param x x座標
 * @return 各種の変更が可能ならTRUEを返す。
 * @details
 * 条件は永久地形でなく、なおかつ該当のマスにアーティファクトが存在しないか、である。英語の旧コメントに反して＊破壊＊の抑止判定には現在使われていない。
 */
bool cave_valid_bold(POSITION y, POSITION x)
{
        grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];
        OBJECT_IDX this_o_idx, next_o_idx = 0;

        /* Forbid perma-grids */
        if (cave_perma_grid(g_ptr)) return (FALSE);

        /* Check objects */
        for (this_o_idx = g_ptr->o_idx; this_o_idx; this_o_idx = next_o_idx)
        {
                object_type *o_ptr;
                o_ptr = &current_floor_ptr->o_list[this_o_idx];

                /* Acquire next object */
                next_o_idx = o_ptr->next_o_idx;

                /* Forbid artifact grids */
                if (object_is_artifact(o_ptr)) return (FALSE);
        }

        /* Accept */
        return (TRUE);
}




/*!
 * 一般的にモンスターシンボルとして扱われる記号を定義する(幻覚処理向け) / Hack -- Legal monster codes
 */
static char image_monster_hack[] = \
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

/*!
 * 一般的にオブジェクトシンボルとして扱われる記号を定義する(幻覚処理向け) /  Hack -- Legal object codes
 */
static char image_object_hack[] = "?/|\\\"!$()_-=[]{},~";

/*!
 * @brief モンスターの表示を幻覚状態に差し替える / Mega-Hack -- Hallucinatory monster
 * @param ap 本来の色
 * @param cp 本来のシンボル
 * @return なし
 */
static void image_monster(TERM_COLOR *ap, SYMBOL_CODE *cp)
{
        /* Random symbol from set above */
        if (use_graphics)
        {
                monster_race *r_ptr = &r_info[randint1(max_r_idx - 1)];

                *cp = r_ptr->x_char;
                *ap = r_ptr->x_attr;
        }
        else
                /* Text mode */
        {
                *cp = (one_in_(25) ?
                        image_object_hack[randint0(sizeof(image_object_hack) - 1)] :
                        image_monster_hack[randint0(sizeof(image_monster_hack) - 1)]);

                /* Random color */
                *ap = randint1(15);
        }
}

/*!
 * @brief オブジェクトの表示を幻覚状態に差し替える / Hallucinatory object
 * @param ap 本来の色
 * @param cp 本来のシンボル
 * @return なし
 */
static void image_object(TERM_COLOR *ap, SYMBOL_CODE *cp)
{
        if (use_graphics)
        {
                object_kind *k_ptr = &k_info[randint1(max_k_idx - 1)];

                *cp = k_ptr->x_char;
                *ap = k_ptr->x_attr;
        }
        else
        {
                int n = sizeof(image_object_hack) - 1;

                *cp = image_object_hack[randint0(n)];

                /* Random color */
                *ap = randint1(15);
        }
}


/*!
 * @brief オブジェクト＆モンスターの表示を幻覚状態に差し替える / Hack -- Random hallucination
 * @param ap 本来の色
 * @param cp 本来のシンボル
 * @return なし
 */
static void image_random(TERM_COLOR *ap, SYMBOL_CODE *cp)
{
        /* Normally, assume monsters */
        if (randint0(100) < 75)
        {
                image_monster(ap, cp);
        }

        /* Otherwise, assume objects */
        else
        {
                image_object(ap, cp);
        }
}

/*!
 * 照明の表現を行うための色合いの関係を{暗闇時, 照明時} で定義する /
 * This array lists the effects of "brightness" on various "base" colours.\n
 *\n
 * This is used to do dynamic lighting effects in ascii :-)\n
 * At the moment, only the various "floor" tiles are affected.\n
 *\n
 * The layout of the array is [x][0] = light and [x][1] = dark.\n
 */
static TERM_COLOR lighting_colours[16][2] =
{
        /* TERM_DARK */
        {TERM_L_DARK, TERM_DARK},

        /* TERM_WHITE */
        {TERM_YELLOW, TERM_SLATE},

        /* TERM_SLATE */
        {TERM_WHITE, TERM_L_DARK},

        /* TERM_ORANGE */
        {TERM_L_UMBER, TERM_UMBER},

        /* TERM_RED */
        {TERM_RED, TERM_RED},

        /* TERM_GREEN */
        {TERM_L_GREEN, TERM_GREEN},

        /* TERM_BLUE */
        {TERM_BLUE, TERM_BLUE},

        /* TERM_UMBER */
        {TERM_L_UMBER, TERM_RED},

        /* TERM_L_DARK */
        {TERM_SLATE, TERM_L_DARK},

        /* TERM_L_WHITE */
        {TERM_WHITE, TERM_SLATE},

        /* TERM_VIOLET */
        {TERM_L_RED, TERM_BLUE},

        /* TERM_YELLOW */
        {TERM_YELLOW, TERM_ORANGE},

        /* TERM_L_RED */
        {TERM_L_RED, TERM_L_RED},

        /* TERM_L_GREEN */
        {TERM_L_GREEN, TERM_GREEN},

        /* TERM_L_BLUE */
        {TERM_L_BLUE, TERM_L_BLUE},

        /* TERM_L_UMBER */
        {TERM_L_UMBER, TERM_UMBER}
};

/*!
 * @brief 調査中
 * @todo コメントを付加すること
 */
void apply_default_feat_lighting(TERM_COLOR f_attr[F_LIT_MAX], SYMBOL_CODE f_char[F_LIT_MAX])
{
        TERM_COLOR s_attr = f_attr[F_LIT_STANDARD];
        SYMBOL_CODE s_char = f_char[F_LIT_STANDARD];
        int i;

        if (is_ascii_graphics(s_attr)) /* For ASCII */
        {
                f_attr[F_LIT_LITE] = lighting_colours[s_attr & 0x0f][0];
                f_attr[F_LIT_DARK] = lighting_colours[s_attr & 0x0f][1];
                for (i = F_LIT_NS_BEGIN; i < F_LIT_MAX; i++) f_char[i] = s_char;
        }
        else /* For tile graphics */
        {
                for (i = F_LIT_NS_BEGIN; i < F_LIT_MAX; i++) f_attr[i] = s_attr;
                f_char[F_LIT_LITE] = s_char + 2;
                f_char[F_LIT_DARK] = s_char + 1;
        }
}


/*!
 * モンスターにより照明が消されている地形か否かを判定する。 / Is this grid "darkened" by monster?
 */
#define darkened_grid(C) \
        ((((C)->info & (CAVE_VIEW | CAVE_LITE | CAVE_MNLT | CAVE_MNDK)) == (CAVE_VIEW | CAVE_MNDK)) && \
        !p_ptr->see_nocto)


 /*!
  * @brief Mコマンドによる縮小マップの表示を行う / Extract the attr/char to display at the given (legal) map location
  * @details
  * Basically, we "paint" the chosen attr/char in several passes, starting\n
  * with any known "terrain features" (defaulting to darkness), then adding\n
  * any known "objects", and finally, adding any known "monsters".  This\n
  * is not the fastest method but since most of the calls to this function\n
  * are made for grids with no monsters or objects, it is fast enough.\n
  *\n
  * Note that this function, if used on the grid containing the "player",\n
  * will return the attr/char of the grid underneath the player, and not\n
  * the actual player attr/char itself, allowing a lot of optimization\n
  * in various "display" functions.\n
  *\n
  * Note that the "zero" entry in the feature/object/monster arrays are\n
  * used to provide "special" attr/char codes, with "monster zero" being\n
  * used for the player attr/char, "object zero" being used for the "stack"\n
  * attr/char, and "feature zero" being used for the "nothing" attr/char,\n
  * though this function makes use of only "feature zero".\n
  *\n
  * Note that monsters can have some "special" flags, including "ATTR_MULTI",\n
  * which means their color changes, and "ATTR_CLEAR", which means they take\n
  * the color of whatever is under them, and "CHAR_CLEAR", which means that\n
  * they take the symbol of whatever is under them.  Technically, the flag\n
  * "CHAR_MULTI" is supposed to indicate that a monster looks strange when\n
  * examined, but this flag is currently ignored.\n
  *\n
  * Currently, we do nothing with multi-hued objects, because there are\n
  * not any.  If there were, they would have to set "shimmer_objects"\n
  * when they were created, and then new "shimmer" code in "dungeon.c"\n
  * would have to be created handle the "shimmer" effect, and the code\n
  * in "current_floor_ptr->grid_array.c" would have to be updated to create the shimmer effect.\n
  *\n
  * Note the effects of hallucination.  Objects always appear as random\n
  * "objects", monsters as random "monsters", and normal grids occasionally\n
  * appear as random "monsters" or "objects", but note that these random\n
  * "monsters" and "objects" are really just "colored ascii symbols".\n
  *\n
  * Note that "floors" and "invisible traps" (and "zero" features) are\n
  * drawn as "floors" using a special check for optimization purposes,\n
  * and these are the only features which get drawn using the special\n
  * lighting effects activated by "view_special_lite".\n
  *\n
  * Note the use of the "mimic" field in the "terrain feature" processing,\n
  * which allows any feature to "pretend" to be another feature.  This is\n
  * used to "hide" secret doors, and to make all "doors" appear the same,\n
  * and all "walls" appear the same, and "hidden" treasure stay hidden.\n
  * It is possible to use this field to make a feature "look" like a floor,\n
  * but the "special lighting effects" for floors will not be used.\n
  *\n
  * Note the use of the new "terrain feature" information.  Note that the\n
  * assumption that all interesting "objects" and "terrain features" are\n
  * memorized allows extremely optimized processing below.  Note the use\n
  * of separate flags on objects to mark them as memorized allows a grid\n
  * to have memorized "terrain" without granting knowledge of any object\n
  * which may appear in that grid.\n
  *\n
  * Note the efficient code used to determine if a "floor" grid is\n
  * "memorized" or "viewable" by the player, where the test for the\n
  * grid being "viewable" is based on the facts that (1) the grid\n
  * must be "lit" (torch-lit or perma-lit), (2) the grid must be in\n
  * line of sight, and (3) the player must not be blind, and uses the\n
  * assumption that all torch-lit grids are in line of sight.\n
  *\n
  * Note that floors (and invisible traps) are the only grids which are\n
  * not memorized when seen, so only these grids need to check to see if\n
  * the grid is "viewable" to the player (if it is not memorized).  Since\n
  * most non-memorized grids are in fact walls, this induces *massive*\n
  * efficiency, at the cost of *forcing* the memorization of non-floor\n
  * grids when they are first seen.  Note that "invisible traps" are\n
  * always treated exactly like "floors", which prevents "cheating".\n
  *\n
  * Note the "special lighting effects" which can be activated for floor\n
  * grids using the "view_special_lite" option (for "white" floor grids),\n
  * causing certain grids to be displayed using special colors.  If the\n
  * player is "blind", we will use "dark gray", else if the grid is lit\n
  * by the torch, and the "view_yellow_lite" option is set, we will use\n
  * "yellow", else if the grid is "dark", we will use "dark gray", else\n
  * if the grid is not "viewable", and the "view_bright_lite" option is\n
  * set, and the we will use "slate" (gray).  We will use "white" for all\n
  * other cases, in particular, for illuminated viewable floor grids.\n
  *\n
  * Note the "special lighting effects" which can be activated for wall\n
  * grids using the "view_granite_lite" option (for "white" wall grids),\n
  * causing certain grids to be displayed using special colors.  If the\n
  * player is "blind", we will use "dark gray", else if the grid is lit\n
  * by the torch, and the "view_yellow_lite" option is set, we will use\n
  * "yellow", else if the "view_bright_lite" option is set, and the grid\n
  * is not "viewable", or is "dark", or is glowing, but not when viewed\n
  * from the player's current location, we will use "slate" (gray).  We\n
  * will use "white" for all other cases, in particular, for correctly\n
  * illuminated viewable wall grids.\n
  *\n
  * Note that, when "view_granite_lite" is set, we use an inline version\n
  * of the "player_can_see_bold()" function to check the "viewability" of\n
  * grids when the "view_bright_lite" option is set, and we do NOT use\n
  * any special colors for "dark" wall grids, since this would allow the\n
  * player to notice the walls of illuminated rooms from a hallway that\n
  * happened to run beside the room.  The alternative, by the way, would\n
  * be to prevent the generation of hallways next to rooms, but this\n
  * would still allow problems when digging towards a room.\n
  *\n
  * Note that bizarre things must be done when the "attr" and/or "char"\n
  * codes have the "high-bit" set, since these values are used to encode\n
  * various "special" pictures in some versions, and certain situations,\n
  * such as "multi-hued" or "clear" monsters, cause the attr/char codes\n
  * to be "scrambled" in various ways.\n
  *\n
  * Note that eventually we may use the "&" symbol for embedded treasure,\n
  * and use the "*" symbol to indicate multiple objects, though this will\n
  * have to wait for Angband 2.8.0 or later.  Note that currently, this\n
  * is not important, since only one object or terrain feature is allowed\n
  * in each grid.  If needed, "k_info[0]" will hold the "stack" attr/char.\n
  *\n
  * Note the assumption that doing "x_ptr = &x_info[x]" plus a few of\n
  * "x_ptr->xxx", is quicker than "x_info[x].xxx", if this is incorrect\n
  * then a whole lot of code should be changed...  XXX XXX\n
  */
void map_info(POSITION y, POSITION x, TERM_COLOR *ap, SYMBOL_CODE *cp, TERM_COLOR *tap, SYMBOL_CODE *tcp)
{
        /* Get the current_floor_ptr->grid_array */
        grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];

        OBJECT_IDX this_o_idx, next_o_idx = 0;

        /* Feature code (applying "mimic" field) */
        FEAT_IDX feat = get_feat_mimic(g_ptr);

        /* Access floor */
        feature_type *f_ptr = &f_info[feat];

        TERM_COLOR a;
        SYMBOL_CODE c;

        /* Boring grids (floors, etc) */
        if (!have_flag(f_ptr->flags, FF_REMEMBER))
        {
                /*
                 * Handle Memorized or visible floor
                 *
                 * No visual when blinded.
                 *   (to prevent strange effects on darkness breath)
                 * otherwise,
                 * - Can see grids with CAVE_MARK.
                 * - Can see grids with CAVE_LITE or CAVE_MNLT.
                 *   (Such grids also have CAVE_VIEW)
                 * - Can see grids with CAVE_VIEW unless darkened by monsters.
                 */
                if (!p_ptr->blind &&
                        ((g_ptr->info & (CAVE_MARK | CAVE_LITE | CAVE_MNLT)) ||
                        ((g_ptr->info & CAVE_VIEW) && (((g_ptr->info & (CAVE_GLOW | CAVE_MNDK)) == CAVE_GLOW) || p_ptr->see_nocto))))
                {
                        /* Normal attr/char */
                        a = f_ptr->x_attr[F_LIT_STANDARD];
                        c = f_ptr->x_char[F_LIT_STANDARD];

                        if (p_ptr->wild_mode)
                        {
                                /* Special lighting effects */
                                /* Handle "night" */
                                if (view_special_lite && !is_daytime())
                                {
                                        /* Use a darkened colour/tile */
                                        a = f_ptr->x_attr[F_LIT_DARK];
                                        c = f_ptr->x_char[F_LIT_DARK];
                                }
                        }

                        /* Mega-Hack -- Handle "in-sight" and "darkened" grids */
                        else if (darkened_grid(g_ptr))
                        {
                                /* Unsafe grid -- idea borrowed from Unangband */
                                feat = (view_unsafe_grids && (g_ptr->info & CAVE_UNSAFE)) ? feat_undetected : feat_none;

                                /* Access darkness */
                                f_ptr = &f_info[feat];

                                /* Char and attr of darkness */
                                a = f_ptr->x_attr[F_LIT_STANDARD];
                                c = f_ptr->x_char[F_LIT_STANDARD];
                        }

                        /* Special lighting effects */
                        else if (view_special_lite)
                        {
                                /* Handle "torch-lit" grids */
                                if (g_ptr->info & (CAVE_LITE | CAVE_MNLT))
                                {
                                        /* Torch lite */
                                        if (view_yellow_lite)
                                        {
                                                /* Use a brightly lit colour/tile */
                                                a = f_ptr->x_attr[F_LIT_LITE];
                                                c = f_ptr->x_char[F_LIT_LITE];
                                        }
                                }

                                /* Handle "dark" grids */
                                else if ((g_ptr->info & (CAVE_GLOW | CAVE_MNDK)) != CAVE_GLOW)
                                {
                                        /* Use a darkened colour/tile */
                                        a = f_ptr->x_attr[F_LIT_DARK];
                                        c = f_ptr->x_char[F_LIT_DARK];
                                }

                                /* Handle "out-of-sight" grids */
                                else if (!(g_ptr->info & CAVE_VIEW))
                                {
                                        /* Special flag */
                                        if (view_bright_lite)
                                        {
                                                /* Use a darkened colour/tile */
                                                a = f_ptr->x_attr[F_LIT_DARK];
                                                c = f_ptr->x_char[F_LIT_DARK];
                                        }
                                }
                        }
                }

                /* Unknown */
                else
                {
                        /* Unsafe grid -- idea borrowed from Unangband */
                        feat = (view_unsafe_grids && (g_ptr->info & CAVE_UNSAFE)) ? feat_undetected : feat_none;

                        /* Access darkness */
                        f_ptr = &f_info[feat];

                        /* Normal attr/char */
                        a = f_ptr->x_attr[F_LIT_STANDARD];
                        c = f_ptr->x_char[F_LIT_STANDARD];
                }
        }

        /* Interesting grids (non-floors) */
        else
        {
                /* Memorized grids */
                if (g_ptr->info & CAVE_MARK)
                {
                        /* Normal attr/char */
                        a = f_ptr->x_attr[F_LIT_STANDARD];
                        c = f_ptr->x_char[F_LIT_STANDARD];

                        if (p_ptr->wild_mode)
                        {
                                /* Special lighting effects */
                                /* Handle "blind" or "night" */
                                if (view_granite_lite && (p_ptr->blind || !is_daytime()))
                                {
                                        /* Use a darkened colour/tile */
                                        a = f_ptr->x_attr[F_LIT_DARK];
                                        c = f_ptr->x_char[F_LIT_DARK];
                                }
                        }

                        /* Mega-Hack -- Handle "in-sight" and "darkened" grids */
                        else if (darkened_grid(g_ptr) && !p_ptr->blind)
                        {
                                if (have_flag(f_ptr->flags, FF_LOS) && have_flag(f_ptr->flags, FF_PROJECT))
                                {
                                        /* Unsafe grid -- idea borrowed from Unangband */
                                        feat = (view_unsafe_grids && (g_ptr->info & CAVE_UNSAFE)) ? feat_undetected : feat_none;

                                        /* Access darkness */
                                        f_ptr = &f_info[feat];

                                        /* Char and attr of darkness */
                                        a = f_ptr->x_attr[F_LIT_STANDARD];
                                        c = f_ptr->x_char[F_LIT_STANDARD];
                                }
                                else if (view_granite_lite && view_bright_lite)
                                {
                                        /* Use a darkened colour/tile */
                                        a = f_ptr->x_attr[F_LIT_DARK];
                                        c = f_ptr->x_char[F_LIT_DARK];
                                }
                        }

                        /* Special lighting effects */
                        else if (view_granite_lite)
                        {
                                /* Handle "blind" */
                                if (p_ptr->blind)
                                {
                                        /* Use a darkened colour/tile */
                                        a = f_ptr->x_attr[F_LIT_DARK];
                                        c = f_ptr->x_char[F_LIT_DARK];
                                }

                                /* Handle "torch-lit" grids */
                                else if (g_ptr->info & (CAVE_LITE | CAVE_MNLT))
                                {
                                        /* Torch lite */
                                        if (view_yellow_lite)
                                        {
                                                /* Use a brightly lit colour/tile */
                                                a = f_ptr->x_attr[F_LIT_LITE];
                                                c = f_ptr->x_char[F_LIT_LITE];
                                        }
                                }

                                /* Handle "view_bright_lite" */
                                else if (view_bright_lite)
                                {
                                        /* Not viewable */
                                        if (!(g_ptr->info & CAVE_VIEW))
                                        {
                                                /* Use a darkened colour/tile */
                                                a = f_ptr->x_attr[F_LIT_DARK];
                                                c = f_ptr->x_char[F_LIT_DARK];
                                        }

                                        /* Not glowing */
                                        else if ((g_ptr->info & (CAVE_GLOW | CAVE_MNDK)) != CAVE_GLOW)
                                        {
                                                /* Use a darkened colour/tile */
                                                a = f_ptr->x_attr[F_LIT_DARK];
                                                c = f_ptr->x_char[F_LIT_DARK];
                                        }

                                        /* Not glowing correctly */
                                        else if (!have_flag(f_ptr->flags, FF_LOS) && !check_local_illumination(y, x))
                                        {
                                                /* Use a darkened colour/tile */
                                                a = f_ptr->x_attr[F_LIT_DARK];
                                                c = f_ptr->x_char[F_LIT_DARK];
                                        }
                                }
                        }
                }

                /* Unknown */
                else
                {
                        /* Unsafe grid -- idea borrowed from Unangband */
                        feat = (view_unsafe_grids && (g_ptr->info & CAVE_UNSAFE)) ? feat_undetected : feat_none;

                        /* Access feature */
                        f_ptr = &f_info[feat];

                        /* Normal attr/char */
                        a = f_ptr->x_attr[F_LIT_STANDARD];
                        c = f_ptr->x_char[F_LIT_STANDARD];
                }
        }

        if (feat_priority == -1) feat_priority = f_ptr->priority;

        /* Save the terrain info for the transparency effects */
        (*tap) = a;
        (*tcp) = c;

        /* Save the info */
        (*ap) = a;
        (*cp) = c;

        /* Hack -- rare random hallucination, except on outer dungeon walls */
        if (p_ptr->image)
        {
                if (one_in_(256))
                {
                        /* Hallucinate */
                        image_random(ap, cp);
                }
        }

        /* Objects */
        for (this_o_idx = g_ptr->o_idx; this_o_idx; this_o_idx = next_o_idx)
        {
                object_type *o_ptr;
                o_ptr = &current_floor_ptr->o_list[this_o_idx];

                /* Acquire next object */
                next_o_idx = o_ptr->next_o_idx;

                /* Memorized objects */
                if (o_ptr->marked & OM_FOUND)
                {
                        if (display_autopick)
                        {
                                byte act;

                                match_autopick = is_autopick(o_ptr);
                                if (match_autopick == -1)
                                        continue;

                                act = autopick_list[match_autopick].action;

                                if ((act & DO_DISPLAY) && (act & display_autopick))
                                {
                                        autopick_obj = o_ptr;
                                }
                                else
                                {
                                        match_autopick = -1;
                                        continue;
                                }
                        }
                        /* Normal char */
                        (*cp) = object_char(o_ptr);

                        /* Normal attr */
                        (*ap) = object_attr(o_ptr);

                        feat_priority = 20;

                        /* Hack -- hallucination */
                        if (p_ptr->image) image_object(ap, cp);

                        break;
                }
        }


        /* Handle monsters */
        if (g_ptr->m_idx && display_autopick == 0)
        {
                monster_type *m_ptr = &current_floor_ptr->m_list[g_ptr->m_idx];

                /* Visible monster */
                if (m_ptr->ml)
                {
                        monster_race *r_ptr = &r_info[m_ptr->ap_r_idx];

                        feat_priority = 30;

                        /* Hallucination */
                        if (p_ptr->image)
                        {
                                /*
                                 * Monsters with both CHAR_CLEAR and ATTR_CLEAR
                                 * flags are always unseen.
                                 */
                                if ((r_ptr->flags1 & (RF1_CHAR_CLEAR | RF1_ATTR_CLEAR)) == (RF1_CHAR_CLEAR | RF1_ATTR_CLEAR))
                                {
                                        /* Do nothing */
                                }
                                else
                                {
                                        /* Hallucinatory monster */
                                        image_monster(ap, cp);
                                }
                        }
                        else
                        {
                                /* Monster attr/char */
                                a = r_ptr->x_attr;
                                c = r_ptr->x_char;

                                /* Normal monsters */
                                if (!(r_ptr->flags1 & (RF1_CHAR_CLEAR | RF1_SHAPECHANGER | RF1_ATTR_CLEAR
                                        | RF1_ATTR_MULTI | RF1_ATTR_SEMIRAND)))
                                {
                                        /* Desired monster attr/char */
                                        *ap = a;
                                        *cp = c;
                                }

                                /*
                                 * Monsters with both CHAR_CLEAR and ATTR_CLEAR
                                 * flags are always unseen.
                                 */
                                else if ((r_ptr->flags1 & (RF1_CHAR_CLEAR | RF1_ATTR_CLEAR)) == (RF1_CHAR_CLEAR | RF1_ATTR_CLEAR))
                                {
                                        /* Do nothing */
                                }

                                else
                                {
                                        /***  Monster's attr  ***/
                                        if ((r_ptr->flags1 & RF1_ATTR_CLEAR) && (*ap != TERM_DARK) && !use_graphics)
                                        {
                                                /* Clear-attr */
                                                /* Do nothing */
                                        }
                                        else if ((r_ptr->flags1 & RF1_ATTR_MULTI) && !use_graphics)
                                        {
                                                /* Multi-hued attr */
                                                if (r_ptr->flags2 & RF2_ATTR_ANY) *ap = randint1(15);
                                                else switch (randint1(7))
                                                {
                                                case 1: *ap = TERM_RED;     break;
                                                case 2: *ap = TERM_L_RED;   break;
                                                case 3: *ap = TERM_WHITE;   break;
                                                case 4: *ap = TERM_L_GREEN; break;
                                                case 5: *ap = TERM_BLUE;    break;
                                                case 6: *ap = TERM_L_DARK;  break;
                                                case 7: *ap = TERM_GREEN;   break;
                                                }
                                        }
                                        else if ((r_ptr->flags1 & RF1_ATTR_SEMIRAND) && !use_graphics)
                                        {
                                                /* Use semi-random attr (usually mimics' colors vary) */
                                                *ap = g_ptr->m_idx % 15 + 1;
                                        }
                                        else
                                        {
                                                /* Normal case */
                                                *ap = a;
                                        }

                                        /***  Monster's char  ***/
                                        if ((r_ptr->flags1 & RF1_CHAR_CLEAR) && (*cp != ' ') && !use_graphics)
                                        {
                                                /* Clear-char */
                                                /* Do nothing */
                                        }
                                        else if (r_ptr->flags1 & RF1_SHAPECHANGER)
                                        {
                                                if (use_graphics)
                                                {
                                                        monster_race *tmp_r_ptr = &r_info[randint1(max_r_idx - 1)];
                                                        *cp = tmp_r_ptr->x_char;
                                                        *ap = tmp_r_ptr->x_attr;
                                                }
                                                else
                                                {
                                                        *cp = (one_in_(25) ?
                                                                image_object_hack[randint0(sizeof(image_object_hack) - 1)] :
                                                                image_monster_hack[randint0(sizeof(image_monster_hack) - 1)]);
                                                }
                                        }
                                        else
                                        {
                                                /* Normal case */
                                                *cp = c;
                                        }
                                }
                        }
                }
        }

        /* Handle "player" */
        if (player_bold(y, x))
        {
                monster_race *r_ptr = &r_info[0];
                *ap = r_ptr->x_attr;
                *cp = r_ptr->x_char;
                feat_priority = 31;
        }
}


/*
 * Calculate panel colum of a location in the map
 */
static int panel_col_of(int col)
{
        col -= panel_col_min;
        if (use_bigtile) col *= 2;
        return col + 13;
}


/*
 * Moves the cursor to a given MAP (y,x) location
 */
void move_cursor_relative(int row, int col)
{
        /* Real co-ords convert to screen positions */
        row -= panel_row_prt;

        /* Go there */
        Term_gotoxy(panel_col_of(col), row);
}



/*
 * Place an attr/char pair at the given map coordinate, if legal.
 */
void print_rel(SYMBOL_CODE c, TERM_COLOR a, TERM_LEN y, TERM_LEN x)
{
        /* Only do "legal" locations */
        if (panel_contains(y, x))
        {
                /* Hack -- fake monochrome */
                if (!use_graphics)
                {
                        if (world_monster) a = TERM_DARK;
                        else if (IS_INVULN() || p_ptr->timewalk) a = TERM_WHITE;
                        else if (p_ptr->wraith_form) a = TERM_L_DARK;
                }

                /* Draw the char using the attr */
                Term_queue_bigchar(panel_col_of(x), y - panel_row_prt, a, c, 0, 0);
        }
}





/*
 * Memorize interesting viewable object/features in the given grid
 *
 * This function should only be called on "legal" grids.
 *
 * This function will memorize the object and/or feature in the given
 * grid, if they are (1) viewable and (2) interesting.  Note that all
 * objects are interesting, all terrain features except floors (and
 * invisible traps) are interesting, and floors (and invisible traps)
 * are interesting sometimes (depending on various options involving
 * the illumination of floor grids).
 *
 * The automatic memorization of all objects and non-floor terrain
 * features as soon as they are displayed allows incredible amounts
 * of optimization in various places, especially "map_info()".
 *
 * Note that the memorization of objects is completely separate from
 * the memorization of terrain features, preventing annoying floor
 * memorization when a detected object is picked up from a dark floor,
 * and object memorization when an object is dropped into a floor grid
 * which is memorized but out-of-sight.
 *
 * This function should be called every time the "memorization" of
 * a grid (or the object in a grid) is called into question, such
 * as when an object is created in a grid, when a terrain feature
 * "changes" from "floor" to "non-floor", when any grid becomes
 * "illuminated" or "viewable", and when a "floor" grid becomes
 * "torch-lit".
 *
 * Note the relatively efficient use of this function by the various
 * "update_view()" and "update_lite()" calls, to allow objects and
 * terrain features to be memorized (and drawn) whenever they become
 * viewable or illuminated in any way, but not when they "maintain"
 * or "lose" their previous viewability or illumination.
 *
 * Note the butchered "internal" version of "player_can_see_bold()",
 * optimized primarily for the most common cases, that is, for the
 * non-marked floor grids.
 */
void note_spot(POSITION y, POSITION x)
{
        grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];
        OBJECT_IDX this_o_idx, next_o_idx = 0;

        /* Blind players see nothing */
        if (p_ptr->blind) return;

        /* Analyze non-torch-lit grids */
        if (!(g_ptr->info & (CAVE_LITE | CAVE_MNLT)))
        {
                /* Require line of sight to the grid */
                if (!(g_ptr->info & (CAVE_VIEW))) return;

                /* Require "perma-lite" of the grid */
                if ((g_ptr->info & (CAVE_GLOW | CAVE_MNDK)) != CAVE_GLOW)
                {
                        /* Not Ninja */
                        if (!p_ptr->see_nocto) return;
                }
        }


        /* Hack -- memorize objects */
        for (this_o_idx = g_ptr->o_idx; this_o_idx; this_o_idx = next_o_idx)
        {
                object_type *o_ptr = &current_floor_ptr->o_list[this_o_idx];

                /* Acquire next object */
                next_o_idx = o_ptr->next_o_idx;

                /* Memorize objects */
                o_ptr->marked |= OM_FOUND;
        }


        /* Hack -- memorize grids */
        if (!(g_ptr->info & (CAVE_MARK)))
        {
                /* Feature code (applying "mimic" field) */
                feature_type *f_ptr = &f_info[get_feat_mimic(g_ptr)];

                /* Memorize some "boring" grids */
                if (!have_flag(f_ptr->flags, FF_REMEMBER))
                {
                        /* Option -- memorize all torch-lit floors */
                        if (view_torch_grids &&
                                ((g_ptr->info & (CAVE_LITE | CAVE_MNLT)) || p_ptr->see_nocto))
                        {
                                g_ptr->info |= (CAVE_MARK);
                        }

                        /* Option -- memorize all perma-lit floors */
                        else if (view_perma_grids && ((g_ptr->info & (CAVE_GLOW | CAVE_MNDK)) == CAVE_GLOW))
                        {
                                g_ptr->info |= (CAVE_MARK);
                        }
                }

                /* Memorize normal grids */
                else if (have_flag(f_ptr->flags, FF_LOS))
                {
                        g_ptr->info |= (CAVE_MARK);
                }

                /* Memorize torch-lit walls */
                else if (g_ptr->info & (CAVE_LITE | CAVE_MNLT))
                {
                        g_ptr->info |= (CAVE_MARK);
                }

                /* Memorize walls seen by noctovision of Ninja */
                else if (p_ptr->see_nocto)
                {
                        g_ptr->info |= (CAVE_MARK);
                }

                /* Memorize certain non-torch-lit wall grids */
                else if (check_local_illumination(y, x))
                {
                        g_ptr->info |= (CAVE_MARK);
                }
        }

        /* Memorize terrain of the grid */
        g_ptr->info |= (CAVE_KNOWN);
}


void display_dungeon(void)
{
        TERM_LEN x, y;
        TERM_COLOR a;
        SYMBOL_CODE c;

        TERM_COLOR ta = 0;
        SYMBOL_CODE tc = '\0';

        for (x = p_ptr->x - Term->wid / 2 + 1; x <= p_ptr->x + Term->wid / 2; x++)
        {
                for (y = p_ptr->y - Term->hgt / 2 + 1; y <= p_ptr->y + Term->hgt / 2; y++)
                {
                        if (in_bounds2(y, x))
                        {

                                /* Examine the grid */
                                map_info(y, x, &a, &c, &ta, &tc);

                                /* Hack -- fake monochrome */
                                if (!use_graphics)
                                {
                                        if (world_monster) a = TERM_DARK;
                                        else if (IS_INVULN() || p_ptr->timewalk) a = TERM_WHITE;
                                        else if (p_ptr->wraith_form) a = TERM_L_DARK;
                                }

                                /* Hack -- Queue it */
                                Term_queue_char(x - p_ptr->x + Term->wid / 2 - 1, y - p_ptr->y + Term->hgt / 2 - 1, a, c, ta, tc);
                        }
                        else
                        {
                                /* Clear out-of-bound tiles */

                                /* Access darkness */
                                feature_type *f_ptr = &f_info[feat_none];

                                /* Normal attr */
                                a = f_ptr->x_attr[F_LIT_STANDARD];

                                /* Normal char */
                                c = f_ptr->x_char[F_LIT_STANDARD];

                                /* Hack -- Queue it */
                                Term_queue_char(x - p_ptr->x + Term->wid / 2 - 1, y - p_ptr->y + Term->hgt / 2 - 1, a, c, ta, tc);
                        }
                }
        }
}


/*
 * Redraw (on the screen) a given MAP location
 *
 * This function should only be called on "legal" grids
 */
void lite_spot(POSITION y, POSITION x)
{
        /* Redraw if on screen */
        if (panel_contains(y, x) && in_bounds2(y, x))
        {
                TERM_COLOR a;
                SYMBOL_CODE c;

                TERM_COLOR ta;
                SYMBOL_CODE tc;

                /* Examine the grid */
                map_info(y, x, &a, &c, &ta, &tc);

                /* Hack -- fake monochrome */
                if (!use_graphics)
                {
                        if (world_monster) a = TERM_DARK;
                        else if (IS_INVULN() || p_ptr->timewalk) a = TERM_WHITE;
                        else if (p_ptr->wraith_form) a = TERM_L_DARK;
                }

                /* Hack -- Queue it */
                Term_queue_bigchar(panel_col_of(x), y - panel_row_prt, a, c, ta, tc);

                /* Update sub-windows */
                p_ptr->window |= (PW_OVERHEAD | PW_DUNGEON);
        }
}


/*
 * Prints the map of the dungeon
 *
 * Note that, for efficiency, we contain an "optimized" version
 * of both "lite_spot()" and "print_rel()", and that we use the
 * "lite_spot()" function to display the player grid, if needed.
 */
void prt_map(void)
{
        POSITION x, y;
        int v;

        /* map bounds */
        POSITION xmin, xmax, ymin, ymax;

        TERM_LEN wid, hgt;

        Term_get_size(&wid, &hgt);

        /* Remove map offset */
        wid -= COL_MAP + 2;
        hgt -= ROW_MAP + 2;

        /* Access the cursor state */
        (void)Term_get_cursor(&v);

        /* Hide the cursor */
        (void)Term_set_cursor(0);

        /* Get bounds */
        xmin = (0 < panel_col_min) ? panel_col_min : 0;
        xmax = (current_floor_ptr->width - 1 > panel_col_max) ? panel_col_max : current_floor_ptr->width - 1;
        ymin = (0 < panel_row_min) ? panel_row_min : 0;
        ymax = (current_floor_ptr->height - 1 > panel_row_max) ? panel_row_max : current_floor_ptr->height - 1;

        /* Bottom section of screen */
        for (y = 1; y <= ymin - panel_row_prt; y++)
        {
                /* Erase the section */
                Term_erase(COL_MAP, y, wid);
        }

        /* Top section of screen */
        for (y = ymax - panel_row_prt; y <= hgt; y++)
        {
                /* Erase the section */
                Term_erase(COL_MAP, y, wid);
        }

        /* Dump the map */
        for (y = ymin; y <= ymax; y++)
        {
                /* Scan the columns of row "y" */
                for (x = xmin; x <= xmax; x++)
                {
                        TERM_COLOR a;
                        SYMBOL_CODE c;

                        TERM_COLOR ta;
                        SYMBOL_CODE tc;

                        /* Determine what is there */
                        map_info(y, x, &a, &c, &ta, &tc);

                        /* Hack -- fake monochrome */
                        if (!use_graphics)
                        {
                                if (world_monster) a = TERM_DARK;
                                else if (IS_INVULN() || p_ptr->timewalk) a = TERM_WHITE;
                                else if (p_ptr->wraith_form) a = TERM_L_DARK;
                        }

                        /* Efficiency -- Redraw that grid of the map */
                        Term_queue_bigchar(panel_col_of(x), y - panel_row_prt, a, c, ta, tc);
                }
        }

        /* Display player */
        lite_spot(p_ptr->y, p_ptr->x);

        /* Restore the cursor */
        (void)Term_set_cursor(v);
}



/*
 * print project path
 */
void prt_path(POSITION y, POSITION x)
{
        int i;
        int path_n;
        u16b path_g[512];
        byte_hack default_color = TERM_SLATE;

        if (!display_path) return;
        if (-1 == project_length)
                return;

        /* Get projection path */
        path_n = project_path(path_g, (project_length ? project_length : MAX_RANGE), p_ptr->y, p_ptr->x, y, x, PROJECT_PATH | PROJECT_THRU);

        p_ptr->redraw |= (PR_MAP);
        handle_stuff();

        /* Draw path */
        for (i = 0; i < path_n; i++)
        {
                POSITION ny = GRID_Y(path_g[i]);
                POSITION nx = GRID_X(path_g[i]);
                grid_type *g_ptr = &current_floor_ptr->grid_array[ny][nx];

                if (panel_contains(ny, nx))
                {
                        TERM_COLOR a = default_color;
                        char c;

                        TERM_COLOR ta = default_color;
                        char tc = '*';

                        if (g_ptr->m_idx && current_floor_ptr->m_list[g_ptr->m_idx].ml)
                        {
                                /* Determine what is there */
                                map_info(ny, nx, &a, &c, &ta, &tc);

                                if (!is_ascii_graphics(a))
                                        a = default_color;
                                else if (c == '.' && (a == TERM_WHITE || a == TERM_L_WHITE))
                                        a = default_color;
                                else if (a == default_color)
                                        a = TERM_WHITE;
                        }

                        if (!use_graphics)
                        {
                                if (world_monster) a = TERM_DARK;
                                else if (IS_INVULN() || p_ptr->timewalk) a = TERM_WHITE;
                                else if (p_ptr->wraith_form) a = TERM_L_DARK;
                        }

                        c = '*';

                        /* Hack -- Queue it */
                        Term_queue_bigchar(panel_col_of(nx), ny - panel_row_prt, a, c, ta, tc);
                }

                /* Known Wall */
                if ((g_ptr->info & CAVE_MARK) && !cave_have_flag_grid(g_ptr, FF_PROJECT)) break;

                /* Change color */
                if (nx == x && ny == y) default_color = TERM_L_DARK;
        }
}


static concptr simplify_list[][2] =
{
#ifdef JP
        {"の魔法書", ""},
        {NULL, NULL}
#else
        {"^Ring of ",   "="},
        {"^Amulet of ", "\""},
        {"^Scroll of ", "?"},
        {"^Scroll titled ", "?"},
        {"^Wand of "  , "-"},
        {"^Rod of "   , "-"},
        {"^Staff of " , "_"},
        {"^Potion of ", "!"},
        {" Spellbook ",""},
        {"^Book of ",   ""},
        {" Magic [",   "["},
        {" Book [",    "["},
        {" Arts [",    "["},
        {"^Set of ",    ""},
        {"^Pair of ",   ""},
        {NULL, NULL}
#endif
};

static void display_shortened_item_name(object_type *o_ptr, int y)
{
        char buf[MAX_NLEN];
        char *c = buf;
        int len = 0;
        TERM_COLOR attr;

        object_desc(buf, o_ptr, (OD_NO_FLAVOR | OD_OMIT_PREFIX | OD_NAME_ONLY));
        attr = tval_to_attr[o_ptr->tval % 128];

        if (p_ptr->image)
        {
                attr = TERM_WHITE;
                strcpy(buf, _("何か奇妙な物", "something strange"));
        }

        for (c = buf; *c; c++)
        {
                int i;
                for (i = 0; simplify_list[i][1]; i++)
                {
                        concptr org_w = simplify_list[i][0];

                        if (*org_w == '^')
                        {
                                if (c == buf)
                                        org_w++;
                                else
                                        continue;
                        }

                        if (!strncmp(c, org_w, strlen(org_w)))
                        {
                                char *s = c;
                                concptr tmp = simplify_list[i][1];
                                while (*tmp)
                                        *s++ = *tmp++;
                                tmp = c + strlen(org_w);
                                while (*tmp)
                                        *s++ = *tmp++;
                                *s = '\0';
                        }
                }
        }

        c = buf;
        len = 0;
        /* 半角 12 文字分で切る */
        while (*c)
        {
#ifdef JP
                if (iskanji(*c))
                {
                        if (len + 2 > 12) break;
                        c += 2;
                        len += 2;
                }
                else
#endif
                {
                        if (len + 1 > 12) break;
                        c++;
                        len++;
                }
        }
        *c = '\0';
        Term_putstr(0, y, 12, attr, buf);
}

/*
 * Display a "small-scale" map of the dungeon in the active Term
 */
void display_map(int *cy, int *cx)
{
        int i, j, x, y;

        TERM_COLOR ta;
        SYMBOL_CODE tc;

        byte tp;

        TERM_COLOR **bigma;
        SYMBOL_CODE **bigmc;
        byte **bigmp;

        TERM_COLOR **ma;
        SYMBOL_CODE **mc;
        byte **mp;

        /* Save lighting effects */
        bool old_view_special_lite = view_special_lite;
        bool old_view_granite_lite = view_granite_lite;

        TERM_LEN hgt, wid, yrat, xrat;

        int **match_autopick_yx;
        object_type ***object_autopick_yx;

        Term_get_size(&wid, &hgt);
        hgt -= 2;
        wid -= 14;
        if (use_bigtile) wid /= 2;

        yrat = (current_floor_ptr->height + hgt - 1) / hgt;
        xrat = (current_floor_ptr->width + wid - 1) / wid;

        /* Disable lighting effects */
        view_special_lite = FALSE;
        view_granite_lite = FALSE;

        /* Allocate the maps */
        C_MAKE(ma, (hgt + 2), TERM_COLOR *);
        C_MAKE(mc, (hgt + 2), char_ptr);
        C_MAKE(mp, (hgt + 2), byte_ptr);
        C_MAKE(match_autopick_yx, (hgt + 2), sint_ptr);
        C_MAKE(object_autopick_yx, (hgt + 2), object_type **);

        /* Allocate and wipe each line map */
        for (y = 0; y < (hgt + 2); y++)
        {
                /* Allocate one row each array */
                C_MAKE(ma[y], (wid + 2), TERM_COLOR);
                C_MAKE(mc[y], (wid + 2), char);
                C_MAKE(mp[y], (wid + 2), byte);
                C_MAKE(match_autopick_yx[y], (wid + 2), int);
                C_MAKE(object_autopick_yx[y], (wid + 2), object_type *);

                for (x = 0; x < wid + 2; ++x)
                {
                        match_autopick_yx[y][x] = -1;
                        object_autopick_yx[y][x] = NULL;

                        /* Nothing here */
                        ma[y][x] = TERM_WHITE;
                        mc[y][x] = ' ';

                        /* No priority */
                        mp[y][x] = 0;
                }
        }

        /* Allocate the maps */
        C_MAKE(bigma, (current_floor_ptr->height + 2), TERM_COLOR *);
        C_MAKE(bigmc, (current_floor_ptr->height + 2), char_ptr);
        C_MAKE(bigmp, (current_floor_ptr->height + 2), byte_ptr);

        /* Allocate and wipe each line map */
        for (y = 0; y < (current_floor_ptr->height + 2); y++)
        {
                /* Allocate one row each array */
                C_MAKE(bigma[y], (current_floor_ptr->width + 2), TERM_COLOR);
                C_MAKE(bigmc[y], (current_floor_ptr->width + 2), char);
                C_MAKE(bigmp[y], (current_floor_ptr->width + 2), byte);

                for (x = 0; x < current_floor_ptr->width + 2; ++x)
                {
                        /* Nothing here */
                        bigma[y][x] = TERM_WHITE;
                        bigmc[y][x] = ' ';

                        /* No priority */
                        bigmp[y][x] = 0;
                }
        }

        /* Fill in the map */
        for (i = 0; i < current_floor_ptr->width; ++i)
        {
                for (j = 0; j < current_floor_ptr->height; ++j)
                {
                        x = i / xrat + 1;
                        y = j / yrat + 1;

                        match_autopick = -1;
                        autopick_obj = NULL;
                        feat_priority = -1;

                        /* Extract the current attr/char at that map location */
                        map_info(j, i, &ta, &tc, &ta, &tc);

                        /* Extract the priority */
                        tp = (byte_hack)feat_priority;

                        if (match_autopick != -1
                                && (match_autopick_yx[y][x] == -1
                                        || match_autopick_yx[y][x] > match_autopick))
                        {
                                match_autopick_yx[y][x] = match_autopick;
                                object_autopick_yx[y][x] = autopick_obj;
                                tp = 0x7f;
                        }

                        /* Save the char, attr and priority */
                        bigmc[j + 1][i + 1] = tc;
                        bigma[j + 1][i + 1] = ta;
                        bigmp[j + 1][i + 1] = tp;
                }
        }

        for (j = 0; j < current_floor_ptr->height; ++j)
        {
                for (i = 0; i < current_floor_ptr->width; ++i)
                {
                        x = i / xrat + 1;
                        y = j / yrat + 1;

                        tc = bigmc[j + 1][i + 1];
                        ta = bigma[j + 1][i + 1];
                        tp = bigmp[j + 1][i + 1];

                        /* rare feature has more priority */
                        if (mp[y][x] == tp)
                        {
                                int t;
                                int cnt = 0;

                                for (t = 0; t < 8; t++)
                                {
                                        if (tc == bigmc[j + 1 + ddy_cdd[t]][i + 1 + ddx_cdd[t]] &&
                                                ta == bigma[j + 1 + ddy_cdd[t]][i + 1 + ddx_cdd[t]])
                                                cnt++;
                                }
                                if (cnt <= 4)
                                        tp++;
                        }

                        /* Save "best" */
                        if (mp[y][x] < tp)
                        {
                                /* Save the char, attr and priority */
                                mc[y][x] = tc;
                                ma[y][x] = ta;
                                mp[y][x] = tp;
                        }
                }
        }


        /* Corners */
        x = wid + 1;
        y = hgt + 1;

        /* Draw the corners */
        mc[0][0] = mc[0][x] = mc[y][0] = mc[y][x] = '+';

        /* Draw the horizontal edges */
        for (x = 1; x <= wid; x++) mc[0][x] = mc[y][x] = '-';

        /* Draw the vertical edges */
        for (y = 1; y <= hgt; y++) mc[y][0] = mc[y][x] = '|';


        /* Display each map line in order */
        for (y = 0; y < hgt + 2; ++y)
        {
                /* Start a new line */
                Term_gotoxy(COL_MAP, y);

                /* Display the line */
                for (x = 0; x < wid + 2; ++x)
                {
                        ta = ma[y][x];
                        tc = mc[y][x];

                        /* Hack -- fake monochrome */
                        if (!use_graphics)
                        {
                                if (world_monster) ta = TERM_DARK;
                                else if (IS_INVULN() || p_ptr->timewalk) ta = TERM_WHITE;
                                else if (p_ptr->wraith_form) ta = TERM_L_DARK;
                        }

                        /* Add the character */
                        Term_add_bigch(ta, tc);
                }
        }


        for (y = 1; y < hgt + 1; ++y)
        {
                match_autopick = -1;
                for (x = 1; x <= wid; x++) {
                        if (match_autopick_yx[y][x] != -1 &&
                                (match_autopick > match_autopick_yx[y][x] ||
                                        match_autopick == -1)) {
                                match_autopick = match_autopick_yx[y][x];
                                autopick_obj = object_autopick_yx[y][x];
                        }
                }

                /* Clear old display */
                Term_putstr(0, y, 12, 0, "            ");

                if (match_autopick != -1)
#if 1
                        display_shortened_item_name(autopick_obj, y);
#else
                {
                        char buf[13] = "\0";
                        strncpy(buf, autopick_list[match_autopick].name, 12);
                        buf[12] = '\0';
                        put_str(buf, y, 0);
                }
#endif

        }

        /* Player location */
        (*cy) = p_ptr->y / yrat + 1 + ROW_MAP;
        if (!use_bigtile)
                (*cx) = p_ptr->x / xrat + 1 + COL_MAP;
        else
                (*cx) = (p_ptr->x / xrat + 1) * 2 + COL_MAP;

        /* Restore lighting effects */
        view_special_lite = old_view_special_lite;
        view_granite_lite = old_view_granite_lite;

        /* Free each line map */
        for (y = 0; y < (hgt + 2); y++)
        {
                /* Free one row each array */
                C_KILL(ma[y], (wid + 2), TERM_COLOR);
                C_KILL(mc[y], (wid + 2), SYMBOL_CODE);
                C_KILL(mp[y], (wid + 2), byte);
                C_KILL(match_autopick_yx[y], (wid + 2), int);
                C_KILL(object_autopick_yx[y], (wid + 2), object_type *);
        }

        /* Free each line map */
        C_KILL(ma, (hgt + 2), TERM_COLOR *);
        C_KILL(mc, (hgt + 2), char_ptr);
        C_KILL(mp, (hgt + 2), byte_ptr);
        C_KILL(match_autopick_yx, (hgt + 2), sint_ptr);
        C_KILL(object_autopick_yx, (hgt + 2), object_type **);

        /* Free each line map */
        for (y = 0; y < (current_floor_ptr->height + 2); y++)
        {
                /* Free one row each array */
                C_KILL(bigma[y], (current_floor_ptr->width + 2), TERM_COLOR);
                C_KILL(bigmc[y], (current_floor_ptr->width + 2), SYMBOL_CODE);
                C_KILL(bigmp[y], (current_floor_ptr->width + 2), byte);
        }

        /* Free each line map */
        C_KILL(bigma, (current_floor_ptr->height + 2), TERM_COLOR *);
        C_KILL(bigmc, (current_floor_ptr->height + 2), char_ptr);
        C_KILL(bigmp, (current_floor_ptr->height + 2), byte_ptr);
}


/*
 * Display a "small-scale" map of the dungeon for the player
 *
 * Currently, the "player" is displayed on the map.
 */
void do_cmd_view_map(void)
{
        int cy, cx;

        screen_save();

        prt(_("お待ち下さい...", "Please wait..."), 0, 0);

        Term_fresh();
        Term_clear();

        display_autopick = 0;

        /* Display the map */
        display_map(&cy, &cx);

        /* Wait for it */
        if (max_autopick && !p_ptr->wild_mode)
        {
                display_autopick = ITEM_DISPLAY;

                while (1)
                {
                        int i;
                        byte flag;

                        int wid, hgt, row_message;

                        Term_get_size(&wid, &hgt);
                        row_message = hgt - 1;

                        put_str(_("何かキーを押してください('M':拾う 'N':放置 'D':M+N 'K':壊すアイテムを表示)",
                                " Hit M, N(for ~), K(for !), or D(same as M+N) to display auto-picker items."), row_message, 1);

                        /* Hilite the player */
                        move_cursor(cy, cx);

                        i = inkey();

                        if ('M' == i)
                                flag = (DO_AUTOPICK | DO_QUERY_AUTOPICK);
                        else if ('N' == i)
                                flag = DONT_AUTOPICK;
                        else if ('K' == i)
                                flag = DO_AUTODESTROY;
                        else if ('D' == i)
                                flag = (DO_AUTOPICK | DO_QUERY_AUTOPICK | DONT_AUTOPICK);
                        else
                                break;

                        Term_fresh();

                        if (~display_autopick & flag)
                                display_autopick |= flag;
                        else
                                display_autopick &= ~flag;
                        /* Display the map */
                        display_map(&cy, &cx);
                }

                display_autopick = 0;

        }
        else
        {
                put_str(_("何かキーを押すとゲームに戻ります", "Hit any key to continue"), 23, 30);
                /* Hilite the player */
                move_cursor(cy, cx);
                /* Get any key */
                inkey();
        }
        screen_load();
}





/*
 * Some comments on the grid flags.  -BEN-
 *
 *
 * One of the major bottlenecks in previous versions of Angband was in
 * the calculation of "line of sight" from the player to various grids,
 * such as monsters.  This was such a nasty bottleneck that a lot of
 * silly things were done to reduce the dependancy on "line of sight",
 * for example, you could not "see" any grids in a lit room until you
 * actually entered the room, and there were all kinds of bizarre grid
 * flags to enable this behavior.  This is also why the "call light"
 * spells always lit an entire room.
 *
 * The code below provides functions to calculate the "field of view"
 * for the player, which, once calculated, provides extremely fast
 * calculation of "line of sight from the player", and to calculate
 * the "field of torch lite", which, again, once calculated, provides
 * extremely fast calculation of "which grids are lit by the player's
 * lite source".  In addition to marking grids as "GRID_VIEW" and/or
 * "GRID_LITE", as appropriate, these functions maintain an array for
 * each of these two flags, each array containing the locations of all
 * of the grids marked with the appropriate flag, which can be used to
 * very quickly scan through all of the grids in a given set.
 *
 * To allow more "semantically valid" field of view semantics, whenever
 * the field of view (or the set of torch lit grids) changes, all of the
 * grids in the field of view (or the set of torch lit grids) are "drawn"
 * so that changes in the world will become apparent as soon as possible.
 * This has been optimized so that only grids which actually "change" are
 * redrawn, using the "temp" array and the "GRID_TEMP" flag to keep track
 * of the grids which are entering or leaving the relevent set of grids.
 *
 * These new methods are so efficient that the old nasty code was removed.
 *
 * Note that there is no reason to "update" the "viewable space" unless
 * the player "moves", or walls/doors are created/destroyed, and there
 * is no reason to "update" the "torch lit grids" unless the field of
 * view changes, or the "light radius" changes.  This means that when
 * the player is resting, or digging, or doing anything that does not
 * involve movement or changing the state of the dungeon, there is no
 * need to update the "view" or the "lite" regions, which is nice.
 *
 * Note that the calls to the nasty "los()" function have been reduced
 * to a bare minimum by the use of the new "field of view" calculations.
 *
 * I wouldn't be surprised if slight modifications to the "update_view()"
 * function would allow us to determine "reverse line-of-sight" as well
 * as "normal line-of-sight", which would allow monsters to use a more
 * "correct" calculation to determine if they can "see" the player.  For
 * now, monsters simply "cheat" somewhat and assume that if the player
 * has "line of sight" to the monster, then the monster can "pretend"
 * that it has "line of sight" to the player.
 *
 *
 * The "update_lite()" function maintains the "CAVE_LITE" flag for each
 * grid and maintains an array of all "CAVE_LITE" grids.
 *
 * This set of grids is the complete set of all grids which are lit by
 * the players light source, which allows the "player_can_see_bold()"
 * function to work very quickly.
 *
 * Note that every "CAVE_LITE" grid is also a "CAVE_VIEW" grid, and in
 * fact, the player (unless blind) can always "see" all grids which are
 * marked as "CAVE_LITE", unless they are "off screen".
 *
 *
 * The "update_view()" function maintains the "CAVE_VIEW" flag for each
 * grid and maintains an array of all "CAVE_VIEW" grids.
 *
 * This set of grids is the complete set of all grids within line of sight
 * of the player, allowing the "player_has_los_bold()" macro to work very
 * quickly.
 *
 *
 * The current "update_view()" algorithm uses the "CAVE_XTRA" flag as a
 * temporary internal flag to mark those grids which are not only in view,
 * but which are also "easily" in line of sight of the player.  This flag
 * is always cleared when we are done.
 *
 *
 * The current "update_lite()" and "update_view()" algorithms use the
 * "CAVE_TEMP" flag, and the array of grids which are marked as "CAVE_TEMP",
 * to keep track of which grids were previously marked as "CAVE_LITE" or
 * "CAVE_VIEW", which allows us to optimize the "screen updates".
 *
 * The "CAVE_TEMP" flag, and the array of "CAVE_TEMP" grids, is also used
 * for various other purposes, such as spreading lite or darkness during
 * "lite_room()" / "unlite_room()", and for calculating monster flow.
 *
 *
 * Any grid can be marked as "CAVE_GLOW" which means that the grid itself is
 * in some way permanently lit.  However, for the player to "see" anything
 * in the grid, as determined by "player_can_see()", the player must not be
 * blind, the grid must be marked as "CAVE_VIEW", and, in addition, "wall"
 * grids, even if marked as "perma lit", are only illuminated if they touch
 * a grid which is not a wall and is marked both "CAVE_GLOW" and "CAVE_VIEW".
 *
 *
 * To simplify various things, a grid may be marked as "CAVE_MARK", meaning
 * that even if the player cannot "see" the grid, he "knows" the terrain in
 * that grid.  This is used to "remember" walls/doors/stairs/floors when they
 * are "seen" or "detected", and also to "memorize" floors, after "wiz_lite()",
 * or when one of the "memorize floor grids" options induces memorization.
 *
 * Objects are "memorized" in a different way, using a special "marked" flag
 * on the object itself, which is set when an object is observed or detected.
 *
 *
 * A grid may be marked as "CAVE_ROOM" which means that it is part of a "room",
 * and should be illuminated by "lite room" and "darkness" spells.
 *
 *
 * A grid may be marked as "CAVE_ICKY" which means it is part of a "vault",
 * and should be unavailable for "teleportation" destinations.
 *
 *
 * The "view_perma_grids" allows the player to "memorize" every perma-lit grid
 * which is observed, and the "view_torch_grids" allows the player to memorize
 * every torch-lit grid.  The player will always memorize important walls,
 * doors, stairs, and other terrain features, as well as any "detected" grids.
 *
 * Note that the new "update_view()" method allows, among other things, a room
 * to be "partially" seen as the player approaches it, with a growing cone of
 * floor appearing as the player gets closer to the door.  Also, by not turning
 * on the "memorize perma-lit grids" option, the player will only "see" those
 * floor grids which are actually in line of sight.
 *
 * And my favorite "plus" is that you can now use a special option to draw the
 * "floors" in the "viewable region" brightly (actually, to draw the *other*
 * grids dimly), providing a "pretty" effect as the player runs around, and
 * to efficiently display the "torch lite" in a special color.
 *
 *
 * Some comments on the "update_view()" algorithm...
 *
 * The algorithm is very fast, since it spreads "obvious" grids very quickly,
 * and only has to call "los()" on the borderline cases.  The major axes/diags
 * even terminate early when they hit walls.  I need to find a quick way
 * to "terminate" the other scans.
 *
 * Note that in the worst case (a big empty area with say 5% scattered walls),
 * each of the 1500 or so nearby grids is checked once, most of them getting
 * an "instant" rating, and only a small portion requiring a call to "los()".
 *
 * The only time that the algorithm appears to be "noticeably" too slow is
 * when running, and this is usually only important in town, since the town
 * provides about the worst scenario possible, with large open regions and
 * a few scattered obstructions.  There is a special "efficiency" option to
 * allow the player to reduce his field of view in town, if needed.
 *
 * In the "best" case (say, a normal stretch of corridor), the algorithm
 * makes one check for each viewable grid, and makes no calls to "los()".
 * So running in corridors is very fast, and if a lot of monsters are
 * nearby, it is much faster than the old methods.
 *
 * Note that resting, most normal commands, and several forms of running,
 * plus all commands executed near large groups of monsters, are strictly
 * more efficient with "update_view()" that with the old "compute los() on
 * demand" method, primarily because once the "field of view" has been
 * calculated, it does not have to be recalculated until the player moves
 * (or a wall or door is created or destroyed).
 *
 * Note that we no longer have to do as many "los()" checks, since once the
 * "view" region has been built, very few things cause it to be "changed"
 * (player movement, and the opening/closing of doors, changes in wall status).
 * Note that door/wall changes are only relevant when the door/wall itself is
 * in the "view" region.
 *
 * The algorithm seems to only call "los()" from zero to ten times, usually
 * only when coming down a corridor into a room, or standing in a room, just
 * misaligned with a corridor.  So if, say, there are five "nearby" monsters,
 * we will be reducing the calls to "los()".
 *
 * I am thinking in terms of an algorithm that "walks" from the central point
 * out to the maximal "distance", at each point, determining the "view" code
 * (above).  For each grid not on a major axis or diagonal, the "view" code
 * depends on the "cave_los_bold()" and "view" of exactly two other grids
 * (the one along the nearest diagonal, and the one next to that one, see
 * "update_view_aux()"...).
 *
 * We "memorize" the viewable space array, so that at the cost of under 3000
 * bytes, we reduce the time taken by "forget_view()" to one assignment for
 * each grid actually in the "viewable space".  And for another 3000 bytes,
 * we prevent "erase + redraw" ineffiencies via the "seen" set.  These bytes
 * are also used by other routines, thus reducing the cost to almost nothing.
 *
 * A similar thing is done for "forget_lite()" in which case the savings are
 * much less, but save us from doing bizarre maintenance checking.
 *
 * In the worst "normal" case (in the middle of the town), the reachable space
 * actually reaches to more than half of the largest possible "circle" of view,
 * or about 800 grids, and in the worse case (in the middle of a dungeon level
 * where all the walls have been removed), the reachable space actually reaches
 * the theoretical maximum size of just under 1500 grids.
 *
 * Each grid G examines the "state" of two (?) other (adjacent) grids, G1 & G2.
 * If G1 is lite, G is lite.  Else if G2 is lite, G is half.  Else if G1 and G2
 * are both half, G is half.  Else G is dark.  It only takes 2 (or 4) bits to
 * "name" a grid, so (for MAX_RAD of 20) we could use 1600 bytes, and scan the
 * entire possible space (including initialization) in one step per grid.  If
 * we do the "clearing" as a separate step (and use an array of "view" grids),
 * then the clearing will take as many steps as grids that were viewed, and the
 * algorithm will be able to "stop" scanning at various points.
 * Oh, and outside of the "torch radius", only "lite" grids need to be scanned.
 */








 /*
  * Actually erase the entire "lite" array, redrawing every grid
  */
void forget_lite(void)
{
        int i, x, y;

        /* None to forget */
        if (!lite_n) return;

        /* Clear them all */
        for (i = 0; i < lite_n; i++)
        {
                y = lite_y[i];
                x = lite_x[i];

                /* Forget "LITE" flag */
                current_floor_ptr->grid_array[y][x].info &= ~(CAVE_LITE);

                /* lite_spot(y, x); Perhaps don't need? */
        }

        /* None left */
        lite_n = 0;
}


/*
 * For delayed visual update
 */
#define cave_note_and_redraw_later(C,Y,X) \
{\
        (C)->info |= CAVE_NOTE; \
        cave_redraw_later((C), (Y), (X)); \
}


 /*
  * For delayed visual update
  */
#define cave_redraw_later(C,Y,X) \
{\
        if (!((C)->info & CAVE_REDRAW)) \
        { \
                (C)->info |= CAVE_REDRAW; \
                redraw_y[redraw_n] = (Y); \
                redraw_x[redraw_n++] = (X); \
        } \
}


  /*
   * This macro allows us to efficiently add a grid to the "lite" array,
   * note that we are never called for illegal grids, or for grids which
   * have already been placed into the "lite" array, and we are never
   * called when the "lite" array is full.
   */
#define cave_lite_hack(Y,X) \
{\
        if (!(current_floor_ptr->grid_array[Y][X].info & (CAVE_LITE))) \
        { \
                current_floor_ptr->grid_array[Y][X].info |= (CAVE_LITE); \
                lite_y[lite_n] = (Y); \
                lite_x[lite_n++] = (X); \
        } \
}


   /*
        * Update the set of grids "illuminated" by the player's lite.
        *
        * This routine needs to use the results of "update_view()"
        *
        * Note that "blindness" does NOT affect "torch lite".  Be careful!
        *
        * We optimize most lites (all non-artifact lites) by using "obvious"
        * facts about the results of "small" lite radius, and we attempt to
        * list the "nearby" grids before the more "distant" ones in the
        * array of torch-lit grids.
        *
        * We assume that "radius zero" lite is in fact no lite at all.
        *
        *     Torch     Lantern     Artifacts
        *     (etc)
        *                              ***
        *                 ***         *****
        *      ***       *****       *******
        *      *@*       **@**       ***@***
        *      ***       *****       *******
        *                 ***         *****
        *                              ***
        */
void update_lite(void)
{
        int i;
        POSITION x, y, min_x, max_x, min_y, max_y;
        int p = p_ptr->cur_lite;
        grid_type *g_ptr;

        /*** Special case ***/

#if 0
        /* Hack -- Player has no lite */
        if (p <= 0)
        {
                /* Forget the old lite */
                /* forget_lite(); Perhaps don't need? */

                /* Add it to later visual update */
                cave_redraw_later(&current_floor_ptr->grid_array[p_ptr->y][p_ptr->x], p_ptr->y, p_ptr->x);
        }
#endif

        /*** Save the old "lite" grids for later ***/

        /* Clear them all */
        for (i = 0; i < lite_n; i++)
        {
                y = lite_y[i];
                x = lite_x[i];

                /* Mark the grid as not "lite" */
                current_floor_ptr->grid_array[y][x].info &= ~(CAVE_LITE);

                /* Mark the grid as "seen" */
                current_floor_ptr->grid_array[y][x].info |= (CAVE_TEMP);

                /* Add it to the "seen" set */
                temp_y[temp_n] = y;
                temp_x[temp_n] = x;
                temp_n++;
        }

        /* None left */
        lite_n = 0;


        /*** Collect the new "lite" grids ***/

        /* Radius 1 -- torch radius */
        if (p >= 1)
        {
                /* Player grid */
                cave_lite_hack(p_ptr->y, p_ptr->x);

                /* Adjacent grid */
                cave_lite_hack(p_ptr->y + 1, p_ptr->x);
                cave_lite_hack(p_ptr->y - 1, p_ptr->x);
                cave_lite_hack(p_ptr->y, p_ptr->x + 1);
                cave_lite_hack(p_ptr->y, p_ptr->x - 1);

                /* Diagonal grids */
                cave_lite_hack(p_ptr->y + 1, p_ptr->x + 1);
                cave_lite_hack(p_ptr->y + 1, p_ptr->x - 1);
                cave_lite_hack(p_ptr->y - 1, p_ptr->x + 1);
                cave_lite_hack(p_ptr->y - 1, p_ptr->x - 1);
        }

        /* Radius 2 -- lantern radius */
        if (p >= 2)
        {
                /* South of the player */
                if (cave_los_bold(p_ptr->y + 1, p_ptr->x))
                {
                        cave_lite_hack(p_ptr->y + 2, p_ptr->x);
                        cave_lite_hack(p_ptr->y + 2, p_ptr->x + 1);
                        cave_lite_hack(p_ptr->y + 2, p_ptr->x - 1);
                }

                /* North of the player */
                if (cave_los_bold(p_ptr->y - 1, p_ptr->x))
                {
                        cave_lite_hack(p_ptr->y - 2, p_ptr->x);
                        cave_lite_hack(p_ptr->y - 2, p_ptr->x + 1);
                        cave_lite_hack(p_ptr->y - 2, p_ptr->x - 1);
                }

                /* East of the player */
                if (cave_los_bold(p_ptr->y, p_ptr->x + 1))
                {
                        cave_lite_hack(p_ptr->y, p_ptr->x + 2);
                        cave_lite_hack(p_ptr->y + 1, p_ptr->x + 2);
                        cave_lite_hack(p_ptr->y - 1, p_ptr->x + 2);
                }

                /* West of the player */
                if (cave_los_bold(p_ptr->y, p_ptr->x - 1))
                {
                        cave_lite_hack(p_ptr->y, p_ptr->x - 2);
                        cave_lite_hack(p_ptr->y + 1, p_ptr->x - 2);
                        cave_lite_hack(p_ptr->y - 1, p_ptr->x - 2);
                }
        }

        /* Radius 3+ -- artifact radius */
        if (p >= 3)
        {
                int d;

                /* Paranoia -- see "LITE_MAX" */
                if (p > 14) p = 14;

                /* South-East of the player */
                if (cave_los_bold(p_ptr->y + 1, p_ptr->x + 1))
                {
                        cave_lite_hack(p_ptr->y + 2, p_ptr->x + 2);
                }

                /* South-West of the player */
                if (cave_los_bold(p_ptr->y + 1, p_ptr->x - 1))
                {
                        cave_lite_hack(p_ptr->y + 2, p_ptr->x - 2);
                }

                /* North-East of the player */
                if (cave_los_bold(p_ptr->y - 1, p_ptr->x + 1))
                {
                        cave_lite_hack(p_ptr->y - 2, p_ptr->x + 2);
                }

                /* North-West of the player */
                if (cave_los_bold(p_ptr->y - 1, p_ptr->x - 1))
                {
                        cave_lite_hack(p_ptr->y - 2, p_ptr->x - 2);
                }

                /* Maximal north */
                min_y = p_ptr->y - p;
                if (min_y < 0) min_y = 0;

                /* Maximal south */
                max_y = p_ptr->y + p;
                if (max_y > current_floor_ptr->height - 1) max_y = current_floor_ptr->height - 1;

                /* Maximal west */
                min_x = p_ptr->x - p;
                if (min_x < 0) min_x = 0;

                /* Maximal east */
                max_x = p_ptr->x + p;
                if (max_x > current_floor_ptr->width - 1) max_x = current_floor_ptr->width - 1;

                /* Scan the maximal box */
                for (y = min_y; y <= max_y; y++)
                {
                        for (x = min_x; x <= max_x; x++)
                        {
                                int dy = (p_ptr->y > y) ? (p_ptr->y - y) : (y - p_ptr->y);
                                int dx = (p_ptr->x > x) ? (p_ptr->x - x) : (x - p_ptr->x);

                                /* Skip the "central" grids (above) */
                                if ((dy <= 2) && (dx <= 2)) continue;

                                /* Hack -- approximate the distance */
                                d = (dy > dx) ? (dy + (dx >> 1)) : (dx + (dy >> 1));

                                /* Skip distant grids */
                                if (d > p) continue;

                                /* Viewable, nearby, grids get "torch lit" */
                                if (current_floor_ptr->grid_array[y][x].info & CAVE_VIEW)
                                {
                                        /* This grid is "torch lit" */
                                        cave_lite_hack(y, x);
                                }
                        }
                }
        }


        /*** Complete the algorithm ***/

        /* Draw the new grids */
        for (i = 0; i < lite_n; i++)
        {
                y = lite_y[i];
                x = lite_x[i];

                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Update fresh grids */
                if (g_ptr->info & (CAVE_TEMP)) continue;

                /* Add it to later visual update */
                cave_note_and_redraw_later(g_ptr, y, x);
        }

        /* Clear them all */
        for (i = 0; i < temp_n; i++)
        {
                y = temp_y[i];
                x = temp_x[i];

                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* No longer in the array */
                g_ptr->info &= ~(CAVE_TEMP);

                /* Update stale grids */
                if (g_ptr->info & (CAVE_LITE)) continue;

                /* Add it to later visual update */
                cave_redraw_later(g_ptr, y, x);
        }

        /* None left */
        temp_n = 0;

        /* Mega-Hack -- Visual update later */
        p_ptr->update |= (PU_DELAY_VIS);
}


static bool mon_invis;
static POSITION mon_fy, mon_fx;

/*
 * Add a square to the changes array
 */
static void mon_lite_hack(POSITION y, POSITION x)
{
        grid_type *g_ptr;
        int dpf, d;
        POSITION midpoint;

        /* We trust this grid is in bounds */
        /* if (!in_bounds2(y, x)) return; */

        g_ptr = &current_floor_ptr->grid_array[y][x];

        /* Want a unlit square in view of the player */
        if ((g_ptr->info & (CAVE_MNLT | CAVE_VIEW)) != CAVE_VIEW) return;

        if (!cave_los_grid(g_ptr))
        {
                /* Hack -- Prevent monster lite leakage in walls */

                /* Horizontal walls between player and a monster */
                if (((y < p_ptr->y) && (y > mon_fy)) || ((y > p_ptr->y) && (y < mon_fy)))
                {
                        dpf = p_ptr->y - mon_fy;
                        d = y - mon_fy;
                        midpoint = mon_fx + ((p_ptr->x - mon_fx) * ABS(d)) / ABS(dpf);

                        /* Only first wall viewed from mid-x is lit */
                        if (x < midpoint)
                        {
                                if (!cave_los_bold(y, x + 1)) return;
                        }
                        else if (x > midpoint)
                        {
                                if (!cave_los_bold(y, x - 1)) return;
                        }

                        /* Hack XXX XXX - Is it a wall and monster not in LOS? */
                        else if (mon_invis) return;
                }

                /* Vertical walls between player and a monster */
                if (((x < p_ptr->x) && (x > mon_fx)) || ((x > p_ptr->x) && (x < mon_fx)))
                {
                        dpf = p_ptr->x - mon_fx;
                        d = x - mon_fx;
                        midpoint = mon_fy + ((p_ptr->y - mon_fy) * ABS(d)) / ABS(dpf);

                        /* Only first wall viewed from mid-y is lit */
                        if (y < midpoint)
                        {
                                if (!cave_los_bold(y + 1, x)) return;
                        }
                        else if (y > midpoint)
                        {
                                if (!cave_los_bold(y - 1, x)) return;
                        }

                        /* Hack XXX XXX - Is it a wall and monster not in LOS? */
                        else if (mon_invis) return;
                }
        }

        /* We trust temp_n does not exceed TEMP_MAX */

        /* New grid */
        if (!(g_ptr->info & CAVE_MNDK))
        {
                /* Save this square */
                temp_x[temp_n] = x;
                temp_y[temp_n] = y;
                temp_n++;
        }

        /* Darkened grid */
        else
        {
                /* No longer dark */
                g_ptr->info &= ~(CAVE_MNDK);
        }

        /* Light it */
        g_ptr->info |= CAVE_MNLT;
}


/*
 * Add a square to the changes array
 */
static void mon_dark_hack(POSITION y, POSITION x)
{
        grid_type *g_ptr;
        int       midpoint, dpf, d;

        /* We trust this grid is in bounds */
        /* if (!in_bounds2(y, x)) return; */

        g_ptr = &current_floor_ptr->grid_array[y][x];

        /* Want a unlit and undarkened square in view of the player */
        if ((g_ptr->info & (CAVE_LITE | CAVE_MNLT | CAVE_MNDK | CAVE_VIEW)) != CAVE_VIEW) return;

        if (!cave_los_grid(g_ptr) && !cave_have_flag_grid(g_ptr, FF_PROJECT))
        {
                /* Hack -- Prevent monster dark lite leakage in walls */

                /* Horizontal walls between player and a monster */
                if (((y < p_ptr->y) && (y > mon_fy)) || ((y > p_ptr->y) && (y < mon_fy)))
                {
                        dpf = p_ptr->y - mon_fy;
                        d = y - mon_fy;
                        midpoint = mon_fx + ((p_ptr->x - mon_fx) * ABS(d)) / ABS(dpf);

                        /* Only first wall viewed from mid-x is lit */
                        if (x < midpoint)
                        {
                                if (!cave_los_bold(y, x + 1) && !cave_have_flag_bold(y, x + 1, FF_PROJECT)) return;
                        }
                        else if (x > midpoint)
                        {
                                if (!cave_los_bold(y, x - 1) && !cave_have_flag_bold(y, x - 1, FF_PROJECT)) return;
                        }

                        /* Hack XXX XXX - Is it a wall and monster not in LOS? */
                        else if (mon_invis) return;
                }

                /* Vertical walls between player and a monster */
                if (((x < p_ptr->x) && (x > mon_fx)) || ((x > p_ptr->x) && (x < mon_fx)))
                {
                        dpf = p_ptr->x - mon_fx;
                        d = x - mon_fx;
                        midpoint = mon_fy + ((p_ptr->y - mon_fy) * ABS(d)) / ABS(dpf);

                        /* Only first wall viewed from mid-y is lit */
                        if (y < midpoint)
                        {
                                if (!cave_los_bold(y + 1, x) && !cave_have_flag_bold(y + 1, x, FF_PROJECT)) return;
                        }
                        else if (y > midpoint)
                        {
                                if (!cave_los_bold(y - 1, x) && !cave_have_flag_bold(y - 1, x, FF_PROJECT)) return;
                        }

                        /* Hack XXX XXX - Is it a wall and monster not in LOS? */
                        else if (mon_invis) return;
                }
        }

        /* We trust temp_n does not exceed TEMP_MAX */

        /* Save this square */
        temp_x[temp_n] = x;
        temp_y[temp_n] = y;
        temp_n++;

        /* Darken it */
        g_ptr->info |= CAVE_MNDK;
}


/*
 * Update squares illuminated or darkened by monsters.
 *
 * Hack - use the CAVE_ROOM flag (renamed to be CAVE_MNLT) to
 * denote squares illuminated by monsters.
 *
 * The CAVE_TEMP and CAVE_XTRA flag are used to store the state during the
 * updating.  Only squares in view of the player, whos state
 * changes are drawn via lite_spot().
 */
void update_mon_lite(void)
{
        int i, rad;
        grid_type *g_ptr;

        POSITION fx, fy;
        void(*add_mon_lite)(POSITION, POSITION);
        int f_flag;

        s16b end_temp;

        /* Non-Ninja player in the darkness */
        int dis_lim = ((d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS) && !p_ptr->see_nocto) ?
                (MAX_SIGHT / 2 + 1) : (MAX_SIGHT + 3);

        /* Clear all monster lit squares */
        for (i = 0; i < mon_lite_n; i++)
        {
                /* Point to grid */
                g_ptr = &current_floor_ptr->grid_array[mon_lite_y[i]][mon_lite_x[i]];

                /* Set temp or xtra flag */
                g_ptr->info |= (g_ptr->info & CAVE_MNLT) ? CAVE_TEMP : CAVE_XTRA;

                /* Clear monster illumination flag */
                g_ptr->info &= ~(CAVE_MNLT | CAVE_MNDK);
        }

        /* Empty temp list of new squares to lite up */
        temp_n = 0;

        /* If a monster stops time, don't process */
        if (!world_monster)
        {
                monster_type *m_ptr;
                monster_race *r_ptr;

                /* Loop through monsters, adding newly lit squares to changes list */
                for (i = 1; i < m_max; i++)
                {
                        m_ptr = &current_floor_ptr->m_list[i];
                        r_ptr = &r_info[m_ptr->r_idx];

                        /* Skip dead monsters */
                        if (!m_ptr->r_idx) continue;

                        /* Is it too far away? */
                        if (m_ptr->cdis > dis_lim) continue;

                        /* Get lite radius */
                        rad = 0;

                        /* Note the radii are cumulative */
                        if (r_ptr->flags7 & (RF7_HAS_LITE_1 | RF7_SELF_LITE_1)) rad++;
                        if (r_ptr->flags7 & (RF7_HAS_LITE_2 | RF7_SELF_LITE_2)) rad += 2;
                        if (r_ptr->flags7 & (RF7_HAS_DARK_1 | RF7_SELF_DARK_1)) rad--;
                        if (r_ptr->flags7 & (RF7_HAS_DARK_2 | RF7_SELF_DARK_2)) rad -= 2;

                        /* Exit if has no light */
                        if (!rad) continue;
                        else if (rad > 0)
                        {
                                if (!(r_ptr->flags7 & (RF7_SELF_LITE_1 | RF7_SELF_LITE_2)) && (MON_CSLEEP(m_ptr) || (!current_floor_ptr->dun_level && is_daytime()) || p_ptr->inside_battle)) continue;
                                if (d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS) rad = 1;
                                add_mon_lite = mon_lite_hack;
                                f_flag = FF_LOS;
                        }
                        else
                        {
                                if (!(r_ptr->flags7 & (RF7_SELF_DARK_1 | RF7_SELF_DARK_2)) && (MON_CSLEEP(m_ptr) || (!current_floor_ptr->dun_level && !is_daytime()))) continue;
                                add_mon_lite = mon_dark_hack;
                                f_flag = FF_PROJECT;
                                rad = -rad; /* Use absolute value */
                        }

                        /* Access the location */
                        mon_fx = m_ptr->fx;
                        mon_fy = m_ptr->fy;

                        /* Is the monster visible? */
                        mon_invis = !(current_floor_ptr->grid_array[mon_fy][mon_fx].info & CAVE_VIEW);

                        /* The square it is on */
                        add_mon_lite(mon_fy, mon_fx);

                        /* Adjacent squares */
                        add_mon_lite(mon_fy + 1, mon_fx);
                        add_mon_lite(mon_fy - 1, mon_fx);
                        add_mon_lite(mon_fy, mon_fx + 1);
                        add_mon_lite(mon_fy, mon_fx - 1);
                        add_mon_lite(mon_fy + 1, mon_fx + 1);
                        add_mon_lite(mon_fy + 1, mon_fx - 1);
                        add_mon_lite(mon_fy - 1, mon_fx + 1);
                        add_mon_lite(mon_fy - 1, mon_fx - 1);

                        /* Radius 2 */
                        if (rad >= 2)
                        {
                                /* South of the monster */
                                if (cave_have_flag_bold(mon_fy + 1, mon_fx, f_flag))
                                {
                                        add_mon_lite(mon_fy + 2, mon_fx + 1);
                                        add_mon_lite(mon_fy + 2, mon_fx);
                                        add_mon_lite(mon_fy + 2, mon_fx - 1);

                                        g_ptr = &current_floor_ptr->grid_array[mon_fy + 2][mon_fx];

                                        /* Radius 3 */
                                        if ((rad == 3) && cave_have_flag_grid(g_ptr, f_flag))
                                        {
                                                add_mon_lite(mon_fy + 3, mon_fx + 1);
                                                add_mon_lite(mon_fy + 3, mon_fx);
                                                add_mon_lite(mon_fy + 3, mon_fx - 1);
                                        }
                                }

                                /* North of the monster */
                                if (cave_have_flag_bold(mon_fy - 1, mon_fx, f_flag))
                                {
                                        add_mon_lite(mon_fy - 2, mon_fx + 1);
                                        add_mon_lite(mon_fy - 2, mon_fx);
                                        add_mon_lite(mon_fy - 2, mon_fx - 1);

                                        g_ptr = &current_floor_ptr->grid_array[mon_fy - 2][mon_fx];

                                        /* Radius 3 */
                                        if ((rad == 3) && cave_have_flag_grid(g_ptr, f_flag))
                                        {
                                                add_mon_lite(mon_fy - 3, mon_fx + 1);
                                                add_mon_lite(mon_fy - 3, mon_fx);
                                                add_mon_lite(mon_fy - 3, mon_fx - 1);
                                        }
                                }

                                /* East of the monster */
                                if (cave_have_flag_bold(mon_fy, mon_fx + 1, f_flag))
                                {
                                        add_mon_lite(mon_fy + 1, mon_fx + 2);
                                        add_mon_lite(mon_fy, mon_fx + 2);
                                        add_mon_lite(mon_fy - 1, mon_fx + 2);

                                        g_ptr = &current_floor_ptr->grid_array[mon_fy][mon_fx + 2];

                                        /* Radius 3 */
                                        if ((rad == 3) && cave_have_flag_grid(g_ptr, f_flag))
                                        {
                                                add_mon_lite(mon_fy + 1, mon_fx + 3);
                                                add_mon_lite(mon_fy, mon_fx + 3);
                                                add_mon_lite(mon_fy - 1, mon_fx + 3);
                                        }
                                }

                                /* West of the monster */
                                if (cave_have_flag_bold(mon_fy, mon_fx - 1, f_flag))
                                {
                                        add_mon_lite(mon_fy + 1, mon_fx - 2);
                                        add_mon_lite(mon_fy, mon_fx - 2);
                                        add_mon_lite(mon_fy - 1, mon_fx - 2);

                                        g_ptr = &current_floor_ptr->grid_array[mon_fy][mon_fx - 2];

                                        /* Radius 3 */
                                        if ((rad == 3) && cave_have_flag_grid(g_ptr, f_flag))
                                        {
                                                add_mon_lite(mon_fy + 1, mon_fx - 3);
                                                add_mon_lite(mon_fy, mon_fx - 3);
                                                add_mon_lite(mon_fy - 1, mon_fx - 3);
                                        }
                                }
                        }

                        /* Radius 3 */
                        if (rad == 3)
                        {
                                /* South-East of the monster */
                                if (cave_have_flag_bold(mon_fy + 1, mon_fx + 1, f_flag))
                                {
                                        add_mon_lite(mon_fy + 2, mon_fx + 2);
                                }

                                /* South-West of the monster */
                                if (cave_have_flag_bold(mon_fy + 1, mon_fx - 1, f_flag))
                                {
                                        add_mon_lite(mon_fy + 2, mon_fx - 2);
                                }

                                /* North-East of the monster */
                                if (cave_have_flag_bold(mon_fy - 1, mon_fx + 1, f_flag))
                                {
                                        add_mon_lite(mon_fy - 2, mon_fx + 2);
                                }

                                /* North-West of the monster */
                                if (cave_have_flag_bold(mon_fy - 1, mon_fx - 1, f_flag))
                                {
                                        add_mon_lite(mon_fy - 2, mon_fx - 2);
                                }
                        }
                }
        }

        /* Save end of list of new squares */
        end_temp = temp_n;

        /*
         * Look at old set flags to see if there are any changes.
         */
        for (i = 0; i < mon_lite_n; i++)
        {
                fx = mon_lite_x[i];
                fy = mon_lite_y[i];

                /* We trust this grid is in bounds */

                /* Point to grid */
                g_ptr = &current_floor_ptr->grid_array[fy][fx];

                if (g_ptr->info & CAVE_TEMP) /* Pervious lit */
                {
                        /* It it no longer lit? */
                        if ((g_ptr->info & (CAVE_VIEW | CAVE_MNLT)) == CAVE_VIEW)
                        {
                                /* It is now unlit */
                                /* Add it to later visual update */
                                cave_note_and_redraw_later(g_ptr, fy, fx);
                        }
                }
                else /* Pervious darkened */
                {
                        /* It it no longer darken? */
                        if ((g_ptr->info & (CAVE_VIEW | CAVE_MNDK)) == CAVE_VIEW)
                        {
                                /* It is now undarken */
                                /* Add it to later visual update */
                                cave_note_and_redraw_later(g_ptr, fy, fx);
                        }
                }

                /* Add to end of temp array */
                temp_x[temp_n] = fx;
                temp_y[temp_n] = fy;
                temp_n++;
        }

        /* Clear the lite array */
        mon_lite_n = 0;

        /* Copy the temp array into the lit array lighting the new squares. */
        for (i = 0; i < end_temp; i++)
        {
                fx = temp_x[i];
                fy = temp_y[i];

                /* We trust this grid is in bounds */

                /* Point to grid */
                g_ptr = &current_floor_ptr->grid_array[fy][fx];

                if (g_ptr->info & CAVE_MNLT) /* Lit */
                {
                        /* The is the square newly lit and visible? */
                        if ((g_ptr->info & (CAVE_VIEW | CAVE_TEMP)) == CAVE_VIEW)
                        {
                                /* It is now lit */
                                /* Add it to later visual update */
                                cave_note_and_redraw_later(g_ptr, fy, fx);
                        }
                }
                else /* Darkened */
                {
                        /* The is the square newly darkened and visible? */
                        if ((g_ptr->info & (CAVE_VIEW | CAVE_XTRA)) == CAVE_VIEW)
                        {
                                /* It is now darkened */
                                /* Add it to later visual update */
                                cave_note_and_redraw_later(g_ptr, fy, fx);
                        }
                }

                /* Save in the monster lit or darkened array */
                mon_lite_x[mon_lite_n] = fx;
                mon_lite_y[mon_lite_n] = fy;
                mon_lite_n++;
        }

        /* Clear the temp flag for the old lit or darken grids */
        for (i = end_temp; i < temp_n; i++)
        {
                /* We trust this grid is in bounds */

                current_floor_ptr->grid_array[temp_y[i]][temp_x[i]].info &= ~(CAVE_TEMP | CAVE_XTRA);
        }

        /* Finished with temp_n */
        temp_n = 0;

        /* Mega-Hack -- Visual update later */
        p_ptr->update |= (PU_DELAY_VIS);

        p_ptr->monlite = (current_floor_ptr->grid_array[p_ptr->y][p_ptr->x].info & CAVE_MNLT) ? TRUE : FALSE;

        if (p_ptr->special_defense & NINJA_S_STEALTH)
        {
                if (p_ptr->old_monlite != p_ptr->monlite)
                {
                        if (p_ptr->monlite)
                        {
                                msg_print(_("影の覆いが薄れた気がする。", "Your mantle of shadow become thin."));
                        }
                        else
                        {
                                msg_print(_("影の覆いが濃くなった！", "Your mantle of shadow restored its original darkness."));
                        }
                }
        }
        p_ptr->old_monlite = p_ptr->monlite;
}

void clear_mon_lite(void)
{
        int i;
        grid_type *g_ptr;

        /* Clear all monster lit squares */
        for (i = 0; i < mon_lite_n; i++)
        {
                /* Point to grid */
                g_ptr = &current_floor_ptr->grid_array[mon_lite_y[i]][mon_lite_x[i]];

                /* Clear monster illumination flag */
                g_ptr->info &= ~(CAVE_MNLT | CAVE_MNDK);
        }

        /* Empty the array */
        mon_lite_n = 0;
}



/*
 * Clear the viewable space
 */
void forget_view(void)
{
        int i;

        grid_type *g_ptr;

        /* None to forget */
        if (!view_n) return;

        /* Clear them all */
        for (i = 0; i < view_n; i++)
        {
                POSITION y = view_y[i];
                POSITION x = view_x[i];
                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Forget that the grid is viewable */
                g_ptr->info &= ~(CAVE_VIEW);

                /* if (!panel_contains(y, x)) continue; */

                /* Update the screen */
                /* lite_spot(y, x); Perhaps don't need? */
        }

        /* None left */
        view_n = 0;
}



/*
 * This macro allows us to efficiently add a grid to the "view" array,
 * note that we are never called for illegal grids, or for grids which
 * have already been placed into the "view" array, and we are never
 * called when the "view" array is full.
 */
#define cave_view_hack(C,Y,X) \
{\
    if (!((C)->info & (CAVE_VIEW))){\
    (C)->info |= (CAVE_VIEW); \
    view_y[view_n] = (Y); \
    view_x[view_n] = (X); \
    view_n++;}\
}



 /*
  * Helper function for "update_view()" below
  *
  * We are checking the "viewability" of grid (y,x) by the player.
  *
  * This function assumes that (y,x) is legal (i.e. on the map).
  *
  * Grid (y1,x1) is on the "diagonal" between (p_ptr->y,p_ptr->x) and (y,x)
  * Grid (y2,x2) is "adjacent", also between (p_ptr->y,p_ptr->x) and (y,x).
  *
  * Note that we are using the "CAVE_XTRA" field for marking grids as
  * "easily viewable".  This bit is cleared at the end of "update_view()".
  *
  * This function adds (y,x) to the "viewable set" if necessary.
  *
  * This function now returns "TRUE" if vision is "blocked" by grid (y,x).
  */
static bool update_view_aux(POSITION y, POSITION x, POSITION y1, POSITION x1, POSITION y2, POSITION x2)
{
        bool f1, f2, v1, v2, z1, z2, wall;

        grid_type *g_ptr;

        grid_type *g1_c_ptr;
        grid_type *g2_c_ptr;

        /* Access the grids */
        g1_c_ptr = &current_floor_ptr->grid_array[y1][x1];
        g2_c_ptr = &current_floor_ptr->grid_array[y2][x2];


        /* Check for walls */
        f1 = (cave_los_grid(g1_c_ptr));
        f2 = (cave_los_grid(g2_c_ptr));

        /* Totally blocked by physical walls */
        if (!f1 && !f2) return (TRUE);


        /* Check for visibility */
        v1 = (f1 && (g1_c_ptr->info & (CAVE_VIEW)));
        v2 = (f2 && (g2_c_ptr->info & (CAVE_VIEW)));

        /* Totally blocked by "unviewable neighbors" */
        if (!v1 && !v2) return (TRUE);

        g_ptr = &current_floor_ptr->grid_array[y][x];


        /* Check for walls */
        wall = (!cave_los_grid(g_ptr));


        /* Check the "ease" of visibility */
        z1 = (v1 && (g1_c_ptr->info & (CAVE_XTRA)));
        z2 = (v2 && (g2_c_ptr->info & (CAVE_XTRA)));

        /* Hack -- "easy" plus "easy" yields "easy" */
        if (z1 && z2)
        {
                g_ptr->info |= (CAVE_XTRA);

                cave_view_hack(g_ptr, y, x);

                return (wall);
        }

        /* Hack -- primary "easy" yields "viewed" */
        if (z1)
        {
                cave_view_hack(g_ptr, y, x);

                return (wall);
        }

        /* Hack -- "view" plus "view" yields "view" */
        if (v1 && v2)
        {
                /* g_ptr->info |= (CAVE_XTRA); */

                cave_view_hack(g_ptr, y, x);

                return (wall);
        }


        /* Mega-Hack -- the "los()" function works poorly on walls */
        if (wall)
        {
                cave_view_hack(g_ptr, y, x);

                return (wall);
        }


        /* Hack -- check line of sight */
        if (los(p_ptr->y, p_ptr->x, y, x))
        {
                cave_view_hack(g_ptr, y, x);

                return (wall);
        }


        /* Assume no line of sight. */
        return (TRUE);
}



/*
 * Calculate the viewable space
 *
 *  1: Process the player
 *  1a: The player is always (easily) viewable
 *  2: Process the diagonals
 *  2a: The diagonals are (easily) viewable up to the first wall
 *  2b: But never go more than 2/3 of the "full" distance
 *  3: Process the main axes
 *  3a: The main axes are (easily) viewable up to the first wall
 *  3b: But never go more than the "full" distance
 *  4: Process sequential "strips" in each of the eight octants
 *  4a: Each strip runs along the previous strip
 *  4b: The main axes are "previous" to the first strip
 *  4c: Process both "sides" of each "direction" of each strip
 *  4c1: Each side aborts as soon as possible
 *  4c2: Each side tells the next strip how far it has to check
 *
 * Note that the octant processing involves some pretty interesting
 * observations involving when a grid might possibly be viewable from
 * a given grid, and on the order in which the strips are processed.
 *
 * Note the use of the mathematical facts shown below, which derive
 * from the fact that (1 < sqrt(2) < 1.5), and that the length of the
 * hypotenuse of a right triangle is primarily determined by the length
 * of the longest side, when one side is small, and is strictly less
 * than one-and-a-half times as long as the longest side when both of
 * the sides are large.
 *
 *   if (manhatten(dy,dx) < R) then (hypot(dy,dx) < R)
 *   if (manhatten(dy,dx) > R*3/2) then (hypot(dy,dx) > R)
 *
 *   hypot(dy,dx) is approximated by (dx+dy+MAX(dx,dy)) / 2
 *
 * These observations are important because the calculation of the actual
 * value of "hypot(dx,dy)" is extremely expensive, involving square roots,
 * while for small values (up to about 20 or so), the approximations above
 * are correct to within an error of at most one grid or so.
 *
 * Observe the use of "full" and "over" in the code below, and the use of
 * the specialized calculation involving "limit", all of which derive from
 * the observations given above.  Basically, we note that the "circle" of
 * view is completely contained in an "octagon" whose bounds are easy to
 * determine, and that only a few steps are needed to derive the actual
 * bounds of the circle given the bounds of the octagon.
 *
 * Note that by skipping all the grids in the corners of the octagon, we
 * place an upper limit on the number of grids in the field of view, given
 * that "full" is never more than 20.  Of the 1681 grids in the "square" of
 * view, only about 1475 of these are in the "octagon" of view, and even
 * fewer are in the "circle" of view, so 1500 or 1536 is more than enough
 * entries to completely contain the actual field of view.
 *
 * Note also the care taken to prevent "running off the map".  The use of
 * explicit checks on the "validity" of the "diagonal", and the fact that
 * the loops are never allowed to "leave" the map, lets "update_view_aux()"
 * use the optimized "cave_los_bold()" macro, and to avoid the overhead
 * of multiple checks on the validity of grids.
 *
 * Note the "optimizations" involving the "se","sw","ne","nw","es","en",
 * "ws","wn" variables.  They work like this: While travelling down the
 * south-bound strip just to the east of the main south axis, as soon as
 * we get to a grid which does not "transmit" viewing, if all of the strips
 * preceding us (in this case, just the main axis) had terminated at or before
 * the same point, then we can stop, and reset the "max distance" to ourself.
 * So, each strip (named by major axis plus offset, thus "se" in this case)
 * maintains a "blockage" variable, initialized during the main axis step,
 * and checks it whenever a blockage is observed.  After processing each
 * strip as far as the previous strip told us to process, the next strip is
 * told not to go farther than the current strip's farthest viewable grid,
 * unless open space is still available.  This uses the "k" variable.
 *
 * Note the use of "inline" macros for efficiency.  The "cave_los_grid()"
 * macro is a replacement for "cave_los_bold()" which takes a pointer to
 * a grid instead of its location.  The "cave_view_hack()" macro is a
 * chunk of code which adds the given location to the "view" array if it
 * is not already there, using both the actual location and a pointer to
 * the grid.  See above.
 *
 * By the way, the purpose of this code is to reduce the dependancy on the
 * "los()" function which is slow, and, in some cases, not very accurate.
 *
 * It is very possible that I am the only person who fully understands this
 * function, and for that I am truly sorry, but efficiency was very important
 * and the "simple" version of this function was just not fast enough.  I am
 * more than willing to replace this function with a simpler one, if it is
 * equally efficient, and especially willing if the new function happens to
 * derive "reverse-line-of-sight" at the same time, since currently monsters
 * just use an optimized hack of "you see me, so I see you", and then use the
 * actual "projectable()" function to check spell attacks.
 */
void update_view(void)
{
        int n, m, d, k, z;
        POSITION y, x;

        int se, sw, ne, nw, es, en, ws, wn;

        int full, over;

        POSITION y_max = current_floor_ptr->height - 1;
        POSITION x_max = current_floor_ptr->width - 1;

        grid_type *g_ptr;

        /*** Initialize ***/

        /* Optimize */
        if (view_reduce_view && !current_floor_ptr->dun_level)
        {
                /* Full radius (10) */
                full = MAX_SIGHT / 2;

                /* Octagon factor (15) */
                over = MAX_SIGHT * 3 / 4;
        }

        /* Normal */
        else
        {
                /* Full radius (20) */
                full = MAX_SIGHT;

                /* Octagon factor (30) */
                over = MAX_SIGHT * 3 / 2;
        }


        /*** Step 0 -- Begin ***/

        /* Save the old "view" grids for later */
        for (n = 0; n < view_n; n++)
        {
                y = view_y[n];
                x = view_x[n];
                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Mark the grid as not in "view" */
                g_ptr->info &= ~(CAVE_VIEW);

                /* Mark the grid as "seen" */
                g_ptr->info |= (CAVE_TEMP);

                /* Add it to the "seen" set */
                temp_y[temp_n] = y;
                temp_x[temp_n] = x;
                temp_n++;
        }

        /* Start over with the "view" array */
        view_n = 0;

        /*** Step 1 -- adjacent grids ***/

        /* Now start on the player */
        y = p_ptr->y;
        x = p_ptr->x;
        g_ptr = &current_floor_ptr->grid_array[y][x];

        /* Assume the player grid is easily viewable */
        g_ptr->info |= (CAVE_XTRA);

        /* Assume the player grid is viewable */
        cave_view_hack(g_ptr, y, x);


        /*** Step 2 -- Major Diagonals ***/

        /* Hack -- Limit */
        z = full * 2 / 3;

        /* Scan south-east */
        for (d = 1; d <= z; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y + d][x + d];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y + d, x + d);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Scan south-west */
        for (d = 1; d <= z; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y + d][x - d];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y + d, x - d);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Scan north-east */
        for (d = 1; d <= z; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y - d][x + d];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y - d, x + d);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Scan north-west */
        for (d = 1; d <= z; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y - d][x - d];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y - d, x - d);
                if (!cave_los_grid(g_ptr)) break;
        }

        /*** Step 3 -- major axes ***/

        /* Scan south */
        for (d = 1; d <= full; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y + d][x];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y + d, x);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Initialize the "south strips" */
        se = sw = d;

        /* Scan north */
        for (d = 1; d <= full; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y - d][x];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y - d, x);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Initialize the "north strips" */
        ne = nw = d;

        /* Scan east */
        for (d = 1; d <= full; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y][x + d];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y, x + d);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Initialize the "east strips" */
        es = en = d;

        /* Scan west */
        for (d = 1; d <= full; d++)
        {
                g_ptr = &current_floor_ptr->grid_array[y][x - d];
                g_ptr->info |= (CAVE_XTRA);
                cave_view_hack(g_ptr, y, x - d);
                if (!cave_los_grid(g_ptr)) break;
        }

        /* Initialize the "west strips" */
        ws = wn = d;


        /*** Step 4 -- Divide each "octant" into "strips" ***/

        /* Now check each "diagonal" (in parallel) */
        for (n = 1; n <= over / 2; n++)
        {
                POSITION ypn, ymn, xpn, xmn;

                /* Acquire the "bounds" of the maximal circle */
                z = over - n - n;
                if (z > full - n) z = full - n;
                while ((z + n + (n >> 1)) > full) z--;


                /* Access the four diagonal grids */
                ypn = y + n;
                ymn = y - n;
                xpn = x + n;
                xmn = x - n;


                /* South strip */
                if (ypn < y_max)
                {
                        /* Maximum distance */
                        m = MIN(z, y_max - ypn);

                        /* East side */
                        if ((xpn <= x_max) && (n < se))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ypn + d, xpn, ypn + d - 1, xpn - 1, ypn + d - 1, xpn))
                                        {
                                                if (n + d >= se) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                se = k + 1;
                        }

                        /* West side */
                        if ((xmn >= 0) && (n < sw))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ypn + d, xmn, ypn + d - 1, xmn + 1, ypn + d - 1, xmn))
                                        {
                                                if (n + d >= sw) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                sw = k + 1;
                        }
                }


                /* North strip */
                if (ymn > 0)
                {
                        /* Maximum distance */
                        m = MIN(z, ymn);

                        /* East side */
                        if ((xpn <= x_max) && (n < ne))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ymn - d, xpn, ymn - d + 1, xpn - 1, ymn - d + 1, xpn))
                                        {
                                                if (n + d >= ne) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                ne = k + 1;
                        }

                        /* West side */
                        if ((xmn >= 0) && (n < nw))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ymn - d, xmn, ymn - d + 1, xmn + 1, ymn - d + 1, xmn))
                                        {
                                                if (n + d >= nw) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                nw = k + 1;
                        }
                }


                /* East strip */
                if (xpn < x_max)
                {
                        /* Maximum distance */
                        m = MIN(z, x_max - xpn);

                        /* South side */
                        if ((ypn <= x_max) && (n < es))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ypn, xpn + d, ypn - 1, xpn + d - 1, ypn, xpn + d - 1))
                                        {
                                                if (n + d >= es) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                es = k + 1;
                        }

                        /* North side */
                        if ((ymn >= 0) && (n < en))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ymn, xpn + d, ymn + 1, xpn + d - 1, ymn, xpn + d - 1))
                                        {
                                                if (n + d >= en) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                en = k + 1;
                        }
                }


                /* West strip */
                if (xmn > 0)
                {
                        /* Maximum distance */
                        m = MIN(z, xmn);

                        /* South side */
                        if ((ypn <= y_max) && (n < ws))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ypn, xmn - d, ypn - 1, xmn - d + 1, ypn, xmn - d + 1))
                                        {
                                                if (n + d >= ws) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                ws = k + 1;
                        }

                        /* North side */
                        if ((ymn >= 0) && (n < wn))
                        {
                                /* Scan */
                                for (k = n, d = 1; d <= m; d++)
                                {
                                        /* Check grid "d" in strip "n", notice "blockage" */
                                        if (update_view_aux(ymn, xmn - d, ymn + 1, xmn - d + 1, ymn, xmn - d + 1))
                                        {
                                                if (n + d >= wn) break;
                                        }

                                        /* Track most distant "non-blockage" */
                                        else
                                        {
                                                k = n + d;
                                        }
                                }

                                /* Limit the next strip */
                                wn = k + 1;
                        }
                }
        }


        /*** Step 5 -- Complete the algorithm ***/

        /* Update all the new grids */
        for (n = 0; n < view_n; n++)
        {
                y = view_y[n];
                x = view_x[n];
                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Clear the "CAVE_XTRA" flag */
                g_ptr->info &= ~(CAVE_XTRA);

                /* Update only newly viewed grids */
                if (g_ptr->info & (CAVE_TEMP)) continue;

                /* Add it to later visual update */
                cave_note_and_redraw_later(g_ptr, y, x);
        }

        /* Wipe the old grids, update as needed */
        for (n = 0; n < temp_n; n++)
        {
                y = temp_y[n];
                x = temp_x[n];
                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* No longer in the array */
                g_ptr->info &= ~(CAVE_TEMP);

                /* Update only non-viewable grids */
                if (g_ptr->info & (CAVE_VIEW)) continue;

                /* Add it to later visual update */
                cave_redraw_later(g_ptr, y, x);
        }

        /* None left */
        temp_n = 0;

        /* Mega-Hack -- Visual update later */
        p_ptr->update |= (PU_DELAY_VIS);
}


/*
 * Mega-Hack -- Delayed visual update
 * Only used if update_view(), update_lite() or update_mon_lite() was called
 */
void delayed_visual_update(void)
{
        int i;
        POSITION y, x;
        grid_type *g_ptr;

        /* Update needed grids */
        for (i = 0; i < redraw_n; i++)
        {
                y = redraw_y[i];
                x = redraw_x[i];
                g_ptr = &current_floor_ptr->grid_array[y][x];

                /* Update only needed grids (prevent multiple updating) */
                if (!(g_ptr->info & CAVE_REDRAW)) continue;

                /* If required, note */
                if (g_ptr->info & CAVE_NOTE) note_spot(y, x);

                lite_spot(y, x);

                /* Hack -- Visual update of monster on this grid */
                if (g_ptr->m_idx) update_monster(g_ptr->m_idx, FALSE);

                /* No longer in the array */
                g_ptr->info &= ~(CAVE_NOTE | CAVE_REDRAW);
        }

        /* None left */
        redraw_n = 0;
}


/*
 * Hack -- forget the "flow" information
 */
void forget_flow(void)
{
        POSITION x, y;

        /* Check the entire dungeon */
        for (y = 0; y < current_floor_ptr->height; y++)
        {
                for (x = 0; x < current_floor_ptr->width; x++)
                {
                        /* Forget the old data */
                        current_floor_ptr->grid_array[y][x].dist = 0;
                        current_floor_ptr->grid_array[y][x].cost = 0;
                        current_floor_ptr->grid_array[y][x].when = 0;
                }
        }
}


/*
 * Hack - speed up the update_flow algorithm by only doing
 * it everytime the player moves out of LOS of the last
 * "way-point".
 */
static POSITION flow_x = 0;
static POSITION flow_y = 0;



/*
 * Hack -- fill in the "cost" field of every grid that the player
 * can "reach" with the number of steps needed to reach that grid.
 * This also yields the "distance" of the player from every grid.
 *
 * In addition, mark the "when" of the grids that can reach
 * the player with the incremented value of "flow_n".
 *
 * Hack -- use the "seen" array as a "circular queue".
 *
 * We do not need a priority queue because the cost from grid
 * to grid is always "one" and we process them in order.
 */
void update_flow(void)
{
        POSITION x, y;
        DIRECTION d;
        int flow_head = 1;
        int flow_tail = 0;

        /* Paranoia -- make sure the array is empty */
        if (temp_n) return;

        /* The last way-point is on the map */
        if (running && in_bounds(flow_y, flow_x))
        {
                /* The way point is in sight - do not update.  (Speedup) */
                if (current_floor_ptr->grid_array[flow_y][flow_x].info & CAVE_VIEW) return;
        }

        /* Erase all of the current flow information */
        for (y = 0; y < current_floor_ptr->height; y++)
        {
                for (x = 0; x < current_floor_ptr->width; x++)
                {
                        current_floor_ptr->grid_array[y][x].cost = 0;
                        current_floor_ptr->grid_array[y][x].dist = 0;
                }
        }

        /* Save player position */
        flow_y = p_ptr->y;
        flow_x = p_ptr->x;

        /* Add the player's grid to the queue */
        temp_y[0] = p_ptr->y;
        temp_x[0] = p_ptr->x;

        /* Now process the queue */
        while (flow_head != flow_tail)
        {
                int ty, tx;

                /* Extract the next entry */
                ty = temp_y[flow_tail];
                tx = temp_x[flow_tail];

                /* Forget that entry */
                if (++flow_tail == TEMP_MAX) flow_tail = 0;

                /* Add the "children" */
                for (d = 0; d < 8; d++)
                {
                        int old_head = flow_head;
                        byte_hack m = current_floor_ptr->grid_array[ty][tx].cost + 1;
                        byte_hack n = current_floor_ptr->grid_array[ty][tx].dist + 1;
                        grid_type *g_ptr;

                        /* Child location */
                        y = ty + ddy_ddd[d];
                        x = tx + ddx_ddd[d];

                        /* Ignore player's grid */
                        if (player_bold(y, x)) continue;

                        g_ptr = &current_floor_ptr->grid_array[y][x];

                        if (is_closed_door(g_ptr->feat)) m += 3;

                        /* Ignore "pre-stamped" entries */
                        if (g_ptr->dist != 0 && g_ptr->dist <= n && g_ptr->cost <= m) continue;

                        /* Ignore "walls" and "rubble" */
                        if (!cave_have_flag_grid(g_ptr, FF_MOVE) && !is_closed_door(g_ptr->feat)) continue;

                        /* Save the flow cost */
                        if (g_ptr->cost == 0 || g_ptr->cost > m) g_ptr->cost = m;
                        if (g_ptr->dist == 0 || g_ptr->dist > n) g_ptr->dist = n;

                        /* Hack -- limit flow depth */
                        if (n == MONSTER_FLOW_DEPTH) continue;

                        /* Enqueue that entry */
                        temp_y[flow_head] = y;
                        temp_x[flow_head] = x;

                        /* Advance the queue */
                        if (++flow_head == TEMP_MAX) flow_head = 0;

                        /* Hack -- notice overflow by forgetting new entry */
                        if (flow_head == flow_tail) flow_head = old_head;
                }
        }
}


static int scent_when = 0;

/*
 * Characters leave scent trails for perceptive monsters to track.
 *
 * Smell is rather more limited than sound.  Many creatures cannot use
 * it at all, it doesn't extend very far outwards from the character's
 * current position, and monsters can use it to home in the character,
 * but not to run away from him.
 *
 * Smell is valued according to age.  When a character takes his current_world_ptr->game_turn,
 * scent is aged by one, and new scent of the current age is laid down.
 * Speedy characters leave more scent, true, but it also ages faster,
 * which makes it harder to hunt them down.
 *
 * Whenever the age count loops, most of the scent trail is erased and
 * the age of the remainder is recalculated.
 */
void update_smell(void)
{
        POSITION i, j;
        POSITION y, x;

        /* Create a table that controls the spread of scent */
        const int scent_adjust[5][5] =
        {
                { -1, 0, 0, 0,-1 },
                {  0, 1, 1, 1, 0 },
                {  0, 1, 2, 1, 0 },
                {  0, 1, 1, 1, 0 },
                { -1, 0, 0, 0,-1 },
        };

        /* Loop the age and adjust scent values when necessary */
        if (++scent_when == 254)
        {
                /* Scan the entire dungeon */
                for (y = 0; y < current_floor_ptr->height; y++)
                {
                        for (x = 0; x < current_floor_ptr->width; x++)
                        {
                                int w = current_floor_ptr->grid_array[y][x].when;
                                current_floor_ptr->grid_array[y][x].when = (w > 128) ? (w - 128) : 0;
                        }
                }

                /* Restart */
                scent_when = 126;
        }


        /* Lay down new scent */
        for (i = 0; i < 5; i++)
        {
                for (j = 0; j < 5; j++)
                {
                        grid_type *g_ptr;

                        /* Translate table to map grids */
                        y = i + p_ptr->y - 2;
                        x = j + p_ptr->x - 2;

                        /* Check Bounds */
                        if (!in_bounds(y, x)) continue;

                        g_ptr = &current_floor_ptr->grid_array[y][x];

                        /* Walls, water, and lava cannot hold scent. */
                        if (!cave_have_flag_grid(g_ptr, FF_MOVE) && !is_closed_door(g_ptr->feat)) continue;

                        /* Grid must not be blocked by walls from the character */
                        if (!player_has_los_bold(y, x)) continue;

                        /* Note grids that are too far away */
                        if (scent_adjust[i][j] == -1) continue;

                        /* Mark the grid with new scent */
                        g_ptr->when = scent_when + scent_adjust[i][j];
                }
        }
}


/*
 * Hack -- map the current panel (plus some) ala "magic mapping"
 */
void map_area(POSITION range)
{
        int i;
        POSITION x, y;
        grid_type *g_ptr;
        FEAT_IDX feat;
        feature_type *f_ptr;

        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS) range /= 3;

        /* Scan that area */
        for (y = 1; y < current_floor_ptr->height - 1; y++)
        {
                for (x = 1; x < current_floor_ptr->width - 1; x++)
                {
                        if (distance(p_ptr->y, p_ptr->x, y, x) > range) continue;

                        g_ptr = &current_floor_ptr->grid_array[y][x];

                        /* Memorize terrain of the grid */
                        g_ptr->info |= (CAVE_KNOWN);

                        /* Feature code (applying "mimic" field) */
                        feat = get_feat_mimic(g_ptr);
                        f_ptr = &f_info[feat];

                        /* All non-walls are "checked" */
                        if (!have_flag(f_ptr->flags, FF_WALL))
                        {
                                /* Memorize normal features */
                                if (have_flag(f_ptr->flags, FF_REMEMBER))
                                {
                                        /* Memorize the object */
                                        g_ptr->info |= (CAVE_MARK);
                                }

                                /* Memorize known walls */
                                for (i = 0; i < 8; i++)
                                {
                                        g_ptr = &current_floor_ptr->grid_array[y + ddy_ddd[i]][x + ddx_ddd[i]];

                                        /* Feature code (applying "mimic" field) */
                                        feat = get_feat_mimic(g_ptr);
                                        f_ptr = &f_info[feat];

                                        /* Memorize walls (etc) */
                                        if (have_flag(f_ptr->flags, FF_REMEMBER))
                                        {
                                                /* Memorize the walls */
                                                g_ptr->info |= (CAVE_MARK);
                                        }
                                }
                        }
                }
        }

        p_ptr->redraw |= (PR_MAP);

        p_ptr->window |= (PW_OVERHEAD | PW_DUNGEON);
}


/*
 * Change the "feat" flag for a grid, and notice/redraw the grid
 */
void cave_set_feat(POSITION y, POSITION x, FEAT_IDX feat)
{
        grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];
        feature_type *f_ptr = &f_info[feat];
        bool old_los, old_mirror;

        if (!character_dungeon)
        {
                /* Clear mimic type */
                g_ptr->mimic = 0;

                /* Change the feature */
                g_ptr->feat = feat;

                /* Hack -- glow the GLOW terrain */
                if (have_flag(f_ptr->flags, FF_GLOW) && !(d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS))
                {
                        DIRECTION i;
                        POSITION yy, xx;

                        for (i = 0; i < 9; i++)
                        {
                                yy = y + ddy_ddd[i];
                                xx = x + ddx_ddd[i];
                                if (!in_bounds2(yy, xx)) continue;
                                current_floor_ptr->grid_array[yy][xx].info |= CAVE_GLOW;
                        }
                }

                return;
        }

        old_los = cave_have_flag_bold(y, x, FF_LOS);
        old_mirror = is_mirror_grid(g_ptr);

        /* Clear mimic type */
        g_ptr->mimic = 0;

        /* Change the feature */
        g_ptr->feat = feat;

        /* Remove flag for mirror/glyph */
        g_ptr->info &= ~(CAVE_OBJECT);

        if (old_mirror && (d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS))
        {
                g_ptr->info &= ~(CAVE_GLOW);
                if (!view_torch_grids) g_ptr->info &= ~(CAVE_MARK);

                update_local_illumination(y, x);
        }

        /* Check for change to boring grid */
        if (!have_flag(f_ptr->flags, FF_REMEMBER)) g_ptr->info &= ~(CAVE_MARK);
        if (g_ptr->m_idx) update_monster(g_ptr->m_idx, FALSE);

        note_spot(y, x);

        lite_spot(y, x);

        /* Check if los has changed */
        if (old_los ^ have_flag(f_ptr->flags, FF_LOS))
        {

#ifdef COMPLEX_WALL_ILLUMINATION /* COMPLEX_WALL_ILLUMINATION */

                update_local_illumination(y, x);

#endif /* COMPLEX_WALL_ILLUMINATION */

                /* Update the visuals */
                p_ptr->update |= (PU_VIEW | PU_LITE | PU_MON_LITE | PU_MONSTERS);
        }

        /* Hack -- glow the GLOW terrain */
        if (have_flag(f_ptr->flags, FF_GLOW) && !(d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS))
        {
                DIRECTION i;
                POSITION yy, xx;
                grid_type *cc_ptr;

                for (i = 0; i < 9; i++)
                {
                        yy = y + ddy_ddd[i];
                        xx = x + ddx_ddd[i];
                        if (!in_bounds2(yy, xx)) continue;
                        cc_ptr = &current_floor_ptr->grid_array[yy][xx];
                        cc_ptr->info |= CAVE_GLOW;

                        if (player_has_los_grid(cc_ptr))
                        {
                                if (cc_ptr->m_idx) update_monster(cc_ptr->m_idx, FALSE);

                                note_spot(yy, xx);

                                lite_spot(yy, xx);
                        }

                        update_local_illumination(yy, xx);
                }

                if (p_ptr->special_defense & NINJA_S_STEALTH)
                {
                        if (current_floor_ptr->grid_array[p_ptr->y][p_ptr->x].info & CAVE_GLOW) set_superstealth(FALSE);
                }
        }
}


FEAT_IDX conv_dungeon_feat(FEAT_IDX newfeat)
{
        feature_type *f_ptr = &f_info[newfeat];

        if (have_flag(f_ptr->flags, FF_CONVERT))
        {
                switch (f_ptr->subtype)
                {
                case CONVERT_TYPE_FLOOR:
                        return feat_ground_type[randint0(100)];
                case CONVERT_TYPE_WALL:
                        return feat_wall_type[randint0(100)];
                case CONVERT_TYPE_INNER:
                        return feat_wall_inner;
                case CONVERT_TYPE_OUTER:
                        return feat_wall_outer;
                case CONVERT_TYPE_SOLID:
                        return feat_wall_solid;
                case CONVERT_TYPE_STREAM1:
                        return d_info[p_ptr->dungeon_idx].stream1;
                case CONVERT_TYPE_STREAM2:
                        return d_info[p_ptr->dungeon_idx].stream2;
                default:
                        return newfeat;
                }
        }
        else return newfeat;
}


/*
 * Take a feature, determine what that feature becomes
 * through applying the given action.
 */
FEAT_IDX feat_state(FEAT_IDX feat, int action)
{
        feature_type *f_ptr = &f_info[feat];
        int i;

        /* Get the new feature */
        for (i = 0; i < MAX_FEAT_STATES; i++)
        {
                if (f_ptr->state[i].action == action) return conv_dungeon_feat(f_ptr->state[i].result);
        }

        if (have_flag(f_ptr->flags, FF_PERMANENT)) return feat;

        return (feature_action_flags[action] & FAF_DESTROY) ? conv_dungeon_feat(f_ptr->destroyed) : feat;
}

/*
 * Takes a location and action and changes the feature at that
 * location through applying the given action.
 */
void cave_alter_feat(POSITION y, POSITION x, int action)
{
        /* Set old feature */
        FEAT_IDX oldfeat = current_floor_ptr->grid_array[y][x].feat;

        /* Get the new feat */
        FEAT_IDX newfeat = feat_state(oldfeat, action);

        /* No change */
        if (newfeat == oldfeat) return;

        /* Set the new feature */
        cave_set_feat(y, x, newfeat);

        if (!(feature_action_flags[action] & FAF_NO_DROP))
        {
                feature_type *old_f_ptr = &f_info[oldfeat];
                feature_type *f_ptr = &f_info[newfeat];
                bool found = FALSE;

                /* Handle gold */
                if (have_flag(old_f_ptr->flags, FF_HAS_GOLD) && !have_flag(f_ptr->flags, FF_HAS_GOLD))
                {
                        /* Place some gold */
                        place_gold(y, x);
                        found = TRUE;
                }

                /* Handle item */
                if (have_flag(old_f_ptr->flags, FF_HAS_ITEM) && !have_flag(f_ptr->flags, FF_HAS_ITEM) && (randint0(100) < (15 - current_floor_ptr->dun_level / 2)))
                {
                        /* Place object */
                        place_object(y, x, 0L);
                        found = TRUE;
                }

                if (found && character_dungeon && player_can_see_bold(y, x))
                {
                        msg_print(_("何かを発見した！", "You have found something!"));
                }
        }

        if (feature_action_flags[action] & FAF_CRASH_GLASS)
        {
                feature_type *old_f_ptr = &f_info[oldfeat];

                if (have_flag(old_f_ptr->flags, FF_GLASS) && character_dungeon)
                {
                        project(PROJECT_WHO_GLASS_SHARDS, 1, y, x, MIN(current_floor_ptr->dun_level, 100) / 4, GF_SHARDS,
                                (PROJECT_GRID | PROJECT_ITEM | PROJECT_KILL | PROJECT_HIDE | PROJECT_JUMP | PROJECT_NO_HANGEKI), -1);
                }
        }
}


/* Remove a mirror */
void remove_mirror(POSITION y, POSITION x)
{
        grid_type *g_ptr = &current_floor_ptr->grid_array[y][x];

        /* Remove the mirror */
        g_ptr->info &= ~(CAVE_OBJECT);
        g_ptr->mimic = 0;

        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS)
        {
                g_ptr->info &= ~(CAVE_GLOW);
                if (!view_torch_grids) g_ptr->info &= ~(CAVE_MARK);
                if (g_ptr->m_idx) update_monster(g_ptr->m_idx, FALSE);

                update_local_illumination(y, x);
        }

        note_spot(y, x);

        lite_spot(y, x);
}


/*
 *  Return TRUE if there is a mirror on the grid.
 */
bool is_mirror_grid(grid_type *g_ptr)
{
        if ((g_ptr->info & CAVE_OBJECT) && have_flag(f_info[g_ptr->mimic].flags, FF_MIRROR))
                return TRUE;
        else
                return FALSE;
}


/*
 *  Return TRUE if there is a mirror on the grid.
 */
bool is_glyph_grid(grid_type *g_ptr)
{
        if ((g_ptr->info & CAVE_OBJECT) && have_flag(f_info[g_ptr->mimic].flags, FF_GLYPH))
                return TRUE;
        else
                return FALSE;
}


/*
 *  Return TRUE if there is a mirror on the grid.
 */
bool is_explosive_rune_grid(grid_type *g_ptr)
{
        if ((g_ptr->info & CAVE_OBJECT) && have_flag(f_info[g_ptr->mimic].flags, FF_MINOR_GLYPH))
                return TRUE;
        else
                return FALSE;
}


/*
 * Calculate "incremental motion". Used by project() and shoot().
 * Assumes that (*y,*x) lies on the path from (y1,x1) to (y2,x2).
 */
void mmove2(POSITION *y, POSITION *x, POSITION y1, POSITION x1, POSITION y2, POSITION x2)
{
        POSITION dy, dx, dist, shift;

        /* Extract the distance travelled */
        dy = (*y < y1) ? y1 - *y : *y - y1;
        dx = (*x < x1) ? x1 - *x : *x - x1;

        /* Number of steps */
        dist = (dy > dx) ? dy : dx;

        /* We are calculating the next location */
        dist++;


        /* Calculate the total distance along each axis */
        dy = (y2 < y1) ? (y1 - y2) : (y2 - y1);
        dx = (x2 < x1) ? (x1 - x2) : (x2 - x1);

        /* Paranoia -- Hack -- no motion */
        if (!dy && !dx) return;


        /* Move mostly vertically */
        if (dy > dx)
        {
                /* Extract a shift factor */
                shift = (dist * dx + (dy - 1) / 2) / dy;

                /* Sometimes move along the minor axis */
                (*x) = (x2 < x1) ? (x1 - shift) : (x1 + shift);

                /* Always move along major axis */
                (*y) = (y2 < y1) ? (y1 - dist) : (y1 + dist);
        }

        /* Move mostly horizontally */
        else
        {
                /* Extract a shift factor */
                shift = (dist * dy + (dx - 1) / 2) / dx;

                /* Sometimes move along the minor axis */
                (*y) = (y2 < y1) ? (y1 - shift) : (y1 + shift);

                /* Always move along major axis */
                (*x) = (x2 < x1) ? (x1 - dist) : (x1 + dist);
        }
}



/*
 * Determine if a bolt spell cast from (y1,x1) to (y2,x2) will arrive
 * at the final destination, assuming no monster gets in the way.
 *
 * This is slightly (but significantly) different from "los(y1,x1,y2,x2)".
 */
bool projectable(POSITION y1, POSITION x1, POSITION y2, POSITION x2)
{
        POSITION y, x;

        int grid_n = 0;
        u16b grid_g[512];

        /* Check the projection path */
        grid_n = project_path(grid_g, (project_length ? project_length : MAX_RANGE), y1, x1, y2, x2, 0);

        /* Identical grid */
        if (!grid_n) return TRUE;

        /* Final grid */
        y = GRID_Y(grid_g[grid_n - 1]);
        x = GRID_X(grid_g[grid_n - 1]);

        /* May not end in an unrequested grid */
        if ((y != y2) || (x != x2)) return (FALSE);

        /* Assume okay */
        return (TRUE);
}


/*
 * Standard "find me a location" function
 *
 * Obtains a legal location within the given distance of the initial
 * location, and with "los()" from the source to destination location.
 *
 * This function is often called from inside a loop which searches for
 * locations while increasing the "d" distance.
 *
 * Currently the "m" parameter is unused.
 */
void scatter(POSITION *yp, POSITION *xp, POSITION y, POSITION x, POSITION d, BIT_FLAGS mode)
{
        POSITION nx, ny;

        /* Pick a location */
        while (TRUE)
        {
                /* Pick a new location */
                ny = rand_spread(y, d);
                nx = rand_spread(x, d);

                /* Ignore annoying locations */
                if (!in_bounds(ny, nx)) continue;

                /* Ignore "excessively distant" locations */
                if ((d > 1) && (distance(y, x, ny, nx) > d)) continue;

                if (mode & PROJECT_LOS)
                {
                        if (los(y, x, ny, nx)) break;
                }
                else
                {
                        if (projectable(y, x, ny, nx)) break;
                }

        }

        /* Save the location */
        (*yp) = ny;
        (*xp) = nx;
}




/*
 * Track a new monster
 */
void health_track(MONSTER_IDX m_idx)
{
        /* Mount monster is already tracked */
        if (m_idx && m_idx == p_ptr->riding) return;

        /* Track a new guy */
        p_ptr->health_who = m_idx;

        /* Redraw (later) */
        p_ptr->redraw |= (PR_HEALTH);
}



/*
 * Hack -- track the given monster race
 */
void monster_race_track(MONRACE_IDX r_idx)
{
        /* Save this monster ID */
        p_ptr->monster_race_idx = r_idx;

        p_ptr->window |= (PW_MONSTER);
}



/*
 * Hack -- track the given object kind
 */
void object_kind_track(KIND_OBJECT_IDX k_idx)
{
        /* Save this monster ID */
        p_ptr->object_kind_idx = k_idx;

        p_ptr->window |= (PW_OBJECT);
}



/*
 * Something has happened to disturb the player.
 *
 * The first arg indicates a major disturbance, which affects search.
 *
 * The second arg is currently unused, but could induce output flush.
 *
 * All disturbance cancels repeated commands, resting, and running.
 */
void disturb(bool stop_search, bool stop_travel)
{
#ifndef TRAVEL
        /* Unused */
        stop_travel = stop_travel;
#endif

        /* Cancel auto-commands */
        /* command_new = 0; */

        /* Cancel repeated commands */
        if (command_rep)
        {
                /* Cancel */
                command_rep = 0;

                /* Redraw the state (later) */
                p_ptr->redraw |= (PR_STATE);
        }

        /* Cancel Resting */
        if ((p_ptr->action == ACTION_REST) || (p_ptr->action == ACTION_FISH) || (stop_search && (p_ptr->action == ACTION_SEARCH)))
        {
                /* Cancel */
                set_action(ACTION_NONE);
        }

        /* Cancel running */
        if (running)
        {
                /* Cancel */
                running = 0;

                /* Check for new panel if appropriate */
                if (center_player && !center_running) verify_panel();

                /* Calculate torch radius */
                p_ptr->update |= (PU_TORCH);

                /* Update monster flow */
                p_ptr->update |= (PU_FLOW);
        }

#ifdef TRAVEL
        if (stop_travel)
        {
                /* Cancel */
                travel.run = 0;

                /* Check for new panel if appropriate */
                if (center_player && !center_running) verify_panel();

                /* Calculate torch radius */
                p_ptr->update |= (PU_TORCH);
        }
#endif

        /* Flush the input if requested */
        if (flush_disturb) flush();
}


/*
 * Glow deep lava and building entrances in the floor
 */
void glow_deep_lava_and_bldg(void)
{
        POSITION y, x, yy, xx;
        DIRECTION i;
        grid_type *g_ptr;

        /* Not in the darkness dungeon */
        if (d_info[p_ptr->dungeon_idx].flags1 & DF1_DARKNESS) return;

        for (y = 0; y < current_floor_ptr->height; y++)
        {
                for (x = 0; x < current_floor_ptr->width; x++)
                {
                        g_ptr = &current_floor_ptr->grid_array[y][x];

                        /* Feature code (applying "mimic" field) */

                        if (have_flag(f_info[get_feat_mimic(g_ptr)].flags, FF_GLOW))
                        {
                                for (i = 0; i < 9; i++)
                                {
                                        yy = y + ddy_ddd[i];
                                        xx = x + ddx_ddd[i];
                                        if (!in_bounds2(yy, xx)) continue;
                                        current_floor_ptr->grid_array[yy][xx].info |= CAVE_GLOW;
                                }
                        }
                }
        }

        /* Update the view and lite */
        p_ptr->update |= (PU_VIEW | PU_LITE | PU_MON_LITE);

        p_ptr->redraw |= (PR_MAP);
}

/*!
* @brief 指定されたマスがモンスターのテレポート可能先かどうかを判定する。
* @param m_idx モンスターID
* @param y 移動先Y座標
* @param x 移動先X座標
* @param mode オプション
* @return テレポート先として妥当ならばtrue
*/
bool cave_monster_teleportable_bold(MONSTER_IDX m_idx, POSITION y, POSITION x, BIT_FLAGS mode)
{
        monster_type *m_ptr = &current_floor_ptr->m_list[m_idx];
        grid_type    *g_ptr = &current_floor_ptr->grid_array[y][x];
        feature_type *f_ptr = &f_info[g_ptr->feat];

        /* Require "teleportable" space */
        if (!have_flag(f_ptr->flags, FF_TELEPORTABLE)) return FALSE;

        if (g_ptr->m_idx && (g_ptr->m_idx != m_idx)) return FALSE;
        if (player_bold(y, x)) return FALSE;

        /* Hack -- no teleport onto glyph of warding */
        if (is_glyph_grid(g_ptr)) return FALSE;
        if (is_explosive_rune_grid(g_ptr)) return FALSE;

        if (!(mode & TELEPORT_PASSIVE))
        {
                if (!monster_can_cross_terrain(g_ptr->feat, &r_info[m_ptr->r_idx], 0)) return FALSE;
        }

        return TRUE;
}

/*!
* @brief 指定されたマスにプレイヤーがテレポート可能かどうかを判定する。
* @param y 移動先Y座標
* @param x 移動先X座標
* @param mode オプション
* @return テレポート先として妥当ならばtrue
*/
bool cave_player_teleportable_bold(POSITION y, POSITION x, BIT_FLAGS mode)
{
        grid_type    *g_ptr = &current_floor_ptr->grid_array[y][x];
        feature_type *f_ptr = &f_info[g_ptr->feat];

        /* Require "teleportable" space */
        if (!have_flag(f_ptr->flags, FF_TELEPORTABLE)) return FALSE;

        /* No magical teleporting into vaults and such */
        if (!(mode & TELEPORT_NONMAGICAL) && (g_ptr->info & CAVE_ICKY)) return FALSE;

        if (g_ptr->m_idx && (g_ptr->m_idx != p_ptr->riding)) return FALSE;

        /* don't teleport on a trap. */
        if (have_flag(f_ptr->flags, FF_HIT_TRAP)) return FALSE;

        if (!(mode & TELEPORT_PASSIVE))
        {
                if (!player_can_enter(g_ptr->feat, 0)) return FALSE;

                if (have_flag(f_ptr->flags, FF_WATER) && have_flag(f_ptr->flags, FF_DEEP))
                {
                        if (!p_ptr->levitation && !p_ptr->can_swim) return FALSE;
                }

                if (have_flag(f_ptr->flags, FF_LAVA) && !p_ptr->immune_fire && !IS_INVULN())
                {
                        /* Always forbid deep lava */
                        if (have_flag(f_ptr->flags, FF_DEEP)) return FALSE;

                        /* Forbid shallow lava when the player don't have levitation */
                        if (!p_ptr->levitation) return FALSE;
                }

        }

        return TRUE;
}

/*!
 * @brief 地形は開くものであって、かつ開かれているかを返す /
 * Attempt to open the given chest at the given location
 * @param feat 地形ID
 * @return 開いた地形である場合TRUEを返す /  Return TRUE if the given feature is an open door
 */
bool is_open(FEAT_IDX feat)
{
        return have_flag(f_info[feat].flags, FF_CLOSE) && (feat != feat_state(feat, FF_CLOSE));
}