Merge pull request #33889 from mlangsdorf/dont_drown

monsters: add a check for vehicles before drowning

src/monmove.cpp

@@ -536,6 +536,23 @@ static float get_stagger_adjust( const tripoint &source, const tripoint &destina
     return std::max( 0.01f, initial_dist - new_dist );
 }
 
+bool monster::die_if_drowning( const tripoint &at_pos, const int chance )
+{
+    if( g->m.has_flag( "LIQUID", at_pos ) && can_drown() && one_in( chance ) ) {
+        // if there's a vehicle here with a boardable part, the monster is on it
+        // and not drowning
+        if( g->m.veh_at( at_pos ).part_with_feature( "BOARDABLE", false ) ) {
+            return false;
+        }
+        die( nullptr );
+        if( g->u.sees( at_pos ) ) {
+            add_msg( _( "The %s drowns!" ), name() );
+        }
+        return true;
+    }
+    return false;
+}
+
 // General movement.
 // Currently, priority goes:
 // 1) Special Attack
@@ -639,11 +656,7 @@ void monster::move()
 
     // The monster is in a deep water tile and has a chance to drown
     if( g->m.has_flag_ter( TFLAG_DEEP_WATER, pos() ) ) {
-        if( g->m.has_flag( "LIQUID", pos() ) && can_drown() && one_in( 10 ) ) {
-            die( nullptr );
-            if( g->u.sees( pos() ) ) {
-                add_msg( _( "The %s drowns!" ), name() );
-            }
+        if( die_if_drowning( pos(), 10 ) ) {
             return;
         }
     }
@@ -1723,13 +1736,9 @@ void monster::knock_back_to( const tripoint &to )
 
     // If we're still in the function at this point, we're actually moving a tile!
     if( g->m.has_flag_ter( TFLAG_DEEP_WATER, to ) ) {
-        if( g->m.has_flag( "LIQUID", to ) && can_drown() ) {
-            die( nullptr );
-            if( u_see ) {
-                add_msg( _( "The %s drowns!" ), name() );
-            }
-
-        } else if( has_flag( MF_AQUATIC ) ) { // We swim but we're NOT in water
+        // die_if_drowning will kill the monster if necessary, but if the deep water
+        // tile is on a vehicle, we should check for swimmers out of water
+        if( !die_if_drowning( to ) && has_flag( MF_AQUATIC ) ) {
             die( nullptr );
             if( u_see ) {
                 add_msg( _( "The %s flops around and dies!" ), name() );

src/monster.h

@@ -198,6 +198,11 @@ class monster : public Creature
         void footsteps( const tripoint &p ); // noise made by movement
         void shove_vehicle( const tripoint &remote_destination,
                             const tripoint &nearby_destination ); // shove vehicles out of the way
+        // check if a monster at a position will drown and kill it if necessary
+        // returns true if the monster dies
+        // chance is the one_in( chance ) that the monster will drown
+        bool die_if_drowning( const tripoint &at_pos, int chance = 1 );
+
 
         tripoint scent_move();
         int calc_movecost( const tripoint &f, const tripoint &t ) const;