Move *_res(ist)_magic to relevant classes, provide actor interface.

Signed-off-by: Jude Brown <bookofjude@users.sourceforge.net>

1 files changed, 72 insertions, 0 deletions

diff --git a/crawl-ref/source/monster.cc b/crawl-ref/source/monster.cc
index 64c71a0486..705e689ce8 100644
--- a/crawl-ref/source/monster.cc
+++ b/crawl-ref/source/monster.cc
@@ -3154,6 +3154,78 @@ int monsters::res_acid() const
     return (get_mons_resists(this).acid);
 }
 
+int monsters::res_magic() const
+{
+    if (mons_immune_magic(this))
+        return MAG_IMMUNE;
+
+    int u = (get_monster_data(this->type))->resist_magic;
+
+    // Negative values get multiplied with monster hit dice.
+    if (u < 0)
+        u = this->hit_dice * -u * 4 / 3;
+
+    // Randarts have a multiplicative effect.
+    u *= (scan_mon_inv_randarts(this, ARTP_MAGIC) + 100);
+    u /= 100;
+
+    // ego armour resistance
+    const int armour = this->inv[MSLOT_ARMOUR];
+    const int _shield = this->inv[MSLOT_SHIELD];
+
+    if (armour != NON_ITEM
+        && get_armour_ego_type( mitm[armour] ) == SPARM_MAGIC_RESISTANCE )
+    {
+        u += 30;
+    }
+
+    if (_shield != NON_ITEM
+        && get_armour_ego_type( mitm[_shield] ) == SPARM_MAGIC_RESISTANCE )
+    {
+        u += 30;
+    }
+
+    if (this->has_ench(ENCH_LOWERED_MR))
+        u /= 2;
+
+    return (u);
+}
+
+bool monsters::check_res_magic(int pow)
+{
+    int mrs = this->res_magic();
+
+    if (mrs == MAG_IMMUNE)
+        return (true);
+
+    // Evil, evil hack to make weak one hd monsters easier for first
+    // level characters who have resistable 1st level spells. Six is
+    // a very special value because mrs = hd * 2 * 3 for most monsters,
+    // and the weak, low level monsters have been adjusted so that the
+    // "3" is typically a 1.  There are some notable one hd monsters
+    // that shouldn't fall under this, so we do < 6, instead of <= 6...
+    // or checking monster->hit_dice.  The goal here is to make the
+    // first level easier for these classes and give them a better
+    // shot at getting to level two or three and spells that can help
+    // them out (or building a level or two of their base skill so they
+    // aren't resisted as often). -- bwr
+    if (mrs < 6 && coinflip())
+        return (false);
+
+    pow = stepdown_value( pow, 30, 40, 100, 120 );
+
+    const int mrchance = (100 + mrs) - pow;
+    const int mrch2 = random2(100) + random2(101);
+
+#if DEBUG_DIAGNOSTICS
+    mprf(MSGCH_DIAGNOSTICS,
+         "Power: %d, monster's MR: %d, target: %d, roll: %d",
+         pow, mrs, mrchance, mrch2 );
+#endif
+
+    return (mrch2 < mrchance);
+}
+
 flight_type monsters::flight_mode() const
 {
     return (mons_flies(this));