Make acid splashes ignore equipped slots for damage/corrosion

splash_with_acid no longer pays any attention to the number or type of
equipped items, or to the fur mutation. Both the corrosion chance and damage
roll are calculated as if having two empty slots under the old system (ignoring
the extra effect of cloaks on corrosion chance).

crawl-ref/source/player.cc

@@ -6750,9 +6750,6 @@ void player::corrode_equipment(const char* corrosion_source, int degree)
 /**
  * Attempts to apply corrosion to the player and deals acid damage.
  *
- * Each full equipment slot gives a chance of applying the corrosion debuff,
- * and each empty equipment slot increases the amount of acid damage taken.
- *
  * @param evildoer the cause of this acid splash.
  * @param acid_strength The strength of the acid.
  * @param allow_corrosion Whether to try and apply the corrosion debuff.
@@ -6761,42 +6758,10 @@ void player::corrode_equipment(const char* corrosion_source, int degree)
 void player::splash_with_acid(const actor* evildoer, int acid_strength,
                               bool allow_corrosion, const char* hurt_msg)
 {
-    int dam = 0;
-    bool do_corrosion = false;
-    const bool wearing_cloak = slot_item(EQ_CLOAK);
-
-    for (int slot = EQ_MIN_ARMOUR; slot <= EQ_MAX_ARMOUR; slot++)
-    {
-        const bool cloak_protects = wearing_cloak && coinflip()
-                                    && slot != EQ_SHIELD && slot != EQ_CLOAK;
-
-        if (!cloak_protects)
-        {
-            item_def *item = you.slot_item(static_cast<equipment_type>(slot));
-            if (!item && slot != EQ_SHIELD)
-                dam++;
-
-            if (item && allow_corrosion && x_chance_in_y(acid_strength + 1, 30))
-                do_corrosion = true;
-        }
-    }
-
-    if (do_corrosion)
+    if (binomial(3, acid_strength + 1, 30))
         corrode_equipment();
 
-    // Covers head, hands and feet.
-    if (player_equip_unrand(UNRAND_LEAR))
-        dam = !wearing_cloak;
-
-    // Without fur, clothed people have dam 0 (+2 later), Sp/Tr/Dr/Og ~1
-    // (randomized), Fe 5. Fur helps only against naked spots.
-    const int fur = player_mutation_level(MUT_SHAGGY_FUR);
-    dam -= fur * dam / 5;
-
-    // two extra virtual slots so players can't be immune
-    dam += 2;
-    dam = roll_dice(dam, acid_strength);
-
+    const int dam = roll_dice(4, acid_strength);
     const int post_res_dam = resist_adjust_damage(&you, BEAM_ACID, dam);
 
     if (post_res_dam > 0)