Soundtrack expanded to 35 pieces with a leitmotif variant generator and 8 new instruments

- generator: leitmotif as scale degrees, keys/modes, augmentation, diminution, inversion,
  fragment sequences, accompaniment and drum styles; hand-written title 2, boss themes, victory 2
- organ, bell, choir, sub bass, tom, crash, harp, timpani; 8-bit samples, unused instruments stripped
- src/tracks.rs generated with categories; music director with boss themes and room moods
- all pieces validated with libopenmpt; notes checked to stay in key

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

src/main.rs

@@ -11,6 +11,7 @@ mod render3d;
 mod save;
 mod settings;
 mod sfx;
+mod tracks;
 mod sound;
 mod ui;
 mod xm;
@@ -73,35 +74,69 @@ fn apply_settings(s: &Settings, r3d: &mut R3d) {
     audio::set_volumes(s.music_volume, s.volume, s.muted);
 }
 
-// Chooses the music for the current situation; build tracks rotate after two loops
+// Chooses the music for the current situation. Each category rotates through its tracks;
+// build and title music switch to the next track after two loops.
 struct MusicDirector {
-    build: usize,
+    next: std::collections::HashMap<u8, usize>, // category -> next index within the category
+    current: Option<audio::Category>,
 }
 
 impl MusicDirector {
-    fn update(&mut self, g: &Game, title: bool) {
-        use audio::Track;
-        const BUILD: [Track; 3] = [Track::Build1, Track::Build2, Track::Build3];
-        let gate_fight = g.time - g.gate_hit_t < 12.0 || g.gate_defenders_alive();
-        let invasion = g.ents.iter().any(|e| e.alive && e.active_hero() && !e.guard);
-        let want = if title {
-            Track::Title
-        } else if g.state == 1 {
-            Track::Victory
-        } else if g.state == 2 {
-            Track::Defeat
-        } else if gate_fight {
-            Track::Battle2
-        } else if invasion {
-            Track::Battle1
-        } else {
-            if BUILD.contains(&audio::current_track().unwrap_or(Track::Title)) && audio::music_loops() >= 2 {
-                self.build = (self.build + 1) % BUILD.len();
+    fn new() -> MusicDirector {
+        MusicDirector { next: std::collections::HashMap::new(), current: None }
+    }
+
+    fn pick(&mut self, c: audio::Category) -> usize {
+        let list = audio::tracks_in(c);
+        let k = self.next.entry(c as u8).or_insert(0);
+        let t = list[*k % list.len()];
+        *k += 1;
+        t
+    }
+
+    fn update(&mut self, g: &Game, title: bool, cam: (f32, f32)) {
+        use audio::Category as C;
+        let alive = |f: &dyn Fn(&game::Ent) -> bool| g.ents.iter().any(|e| e.alive && f(e));
+        let near_room = |k: map::Kind| {
+            let (cx, cz) = (cam.0 as i32, cam.1 as i32);
+            let mut n = 0;
+            for y in cz - 5..=cz + 5 {
+                for x in cx - 5..=cx + 5 {
+                    if g.map.get(x, y).map_or(false, |t| t.kind == k) {
+                        n += 1;
+                    }
+                }
             }
-            BUILD[self.build]
+            n >= 4
         };
-        let fade = if matches!(want, Track::Victory | Track::Defeat) { 1.0 } else { 2.5 };
-        audio::play_music(want, fade);
+        let want = if title {
+            C::Title
+        } else if g.state == 1 {
+            C::Victory
+        } else if g.state == 2 {
+            C::Defeat
+        } else if alive(&|e| e.active_hero() && e.kind == game::EK::Paladin && e.guard) {
+            C::BossWarden
+        } else if alive(&|e| e.active_hero() && e.kind == game::EK::Paladin) {
+            C::BossPaladin
+        } else if g.time - g.gate_hit_t < 12.0 || g.gate_defenders_alive() {
+            C::Assault
+        } else if alive(&|e| e.active_hero() && !e.guard) {
+            C::Battle
+        } else if near_room(map::Kind::Torture) {
+            C::Torture
+        } else if near_room(map::Kind::Temple) {
+            C::Temple
+        } else {
+            C::Build
+        };
+        let rotate = matches!(want, C::Build | C::Title) && self.current == Some(want) && audio::music_loops() >= 2;
+        if self.current != Some(want) || rotate || audio::current_track().is_none() {
+            self.current = Some(want);
+            let t = self.pick(want);
+            let fade = if matches!(want, C::Victory | C::Defeat) { 1.0 } else { 2.5 };
+            audio::play_music(t, fade);
+        }
     }
 }
 
@@ -175,7 +210,7 @@ async fn main() {
     let gfx = Gfx::new();
     let mut r3d = R3d::new();
     let mut sounds = SoundBank::new();
-    let mut music = MusicDirector { build: 0 };
+    let mut music = MusicDirector::new();
     let mut ui = Ui::new();
     let mut menu = Menu::new();
 
@@ -542,7 +577,8 @@ async fn main() {
         for ev in app.game.events.drain(..) {
             sounds.play(ev, vec2(app.cam.tx, app.cam.tz), right, hear, now);
         }
-        music.update(&app.game, menu.page == Some(Page::Title) || matches!(menu.page, Some(Page::Settings { from_title: true, .. }) | Some(Page::KeyCapture { from_title: true, .. })));
+        let on_title = menu.page == Some(Page::Title) || matches!(menu.page, Some(Page::Settings { from_title: true, .. }) | Some(Page::KeyCapture { from_title: true, .. }) | Some(Page::NewGame));
+        music.update(&app.game, on_title, (app.cam.tx, app.cam.tz));
         for m in app.game.msgs.drain(..) {
             ui.log.push((m, now));
         }