[1757174] Disallow mapping in labyrinths.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@2536 c06c8d41-db1a-0410-9941-cceddc491573

6 files changed, 37 insertions, 16 deletions

diff --git a/crawl-ref/source/abl-show.cc b/crawl-ref/source/abl-show.cc
index 6610746402..7dce230919 100644
--- a/crawl-ref/source/abl-show.cc
+++ b/crawl-ref/source/abl-show.cc
@@ -1030,8 +1030,9 @@ static bool do_ability(const ability_def& abil)
 
     case ABIL_EVOKE_MAPPING:    // randarts
     case ABIL_MAPPING:          // Gnome + sense surrounds mut
-        if (abil.ability == ABIL_MAPPING && you.mutation[MUT_MAPPING] < 3 &&
-            you.level_type == LEVEL_PANDEMONIUM)
+        if (abil.ability == ABIL_MAPPING && you.mutation[MUT_MAPPING] < 3
+            && (you.level_type == LEVEL_PANDEMONIUM
+                || you.level_type == LEVEL_LABYRINTH))
         {
             mpr("You feel momentarily disoriented.");
             return (false);
diff --git a/crawl-ref/source/it_use3.cc b/crawl-ref/source/it_use3.cc
index 829c967ef9..6379dc4773 100644
--- a/crawl-ref/source/it_use3.cc
+++ b/crawl-ref/source/it_use3.cc
@@ -719,7 +719,8 @@ static bool ball_of_seeing(void)
 
     mpr("You gaze into the crystal ball.");
 
-    use = ((!you.duration[DUR_CONF]) ? random2(you.skills[SK_EVOCATIONS] * 6) : random2(5));
+    use = ((!you.duration[DUR_CONF]) ?
+           random2(you.skills[SK_EVOCATIONS] * 6) : random2(5));
 
     if (use < 2)
     {
@@ -730,8 +731,10 @@ static bool ball_of_seeing(void)
         mpr("You feel power drain from you!");
         set_mp(0, false);
     }
-    else if (use < 10)
+    else if (use < 10 || you.level_type == LEVEL_LABYRINTH)
     {
+        if (you.level_type == LEVEL_LABYRINTH)
+            mpr("You see a maze of twisty little passages, all alike.");
         confuse_player( 10 + random2(10), false );
     }
     else if (use < 15 || coinflip())
diff --git a/crawl-ref/source/spl-book.cc b/crawl-ref/source/spl-book.cc
index 70b194e551..3e4383ce88 100644
--- a/crawl-ref/source/spl-book.cc
+++ b/crawl-ref/source/spl-book.cc
@@ -1499,17 +1499,22 @@ int staff_spell( int staff )
         return (-1);
     }
 
-    // All checks passed, we can cast the spell
-    if (your_spells(spell, powc, false) == SPRET_ABORT)
+    const int flags = get_spell_flags(spell);
+    // Labyrinths block divinations.
+    if (you.level_type == LEVEL_LABYRINTH
+        && testbits(flags, SPFLAG_MAPPING))
+    {
+        mpr("Something interferes with your magic!");
+    }
+    // All checks passed, we can cast the spell    
+    else if (your_spells(spell, powc, false) == SPRET_ABORT)
     {
         crawl_state.zero_turns_taken();
         return (-1);
     }
 
     make_hungry( food, true );
-
     istaff.plus -= mana;
-
     you.wield_change = true;
     you.turn_is_over = true;
 
diff --git a/crawl-ref/source/spl-cast.cc b/crawl-ref/source/spl-cast.cc
index e665d1d4d1..335aa9003e 100644
--- a/crawl-ref/source/spl-cast.cc
+++ b/crawl-ref/source/spl-cast.cc
@@ -944,7 +944,18 @@ spret_type your_spells( spell_type spell, int powc, bool allow_fail )
                 dec_penance(GOD_SIF_MUNA, 1);
         }
 
-        if (spfl < spell_fail(spell))
+        const int spfail_chance = spell_fail(spell);
+        // Divination mappings backfire in Labyrinths.
+        if (you.level_type == LEVEL_LABYRINTH
+            && testbits(flags, SPFLAG_MAPPING))
+        {
+            mprf(MSGCH_WARN,
+                 "The warped magic of this place twists your "
+                 "spell in on itself!");
+            spfl = spfail_chance / 2 - 1;
+        }
+
+        if (spfl < spfail_chance)
         {
             spellcasting_side_effects(spell, true);
 
@@ -972,14 +983,14 @@ spret_type your_spells( spell_type spell, int powc, bool allow_fail )
             // spells can be quite nasty: 9 * 9 * 90 / 500 = 15
             // points of contamination!
             int nastiness = spell_mana(spell) * spell_mana(spell)
-                                    * (spell_fail(spell) - spfl) + 250;
+                                    * (spfail_chance - spfl) + 250;
 
             const int cont_points = div_rand_round(nastiness, 500);
 
             contaminate_player( cont_points );
 
             miscast_effect( sptype, spell_mana(spell),
-                            spell_fail(spell) - spfl, 100 );
+                            spfail_chance - spfl, 100 );
 
             return (SPRET_FAIL);
         }
diff --git a/crawl-ref/source/spl-cast.h b/crawl-ref/source/spl-cast.h
index 350a07d6da..75f50d82ae 100644
--- a/crawl-ref/source/spl-cast.h
+++ b/crawl-ref/source/spl-cast.h
@@ -26,7 +26,8 @@ enum spflag_type
     SPFLAG_TARGETING_MASK       = 0x000f,       // used to test for targeting
     SPFLAG_HELPFUL              = 0x0010,       // TARG_FRIENDS used
     SPFLAG_NOT_SELF             = 0x0020,       // aborts on isMe
-    SPFLAG_UNHOLY               = 0x0040        // counts at "unholy"
+    SPFLAG_UNHOLY               = 0x0040,       // counts at "unholy"
+    SPFLAG_MAPPING              = 0x0080        // a mapping spell of some kind
 };
 
 enum spret_type
diff --git a/crawl-ref/source/spl-data.h b/crawl-ref/source/spl-data.h
index 812ba85aae..c50c5e40da 100644
--- a/crawl-ref/source/spl-data.h
+++ b/crawl-ref/source/spl-data.h
@@ -715,7 +715,7 @@
 {
     SPELL_DETECT_TRAPS, "Detect Traps",
      SPTYP_DIVINATION,
-     SPFLAG_NONE,
+     SPFLAG_MAPPING,
      2,
      50,
      NULL,
@@ -782,7 +782,7 @@
 {
     SPELL_MAGIC_MAPPING, "Magic Mapping",
      SPTYP_DIVINATION | SPTYP_EARTH,
-     SPFLAG_NONE,
+     SPFLAG_MAPPING,
      4,
      45,
      NULL,
@@ -879,7 +879,7 @@
 {
     SPELL_DETECT_ITEMS, "Detect Items",
      SPTYP_DIVINATION,
-     SPFLAG_NONE,
+     SPFLAG_MAPPING,
      2,
      50,
      NULL,
@@ -1385,7 +1385,7 @@
 {
     SPELL_DETECT_CREATURES, "Detect Creatures",
      SPTYP_DIVINATION,
-     SPFLAG_NONE,
+     SPFLAG_MAPPING,
      2,
      60,                        // not 50, note the fuzz
      NULL,