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

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

src/game.rs

@@ -750,6 +750,8 @@ pub const ROOM_NAMES: [&str; N_ROOMS] = [
 
 // bridge cost per tile: over water, over lava
 pub const BRIDGE_COST: [i32; 2] = [30, 75];
+// a drawbridge tile (over water or lava)
+pub const DRAWBRIDGE_COST: i32 = 150;
 // steel wall cost per tile: from earth, from a reinforced wall
 pub const STEEL_COST: [i32; 2] = [80, 40];
 pub const STEEL_HP: f32 = 40.0;
@@ -2820,7 +2822,7 @@ impl Game {
 
     // the ground of tile i turned into river (bridge removed): units on it fall in
     pub(crate) fn ground_lost(&mut self, i: usize) {
-        let lava = self.map.t[i].kind == Kind::Lava;
+        let lava = self.map.t[i].river() == Some(Kind::Lava);
         let (x, y) = xy(i);
         for j in 0..self.ents.len() {
             let e = &self.ents[j];
@@ -2890,6 +2892,10 @@ impl Game {
     }
 
     pub fn build_bridges(&mut self, x0: i32, y0: i32, x1: i32, y1: i32) {
+        self.build_bridges_of(x0, y0, x1, y1, false);
+    }
+
+    pub fn build_bridges_of(&mut self, x0: i32, y0: i32, x1: i32, y1: i32, draw: bool) {
         let (mut built, mut broke, mut any_river) = (0, false, false);
         loop {
             let mut add = Vec::new();
@@ -2911,14 +2917,21 @@ impl Game {
             let mut progress = false;
             for i in add {
                 let lava = self.map.t[i].kind == Kind::Lava;
-                let cost = BRIDGE_COST[lava as usize] as f32;
+                let cost = if draw { DRAWBRIDGE_COST } else { BRIDGE_COST[lava as usize] } as f32;
                 if self.gold < cost {
                     broke = true;
                     continue;
                 }
                 self.gold -= cost;
                 let t = &mut self.map.t[i];
-                t.kind = if lava { Kind::LavaBridge } else { Kind::Bridge };
+                t.kind = if draw {
+                    Kind::Drawbridge
+                } else if lava {
+                    Kind::LavaBridge
+                } else {
+                    Kind::Bridge
+                };
+                t.res = if draw && lava { DB_LAVA } else { 0 };
                 t.owner = self.me;
                 built += 1;
                 progress = true;
@@ -3060,7 +3073,7 @@ impl Game {
                         continue;
                     }
                     if let Some(t) = self.map.get(cx + dx, cy + dy) {
-                        if t.bridge() && t.owner == self.me {
+                        if t.bridge() && !t.raised() && t.owner == self.me {
                             return Some(idx(cx + dx, cy + dy));
                         }
                     }
@@ -3073,7 +3086,7 @@ impl Game {
     // a knight walks next to the bridge tile and tears it down
     fn tear_bridge(&mut self, e: &mut Ent, i: usize, dt: f32) -> bool {
         let t = self.map.t[i];
-        if !t.bridge() || t.owner != self.me {
+        if !t.bridge() || t.raised() || t.owner != self.me {
             return false;
         }
         let (bx, by) = xy(i);
@@ -4714,11 +4727,13 @@ impl Game {
                     continue;
                 }
                 if t.owner == self.me && t.bridge() {
-                    let lava = t.kind == Kind::LavaBridge;
+                    let lava = t.river() == Some(Kind::Lava);
+                    let cost = if t.kind == Kind::Drawbridge { DRAWBRIDGE_COST } else { BRIDGE_COST[lava as usize] };
                     t.kind = if lava { Kind::Lava } else { Kind::Water };
                     t.owner = Owner::None;
                     t.reserved = 0;
-                    refund += BRIDGE_COST[lava as usize] as f32 * 0.5;
+                    t.res = 0;
+                    refund += cost as f32 * 0.5;
                     self.ground_lost(i);
                     continue;
                 }