[WIP] Skylights and other fragile terrain break when creatures step on them

data/json/furniture_and_terrain/terrain-roofs.json

@@ -182,7 +182,7 @@
     "color": "cyan",
     "move_cost": 2,
     "//": "TODO: Should break when you step on it if there's no supporting terrain below, might want some warning akin to examine_action ledge",
-    "flags": [ "TRANSPARENT", "TRANSPARENT_FLOOR" ],
+    "flags": [ "TRANSPARENT", "TRANSPARENT_FLOOR", "FRAGILE" ],
     "bash": {
       "str_min": 3,
       "str_max": 6,

data/json/furniture_and_terrain/terrain-windows.json

@@ -4457,15 +4457,15 @@
     "move_cost": 2,
     "coverage": 0,
     "examine_action": "ledge",
-    "deconstruct": { "ter_set": "t_null", "items": [ { "item": "2x4", "count": [ 3, 4 ] }, { "item": "nail", "charges": [ 12, 16 ] } ] },
+    "deconstruct": { "ter_set": "t_open_air", "items": [ { "item": "2x4", "count": [ 3, 4 ] }, { "item": "nail", "charges": [ 12, 16 ] } ] },
     "bash": {
       "str_min": 1,
       "str_max": 1,
       "sound": "whump!",
       "sound_fail": "whack!",
       "sound_vol": 12,
       "sound_fail_vol": 8,
-      "ter_set": "t_null",
+      "ter_set": "t_open_air",
       "items": [ { "item": "2x4", "count": [ 2, 4 ] } ]
     },
     "flags": [ "TRANSPARENT", "NO_FLOOR", "FLAMMABLE" ]

src/creature.cpp

@@ -211,12 +211,60 @@ tripoint_bub_ms Creature::pos_bub( const map &here ) const
     return here.get_bub( location );
 }
 
+void Creature::maybe_break_fragile_underfoot(Creature &cr, const tripoint_bub_ms &p)
+{
+    map& here = get_map();
+    if (here.has_flag(ter_furn_flag::TFLAG_FRAGILE, p)) {
+        bool can_fly = false;
+        if (const monster* mon = dynamic_cast<const monster*>(&cr)) {
+            can_fly = mon->flies();
+        }
+        if (!cr.is_hallucination() && !can_fly && cr.get_weight() >= 5_kilogram) {
+            std::string who_name;
+            int bash_strength = cr.get_weight() / 5_kilogram;
+            //check if monster
+            if (const monster* mon = dynamic_cast<const monster*>(&cr)) {
+                who_name = mon->disp_name();
+                bash_strength = bash_strength / 2;
+
+            } //check for character
+            else if (const Character* ch = dynamic_cast<const Character*>(&cr)) {
+                who_name = ch->disp_name();
+                //if char is prone, less likely to break glass
+                if (ch->is_prone()) {
+                    bash_strength = bash_strength / 8;
+                }
+                else {
+                    bash_strength = bash_strength / 2;
+                }
+            } //default case
+            else {
+                who_name = _("something");
+                bash_strength = bash_strength / 2;
+            }
+            //store terrain name for message
+            const std::string old_name = here.tername(p);
+            //damage fragile terrain
+            const auto res = here.bash(p, bash_strength, true, false, false, nullptr, false);
+            //if broken output message
+            if (res.success) {
+                add_msg(m_warning,
+                    string_format(_("The %s breaks under the weight of %s!"),
+                        old_name, who_name));
+            }
+        }
+    }
+    return;
+}
+
 void Creature::setpos( map &here, const tripoint_bub_ms &p, bool check_gravity/* = true*/ )
 {
     const tripoint_abs_ms old_loc = pos_abs();
     set_pos_abs_only( here.get_abs( p ) );
     on_move( old_loc );
+
     if( check_gravity ) {
+        maybe_break_fragile_underfoot(*this, p);
         gravity_check( &here );
     }
 }
@@ -227,6 +275,10 @@ void Creature::setpos( const tripoint_abs_ms &p, bool check_gravity/* = true*/ )
     set_pos_abs_only( p );
     on_move( old_loc );
     if( check_gravity ) {
+        map& here = get_map();
+        if (here.inbounds(p)) {
+            maybe_break_fragile_underfoot(*this, here.get_bub( p ));
+        }
         gravity_check();
     }
 }

src/creature.h

@@ -323,6 +323,7 @@ class Creature : public viewer
         }
         virtual void gravity_check();
         virtual void gravity_check( map *here );
+        void maybe_break_fragile_underfoot(Creature& cr, const tripoint_bub_ms& p);
         void setpos( map &here, const tripoint_bub_ms &p, bool check_gravity = true );
         void setpos( const tripoint_abs_ms &p, bool check_gravity = true );
 

src/mapdata.cpp

@@ -325,6 +325,7 @@ std::string enum_to_string<ter_furn_flag>( ter_furn_flag data )
         case ter_furn_flag::TFLAG_WIRED_WALL: return "WIRED_WALL";
         case ter_furn_flag::TFLAG_MON_AVOID_STRICT: return "MON_AVOID_STRICT";
         case ter_furn_flag::TFLAG_REGION_PSEUDO: return "REGION_PSEUDO";
+        case ter_furn_flag::TFLAG_FRAGILE: return "FRAGILE";
 
         // *INDENT-ON*
         case ter_furn_flag::NUM_TFLAG_FLAGS:

src/mapdata.h

@@ -375,6 +375,7 @@ enum class ter_furn_flag : int {
     TFLAG_WIRED_WALL,
     TFLAG_MON_AVOID_STRICT,
     TFLAG_REGION_PSEUDO,
+    TFLAG_FRAGILE,
 
     NUM_TFLAG_FLAGS
 };