fail to feed for non-standard mags

data/json/faults/faults_guns.json

@@ -7,14 +7,6 @@
     "item_prefix": "rusting",
     "flags": [ "BLACKPOWDER_FOULING_DAMAGE", "NO_DIRTYING" ]
   },
-  {
-    "id": "fault_gun_chamber_spent",
-    "type": "fault",
-    "name": { "str": "Spent casing in chamber" },
-    "description": "This gun currently has an empty casing chambered.  It will have to be removed before firing.",
-    "item_prefix": "jammed",
-    "flags": [ "JAMMED_GUN" ]
-  },
   {
     "id": "fault_gun_unlubricated",
     "type": "fault",
@@ -54,6 +46,42 @@
     "type": "fault",
     "name": { "str": "Overheat safety" },
     "description": "This weapon will attempt to enter a cooling cycle when overheated.",
-    "flags": [ "JAMMED_GUN" ]
+    "flags": [ "OVERHEATED_GUN" ]
+  },
+  {
+    "id": "fault_fail_to_feed",
+    "type": "fault",
+    "//": "gun_mechanical_simple can be fixed on the fly",
+    "fault_type": "gun_mechanical_simple",
+    "name": { "str": "Fail to feed" },
+    "description": "This gun did not load the round in the chamber properly.",
+    "item_prefix": "jammed"
+  },
+  {
+    "id": "fault_gun_chamber_spent",
+    "//": "aka fail to extract",
+    "type": "fault",
+    "fault_type": "gun_mechanical_simple",
+    "name": { "str": "Spent casing in chamber" },
+    "description": "This gun currently has an empty casing in the chamber.",
+    "item_prefix": "jammed"
+  },
+  {
+    "id": "fault_stovepipe",
+    "//": "only closed bolt",
+    "type": "fault",
+    "fault_type": "gun_mechanical_simple",
+    "name": { "str": "Stovepipe" },
+    "description": "Casing of the bullet stuck without being properly ejected.",
+    "item_prefix": "jammed"
+  },
+  {
+    "id": "fault_double_feed",
+    "//": "only magazine-fed firearms",
+    "type": "fault",
+    "fault_type": "gun_mechanical_simple",
+    "name": { "str": "Double feed" },
+    "description": "Magazine of the gun tried to put two rounds in the chamber at once.",
+    "item_prefix": "jammed"
   }
 ]

data/json/faults/fixes_gun.json

@@ -66,14 +66,42 @@
     "time_save_profs": { "prof_gun_cleaning": 0.5 },
     "time_save_flags": { "EASY_CLEAN": 0.5 }
   },
+  {
+    "type": "fault_fix",
+    "id": "mend_fault_fail_to_feed_manual_feed",
+    "name": "Manual cycle",
+    "success_msg": "You manually cycle your %s to put round in the chamber.",
+    "time": "10 s",
+    "set_variables": { "u_know_round_in_chamber": "true" },
+    "faults_removed": [ "fault_fail_to_feed" ]
+  },
   {
     "type": "fault_fix",
     "id": "mend_fault_gun_chamber_spent_eject",
     "name": "Eject spent casing",
-    "success_msg": "You eject the spent casing from the %s.",
-    "time": "1 s",
+    "success_msg": "You eject the spent casing from the %s's chamber.",
+    "time": "10 s",
+    "set_variables": { "u_know_round_in_chamber": "true" },
     "faults_removed": [ "fault_gun_chamber_spent" ]
   },
+  {
+    "type": "fault_fix",
+    "id": "mend_fault_stovepipe_eject",
+    "name": "Eject spent casing",
+    "success_msg": "You eject the spent casing, stuck in %s's slide.",
+    "time": "10 s",
+    "set_variables": { "u_know_round_in_chamber": "true" },
+    "faults_removed": [ "fault_stovepipe" ]
+  },
+  {
+    "type": "fault_fix",
+    "id": "mend_fault_double_feed_clean",
+    "name": "Clean double feed",
+    "success_msg": "You eject the second round stuck in %s's chamber.",
+    "time": "10 s",
+    "set_variables": { "u_know_round_in_chamber": "true" },
+    "faults_removed": [ "fault_double_feed" ]
+  },
   {
     "type": "fault_fix",
     "id": "mend_fault_gun_unlubricated",

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." }
+              ]
+            }
+          }
+        }
+      ]
+    }
   }
 ]

doc/JSON_INFO.md

@@ -3608,6 +3608,7 @@ ammo_effects define what effect the projectile, that you shoot, would have. List
 "count" : 0,                     // Default amount of ammo contained by a magazine (set this for ammo belts)
 "default_ammo": "556",           // If specified override the default ammo (optionally set this for ammo belts)
 "reload_time" : 100,             // How long it takes to load each unit of ammo into the magazine
+"mag_jam_mult": 1.25             // Multiplier for gun mechanincal malfunctioning from magazine, mostly when it's damaged; Values lesser than 1 reflect better quality of the magazine, that jam less; bigger than 1 result in gun being more prone to malfunction and jam at lesser damage level; zero mag_jam_mult (and zero gun_jam_mult in a gun) would remove any chance for a gun to malfunction. Only works if gun has any fault from gun_mechanical_simple group presented; Jam chances are described in Character::handle_gun_damage(); at this moment it is roughly: 0.000288% for undamaged magazine, 5% for 1 damage (|\), 24% for 2 damage (|.), 96% for 3 damage (\.), and 250% for 4 damage (XX), then this and gun values are summed up and multiplied by 1.8. 
 "linkage" : "ammolink"           // If set one linkage (of given type) is dropped for each unit of ammo consumed (set for disintegrating ammo belts)
 ```
 
@@ -4155,6 +4156,7 @@ Guns can be defined like this:
 "sight_dispersion": 10,    // Inaccuracy of gun derived from the sight mechanism, measured in 100ths of Minutes Of Angle (MOA)
 "recoil": 0,               // Recoil caused when firing, measured in 100ths of Minutes Of Angle (MOA)
 "durability": 8,           // Resistance to damage/rusting, also determines misfire chance
+"gun_jam_mult": 1.25       // Multiplier for gun mechanincal malfunctioning, mostly when it's damaged; Values lesser than 1 reflect better quality of the gun, that jam less; bigger than 1 result in gun being more prone to malfunction and jam at lesser damage level; zero gun_jam_mult (and zero mag_jam_mult if magazine is presented) would remove any chance for a gun to malfunction. Only apply if gun has any fault from gun_mechanical_simple group presented; Jam chances are described in Character::handle_gun_damage(); at this moment it is roughly: 0.00018% for undamaged gun, 3% for 1 damage (|\), 15% for 2 damage (|.), 45% for 3 damage (\.), and 80% for 4 damage (XX), then this and magazine values are summed up and multiplied by 1.8
 "blackpowder_tolerance": 8,// One in X chance to get clogged up (per shot) when firing blackpowder ammunition (higher is better). Optional, default is 8.
 "min_cycle_recoil": 0,     // Minimum ammo recoil for gun to be able to fire more than once per attack.
 "clip_size": 100,          // Maximum amount of ammo that can be loaded

src/activity_actor.cpp

@@ -46,6 +46,7 @@
 #include "event_bus.h"
 #include "faction.h"
 #include "field_type.h"
+#include "fault.h"
 #include "flag.h"
 #include "flexbuffer_json-inl.h"
 #include "flexbuffer_json.h"
@@ -252,6 +253,7 @@ static const quality_id qual_SHEAR( "SHEAR" );
 static const skill_id skill_computer( "computer" );
 static const skill_id skill_electronics( "electronics" );
 static const skill_id skill_fabrication( "fabrication" );
+static const skill_id skill_gun( "gun" );
 static const skill_id skill_mechanics( "mechanics" );
 static const skill_id skill_survival( "survival" );
 static const skill_id skill_traps( "traps" );
@@ -283,6 +285,8 @@ static const zone_type_id zone_type_LOOT_IGNORE_FAVORITES( "LOOT_IGNORE_FAVORITE
 static const zone_type_id zone_type_STRIP_CORPSES( "STRIP_CORPSES" );
 static const zone_type_id zone_type_UNLOAD_ALL( "UNLOAD_ALL" );
 
+static const std::string gun_mechanical_simple( "gun_mechanical_simple" );
+
 std::string activity_actor::get_progress_message( const player_activity &act ) const
 {
     if( act.moves_total > 0 ) {
@@ -317,13 +321,60 @@ aim_activity_actor aim_activity_actor::use_mutation( const item &fake_gun )
     return act;
 }
 
-void aim_activity_actor::start( player_activity &act, Character &/*who*/ )
+void aim_activity_actor::start( player_activity &act, Character &who )
 {
+    item_location weapon = get_weapon();
+    item &it = *weapon.get_item();
+
+    if( !check_gun_ability_to_shoot( who, it ) ) {
+        aborted = true; // why doesn't interrupt?
+        act.set_to_null();
+    }
+
     // Time spent on aiming is determined on the go by the player
     act.moves_total = 1;
     act.moves_left = 1;
 }
 
+bool aim_activity_actor::check_gun_ability_to_shoot( Character &who, item &it )
+{
+
+    if( it.has_fault_flag( "RUINED_GUN" ) ) {
+        who.add_msg_if_player( m_bad, _( "Your %s is little more than an awkward club now." ), it.tname() );
+        return false;
+    }
+
+    // if it's a simple fault, character can try to fix it on the fly
+    if( faults::random_of_type_item_has( it, gun_mechanical_simple ) != fault_id::NULL_ID() ) {
+        // fixing fault should cost more than 1 second
+        // but until game running the next activity actor without ever verifying
+        // was the previous one successful or not will be resolved,
+        // it would be safer to limit it somewhat
+        who.mod_moves( -who.get_speed() );
+        who.recoil = MAX_RECOIL;
+        if( one_in( std::max( 7.0f, ( 15.0f - ( 4.0f * who.get_skill_level( skill_gun ) ) ) ) ) ) {
+            who.add_msg_if_player( m_good,
+                                   _( "Your %s has some mechanical malfunction.  You tried to quickly fix it, and it works now!" ),
+                                   it.tname() );
+            it.faults.erase( faults::random_of_type_item_has( it, gun_mechanical_simple ) );
+            it.set_var( "u_know_round_in_chamber", true );
+        } else {
+            who.add_msg_if_player( m_bad,
+                                   _( "Your %s has some mechanical malfunction.  You tried to quickly fix it, but failed!" ),
+                                   it.tname() );
+            return false;
+        }
+    }
+
+    if( it.has_fault_flag( "OVERHEATED_GUN" ) ) {
+        who.add_msg_if_player( m_warning,
+                               _( "Your %s is too hot, and little screen signalizes the gun is inoperable." ), it.tname() );
+        return false;
+    }
+
+    return true;
+}
+
 void aim_activity_actor::do_turn( player_activity &act, Character &who )
 {
     if( !who.is_avatar() ) {

src/activity_actor_definitions.h

@@ -90,6 +90,7 @@ class aim_activity_actor : public activity_actor
         }
 
         void start( player_activity &act, Character &who ) override;
+        bool check_gun_ability_to_shoot( Character &who, item &it );
         void do_turn( player_activity &act, Character &who ) override;
         void finish( player_activity &act, Character &who ) override;
         void canceled( player_activity &act, Character &who ) override;

src/fault.cpp

@@ -32,6 +32,41 @@ const fault_id &faults::random_of_type( const std::string &type )
     return random_entry_ref( typed->second );
 }
 
+const fault_id &faults::random_of_type_item_has( const item &it, const std::string &type )
+{
+    const auto &typed = faults_by_type.find( type );
+    if( typed == faults_by_type.end() ) {
+        debugmsg( "there are no faults with type '%s'", type );
+        return fault_id::NULL_ID();
+    }
+
+    // not actually random
+    for( const fault_id &fid : typed->second ) {
+        if( it.has_fault( fid ) ) {
+            return fid;
+        }
+    }
+
+    return fault_id::NULL_ID();
+}
+
+const fault_id &faults::get_random_of_type_item_can_have( const item &it, const std::string &type )
+{
+    const auto &typed = faults_by_type.find( type );
+    if( typed == faults_by_type.end() ) {
+        debugmsg( "there are no faults with type '%s'", type );
+        return fault_id::NULL_ID();
+    }
+
+    for( const fault_id &fid : typed->second ) {
+        if( it.faults_potential().count( fid ) ) {
+            return fid;
+        }
+    }
+
+    return fault_id::NULL_ID();
+}
+
 void faults::load_fault( const JsonObject &jo, const std::string &src )
 {
     fault_factory.load( jo, src );

src/fault.h

@@ -29,7 +29,10 @@ void reset();
 void finalize();
 void check_consistency();
 
+const fault_id &get_random_of_type_item_can_have( const item &it, const std::string &type );
+
 const fault_id &random_of_type( const std::string &type );
+const fault_id &random_of_type_item_has( const item &it, const std::string &type );
 } // namespace faults
 
 class fault_fix

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_jam_mult", slot.gun_jam_mult, 1 );
 
     if( jo.has_array( "valid_mod_locations" ) ) {
         slot.valid_mod_locations.clear();
@@ -3573,6 +3574,7 @@ 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 );
+    optional( jo, false, "mag_jam_mult", slot.mag_jam_mult, 1 );
     assign( jo, "linkage", slot.linkage, strict );
 }
 

src/itype.h

@@ -787,6 +787,11 @@ struct islot_gun : common_ranged_data {
     */
     double overheat_threshold = -1.0;
 
+    /**
+    *  Multiplier of the chance for the gun to jam.
+    */
+    double gun_jam_mult = 1;
+
     std::map<ammotype, std::set<itype_id>> cached_ammos;
 
     /**
@@ -948,6 +953,9 @@ struct islot_magazine {
     /** How long it takes to load each unit of ammo into the magazine */
     int reload_time = 100;
 
+    /** Multiplier for the gun jamming from physical damage */
+    double mag_jam_mult = 1 ;
+
     /** For ammo belts one linkage (of given type) is dropped for each unit of ammo consumed */
     std::optional<itype_id> linkage;