refine calculations, add field for guns also, add debug tool to damag…

…e items

data/json/items/tool/debug_tools.json

@@ -11,5 +11,70 @@
     "symbol": ";",
     "color": "light_gray",
     "use_action": [ "DBG_LUX_METER" ]
+  },
+  {
+    "id": "debug_item_damager",
+    "type": "TOOL",
+    "category": "tools",
+    "name": { "str_sp": "debug item damager (simple)" },
+    "description": "Deals 1 full bar of damage to an item you wield.",
+    "weight": "1 g",
+    "volume": "1 ml",
+    "material": [ "plastic" ],
+    "symbol": ";",
+    "color": "light_gray",
+    "use_action": {
+      "type": "effect_on_conditions",
+      "menu_text": "Damage item",
+      "effect_on_conditions": [
+        {
+          "id": "EOC_FIND_ITEM_simple",
+          "effect": {
+            "u_run_inv_eocs": "all",
+            "search_data": [ { "wielded_only": true } ],
+            "true_eocs": {
+              "id": "EOC_DAMAGE_ITEM_simple",
+              "effect": [
+                { "math": [ "_hp_before", "=", "n_hp('ALL')" ] },
+                { "math": [ "n_hp('ALL')", "-=", "1000" ] },
+                { "math": [ "_hp_after", "=", "n_hp('ALL')" ] },
+                { "u_message": "<npc_name> have had <context_val:hp_before> hp, now has <context_val:hp_after> hp." }
+              ]
+            }
+          }
+        }
+      ]
+    }
+  },
+  {
+    "id": "debug_item_damager_adv",
+    "type": "TOOL",
+    "category": "tools",
+    "name": { "str_sp": "debug item damager (advanced)" },
+    "description": "Deals damage to items you pick.",
+    "weight": "1 g",
+    "volume": "1 ml",
+    "material": [ "plastic" ],
+    "symbol": ";",
+    "color": "light_gray",
+    "use_action": {
+      "type": "effect_on_conditions",
+      "menu_text": "Damage item",
+      "effect_on_conditions": [
+        {
+          "id": "EOC_FIND_ITEM",
+          "effect": {
+            "u_run_inv_eocs": "manual_mult",
+            "true_eocs": {
+              "id": "EOC_DAMAGE_ITEM",
+              "effect": [
+                { "math": [ "n_hp('ALL')", "-=", "num_input('Amount of damage, 1000 is one bar of damage.', 1000)" ] },
+                { "u_message": "Dealt damage to all items." }
+              ]
+            }
+          }
+        }
+      ]
+    }
   }
 ]

src/item_factory.cpp

@@ -2839,6 +2839,7 @@ void Item_factory::load( islot_gun &slot, const JsonObject &jo, const std::strin
     assign( jo, "heat_per_shot", slot.heat_per_shot, strict, 0.0 );
     assign( jo, "cooling_value", slot.cooling_value, strict, 0.0 );
     assign( jo, "overheat_threshold", slot.overheat_threshold, strict, -1.0 );
+    optional(jo, false, "gun_fail_to_feed_chance", slot.gun_fail_to_feed_chance, 0.00027 );
 
     if( jo.has_array( "valid_mod_locations" ) ) {
         slot.valid_mod_locations.clear();
@@ -3571,7 +3572,7 @@ void Item_factory::load( islot_magazine &slot, const JsonObject &jo, const std::
     assign( jo, "count", slot.count, strict, 0 );
     assign( jo, "default_ammo", slot.default_ammo, strict );
     assign( jo, "reload_time", slot.reload_time, strict, 0 );
-    assign( jo, "mag_jam_odds", slot.mag_jam_odds, strict, 0, 1000 );
+    optional(jo, false, "mag_fail_to_feed_chance", slot.mag_fail_to_feed_chance, 0.00053 );
     assign( jo, "linkage", slot.linkage, strict );
 }
 

src/itype.h

@@ -787,6 +787,11 @@ struct islot_gun : common_ranged_data {
     */
     double overheat_threshold = -1.0;
 
+    /**
+    *  Chance for the gun to fail to feed.
+    */
+    double gun_fail_to_feed_chance = 0.00027;
+
     std::map<ammotype, std::set<itype_id>> cached_ammos;
 
     /**
@@ -945,8 +950,8 @@ struct islot_magazine {
     /** How long it takes to load each unit of ammo into the magazine */
     int reload_time = 100;
 
-    /** Permille for the gun to jam, usually due the size of the magazine*/
-    int mag_jam_odds = 0;
+    /** Permille for the gun to fail to feed, usually due the size of the magazine*/
+    double mag_fail_to_feed_chance = 0.00053 ;
 
     /** For ammo belts one linkage (of given type) is dropped for each unit of ammo consumed */
     std::optional<itype_id> linkage;

src/ranged.cpp

@@ -675,6 +675,20 @@ bool Character::handle_gun_damage( item &it )
         return false;
     }
 
+
+    double mag_ftf_chance = 0.0;
+    double mag_damage = 0.0;
+    if (it.magazine_current()) { 
+    mag_ftf_chance = it.magazine_current()->type->magazine->mag_fail_to_feed_chance;
+    mag_damage = it.magazine_current()->damage() / 1000.0;
+    }
+    const double gun_damage = it.damage() / 1000.0;
+    const double gun_ftf_chance = firing.gun_fail_to_feed_chance;
+
+    const double jam_chance = (mag_ftf_chance + gun_ftf_chance) * std::pow(2, (gun_damage * 1.75) + (mag_damage * 2));
+
+    add_msg_debug(debugmode::DF_RANGED, "Gun fail to feed chance: %g\nMagazine fail to feed chance: %g\nGun damage level: %g\nMagazine damage level: %g\nFail to feed chance: %g%%", gun_ftf_chance, mag_ftf_chance, gun_damage, mag_damage, jam_chance * 100);
+
     // Here we check if we're underwater and whether we should misfire.
     // As a result this causes no damage to the firearm, note that some guns are waterproof
     // and so are immune to this effect, note also that WATERPROOF_GUN status does not
@@ -690,14 +704,16 @@ bool Character::handle_gun_damage( item &it )
         // effect as current guns have a durability between 5 and 9 this results in
         // a chance of mechanical failure between 1/(64*3) and 1/(1024*3) on any given shot.
         // the malfunction can't cause damage
-    } else if( one_in( ( 2 << effective_durability ) * 3 ) && !it.has_flag( flag_NEVER_JAMS ) ) {
-        add_msg_player_or_npc( _( "Your %s malfunctions!" ),
-                               _( "<npcname>'s %s malfunctions!" ),
-                               it.tname() );
+    }
+    else if (one_in((2 << effective_durability) * 3) && !it.has_flag(flag_NEVER_JAMS)) {
+        add_msg_player_or_npc(_("Your %s malfunctions!"),
+            _("<npcname>'s %s malfunctions!"),
+            it.tname());
         return false;
         // Here we check for a chance for the weapon to suffer a failure to feed
         // usually caused by the magazine size or condition
-    else if ( x_in_y( it.magazine_current()->type->magazine->mag_jam_odds, 1000 )) {
+    }
+    else if (x_in_y(jam_chance, 1 )) {
         add_msg_player_or_npc(_("Your %s didn't load into the chamber!"),
             _("<npcname>'s %s didn't load into the chamber!"),
             it.tname());