Hydras now behave the same way in monster-vs-monster combat as they do in

player vs monster. Specifically, hydras get their as many attacks as they have
heads vs other monsters, and other monsters can chop off hydra heads (at 25% of
the probability that the player has of chopping off heads).

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@936 c06c8d41-db1a-0410-9941-cceddc491573

1 files changed, 172 insertions, 104 deletions

diff --git a/crawl-ref/source/fight.cc b/crawl-ref/source/fight.cc
index 0c41990f30..3fbae8f4e5 100644
--- a/crawl-ref/source/fight.cc
+++ b/crawl-ref/source/fight.cc
@@ -375,6 +375,112 @@ int calc_heavy_armour_penalty( bool random_factor )
     return heavy_armour;
 }
 
+// Returns true if a head got lopped off.
+static bool chop_hydra_head( const monsters *attacker,
+                             monsters *defender,
+                             int damage_done,
+                             int dam_type,
+                             int wpn_brand )
+{
+    const bool defender_visible = mons_near(defender);
+
+    // Monster attackers have only a 25% chance of making the
+    // chop-check to prevent runaway head inflation.
+    if (attacker && !one_chance_in(4))
+        return (false);
+    
+    if ((dam_type == DVORP_SLICING || dam_type == DVORP_CHOPPING
+         || dam_type == DVORP_CLAWING)
+        && damage_done > 0
+        && (damage_done >= 4 || wpn_brand == SPWPN_VORPAL || coinflip()))
+    {
+        defender->number--;
+
+        const char *verb = NULL;
+
+        if (dam_type == DVORP_CLAWING)
+        {
+            static const char *claw_verbs[] = { "rip", "tear", "claw" };
+            verb =
+                claw_verbs[
+                    random2( sizeof(claw_verbs) / sizeof(*claw_verbs) ) ];
+        }
+        else
+        {
+            static const char *slice_verbs[] =
+            {
+                "slice", "lop", "chop", "hack"
+            };
+            verb =
+                slice_verbs[
+                    random2( sizeof(slice_verbs) / sizeof(*slice_verbs) ) ];
+        }
+
+        if (defender->number < 1)
+        {
+            if (defender_visible)
+                mprf( "%s %s %s's last head off!",
+                      actor_name(attacker, DESC_CAP_THE).c_str(),
+                      actor_verb(attacker, verb).c_str(),
+                      str_monam(defender, DESC_NOCAP_THE).c_str() );
+
+            defender->hit_points = -1;
+        }
+        else
+        {
+            if (defender_visible)
+                mprf( "%s %s one of %s's heads off!",
+                      actor_name(attacker, DESC_CAP_THE).c_str(),
+                      actor_verb(attacker, verb).c_str(),
+                      str_monam(defender, DESC_NOCAP_THE).c_str() );
+
+            if (wpn_brand == SPWPN_FLAMING)
+            {
+                if (defender_visible)
+                    mpr( "The flame cauterises the wound!" );
+            }
+            else if (defender->number < 19)
+            {
+                simple_monster_message( defender, " grows two more!" );
+                defender->number += 2;
+                heal_monster( defender, 8 + random2(8), true );
+            }
+        }
+
+        return (true);
+    }
+
+    return (false);
+}
+
+static bool actor_decapitates_hydra(monsters *attacker, monsters *defender,
+                                    int damage_done)
+{
+    if (defender->type == MONS_HYDRA)
+    {
+        const int dam_type = actor_damage_type(attacker);
+        const int wpn_brand = actor_damage_brand(attacker);
+
+        return chop_hydra_head(attacker, defender, damage_done,
+                               dam_type, wpn_brand);
+    }
+    return (false);
+}
+
+static bool player_fumbles_attack()
+{
+    // fumbling in shallow water <early return>:
+    if (player_in_water() && !player_is_swimming())
+    {
+        if (random2(you.dex) < 4 || one_chance_in(5))
+        {
+            mpr("Unstable footing causes you to fumble your attack.");
+            return (true);
+        }
+    }
+    return (false);
+}
+
 // Returns true if you hit the monster.
 bool you_attack(int monster_attacked, bool unarmed_attacks)
 {
@@ -485,23 +591,11 @@ bool you_attack(int monster_attacked, bool unarmed_attacks)
     if (you.pet_target == MHITNOT) 
         you.pet_target = monster_attacked;
 
-    // fumbling in shallow water <early return>:
-    if (player_in_water() && !player_is_swimming())
-    {
-        if (random2(you.dex) < 4 || one_chance_in(5))
-        {
-            mpr("Unstable footing causes you to fumble your attack.");
-            return (false);
-        }
-    }
+    if (player_fumbles_attack())
+        return (false);
 
-    // wet merfolk
-    if (player_is_swimming()
-        // monster not a water creature, but is in water
-        && monster_floundering(defender))
-    {
-        water_attack = true;
-    }
+    // Swimmers get bonus against non-swimmers wading in water.
+    water_attack = player_is_swimming() && monster_floundering(defender);
 
     // new unified to-hit calculation
     your_to_hit = calc_your_to_hit( heavy_armour, use_hand_and_a_half_bonus,
@@ -509,7 +603,7 @@ bool you_attack(int monster_attacked, bool unarmed_attacks)
 
     //jmf: check for backlight enchantment
     if (mons_has_ench(defender, ENCH_BACKLIGHT_I, ENCH_BACKLIGHT_IV))
-	your_to_hit += 2 + random2(8);
+        your_to_hit += 2 + random2(8);
 
     // energy expenditure in terms of food:
     make_hungry(3, true);
@@ -517,10 +611,10 @@ bool you_attack(int monster_attacked, bool unarmed_attacks)
     if (ur_armed &&
         you.inv[ weapon ].base_type == OBJ_WEAPONS &&
         is_random_artefact( you.inv[ weapon ] ) &&
-	art_proprt[RAP_ANGRY] >= 1 &&
-	random2(1 + art_proprt[RAP_ANGRY]))
+        art_proprt[RAP_ANGRY] >= 1 &&
+        random2(1 + art_proprt[RAP_ANGRY]))
     {
-	go_berserk(false);
+        go_berserk(false);
     }
 
     switch (you.special_wield)
@@ -1136,16 +1230,16 @@ bool you_attack(int monster_attacked, bool unarmed_attacks)
     /* remember, damage_done is still useful! */
     if (hit)
     {
-	if (defender->type == MONS_JELLY
-	    || defender->type == MONS_BROWN_OOZE
-	    || defender->type == MONS_ACID_BLOB
-	    || defender->type == MONS_ROYAL_JELLY)
-	{
-	    weapon_acid(5);
-	}
-
+        if (defender->type == MONS_JELLY
+            || defender->type == MONS_BROWN_OOZE
+            || defender->type == MONS_ACID_BLOB
+            || defender->type == MONS_ROYAL_JELLY)
+        {
+            weapon_acid(5);
+        }
+        
         int specdam = 0;
-
+        
         if (ur_armed 
             && you.inv[ weapon ].base_type == OBJ_WEAPONS
             && is_demonic( you.inv[ weapon ] ))
@@ -1156,56 +1250,9 @@ bool you_attack(int monster_attacked, bool unarmed_attacks)
         if (mons_holiness(defender) == MH_HOLY)
             did_god_conduct(DID_ATTACK_HOLY, defender->hit_dice);
 
-        if (defender->type == MONS_HYDRA)
-        {
-            const int dam_type = player_damage_type();
-            const int wpn_brand = player_damage_brand();
-
-            if ((dam_type == DVORP_SLICING || dam_type == DVORP_CHOPPING)
-                && damage_done > 0
-                && (damage_done >= 4 || wpn_brand == SPWPN_VORPAL || coinflip()))
-            {
-                defender->number--;
-
-                temp_rand = random2(4);
-                const char *const verb = (temp_rand == 0) ? "slice" :
-                                         (temp_rand == 1) ? "lop" :
-                                         (temp_rand == 2) ? "chop" : "hack";
-
-                if (defender->number < 1)
-                {
-                    snprintf( info, INFO_SIZE, "You %s %s's last head off!",
-                              verb, ptr_monam(defender, DESC_NOCAP_THE) );
-                    mpr( info );
-                              
-                    defender->hit_points = -1; 
-                }
-                else
-                {
-                    snprintf( info, INFO_SIZE, "You %s one of %s's heads off!",
-                              verb, ptr_monam(defender, DESC_NOCAP_THE) );
-                    mpr( info );
-
-                    if (wpn_brand == SPWPN_FLAMING) 
-                        mpr( "The flame cauterises the wound!" );
-                    else if (defender->number < 19)
-                    {
-                        simple_monster_message( defender, " grows two more!" );
-                        defender->number += 2;
-                        heal_monster( defender, 8 + random2(8), true );
-                    }
-                }
-
-                // if the hydra looses a head:
-                // - it's dead if it has none remaining (HP set to -1)
-                // - flame used to cauterise doesn't do extra damage
-                // - ego weapons do their additional damage to the 
-                //   hydra's decapitated head, so it's ignored.
-                //
-                // ... and so we skip the special damage.
-                goto mons_dies;
-            }
-        }
+        // If decapitation, extra damage is bypassed.
+        if (actor_decapitates_hydra(NULL, defender, damage_done))
+            goto mons_dies;
 
         // jmf: BEGIN STAFF HACK
         // How much bonus damage will a staff of <foo> do?
@@ -2015,6 +2062,20 @@ bool you_attack(int monster_attacked, bool unarmed_attacks)
     return (hit);
 }                               // end you_attack()
 
+static void mons_lose_attack_energy(monsters *attacker, int wpn_speed,
+                                    int which_attack)
+{
+    // speed adjustment for weapon using monsters
+    if (wpn_speed > 0)
+    {
+        // only get one third penalty/bonus for second weapons.
+        if (which_attack > 0)
+            wpn_speed = (20 + wpn_speed) / 3;
+
+        attacker->speed_increment -= (wpn_speed - 10) / 2;
+    }
+}
+
 void monster_attack(int monster_attacking)
 {
     struct monsters *attacker = &menv[monster_attacking];
@@ -3085,15 +3146,7 @@ commented out for now
             }
         }
 
-        // adjust time taken if monster used weapon
-        if (wpn_speed > 0)
-        {
-            // only get one third penalty/bonus for second weapons.
-            if (runthru > 0)
-                wpn_speed = (20 + wpn_speed) / 3;
-
-            attacker->speed_increment -= (wpn_speed - 10) / 2;
-        }
+        mons_lose_attack_energy(attacker, wpn_speed, runthru);
     }                           // end of for runthru
 
     if (player_perceives_attack)
@@ -3162,11 +3215,21 @@ bool monsters_fight(int monster_attacking, int monster_attacked)
     // now disturb defender, regardless
     behaviour_event(defender, ME_WHACK, monster_attacking);
 
-    char runthru;
+    int heads = 0;
 
-    for (runthru = 0; runthru < 4; runthru++)
+    if (attacker->type == MONS_HYDRA)
+        heads = attacker->number;
+    
+    for (int runthru = 0; runthru < 4; runthru++)
     {
-        char mdam = mons_damage(attacker->type, runthru);
+        if (attacker->type == MONS_HYDRA)
+        {
+            runthru = 0;
+            if (heads-- < 1)
+                break;
+        }
+        
+        int mdam = mons_damage(attacker->type, runthru);
         wpn_speed = 0;
 
         if (attacker->type == MONS_ZOMBIE_SMALL
@@ -3194,8 +3257,7 @@ bool monsters_fight(int monster_attacking, int monster_attacked)
         if (mdam == 0)
             break;
 
-        if ((attacker->type == MONS_TWO_HEADED_OGRE 
-                    || attacker->type == MONS_ETTIN)
+        if (mons_wields_two_weapons(attacker)
             && runthru == 1 && attacker->inv[MSLOT_MISSILE] != NON_ITEM)
         {
             hand_used = 1;
@@ -3223,8 +3285,8 @@ bool monsters_fight(int monster_attacking, int monster_attacked)
         mons_to_hit = random2(mons_to_hit);
 
         if (mons_to_hit >= defender->evasion ||
-	    ((mons_is_paralysed(defender) || defender->behaviour == BEH_SLEEP)
-	     && !one_chance_in(20)))
+            ((mons_is_paralysed(defender) || defender->behaviour == BEH_SLEEP)
+             && !one_chance_in(20)))
         {
             hit = true;
 
@@ -3337,6 +3399,20 @@ bool monsters_fight(int monster_attacking, int monster_attacked)
                 mpr(info);
             }
 
+            if (actor_decapitates_hydra(attacker, defender, damage_taken))
+            {
+                mons_lose_attack_energy(attacker, wpn_speed, runthru);
+                
+                if (defender->hit_points < 1)
+                {
+                    monster_die(defender, KILL_MON, monster_attacking);
+                    return (true);
+                }
+
+                // Skip rest of attack.
+                continue;
+            }
+
             // special attacks:
             switch (attacker->type)
             {
@@ -3883,15 +3959,7 @@ bool monsters_fight(int monster_attacking, int monster_attacked)
             }
         }
 
-        // speed adjustment for weapon using monsters
-        if (wpn_speed > 0)
-        {
-            // only get one third penalty/bonus for second weapons.
-            if (runthru > 0)
-                wpn_speed = (20 + wpn_speed) / 3;
-
-            attacker->speed_increment -= (wpn_speed - 10) / 2;
-        }
+        mons_lose_attack_energy(attacker, wpn_speed, runthru);
     }                           // end of for runthru
 
     return true;