Drawbridges (down, up, automatic), frost spell and obsidian over cooled lava

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/map.rs

@@ -68,8 +68,15 @@ pub enum Kind {
     GuardPost,  // room: creatures hold the position
     Arena,      // room: sparring
     Altar,      // room: sacrifices
+    Drawbridge, // bridge that can be raised (res: see DB_RAISED, DB_AUTO, DB_LAVA)
+    Obsidian,   // lava cooled by frost: walkable until it melts again
 }
 
+// drawbridge state in Tile::res
+pub const DB_RAISED: u8 = 1; // raised: nobody can cross
+pub const DB_AUTO: u8 = 2; // rises by itself when enemies come near
+pub const DB_LAVA: u8 = 4; // spans lava (stone), else water (wood)
+
 // options for the map generator (campaign missions)
 #[derive(Clone, Debug)]
 pub struct GenOpts {
@@ -96,7 +103,7 @@ pub struct River {
 }
 
 // order matters for the packed savegame codec: only append new kinds
-const KINDS: [Kind; 34] = [
+const KINDS: [Kind; 36] = [
     Kind::Rock,
     Kind::Earth,
     Kind::Gold,
@@ -131,6 +138,8 @@ const KINDS: [Kind; 34] = [
     Kind::GuardPost,
     Kind::Arena,
     Kind::Altar,
+    Kind::Drawbridge,
+    Kind::Obsidian,
 ];
 
 // treasures (veins, treasury content, imp loads): 0 gold, 1 silver, 2 ruby, 3 diamond
@@ -151,6 +160,18 @@ pub enum Owner {
 const OWNERS: [Owner; 6] = [Owner::None, Owner::Player, Owner::Hero, Owner::Rival1, Owner::Rival2, Owner::Rival3];
 
 impl Owner {
+    // the side of a ground owner (255: nobody)
+    pub fn side(self) -> u8 {
+        match self {
+            Owner::Player => 0,
+            Owner::Hero => 1,
+            Owner::Rival1 => 2,
+            Owner::Rival2 => 3,
+            Owner::Rival3 => 4,
+            Owner::None => 255,
+        }
+    }
+
     pub fn of_side(side: u8) -> Owner {
         match side {
             0 => Owner::Player,
@@ -240,20 +261,26 @@ impl Tile {
                 | Kind::GuardPost
                 | Kind::Arena
                 | Kind::Altar
-        )
+                | Kind::Obsidian
+        ) || (self.kind == Kind::Drawbridge && self.res & DB_RAISED == 0)
     }
     // river tiles (open, but nobody can walk there)
     pub fn liquid(&self) -> bool {
         matches!(self.kind, Kind::Water | Kind::Lava)
     }
     pub fn bridge(&self) -> bool {
-        matches!(self.kind, Kind::Bridge | Kind::LavaBridge)
+        matches!(self.kind, Kind::Bridge | Kind::LavaBridge | Kind::Drawbridge)
     }
-    // the river below a bridge or river tile
+    pub fn raised(&self) -> bool {
+        self.kind == Kind::Drawbridge && self.res & DB_RAISED != 0
+    }
+    // the river below a bridge or river tile (obsidian: the lava under the crust)
     pub fn river(&self) -> Option<Kind> {
         match self.kind {
             Kind::Water | Kind::Bridge => Some(Kind::Water),
-            Kind::Lava | Kind::LavaBridge => Some(Kind::Lava),
+            Kind::Lava | Kind::LavaBridge | Kind::Obsidian => Some(Kind::Lava),
+            Kind::Drawbridge if self.res & DB_LAVA != 0 => Some(Kind::Lava),
+            Kind::Drawbridge => Some(Kind::Water),
             _ => None,
         }
     }