Unify mesmerisation code.

There were several places that had copies of the same code, checking
whether mesmerisation blocked movement to a given target.

The various mesmerisation functions have become methods of player
and were moved into behold.cc.

19 files changed, 248 insertions, 308 deletions

diff --git a/crawl-ref/source/acr.cc b/crawl-ref/source/acr.cc
index 02ee5a3772..1976e1405b 100644
--- a/crawl-ref/source/acr.cc
+++ b/crawl-ref/source/acr.cc
@@ -920,7 +920,7 @@ static void _input()
     crawl_state.clear_mon_acting();
 
     religion_turn_start();
-    check_beholders();
+    you.update_beholders();
 
     // Currently only set if Xom accidentally kills the player.
     you.reset_escaped_death();
@@ -1188,10 +1188,11 @@ static void _input()
 
 static bool _stairs_check_mesmerised()
 {
-    if (you.duration[DUR_MESMERISED] && !you.confused())
+    if (you.beheld() && !you.confused())
     {
+        const monsters* beholder = you.get_any_beholder();
         mprf("You cannot move away from %s!",
-             menv[you.mesmerised_by[0]].name(DESC_NOCAP_THE, true).c_str());
+             beholder->name(DESC_NOCAP_THE, true).c_str());
         return (true);
     }
 
@@ -2370,7 +2371,7 @@ static void _decrement_durations()
     if (_decrement_a_duration(DUR_MESMERISED, "You break out of your daze.",
                               0, NULL, MSGCH_RECOVERY))
     {
-        you.mesmerised_by.clear();
+        you.clear_beholders();
     }
 
     dec_slow_player();
@@ -3913,21 +3914,8 @@ static void _move_player(coord_def move)
     // You cannot move away from a mermaid but you CAN fight monsters on
     // neighbouring squares.
     monsters *beholder = NULL;
-    if (you.duration[DUR_MESMERISED] && !you.confused())
-    {
-        for (unsigned int i = 0; i < you.mesmerised_by.size(); ++i)
-        {
-            monsters& mon = menv[you.mesmerised_by[i]];
-            int olddist = grid_distance(you.pos(), mon.pos());
-            int newdist = grid_distance(targ, mon.pos());
-
-            if (olddist < newdist)
-            {
-                beholder = &mon;
-                break;
-            }
-        }
-    }
+    if (!you.confused())
+        beholder = you.get_beholder(targ);
 
     if (you.running.check_stop_running())
     {
diff --git a/crawl-ref/source/behold.cc b/crawl-ref/source/behold.cc
new file mode 100644
index 0000000000..37571e1b0a
--- /dev/null
+++ b/crawl-ref/source/behold.cc
@@ -0,0 +1,173 @@
+#include "AppHdr.h"
+
+#include "player.h"
+
+#include "coord.h"
+#include "debug.h"
+#include "env.h"
+#include "los.h"
+#include "mon-util.h"
+#include "monster.h"
+#include "random.h"
+#include "stuff.h"
+#include "view.h"
+
+// Add a monster to the list of beholders.
+void player::add_beholder(const monsters* mon)
+{
+    if (!duration[DUR_MESMERISED])
+    {
+        duration[DUR_MESMERISED] = 7;
+        beholders.push_back(mon->mindex());
+        mprf(MSGCH_WARN, "You are mesmerised by %s!",
+                         mon->name(DESC_NOCAP_THE).c_str());
+    }
+    else
+    {
+        duration[DUR_MESMERISED] += 5;
+        if (!beheld_by(mon))
+            beholders.push_back(mon->mindex());
+    }
+
+    if (duration[DUR_MESMERISED] > 12)
+        duration[DUR_MESMERISED] = 12;
+}
+
+// Whether player is mesmerised.
+bool player::beheld() const
+{
+    ASSERT(duration[DUR_MESMERISED] > 0 == !beholders.empty());
+    return (duration[DUR_MESMERISED] > 0);
+}
+
+// Whether player is mesmerised by the given monster.
+bool player::beheld_by(const monsters* mon) const
+{
+    for (unsigned int i = 0; i < beholders.size(); i++)
+        if (beholders[i] == mon->mindex())
+            return (true);
+    return (false);
+}
+
+// Checks whether a beholder keeps you from moving to
+// target, and returns one if it exists.
+monsters* player::get_beholder(const coord_def &target) const
+{
+    for (unsigned int i = 0; i < beholders.size(); i++)
+    {
+        monsters *mon = &menv[beholders[i]];
+        const int olddist = grid_distance(you.pos(), mon->pos());
+        const int newdist = grid_distance(target, mon->pos());
+
+        if (olddist < newdist)
+            return (mon);
+    }
+    return (NULL);
+}
+
+monsters* player::get_any_beholder() const
+{
+    if (beholders.size() > 0)
+        return (&menv[beholders[0]]);
+    else
+        return (NULL);
+}
+
+// Removes a monster from the list of beholders if present.
+void player::remove_beholder(const monsters *mon)
+{
+    for (unsigned int i = 0; i < beholders.size(); i++)
+        if (beholders[i] == mon->mindex())
+        {
+            beholders.erase(beholders.begin() + i);
+            _removed_beholder();
+            return;
+        }
+}
+
+// Clear the list of beholders. Doesn't message.
+void player::clear_beholders()
+{
+    beholders.clear();
+    duration[DUR_MESMERISED] = 0;
+}
+
+// Possibly end mesmerisation if a loud noise happened.
+void player::beholders_check_noise(int loudness)
+{
+    if (loudness >= 20 && you.beheld())
+    {
+        mprf("For a moment, you cannot hear the mermaid%s!",
+             beholders.size() > 1 ? "s" : "");
+        clear_beholders();
+        _removed_beholder();
+    }
+}
+
+// Update all beholders' status after changes.
+void player::update_beholders()
+{
+    if (!beheld())
+        return;
+    bool removed = false;
+    for (int i = beholders.size() - 1; i >= 0; i--)
+    {
+        const monsters* mon = &menv[beholders[i]];
+        if (!_possible_beholder(mon))
+        {
+            beholders.erase(beholders.begin() + i);
+            removed = true;
+        }
+    }
+    if (removed)
+        _removed_beholder();
+}
+
+// Update a single beholder.
+void player::update_beholder(const monsters *mon)
+{
+    if (_possible_beholder(mon))
+        return;
+    for (unsigned int i = 0; i < beholders.size(); i++)
+        if (beholders[i] = mon->mindex())
+        {
+            beholders.erase(beholders.begin() + i);
+            _removed_beholder();
+            return;
+        }
+}
+
+// Helper function that resets the duration and messages if the player
+// is no longer mesmerised.
+void player::_removed_beholder()
+{
+    if (beholders.empty())
+    {
+        duration[DUR_MESMERISED] = 0;
+        mpr(coinflip() ? "You break out of your daze!"
+                       : "You are no longer entranced.",
+            MSGCH_DURATION);
+    }
+}
+
+// Helper function that checks whether the given monster is a possible
+// beholder.
+bool player::_possible_beholder(const monsters *mon) const
+{
+    if (silenced(you.pos()))
+        return (false);
+    if (!mon->alive() || !mons_near(mon) || mons_friendly(mon)
+        || mon->submerged() || mon->confused() || mons_cannot_move(mon)
+        || mon->asleep() || silenced(mon->pos()))
+    {
+        return (false);
+    }
+
+    // TODO: replace this by see/see_no_trans.
+    int walls = num_feats_between(you.pos(), mon->pos(),
+                                  DNGN_UNSEEN, DNGN_MAXOPAQUE);
+    if (walls > 0)
+        return (false);
+
+    return (true);
+}
diff --git a/crawl-ref/source/debug.cc b/crawl-ref/source/debug.cc
index fee098066b..90ae37f211 100644
--- a/crawl-ref/source/debug.cc
+++ b/crawl-ref/source/debug.cc
@@ -2140,11 +2140,8 @@ void wizard_heal(bool super_heal)
         // Clear more stuff and give a HP boost.
         you.magic_contamination = 0;
         you.duration[DUR_LIQUID_FLAMES] = 0;
-        if (you.duration[DUR_MESMERISED])
-        {
-            you.duration[DUR_MESMERISED] = 0;
-            you.mesmerised_by.clear();
-        }
+        you.clear_beholders();
+
         // If we're repeating then do the HP increase all at once.
         int amount = 10;
         if (crawl_state.cmd_repeat_goal > 0)
diff --git a/crawl-ref/source/directn.cc b/crawl-ref/source/directn.cc
index 4ea97767f0..cd75cf221d 100644
--- a/crawl-ref/source/directn.cc
+++ b/crawl-ref/source/directn.cc
@@ -627,7 +627,7 @@ void full_describe_view()
             std::string str = get_monster_equipment_desc(list_mons[i], true,
                                                          DESC_CAP_A, true);
 
-            if (player_mesmerised_by(list_mons[i]))
+            if (you.beheld_by(list_mons[i]))
                 str += ", keeping you mesmerised";
 
             if (damage_level != MDAM_OKAY)
@@ -3123,7 +3123,7 @@ static std::string _get_monster_desc(const monsters *mon)
     std::string text    = "";
     std::string pronoun = mon->pronoun(PRONOUN_CAP);
 
-    if (player_mesmerised_by(mon))
+    if (you.beheld_by(mon))
         text += "You are mesmerised by her song.\n";
 
     if (!mons_is_mimic(mon->type) && mons_behaviour_perceptible(mon))
diff --git a/crawl-ref/source/makefile.obj b/crawl-ref/source/makefile.obj
index 9ebecb6531..30815c01f6 100644
--- a/crawl-ref/source/makefile.obj
+++ b/crawl-ref/source/makefile.obj
@@ -6,6 +6,7 @@ actor.o \
 arena.o \
 artefact.o \
 beam.o \
+behold.o \
 bitary.o \
 branch.o \
 chardump.o \
diff --git a/crawl-ref/source/misc.cc b/crawl-ref/source/misc.cc
index 9f10f2ad3c..bdfd78fbe0 100644
--- a/crawl-ref/source/misc.cc
+++ b/crawl-ref/source/misc.cc
@@ -2580,11 +2580,7 @@ void down_stairs( int old_level, dungeon_feature_type force_stair,
     }
 
     // Clear list of beholding monsters.
-    if (you.duration[DUR_MESMERISED])
-    {
-        you.mesmerised_by.clear();
-        you.duration[DUR_MESMERISED] = 0;
-    }
+    you.clear_beholders();
 
     if (you.skills[SK_TRANSLOCATIONS] > 0 && !allow_control_teleport( true ))
         mpr( "You sense a powerful magical force warping space.", MSGCH_WARN );
diff --git a/crawl-ref/source/mon-abil.cc b/crawl-ref/source/mon-abil.cc
index 680c86f02d..cd5d2909ad 100644
--- a/crawl-ref/source/mon-abil.cc
+++ b/crawl-ref/source/mon-abil.cc
@@ -1202,7 +1202,7 @@ bool mon_special_ability(monsters *monster, bolt & beem)
             break;
         }
 
-        bool already_mesmerised = player_mesmerised_by(monster);
+        bool already_mesmerised = you.beheld_by(monster);
 
         if (one_chance_in(5)
             || monster->foe == MHITYOU && !already_mesmerised && coinflip())
@@ -1257,23 +1257,9 @@ bool mon_special_ability(monsters *monster, bolt & beem)
                 break;
             }
 
-            if (!you.duration[DUR_MESMERISED])
-            {
-                you.duration[DUR_MESMERISED] = 7;
-                you.mesmerised_by.push_back(monster_index(monster));
-                mprf(MSGCH_WARN, "You are mesmerised by %s!",
-                                 monster->name(DESC_NOCAP_THE).c_str());
-            }
-            else
-            {
-                you.duration[DUR_MESMERISED] += 5;
-                if (!already_mesmerised)
-                    you.mesmerised_by.push_back(monster_index(monster));
-            }
-            used = true;
+            you.add_beholder(monster);
 
-            if (you.duration[DUR_MESMERISED] > 12)
-                you.duration[DUR_MESMERISED] = 12;
+            used = true;
         }
         break;
     }
@@ -1361,7 +1347,7 @@ void mon_nearby_ability(monsters *monster)
 
     if (monster_can_submerge(monster, grd(monster->pos()))
         && !monster->caught()             // No submerging while caught.
-        && !player_mesmerised_by(monster) // No submerging if player entranced.
+        && !you.beheld_by(monster) // No submerging if player entranced.
         && !mons_is_lurking(monster)  // Handled elsewhere.
         && monster->wants_submerge())
     {
@@ -1369,7 +1355,6 @@ void mon_nearby_ability(monsters *monster)
 
         monster->add_ench(ENCH_SUBMERGED);
         monster->speed_increment -= ENERGY_SUBMERGE(entry);
-        update_beholders(monster);
         return;
     }
 
diff --git a/crawl-ref/source/mon-act.cc b/crawl-ref/source/mon-act.cc
index 09f3a93c80..ebd07d6fcf 100644
--- a/crawl-ref/source/mon-act.cc
+++ b/crawl-ref/source/mon-act.cc
@@ -2040,7 +2040,7 @@ static void _handle_monster_move(monsters *monster)
             if (mons_cannot_move(monster) || !_monster_move(monster))
                 monster->speed_increment -= non_move_energy;
         }
-        update_beholders(monster);
+        you.update_beholder(monster);
 
         // Reevaluate behaviour, since the monster's surroundings have
         // changed (it may have moved, or died for that matter).  Don't
@@ -2087,11 +2087,7 @@ void handle_monsters()
         if (you.banished)
         {
             // Clear list of mesmerising monsters.
-            if (you.duration[DUR_MESMERISED])
-            {
-                you.mesmerised_by.clear();
-                you.duration[DUR_MESMERISED] = 0;
-            }
+            you.clear_beholders();
             break;
         }
     }
diff --git a/crawl-ref/source/mon-behv.cc b/crawl-ref/source/mon-behv.cc
index d3eff47330..ae406d0e49 100644
--- a/crawl-ref/source/mon-behv.cc
+++ b/crawl-ref/source/mon-behv.cc
@@ -1391,7 +1391,7 @@ void handle_behaviour(monsters *mon)
             {
                 // The foe is the player.
                 if (mon->type == MONS_SIREN
-                    && player_mesmerised_by(mon)
+                    && you.beheld_by(mon)
                     && _find_siren_water_target(mon))
                 {
                     break;
diff --git a/crawl-ref/source/monstuff.cc b/crawl-ref/source/monstuff.cc
index 1f9cb7b05d..6c65a4a923 100644
--- a/crawl-ref/source/monstuff.cc
+++ b/crawl-ref/source/monstuff.cc
@@ -1323,8 +1323,7 @@ int monster_die(monsters *monster, killer_type killer,
 
     mons_clear_trapping_net(monster);
 
-    // Update list of monsters beholding player.
-    update_beholders(monster, true);
+    you.remove_beholder(monster);
 
     // Clear auto exclusion now the monster is killed -- if we know about it.
     if (mons_near(monster) || wizard)
@@ -2257,7 +2256,7 @@ bool monster_polymorph(monsters *monster, monster_type targetc,
     // the polymorph disrupts the beholding process.  Do this before
     // changing monster->type, since unbeholding can only happen while
     // the monster is still a mermaid/siren.
-    update_beholders(monster, true);
+    you.remove_beholder(monster);
 
     // Inform listeners that the original monster is gone.
     _fire_monster_death_event(monster, KILL_MISC, NON_MONSTER, true);
diff --git a/crawl-ref/source/output.cc b/crawl-ref/source/output.cc
index d5505d48ac..fcc94f0cd7 100644
--- a/crawl-ref/source/output.cc
+++ b/crawl-ref/source/output.cc
@@ -737,7 +737,7 @@ static void _get_status_lights(std::vector<status_light>& out)
         out.push_back(status_light(RED, "-MR"));
 
     // TODO: Differentiate between mermaids and sirens!
-    if (you.duration[DUR_MESMERISED])
+    if (you.beheld())
         out.push_back(status_light(RED, "Mesm"));
 
     if (you.duration[DUR_LIQUID_FLAMES])
@@ -2056,7 +2056,7 @@ std::string _status_mut_abilities()
         status.push_back("short of breath");
 
     // TODO: Differentiate between mermaids and sirens!
-    if (you.duration[DUR_MESMERISED])
+    if (you.beheld())
         status.push_back("mesmerised");
 
     if (you.duration[DUR_LIQUID_FLAMES])
diff --git a/crawl-ref/source/player.cc b/crawl-ref/source/player.cc
index 6bb655a253..5d00539bc9 100644
--- a/crawl-ref/source/player.cc
+++ b/crawl-ref/source/player.cc
@@ -2554,127 +2554,6 @@ int player_shield_class(void)   //jmf: changes for new spell
     return (base_shield);
 }
 
-// Returns true if player is mesmerised by a given monster.
-bool player_mesmerised_by(const monsters *mon)
-{
-    if (!you.duration[DUR_MESMERISED])
-        return (false);
-
-    // Can this monster even behold you?
-    if (mons_genus(mon->type) != MONS_MERMAID)
-        return (false);
-
-#ifdef DEBUG_DIAGNOSTICS
-    mprf(MSGCH_DIAGNOSTICS, "mesmerised_by.size: %d, DUR_MESMERISED: %d, "
-                            "current mon: %d", you.mesmerised_by.size(),
-                            you.duration[DUR_MESMERISED], mon->mindex());
-#endif
-
-    if (you.mesmerised_by.empty()) // shouldn't happen
-    {
-        you.duration[DUR_MESMERISED] = 0;
-        return (false);
-    }
-
-    for (unsigned int i = 0; i < you.mesmerised_by.size(); i++)
-    {
-         unsigned int which_mon = you.mesmerised_by[i];
-         if (monster_index(mon) == which_mon)
-             return (true);
-    }
-
-    return (false);
-}
-
-// Removes a monster from the list of beholders if force == true
-// (e.g. monster dead) or one of several cases is met.
-void update_beholders(const monsters *mon, bool force)
-{
-    if (!player_mesmerised_by(mon)) // Not in list?
-        return;
-
-    // Is an update even necessary?
-    if (force || !mons_near(mon) || mons_friendly(mon) || mon->submerged()
-        || mon->has_ench(ENCH_CONFUSION) || mons_cannot_move(mon)
-        || mon->asleep() || silenced(you.pos()) || silenced(mon->pos()))
-    {
-        const std::vector<int> help = you.mesmerised_by;
-        you.mesmerised_by.clear();
-
-        for (unsigned int i = 0; i < help.size(); i++)
-        {
-             unsigned int which_mon = help[i];
-             if (monster_index(mon) != which_mon)
-                 you.mesmerised_by.push_back(which_mon);
-        }
-
-        if (you.mesmerised_by.empty())
-        {
-            mpr("You are no longer entranced.", MSGCH_RECOVERY);
-            you.duration[DUR_MESMERISED] = 0;
-        }
-    }
-}
-
-void check_beholders()
-{
-    for (int i = you.mesmerised_by.size() - 1; i >= 0; i--)
-    {
-        const monsters* mon = &menv[you.mesmerised_by[i]];
-        if (!mon->alive() || mons_genus(mon->type) != MONS_MERMAID
-            || mon->submerged())
-        {
-#ifdef DEBUG
-            if (!mon->alive())
-                mpr("Dead mermaid/siren still mesmerising?", MSGCH_DIAGNOSTICS);
-            else if (mons_genus(mon->type) != MONS_MERMAID)
-            {
-                mprf(MSGCH_DIAGNOSTICS, "Non-mermaid/siren '%s' mesmerising?",
-                     mon->name(DESC_PLAIN, true).c_str());
-            }
-#endif
-
-            you.mesmerised_by.erase(you.mesmerised_by.begin() + i);
-            if (you.mesmerised_by.empty())
-            {
-                mpr("You are no longer entranced.", MSGCH_RECOVERY);
-                you.duration[DUR_MESMERISED] = 0;
-                break;
-            }
-            continue;
-        }
-        const coord_def pos = mon->pos();
-        int walls = num_feats_between(you.pos(), pos,
-                                      DNGN_UNSEEN, DNGN_MAXOPAQUE);
-
-        if (walls > 0)
-        {
-#ifdef DEBUG
-            mprf(MSGCH_DIAGNOSTICS, "%d walls between mesmerising '%s' "
-                 "and player", walls, mon->name(DESC_PLAIN, true).c_str());
-#endif
-            you.mesmerised_by.erase(you.mesmerised_by.begin() + i);
-            if (you.mesmerised_by.empty())
-            {
-                mpr("You are no longer entranced.", MSGCH_RECOVERY);
-                you.duration[DUR_MESMERISED] = 0;
-                break;
-            }
-            continue;
-        }
-    }
-
-    if (you.duration[DUR_MESMERISED] > 0 && you.mesmerised_by.empty())
-    {
-#ifdef DEBUG
-        mpr("Mesmerised with no mermaids/sirens left?", MSGCH_DIAGNOSTICS);
-#endif
-
-        mpr("You are no longer entranced.", MSGCH_RECOVERY);
-        you.duration[DUR_MESMERISED] = 0;
-    }
-}
-
 int player_sust_abil(bool calc_unid)
 {
     int sa = 0;
@@ -3949,7 +3828,7 @@ void display_char_status()
         mpr("You are confused.");
 
     // TODO: Distinguish between mermaids and sirens!
-    if (you.duration[DUR_MESMERISED])
+    if (you.beheld())
         mpr("You are mesmerised.");
 
     // How exactly did you get to show the status?
@@ -6324,7 +6203,7 @@ bool player::can_go_berserk(bool verbose) const
         return (false);
     }
 
-    if (this->duration[DUR_MESMERISED])
+    if (beheld())
     {
         if (verbose)
             mpr("You are too mesmerised to rage.");
diff --git a/crawl-ref/source/player.h b/crawl-ref/source/player.h
index 97fc296692..8ec9756c8d 100644
--- a/crawl-ref/source/player.h
+++ b/crawl-ref/source/player.h
@@ -35,8 +35,6 @@ public:
   bool banished;
   std::string banished_by;
 
-  std::vector<int> mesmerised_by; // monsters mesmerising player
-
   int  friendly_pickup;       // pickup setting for allies
 
   unsigned short prev_targ;
@@ -283,10 +281,15 @@ public:
   // When other levels are loaded (e.g. viewing), is the player on this level?
   bool on_current_level;
 
+  // monsters mesmerising player; should be proteced, but needs to be saved
+  // and restored.
+  std::vector<int> beholders;
+
 protected:
   FixedVector<PlaceInfo, NUM_BRANCHES>             branch_info;
   FixedVector<PlaceInfo, NUM_LEVEL_AREA_TYPES - 1> non_branch_info;
 
+
 public:
     player();
     player(const player &other);
@@ -319,6 +322,18 @@ public:
     bool light_flight() const;
     bool travelling_light() const;
 
+    // Dealing with beholders. Implemented in behold.cc.
+    void add_beholder(const monsters *mon);
+    bool beheld() const;
+    bool beheld_by(const monsters *mon) const;
+    monsters* get_beholder(const coord_def &pos) const;
+    monsters* get_any_beholder() const;
+    void remove_beholder(const monsters *mon);
+    void clear_beholders();
+    void beholders_check_noise(int loudness);
+    void update_beholders();
+    void update_beholder(const monsters *mon);
+
     kill_category kill_alignment() const;
 
     bool has_spell(spell_type spell) const;
@@ -489,6 +504,9 @@ public:
 
 protected:
     void base_moveto(const coord_def &c);
+
+    void _removed_beholder();
+    bool _possible_beholder(const monsters *mon) const;
 };
 
 extern player you;
@@ -633,11 +651,6 @@ int scan_artefacts(artefact_prop_type which_property, bool calc_unid = true);
 
 int slaying_bonus(char which_affected, bool ranged = false);
 
-
-bool player_mesmerised_by(const monsters *mon);
-void update_beholders(const monsters *mon, bool force = false);
-void check_beholders();
-
 unsigned long exp_needed(int lev);
 
 int get_expiration_threshold(duration_type dur);
diff --git a/crawl-ref/source/spells1.cc b/crawl-ref/source/spells1.cc
index 0267230e41..e94fc43957 100644
--- a/crawl-ref/source/spells1.cc
+++ b/crawl-ref/source/spells1.cc
@@ -117,27 +117,12 @@ int blink(int pow, bool high_level_controlled_blink, bool wizard_blink)
                 return (-1);         // early return {dlb}
             }
 
-            if (!wizard_blink && you.duration[DUR_MESMERISED])
+            monsters* beholder = you.get_beholder(beam.target);
+            if (!wizard_blink && beholder)
             {
-                bool blocked_movement = false;
-                for (unsigned int i = 0; i < you.mesmerised_by.size(); i++)
-                {
-                    monsters& mon = menv[you.mesmerised_by[i]];
-                    const int olddist = grid_distance(you.pos(), mon.pos());
-                    const int newdist = grid_distance(beam.target, mon.pos());
-
-                    if (olddist < newdist)
-                    {
-                        mprf("You cannot blink away from %s!",
-                             mon.name(DESC_NOCAP_THE, true).c_str());
-
-                        blocked_movement = true;
-                        break;
-                    }
-                }
-
-                if (blocked_movement)
-                    continue;
+                mprf("You cannot blink away from %s!",
+                    beholder->name(DESC_NOCAP_THE, true).c_str());
+                continue;
             }
 
             if (grd(beam.target) == DNGN_OPEN_SEA)
diff --git a/crawl-ref/source/spells3.cc b/crawl-ref/source/spells3.cc
index d6293b7063..9ccd1ec3e7 100644
--- a/crawl-ref/source/spells3.cc
+++ b/crawl-ref/source/spells3.cc
@@ -1478,30 +1478,16 @@ static bool _teleport_player(bool allow_control, bool new_abyss_area)
                 return (false);
             }
 
-            if (you.duration[DUR_MESMERISED])
+            monsters *beholder = you.get_beholder(pos);
+            if (beholder)
             {
-                bool blocked_movement = false;
-                for (unsigned int i = 0; i < you.mesmerised_by.size(); i++)
-                {
-                    monsters& mon = menv[you.mesmerised_by[i]];
-                    const int olddist = grid_distance(you.pos(), mon.pos());
-                    const int newdist = grid_distance(pos, mon.pos());
-
-                    if (olddist < newdist)
-                    {
-                        mprf("You cannot teleport away from %s!",
-                             mon.name(DESC_NOCAP_THE, true).c_str());
-                        mpr("Choose another destination (press '.' or delete to select).");
-                        more();
-
-                        blocked_movement = true;
-                        break;
-                    }
-                }
-
-                if (blocked_movement)
-                    continue;
+                mprf("You cannot teleport away from %s!",
+                     beholder->name(DESC_NOCAP_THE, true).c_str());
+                mpr("Choose another destination (press '.' or delete to select).");
+                more();
+                continue;
             }
+
             break;
         }
 
@@ -1717,25 +1703,7 @@ bool entomb(int powc)
     if (number_built > 0)
     {
         mpr("Walls emerge from the floor!");
-
-        for (int i = you.mesmerised_by.size() - 1; i >= 0; i--)
-        {
-            const monsters* mon = &menv[you.mesmerised_by[i]];
-            int walls = num_feats_between(you.pos(), mon->pos(),
-                                          DNGN_UNSEEN, DNGN_MAXWALL,
-                                          true, true);
-
-            if (walls > 0)
-            {
-                update_beholders(mon, true);
-                if (you.mesmerised_by.empty())
-                {
-                    you.duration[DUR_MESMERISED] = 0;
-                    break;
-                }
-                continue;
-            }
-        }
+        you.update_beholders();
     }
     else
         canned_msg(MSG_NOTHING_HAPPENS);
diff --git a/crawl-ref/source/spells4.cc b/crawl-ref/source/spells4.cc
index 15566f5cf5..bf965913da 100644
--- a/crawl-ref/source/spells4.cc
+++ b/crawl-ref/source/spells4.cc
@@ -767,11 +767,10 @@ void cast_silence(int pow)
     if (you.duration[DUR_SILENCE] > 100)
         you.duration[DUR_SILENCE] = 100;
 
-    if (you.duration[DUR_MESMERISED])
+    if (you.beheld())
     {
+        you.clear_beholders();
         mpr("You break out of your daze!", MSGCH_RECOVERY);
-        you.duration[DUR_MESMERISED] = 0;
-        you.mesmerised_by.clear();
     }
 }
 
diff --git a/crawl-ref/source/tags.cc b/crawl-ref/source/tags.cc
index 45471455d9..f65421e5a1 100644
--- a/crawl-ref/source/tags.cc
+++ b/crawl-ref/source/tags.cc
@@ -1007,9 +1007,9 @@ static void tag_construct_you(writer &th)
     // be recalculated on game start.
 
     // List of currently beholding monsters (usually empty).
-    marshallByte(th, you.mesmerised_by.size());
-    for (unsigned int k = 0; k < you.mesmerised_by.size(); k++)
-         marshallByte(th, you.mesmerised_by[k]);
+    marshallByte(th, you.beholders.size());
+    for (unsigned int k = 0; k < you.beholders.size(); k++)
+         marshallByte(th, you.beholders[k]);
 
     marshallByte(th, you.piety_hysteresis);
 
@@ -1449,7 +1449,7 @@ static void tag_read_you(reader &th, char minorVersion)
     // List of currently beholding monsters (usually empty).
     count_c = unmarshallByte(th);
     for (i = 0; i < count_c; i++)
-         you.mesmerised_by.push_back(unmarshallByte(th));
+         you.beholders.push_back(unmarshallByte(th));
 
     you.piety_hysteresis = unmarshallByte(th);
 
diff --git a/crawl-ref/source/view.cc b/crawl-ref/source/view.cc
index e032183849..a17925354d 100644
--- a/crawl-ref/source/view.cc
+++ b/crawl-ref/source/view.cc
@@ -158,31 +158,14 @@ static void _get_symbol( const coord_def& where,
                                     && feat <= DNGN_ESCAPE_HATCH_UP
                                     && is_exclude_root(where));
 
-            bool blocked_movement = false;
-            if (!excluded_stairs
-                && feat >= DNGN_MINMOVE
-                && you.duration[DUR_MESMERISED])
+            if (excluded_stairs)
+                *colour = Options.tc_excluded | colmask;
+            else if (feat >= DNGN_MINMOVE && you.get_beholder(where))
             {
                 // Colour grids that cannot be reached due to beholders
                 // dark grey.
-                for (unsigned int i = 0; i < you.mesmerised_by.size(); i++)
-                {
-                    monsters& mon = menv[you.mesmerised_by[i]];
-                    const int olddist = grid_distance(you.pos(), mon.pos());
-                    const int newdist = grid_distance(where, mon.pos());
-
-                    if (olddist < newdist)
-                    {
-                        blocked_movement = true;
-                        break;
-                    }
-                }
-            }
-
-            if (excluded_stairs)
-                *colour = Options.tc_excluded | colmask;
-            else if (blocked_movement)
                 *colour = DARKGREY | colmask;
+            }
             else if (feat >= DNGN_MINMOVE && is_sanctuary(where))
             {
                 if (testbits(env.map(where).property, FPROP_SANCTUARY_1))
@@ -953,14 +936,8 @@ bool noisy(int loudness, const coord_def& where, const char *msg, int who,
 
         you.check_awaken(dist - player_distance);
 
-        if (!mermaid && loudness >= 20 && you.duration[DUR_MESMERISED])
-        {
-            mprf("For a moment, you cannot hear the mermaid%s!",
-                 you.mesmerised_by.size() == 1? "" : "s");
-            mpr("You break out of your daze!", MSGCH_DURATION);
-            you.duration[DUR_MESMERISED] = 0;
-            you.mesmerised_by.clear();
-        }
+        if (!mermaid)
+            you.beholders_check_noise(loudness);
 
         ret = true;
     }
diff --git a/crawl-ref/source/viewmap.cc b/crawl-ref/source/viewmap.cc
index b7d2f066e1..33a2e92a2b 100644
--- a/crawl-ref/source/viewmap.cc
+++ b/crawl-ref/source/viewmap.cc
@@ -1142,30 +1142,14 @@ screen_buffer_t colour_code_map(const coord_def& p, bool item_colour,
 
     if (feature_colour != DARKGREY)
         tc = feature_colour;
-    else if (you.duration[DUR_MESMERISED] && on_level)
+    else if (on_level && you.beheld())
     {
         // If mesmerised, colour the few grids that can be reached anyway
         // lightgrey.
         const monsters *blocker = monster_at(p);
         const bool seen_blocker = blocker && you.can_see(blocker);
-        if (grd(p) >= DNGN_MINMOVE && !seen_blocker)
-        {
-            bool blocked_movement = false;
-            for (unsigned int i = 0; i < you.mesmerised_by.size(); i++)
-            {
-                const monsters& mon = menv[you.mesmerised_by[i]];
-                const int olddist = grid_distance(you.pos(), mon.pos());
-                const int newdist = grid_distance(p, mon.pos());
-
-                if (olddist < newdist || !see_cell(env.show_los, p, mon.pos()))
-                {
-                    blocked_movement = true;
-                    break;
-                }
-            }
-            if (!blocked_movement)
-                tc = LIGHTGREY;
-        }
+        if (grd(p) >= DNGN_MINMOVE && !seen_blocker && !you.get_beholder(p))
+            tc = LIGHTGREY;
     }
 
     if (Options.feature_item_brand