Ablative armor can cover more than base armor

data/mods/TEST_DATA/items.json

@@ -3553,6 +3553,67 @@
       }
     ]
   },
+  {
+    "id": "test_ghost_vest",
+    "type": "ARMOR",
+    "category": "armor",
+    "//": "Vest with no coverage to test if it still protects",
+    "name": { "str": "US ghost vest" },
+    "description": "Ballistic armor with specialized pockets on the front, back and sides for armored plates.  The soft armor plate carrier is still protective but it won't stop high energy projectiles.",
+    "weight": "2911 g",
+    "volume": "6 L",
+    "price": 160000,
+    "price_postapoc": 1000,
+    "symbol": "[",
+    "material": [ "nylon", "kevlar" ],
+    "color": "light_gray",
+    "warmth": 15,
+    "flags": [ "STURDY", "OUTER", "WATER_FRIENDLY" ],
+    "use_action": [ { "type": "attach_molle", "size": 6 }, { "type": "detach_molle" } ],
+    "pocket_data": [
+      {
+        "pocket_type": "CONTAINER",
+        "ablative": true,
+        "volume_encumber_modifier": 0,
+        "max_contains_volume": "1600 ml",
+        "max_contains_weight": "5 kg",
+        "moves": 200,
+        "description": "Pocket for front plate",
+        "flag_restriction": [ "ABLATIVE_LARGE" ]
+      },
+      {
+        "pocket_type": "CONTAINER",
+        "ablative": true,
+        "volume_encumber_modifier": 0,
+        "max_contains_volume": "1600 ml",
+        "max_contains_weight": "5 kg",
+        "moves": 200,
+        "description": "Pocket for back plate",
+        "flag_restriction": [ "ABLATIVE_LARGE" ]
+      },
+      {
+        "pocket_type": "CONTAINER",
+        "ablative": true,
+        "volume_encumber_modifier": 0,
+        "max_contains_volume": "800 ml",
+        "max_contains_weight": "2 kg",
+        "moves": 200,
+        "description": "Pocket for right side plate",
+        "flag_restriction": [ "ABLATIVE_MEDIUM" ]
+      },
+      {
+        "pocket_type": "CONTAINER",
+        "ablative": true,
+        "volume_encumber_modifier": 0,
+        "max_contains_volume": "800 ml",
+        "max_contains_weight": "2 kg",
+        "moves": 200,
+        "description": "Pocket for left side plate",
+        "flag_restriction": [ "ABLATIVE_MEDIUM" ]
+      }
+    ],
+    "armor": [ { "encumbrance": 2, "coverage": 100, "covers": [ "torso" ], "specifically_covers": [ "torso_lower" ] } ]
+  },
   {
     "id": "test_plate",
     "type": "ARMOR",

src/character_armor.cpp

@@ -356,17 +356,15 @@ bool Character::armor_absorb( damage_unit &du, item &armor, const bodypart_id &b
 {
     item::cover_type ctype = item::get_cover_type( du.type );
 
-    if( roll > armor.get_coverage( sbp, ctype ) ) {
-        return false;
-    }
-
     // if the armor location has ablative armor apply that first
     if( armor.is_ablative() ) {
         ablative_armor_absorb( du, armor, sbp, roll );
     }
 
-    // if we hit the specific location then we should continue with absorption as normal
-
+    // if the core armor is missed then exit
+    if( roll > armor.get_coverage( sbp, ctype ) ) {
+        return false;
+    }
 
     // reduce the damage
     // -1 is passed as roll so that each material is rolled individually
@@ -415,16 +413,7 @@ bool Character::ablative_armor_absorb( damage_unit &du, item &armor, const sub_b
             // get the contained plate
             item &ablative_armor = pocket->front();
 
-            float ablative_coverage = ablative_armor.get_coverage( bp, ctype );
-            float armor_coverage = armor.get_coverage( bp, ctype );
-
-            // ablative armor stores its overall coverage ex: covers 30% of the torso
-            // but if that plate is in a vest that only covers 60% of the torso then
-            // it covers 50% of the vest so need to scale the coverage appropriately
-            // since the attack has already hit the vest now we are checking if it hits
-            // a plate
-
-            float coverage = ( ablative_coverage / armor_coverage ) * 100;
+            float coverage = ablative_armor.get_coverage( bp, ctype );
 
             // if the attack hits this plate
             if( roll < coverage ) {

src/item.cpp

@@ -859,19 +859,46 @@ bool item::covers( const sub_bodypart_id &bp ) const
     }
 
     bool does_cover = false;
+    bool subpart_cover = false;
+
     iterate_covered_sub_body_parts_internal( get_side(), [&]( const sub_bodypart_str_id & covered ) {
         does_cover = does_cover || bp == covered;
     } );
-    return does_cover;
+
+    // check if a piece of ablative armor covers the location
+    for( const item_pocket *pocket : get_all_contained_pockets() ) {
+        // if the pocket is ablative and not empty we should check it
+        if( pocket->get_pocket_data()->ablative && !pocket->empty() ) {
+            // get the contained plate
+            const item &ablative_armor = pocket->front();
+
+            subpart_cover = subpart_cover || ablative_armor.covers( bp );
+        }
+    }
+
+    return does_cover || subpart_cover;
 }
 
 bool item::covers( const bodypart_id &bp ) const
 {
     bool does_cover = false;
+    bool subpart_cover = false;
     iterate_covered_body_parts_internal( get_side(), [&]( const bodypart_str_id & covered ) {
         does_cover = does_cover || bp == covered;
     } );
-    return does_cover;
+
+    // check if a piece of ablative armor covers the location
+    for( const item_pocket *pocket : get_all_contained_pockets() ) {
+        // if the pocket is ablative and not empty we should check it
+        if( pocket->get_pocket_data()->ablative && !pocket->empty() ) {
+            // get the contained plate
+            const item &ablative_armor = pocket->front();
+
+            subpart_cover = subpart_cover || ablative_armor.covers( bp );
+        }
+    }
+
+    return does_cover || subpart_cover;
 }
 
 cata::optional<side> item::covers_overlaps( const item &rhs ) const

tests/coverage_test.cpp

@@ -79,6 +79,41 @@ static float get_avg_melee_dmg( std::string clothing_id, bool infect_risk = fals
     return static_cast<float>( dam_acc ) / num_hits;
 }
 
+static float get_avg_melee_dmg( item cloth, bool infect_risk = false )
+{
+    monster zed( mon_manhack, mon_pos );
+    standard_npc dude( "TestCharacter", dude_pos, {}, 0, 8, 8, 8, 8 );
+    if( infect_risk ) {
+        cloth.set_flag( json_flag_FILTHY );
+    }
+    int dam_acc = 0;
+    int num_hits = 0;
+    for( int i = 0; i < num_iters; i++ ) {
+        clear_character( dude, true );
+        dude.setpos( dude_pos );
+        dude.wear_item( cloth, false );
+        dude.add_effect( effect_sleep, 1_hours );
+        if( zed.melee_attack( dude, 10000.0f ) ) {
+            num_hits++;
+        }
+        cloth.set_damage( cloth.min_damage() );
+        if( !infect_risk ) {
+            dam_acc += dude.get_hp_max() - dude.get_hp();
+        } else if( dude.has_effect( effect_bite ) ) {
+            dam_acc++;
+        }
+        if( dude.is_dead() ) {
+            break;
+        }
+    }
+    CAPTURE( dude.is_dead() );
+    const std::string ret_type = infect_risk ? "infections" : "damage total";
+    INFO( string_format( "%s landed %d hits on character, causing %d %s.", zed.get_name(), num_hits,
+                         dam_acc, ret_type ) );
+    num_hits = num_hits ? num_hits : 1;
+    return static_cast<float>( dam_acc ) / num_hits;
+}
+
 static float get_avg_bullet_dmg( std::string clothing_id )
 {
     clear_map();
@@ -181,3 +216,22 @@ TEST_CASE( "Proportional armor material resistances", "[material]" )
         check_not_near( "Average damage", dmg, base_line, 0.05f );
     }
 }
+
+TEST_CASE( "Ghost ablative vest", "[coverage]" )
+{
+    SECTION( "Ablative not covered" ) {
+        item full = item( "test_ghost_vest" );
+        full.force_insert_item( item( "test_plate" ), item_pocket::pocket_type::CONTAINER );
+        full.force_insert_item( item( "test_plate" ), item_pocket::pocket_type::CONTAINER );
+        item empty = item( "test_ghost_vest" );
+
+        // make sure vest only covers torso_upper when it has armor in it
+        REQUIRE( full.covers( sub_bodypart_id( "torso_upper" ) ) );
+        REQUIRE( !empty.covers( sub_bodypart_id( "torso_upper" ) ) );
+        const float dmg_full = get_avg_melee_dmg( full );
+        const float dmg_empty = get_avg_melee_dmg( empty );
+        // make sure the armor is counting even if the base vest doesn't do anything
+        check_not_near( "Average damage", dmg_full, dmg_empty, 0.5f );
+    }
+}
+