Overhaul trapping net escape functions.

With the help of several factors (such as size, wielded weapon
or stats) the game decides whether you should try to destroy the
net to come free, or try to slip out of it. The same calculation
also influences how long this will take.


git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@2278 c06c8d41-db1a-0410-9941-cceddc491573

1 files changed, 136 insertions, 32 deletions

diff --git a/crawl-ref/source/traps.cc b/crawl-ref/source/traps.cc
index 0cff14c334..cc4638c842 100644
--- a/crawl-ref/source/traps.cc
+++ b/crawl-ref/source/traps.cc
@@ -21,6 +21,7 @@
 #include "items.h"
 #include "itemprop.h"
 #include "makeitem.h"
+#include "misc.h"
 #include "mon-util.h"
 #include "monstuff.h"
 #include "ouch.h"
@@ -549,7 +550,82 @@ void remove_net_from(monsters *mon)
 
 }
 
-void free_self_from_net(bool damage_net)
+// decides whether you will try to tear the net (result <= 0)
+// or try to slip out of it (result > 0)
+// both damage and escape could be 9 (more likely for damage)
+// but are capped at 5 (damage) and 4 (escape)
+static int damage_or_escape_net(int hold)
+{
+    // Spriggan: little (+2)
+    // Halfling, Kobold, Gnome: small (+1)
+    // Ogre, Troll, Centaur, Naga: large (-1)
+    // transformations: spider, bat: tiny (+3); ice beast: large (-1)
+    int escape = SIZE_MEDIUM - you.body_size(PSIZE_BODY);
+    
+    int damage = -escape;
+
+    // your weapon may damage the net, max. bonus of 2
+    if (you.equip[EQ_WEAPON] != -1)
+    {
+        if (can_cut_meat(you.inv[you.equip[EQ_WEAPON]]))
+            damage++;
+            
+        int brand = get_weapon_brand( you.inv[you.equip[EQ_WEAPON]] );
+        if (brand == SPWPN_FLAMING || brand == SPWPN_VORPAL)
+            damage++;
+    }
+    else if (you.attribute[ATTR_TRANSFORMATION] == TRAN_BLADE_HANDS)
+        damage += 2;
+    else if (you.mutation[MUT_CLAWS])
+        damage += random2(you.mutation[MUT_CLAWS]);
+        
+    // Berserkers get a fighting bonus
+    if (you.duration[DUR_BERSERKER])
+        damage += 2;
+
+    // damaged nets are easier to slip out of
+    if (hold < 0)
+    {
+        escape += random2(-hold/2) + 1;
+        damage += random2(-hold/3 + 1); // ... and easier to destroy
+    }
+        
+    // check stats
+    if (you.strength > random2(18))
+        damage++;
+    if (you.dex > random2(12))
+        escape++;
+    if (player_evasion() > random2(20))
+        escape++;
+
+    // monsters around you add urgency
+    if (!i_feel_safe())
+    {
+        damage++;
+        escape++;
+    }
+    
+    // confusion makes the whole thing somewhat harder
+    // (less so for trying to escape)
+    if (you.duration[DUR_CONF])
+    {
+        if (escape > 1)
+            escape--;
+        else if (damage >= 2)
+            damage -= 2;
+    }
+    
+    // if undecided, choose damaging approach (it's quicker)
+    if (damage >= escape)
+        return (-damage); // negate value
+        
+    return (escape);
+}
+
+// calls the above function to decide on how to get free
+// note that usually the net will be damaged until trying to slip out
+// becomes feasible (for size etc.), so it may take even longer
+void free_self_from_net()
 {
     int net = get_trapping_net(you.x_pos, you.y_pos);
 
@@ -558,58 +634,86 @@ void free_self_from_net(bool damage_net)
         you.attribute[ATTR_HELD] = 0;
         return;
     }
-    int hold = mitm[net].plus;
 
-    if (damage_net)
-    {
-        mpr("You struggle against the net.");
+    int do_what = damage_or_escape_net(mitm[net].plus);
+#ifdef DEBUG
+    mprf(MSGCH_DIAGNOSTICS, "net.plus: %d, ATTR_HELD: %d, do_what: %d",
+         mitm[net].plus, you.attribute[ATTR_HELD], do_what);
+#endif
+
+    if (do_what <= 0) // you try to destroy the net
+    {                 // for previously undamaged nets this takes at least 2 
+                      // and at most 8 turns
+        bool can_slice = you.attribute[ATTR_TRANSFORMATION] == TRAN_BLADE_HANDS
+                         || you.equip[EQ_WEAPON] != -1
+                            && can_cut_meat(you.inv[you.equip[EQ_WEAPON]]);
+                         
         int damage = 1;
-
-        // extra damage for cutting weapons
-        if (you.equip[EQ_WEAPON] != -1
-            && can_cut_meat(you.inv[you.equip[EQ_WEAPON]]))
-        {
-            damage++;
-        }
+        damage += random2(-do_what);
         
-        if (you.body_size(PSIZE_BODY) > SIZE_MEDIUM)
-            damage++;
-            
-        if (hold < 0 && !one_chance_in(-hold/2))
-            damage++;
-         
         if (you.duration[DUR_BERSERKER])
             damage *= 2;
-            
+
+        if (damage > 5)
+            damage = 5;
+                    
         mitm[net].plus -= damage;
-        
+
         if (mitm[net].plus < -7)
         {
-            mpr("You rip the net and break free!");
+            mprf("You %s the net and break free!",
+                 can_slice ? (damage >= 4? "slice" : "cut") :
+                             (damage >= 4? "shred" : "rip"));
+                  
             destroy_item(net);
 
             you.attribute[ATTR_HELD] = 0;
             return;
         }
-   }
-   else // you try to escape
-   {
-        mpr("You struggle to escape from the net.");
-        you.attribute[ATTR_HELD]--;
+        
+        if (damage >= 4)
+        {
+            mprf("You %s into the net.",
+                 can_slice? "slice" : "tear a large gash");
+        }
+        else
+            mpr("You struggle against the net.");
 
-        if (you.body_size(PSIZE_BODY) < SIZE_MEDIUM)
+        // occasionally decrease duration a bit
+        // (this is so switching from damage to escape does not hurt as much)
+        if (you.attribute[ATTR_HELD] > 1 && one_chance_in(3))
             you.attribute[ATTR_HELD]--;
+   }
+   else // you try to escape (takes at least 3 turns, and at most 10)
+   {
+        int escape = random2(do_what);
+        
+        if (you.duration[DUR_HASTE]) // extra bonus, also Berserk
+            escape++;
             
-        if (hold < 0 && !one_chance_in(-hold/2))
-            you.attribute[ATTR_HELD]--;
-
-        if (you.attribute[ATTR_HELD] <= 0)
+        if (escape < 1)
+            escape = 1;
+        else if (escape > 4)
+            escape = 4;
+            
+        if (escape >= you.attribute[ATTR_HELD])
         {
-            mpr("You break free from the net!");
+            if (escape >= 3)
+                mpr("You slip out of the net!");
+            else
+                mpr("You break free from the net!");
+                
             you.attribute[ATTR_HELD] = 0;
             remove_item_stationary(mitm[net]);
             return;
         }
+        
+        if (escape >= 3)
+            mpr("You try to slip out of the net.");
+        else
+            mpr("You struggle to escape the net.");
+
+        you.attribute[ATTR_HELD] -= escape;
    }
 }