magic cancellation and Protection (trunk only)

     Magic cancellation comes from some types of worn armor and has a
value of 0 through 3.  A non-zero value guards against some forms of
monster magic attacks (most notably, level drain by vampires and wraiths
and lycanthropy from werecritter bites).  This reduces the effectiveness
of mc a moderate amount (the new values happen to be the same as those
adopted by the Spork variant):
 chance to block various touch effects
  mc  old     new
   1  34.67%  30%
   2  67.33%  60%
   3  98%     90%

    This also makes the Protection intrinsic (strictly speaking, extrinsic)
be the only way to attain an mc factor of 3.  Cloak of protection is the
only way to get mc 3 from a single item.  Otherwise you need an mc 2 item
and a ring of protection (or one of the recently modified quest artifacts).

     Cancellation factor for elven and dwarvish mithril coats and for
robes and oilskin cloaks is reduced from 3 to 2; for elven cloak and
cloak of magic resistance from 3 to 1 (play balance; they're valuable
even without magic cancellation); for dwarven and orcish cloaks and
clocks of invisibility and displacement and for cornuthaum (wizard hat)
from 2 to 1.  Plate mail and crystal plate mail stay at 2.  A variety of
suits which were at 0 are increased to 1; leather jacket and dragon
scales/scale mail stay at 0 (the latter for play balance rather than for
the amount of your body that's covered).

     Having extrinsic protection will increase mc by 1 (unless it's
already 3).  That's obtained by wearing a cloak of protection (where the
increase is redundant), a ring (or two) of protection (even if conferring
a negative AC amount), or wearing the Mitre of Holiness or wielding the
Tsurugi of Muramasa.  Having multiple sources doesn't make the benefit
cumulative; it's just +1.

     Intrinsic protection (bought from priest, gained from prayer, gained
from eating rings of protection while polymorphed into metallivore, or
temporary while spell of protection is active) doesn't increase mc from
armor but does provide minimum mc 1 instead of naked 0 (play balance
again; buying it is too easy to let it increase mc 1 or 2 to 2 or 3).
(Extrinsic protection is a superset; its +1 bonus also increases 0 to 1.)

    TODO: add an amulet of protection so player has another option for
extrinsic protection.

diff --git a/doc/fixes35.0 b/doc/fixes35.0
index b960030828c30d906fd73dac4256173a66610fc6..8983b30e5baaae33a77af7471bfcfae85226b03b 100644 (file)
--- a/doc/fixes35.0
+++ b/doc/fixes35.0
@@ -353,6 +353,8 @@ spellcasting monsters' spell selection became less likely to choose harder
 Eye of the Aethiopica, Eyes of the Overworld, and Sceptre of Might must be
        worn or wielded rather than just carried to convey magic resistance
 Mitre of Holiness and Tsurugi of Muramasa convey Protection when worn/wielded
+effectiveness of magic cancellation by worn armor has been reduced
+Protection improves the effectiveness of magic cancellation
 
 
 Platform- and/or Interface-Specific Fixes

diff --git a/src/mhitm.c b/src/mhitm.c
index c25432fec1cd7a14911f2ddb0c80844aa1b898b7..ade47bf26c7ec8df302f42380685b4c5ad3ace46 100644 (file)
--- a/src/mhitm.c
+++ b/src/mhitm.c
@@ -719,7 +719,7 @@ mdamagem(magr, mdef, mattk)
 
        /* cancellation factor is the same as when attacking the hero */
        armpro = magic_negation(mdef);
-       cancelled = magr->mcan || !((rn2(3) >= armpro) || !rn2(50));
+       cancelled = magr->mcan || !(rn2(10) >= 3 * armpro);
 
        switch(mattk->adtyp) {
            case AD_DGST:

diff --git a/src/mhitu.c b/src/mhitu.c
index e16d982e71ec5f099c6a344e9df619437124a189..204d8d7ad27249bfca57e2a03344f4a67e38551d 100644 (file)
--- a/src/mhitu.c
+++ b/src/mhitu.c
@@ -819,44 +819,53 @@ int
 magic_negation(mon)
 struct monst *mon;
 {
-       struct obj *armor;
-       int armpro = 0;
-
-       armor = (mon == &youmonst) ? uarm : which_armor(mon, W_ARM);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-       armor = (mon == &youmonst) ? uarmc : which_armor(mon, W_ARMC);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-       armor = (mon == &youmonst) ? uarmh : which_armor(mon, W_ARMH);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-
-       /* armor types for shirt, gloves, shoes, and shield don't currently
-          provide any magic cancellation but we might as well be complete */
-#ifdef TOURIST
-       armor = (mon == &youmonst) ? uarmu : which_armor(mon, W_ARMU);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-#endif
-       armor = (mon == &youmonst) ? uarmg : which_armor(mon, W_ARMG);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-       armor = (mon == &youmonst) ? uarmf : which_armor(mon, W_ARMF);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-       armor = (mon == &youmonst) ? uarms : which_armor(mon, W_ARMS);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
+       struct obj *o;
+       long wearmask;
+       int armpro, mc = 0;
+       boolean is_you = (mon == &youmonst), gotprot = FALSE;
+
+       for (o = is_you ? invent : mon->minvent; o; o = o->nobj) {
+           /* a_can field is only applicable for armor (which must be worn) */
+           if ((o->owornmask & W_ARMOR) != 0L) {
+               armpro = objects[o->otyp].a_can;
+               if (armpro > mc) mc = armpro;
+           }
+           /* if we've already confirmed Protection, skip additional checks */
+           if (gotprot) continue;
+
+           /* omit W_SWAPWEP+W_QUIVER; W_ART+W_ARTI handled by protects() */
+           wearmask = W_ARMOR | W_RING | W_AMUL | W_TOOL;
+           if (o->oclass == WEAPON_CLASS || is_weptool(o)) wearmask |= W_WEP;
+           if (protects(o, ((o->owornmask & wearmask) != 0L) ? TRUE : FALSE))
+               gotprot = TRUE;
+       }
 
-#ifdef STEED
-       /* this one is really a stretch... */
-       armor = (mon == &youmonst) ? 0 : which_armor(mon, W_SADDLE);
-       if (armor && armpro < objects[armor->otyp].a_can)
-           armpro = objects[armor->otyp].a_can;
-#endif
+       /* extrinsic Protection increases mc factor */
+       if (!gotprot) {
+           /* in case hero has extrinsic protection from some other source */
+           if (is_you && EProtection) gotprot = TRUE;
+           /* high priests have innate intrinsic protection which is as
+              strong as extrinsic protection */
+           if (mon->data == &mons[PM_HIGH_PRIEST]) gotprot = TRUE;
+       }
+       /* extrinsic Protection increases mc by 1 */
+       if (gotprot && mc < 3)
+           mc += 1;
+
+       /* intrinsic Protection is weaker than Extrinsic (play balance;
+          obtaining divine protection is too easy) */
+       if (!gotprot) {
+           if (is_you && ((HProtection && u.ublessed > 0) || u.uspellprot))
+               gotprot = TRUE;
+           /* aligned priests and angels have innate intrinsic Protection */
+           if (mon->data == &mons[PM_ALIGNED_PRIEST] || is_minion(mon->data))
+               gotprot = TRUE;
+       }
+       /* intrinsic Protection confers minimum mc 1 instead of 0 */
+       if (gotprot && mc < 1)
+           mc = 1;
 
-       return armpro;
+       return mc;
 }
 
 /*
@@ -913,7 +922,7 @@ hitmu(mtmp, mattk)
  *     armor's special magic protection.  Otherwise just use !mtmp->mcan.
  */
        armpro = magic_negation(&youmonst);
-       uncancelled = !mtmp->mcan && ((rn2(3) >= armpro) || !rn2(50));
+       uncancelled = !mtmp->mcan && (rn2(10) >= 3 * armpro);
 
        permdmg = 0;
 /*     Now, adjust damages via resistances or specific attacks */

diff --git a/src/objects.c b/src/objects.c
index 742d6d41b3c52884a504e32fe92515aa1a7e7869..46b4101e51dd06af5dd8ce43c5c10cc3d9ef591e 100644 (file)
--- a/src/objects.c
+++ b/src/objects.c
@@ -1,5 +1,4 @@
 /* NetHack 3.5 objects.c       $Date$  $Revision$ */
-/*     SCCS Id: @(#)objects.c  3.5     2006/12/14      */
 /* Copyright (c) Mike Threepoint, 1989.                                  */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -307,7 +306,7 @@ HELM("fedora", (char *)0,
                1, 0,  0,       0, 0,  3,   1,10, 0, CLOTH, CLR_BROWN),
 HELM("cornuthaum", "conical hat",
                0, 1,  CLAIRVOYANT,
-                               3, 1,  4,  80,10, 2, CLOTH, CLR_BLUE),
+                               3, 1,  4,  80,10, 1, CLOTH, CLR_BLUE),
 HELM("dunce cap", "conical hat",
                0, 1,  0,       3, 1,  4,   1,10, 0, CLOTH, CLR_BLUE),
 HELM("dented pot", (char *)0,
@@ -371,33 +370,33 @@ ARMOR("crystal plate mail", (char *)0,
        1, 0, 1, 0,     10, 5, 450, 820,  3, 2, ARM_SUIT, GLASS, CLR_WHITE),
 #ifdef TOURIST
 ARMOR("bronze plate mail", (char *)0,
-       1, 0, 1, 0,     25, 5, 450, 400,  4, 0, ARM_SUIT, COPPER, HI_COPPER),
+       1, 0, 1, 0,     25, 5, 450, 400,  4, 1, ARM_SUIT, COPPER, HI_COPPER),
 #else
 ARMOR("bronze plate mail", (char *)0,
-       1, 0, 1, 0,     35, 5, 450, 400,  4, 0, ARM_SUIT, COPPER, HI_COPPER),
+       1, 0, 1, 0,     35, 5, 450, 400,  4, 1, ARM_SUIT, COPPER, HI_COPPER),
 #endif
 ARMOR("splint mail", (char *)0,
        1, 0, 1, 0,     62, 5, 400,  80,  4, 1, ARM_SUIT, IRON, HI_METAL),
 ARMOR("banded mail", (char *)0,
-       1, 0, 1, 0,     72, 5, 350,  90,  4, 0, ARM_SUIT, IRON, HI_METAL),
+       1, 0, 1, 0,     72, 5, 350,  90,  4, 1, ARM_SUIT, IRON, HI_METAL),
 ARMOR("dwarvish mithril-coat", (char *)0,
-       1, 0, 0, 0,     10, 1, 150, 240,  4, 3, ARM_SUIT, MITHRIL, HI_METAL),
+       1, 0, 0, 0,     10, 1, 150, 240,  4, 2, ARM_SUIT, MITHRIL, HI_METAL),
 ARMOR("elven mithril-coat", (char *)0,
-       1, 0, 0, 0,     15, 1, 150, 240,  5, 3, ARM_SUIT, MITHRIL, HI_METAL),
+       1, 0, 0, 0,     15, 1, 150, 240,  5, 2, ARM_SUIT, MITHRIL, HI_METAL),
 ARMOR("chain mail", (char *)0,
        1, 0, 0, 0,     72, 5, 300,  75,  5, 1, ARM_SUIT, IRON, HI_METAL),
 ARMOR("orcish chain mail", "crude chain mail",
        0, 0, 0, 0,     20, 5, 300,  75,  6, 1, ARM_SUIT, IRON, CLR_BLACK),
 ARMOR("scale mail", (char *)0,
-       1, 0, 0, 0,     72, 5, 250,  45,  6, 0, ARM_SUIT, IRON, HI_METAL),
+       1, 0, 0, 0,     72, 5, 250,  45,  6, 1, ARM_SUIT, IRON, HI_METAL),
 ARMOR("studded leather armor", (char *)0,
        1, 0, 0, 0,     72, 3, 200,  15,  7, 1, ARM_SUIT, LEATHER, HI_LEATHER),
 ARMOR("ring mail", (char *)0,
-       1, 0, 0, 0,     72, 5, 250, 100,  7, 0, ARM_SUIT, IRON, HI_METAL),
+       1, 0, 0, 0,     72, 5, 250, 100,  7, 1, ARM_SUIT, IRON, HI_METAL),
 ARMOR("orcish ring mail", "crude ring mail",
        0, 0, 0, 0,     20, 5, 250,  80,  8, 1, ARM_SUIT, IRON, CLR_BLACK),
 ARMOR("leather armor", (char *)0,
-       1, 0, 0, 0,     82, 3, 150,   5,  8, 0, ARM_SUIT, LEATHER, HI_LEATHER),
+       1, 0, 0, 0,     82, 3, 150,   5,  8, 1, ARM_SUIT, LEATHER, HI_LEATHER),
 ARMOR("leather jacket", (char *)0,
        1, 0, 0, 0,     12, 0,  30,  10,  9, 0, ARM_SUIT, LEATHER, CLR_BLACK),
 
@@ -414,15 +413,15 @@ ARMOR("T-shirt", (char *)0,
 CLOAK("mummy wrapping", (char *)0,
                1, 0,   0,          0, 0,  3,  2, 10, 1, CLOTH, CLR_GRAY),
 CLOAK("elven cloak", "faded pall",
-               0, 1,   STEALTH,    8, 0, 10, 60,  9, 3, CLOTH, CLR_BLACK),
+               0, 1,   STEALTH,    8, 0, 10, 60,  9, 1, CLOTH, CLR_BLACK),
 CLOAK("orcish cloak", "coarse mantelet",
-               0, 0,   0,          8, 0, 10, 40, 10, 2, CLOTH, CLR_BLACK),
+               0, 0,   0,          8, 0, 10, 40, 10, 1, CLOTH, CLR_BLACK),
 CLOAK("dwarvish cloak", "hooded cloak",
-               0, 0,   0,          8, 0, 10, 50, 10, 2, CLOTH, HI_CLOTH),
+               0, 0,   0,          8, 0, 10, 50, 10, 1, CLOTH, HI_CLOTH),
 CLOAK("oilskin cloak", "slippery cloak",
-               0, 0,   0,          8, 0, 10, 50,  9, 3, CLOTH, HI_CLOTH),
+               0, 0,   0,          8, 0, 10, 50,  9, 2, CLOTH, HI_CLOTH),
 CLOAK("robe", (char *)0,
-               1, 1,   0,          3, 0, 15, 50,  8, 3, CLOTH, CLR_RED),
+               1, 1,   0,          3, 0, 15, 50,  8, 2, CLOTH, CLR_RED),
 CLOAK("alchemy smock", "apron",
                0, 1,   POISON_RES, 9, 0, 10, 50,  9, 1, CLOTH, CLR_WHITE),
 CLOAK("leather cloak", (char *)0,
@@ -431,11 +430,11 @@ CLOAK("leather cloak", (char *)0,
 CLOAK("cloak of protection", "tattered cape",
                0, 1,   PROTECTION, 9, 0, 10, 50,  7, 3, CLOTH, HI_CLOTH),
 CLOAK("cloak of invisibility", "opera cloak",
-               0, 1,   INVIS,     10, 0, 10, 60,  9, 2, CLOTH, CLR_BRIGHT_MAGENTA),
+               0, 1,   INVIS,     10, 0, 10, 60,  9, 1, CLOTH, CLR_BRIGHT_MAGENTA),
 CLOAK("cloak of magic resistance", "ornamental cope",
-               0, 1,   ANTIMAGIC,  2, 0, 10, 60,  9, 3, CLOTH, CLR_WHITE),
+               0, 1,   ANTIMAGIC,  2, 0, 10, 60,  9, 1, CLOTH, CLR_WHITE),
 CLOAK("cloak of displacement", "piece of cloth",
-               0, 1,   DISPLACED, 10, 0, 10, 50,  9, 2, CLOTH, HI_CLOTH),
+               0, 1,   DISPLACED, 10, 0, 10, 50,  9, 1, CLOTH, HI_CLOTH),
 
 /* shields */
 SHIELD("small shield", (char *)0,

diff --git a/src/uhitm.c b/src/uhitm.c
index f9434e474eadc14b51b8f7a4a802b8fd6530293f..9dae57f099000d99fa15929f267f488950151b4e 100644 (file)
--- a/src/uhitm.c
+++ b/src/uhitm.c
@@ -1356,7 +1356,7 @@ register struct attack *mattk;
 
        armpro = magic_negation(mdef);
        /* since hero can't be cancelled, only defender's armor applies */
-       negated = !((rn2(3) >= armpro) || !rn2(50));
+       negated = !(rn2(10) >= 3 * armpro);
 
        if (is_demon(youmonst.data) && !rn2(13) && !uwep
                && u.umonnum != PM_SUCCUBUS && u.umonnum != PM_INCUBUS