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/audio.rs

@@ -3,32 +3,30 @@
 // which starts the AudioContext on the first user interaction.
 
 use crate::sfx;
+use crate::tracks::TRACKS;
 use crate::xm::{self, Module, Player};
 use std::cell::RefCell;
 use std::rc::Rc;
 
+// Music categories; the tracks themselves are listed in tracks.rs (generated by the composer)
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
-pub enum Track {
+pub enum Category {
     Title,
-    Build1,
-    Build2,
-    Build3,
-    Battle1,
-    Battle2,
+    Build,
+    Battle,
+    Assault,
+    BossPaladin,
+    BossWarden,
+    Torture,
+    Temple,
     Victory,
     Defeat,
 }
 
-const TRACKS: [(Track, &[u8]); 8] = [
-    (Track::Title, include_bytes!("../assets/music/title.xm")),
-    (Track::Build1, include_bytes!("../assets/music/build1.xm")),
-    (Track::Build2, include_bytes!("../assets/music/build2.xm")),
-    (Track::Build3, include_bytes!("../assets/music/build3.xm")),
-    (Track::Battle1, include_bytes!("../assets/music/battle1.xm")),
-    (Track::Battle2, include_bytes!("../assets/music/battle2.xm")),
-    (Track::Victory, include_bytes!("../assets/music/victory.xm")),
-    (Track::Defeat, include_bytes!("../assets/music/defeat.xm")),
-];
+// indices of all tracks of a category, in play order
+pub fn tracks_in(c: Category) -> Vec<usize> {
+    TRACKS.iter().enumerate().filter(|(_, t)| t.1 == c).map(|(i, _)| i).collect()
+}
 
 const MUSIC_GAIN: f32 = 0.45; // our replayer is ~4x louder than libopenmpt; leaves headroom for effects
 const SFX_GAIN: f32 = 0.55;
@@ -61,7 +59,7 @@ struct State {
     music_vol: f32,
     sfx_vol: f32,
     muted: bool,
-    track: Option<Track>,
+    track: Option<usize>,
     engine: Option<Engine>,
 }
 
@@ -69,24 +67,20 @@ thread_local! {
     static STATE: RefCell<State> = RefCell::new(State { music_vol: 0.6, sfx_vol: 0.7, muted: false, track: None, engine: None });
 }
 
-fn track_index(t: Track) -> usize {
-    TRACKS.iter().position(|(k, _)| *k == t).unwrap_or(0)
-}
-
 impl Engine {
     fn new(rate: f32) -> Engine {
-        let modules = TRACKS.iter().map(|(_, d)| Rc::new(xm::load(d).expect("built-in music"))).collect();
+        let modules = TRACKS.iter().map(|(_, _, d)| Rc::new(xm::load(d).expect("built-in music"))).collect();
         let sfx = sfx::generate_all(rate).into_iter().map(Rc::new).collect();
         Engine { rate, modules, music: Vec::new(), voices: Vec::new(), sfx, buf: Vec::new() }
     }
 
-    fn start_track(&mut self, t: Track, fade: f32) {
+    fn start_track(&mut self, t: usize, fade: f32) {
         let speed = 1.0 / fade.max(0.01);
         for v in self.music.iter_mut() {
             v.target = 0.0;
             v.speed = speed;
         }
-        let player = Player::new(self.modules[track_index(t)].clone(), self.rate);
+        let player = Player::new(self.modules[t.min(self.modules.len() - 1)].clone(), self.rate);
         let instant = self.music.is_empty() || fade <= 0.0;
         self.music.push(MusicVoice { player, gain: if instant { 1.0 } else { 0.0 }, target: 1.0, speed });
     }
@@ -143,7 +137,7 @@ pub fn set_volumes(music: f32, sfx: f32, muted: bool) {
 }
 
 // Switch music with a crossfade (seconds); does nothing if the track already plays
-pub fn play_music(t: Track, fade: f32) {
+pub fn play_music(t: usize, fade: f32) {
     STATE.with(|s| {
         let mut s = s.borrow_mut();
         if s.track == Some(t) {
@@ -164,7 +158,7 @@ pub fn music_loops() -> u32 {
     })
 }
 
-pub fn current_track() -> Option<Track> {
+pub fn current_track() -> Option<usize> {
     STATE.with(|s| s.borrow().track)
 }
 
@@ -225,11 +219,14 @@ mod tests {
     #[test]
     fn engine_crossfade_and_sfx() {
         dc_audio_init(48000.0);
-        play_music(Track::Build1, 0.0);
+        let build = tracks_in(Category::Build);
+        let battle = tracks_in(Category::Battle);
+        assert_eq!(build.len(), 15);
+        play_music(build[0], 0.0);
         let mut peak = 0.0f32;
         for k in 0..200 {
             if k == 50 {
-                play_music(Track::Battle1, 2.5);
+                play_music(battle[0], 2.5);
             }
             if k % 10 == 0 {
                 play_sfx(k % crate::game::SFX_ALL.len(), 1.0, 0.3);
@@ -243,6 +240,6 @@ mod tests {
             }
         }
         assert!(peak > 0.05);
-        assert_eq!(current_track(), Some(Track::Battle1));
+        assert_eq!(current_track(), Some(battle[0]));
     }
 }

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));
         }

src/tracks.rs

@@ -0,0 +1,42 @@
+// Generated by tools/compose_music.py - do not edit.
+// All music modules with their category (see audio::Category).
+
+use crate::audio::Category;
+
+pub const TRACKS: [(&str, Category, &[u8]); 35] = [
+    ("title", Category::Title, include_bytes!("../assets/music/title.xm")),
+    ("title2", Category::Title, include_bytes!("../assets/music/title2.xm")),
+    ("build1", Category::Build, include_bytes!("../assets/music/build1.xm")),
+    ("build2", Category::Build, include_bytes!("../assets/music/build2.xm")),
+    ("build3", Category::Build, include_bytes!("../assets/music/build3.xm")),
+    ("build4", Category::Build, include_bytes!("../assets/music/build4.xm")),
+    ("build5", Category::Build, include_bytes!("../assets/music/build5.xm")),
+    ("build6", Category::Build, include_bytes!("../assets/music/build6.xm")),
+    ("build7", Category::Build, include_bytes!("../assets/music/build7.xm")),
+    ("build8", Category::Build, include_bytes!("../assets/music/build8.xm")),
+    ("build9", Category::Build, include_bytes!("../assets/music/build9.xm")),
+    ("build10", Category::Build, include_bytes!("../assets/music/build10.xm")),
+    ("build11", Category::Build, include_bytes!("../assets/music/build11.xm")),
+    ("build12", Category::Build, include_bytes!("../assets/music/build12.xm")),
+    ("build13", Category::Build, include_bytes!("../assets/music/build13.xm")),
+    ("build14", Category::Build, include_bytes!("../assets/music/build14.xm")),
+    ("build15", Category::Build, include_bytes!("../assets/music/build15.xm")),
+    ("battle1", Category::Battle, include_bytes!("../assets/music/battle1.xm")),
+    ("battle3", Category::Battle, include_bytes!("../assets/music/battle3.xm")),
+    ("battle4", Category::Battle, include_bytes!("../assets/music/battle4.xm")),
+    ("battle5", Category::Battle, include_bytes!("../assets/music/battle5.xm")),
+    ("battle6", Category::Battle, include_bytes!("../assets/music/battle6.xm")),
+    ("battle7", Category::Battle, include_bytes!("../assets/music/battle7.xm")),
+    ("battle8", Category::Battle, include_bytes!("../assets/music/battle8.xm")),
+    ("battle2", Category::Assault, include_bytes!("../assets/music/battle2.xm")),
+    ("assault2", Category::Assault, include_bytes!("../assets/music/assault2.xm")),
+    ("assault3", Category::Assault, include_bytes!("../assets/music/assault3.xm")),
+    ("assault4", Category::Assault, include_bytes!("../assets/music/assault4.xm")),
+    ("boss_paladin", Category::BossPaladin, include_bytes!("../assets/music/boss_paladin.xm")),
+    ("boss_warden", Category::BossWarden, include_bytes!("../assets/music/boss_warden.xm")),
+    ("mood_torture", Category::Torture, include_bytes!("../assets/music/mood_torture.xm")),
+    ("mood_temple", Category::Temple, include_bytes!("../assets/music/mood_temple.xm")),
+    ("victory", Category::Victory, include_bytes!("../assets/music/victory.xm")),
+    ("victory2", Category::Victory, include_bytes!("../assets/music/victory2.xm")),
+    ("defeat", Category::Defeat, include_bytes!("../assets/music/defeat.xm")),
+];

src/xm.rs

@@ -1126,23 +1126,11 @@ mod tests {
     use super::*;
     use std::rc::Rc;
 
-    const SONGS: [&[u8]; 8] = [
-        include_bytes!("../assets/music/title.xm"),
-        include_bytes!("../assets/music/build1.xm"),
-        include_bytes!("../assets/music/build2.xm"),
-        include_bytes!("../assets/music/build3.xm"),
-        include_bytes!("../assets/music/battle1.xm"),
-        include_bytes!("../assets/music/battle2.xm"),
-        include_bytes!("../assets/music/victory.xm"),
-        include_bytes!("../assets/music/defeat.xm"),
-    ];
-
     #[test]
     fn render_all_songs() {
-        for (k, data) in SONGS.iter().enumerate() {
+        for (k, (name, _, data)) in crate::tracks::TRACKS.iter().enumerate() {
             let m = Rc::new(load(data).expect("load"));
-            assert_eq!(m.channels, 8);
-            assert_eq!(m.instruments.len(), 8);
+            assert_eq!(m.channels, 8, "{}", name);
             let mut p = Player::new(m, 48000.0);
             let mut buf = vec![0.0f32; 48000 * 2];
             let mut peak = 0.0f32;
@@ -1157,8 +1145,8 @@ mod tests {
                 }
             }
             let rms = (sum / (20.0 * 96000.0)).sqrt();
-            println!("song {}: peak {:.3} rms {:.4} loops {}", k, peak, rms, p.loops);
-            assert!(rms > 0.005, "song {} is silent", k);
+            println!("{:2} {:14}: peak {:.3} rms {:.4} loops {}", k, name, peak, rms, p.loops);
+            assert!(rms > 0.005, "song {} is silent", name);
         }
     }
 }
@@ -1173,8 +1161,7 @@ mod render_dump {
     #[test]
     fn dump_renders() {
         let Ok(dir) = std::env::var("DC_RENDER_DIR") else { return };
-        let names = ["title", "build1", "build2", "build3", "battle1", "battle2", "victory", "defeat"];
-        for n in names {
+        for (n, _, _) in crate::tracks::TRACKS.iter() {
             let data = std::fs::read(format!("assets/music/{}.xm", n)).unwrap();
             let mut p = Player::new(Rc::new(load(&data).unwrap()), 48000.0);
             let mut buf = vec![0.0f32; 48000 * 2 * 30];