Own XM/MOD replayer, audio mixer with crossfades, synthesised chip sound effects, music director

- src/xm.rs: FastTracker 2 XM and ProTracker MOD replayer (verified against libopenmpt)
- src/audio.rs: music players with crossfade + effect voices, rendered on demand
- src/sfx.rs: 29 synthesised chip sound effects
- www/dc_plugin.js: AudioContext started on first input, streams samples from WASM
- music follows the game: title, rotating build tracks, battle, gate assault, jingles
- macroquad audio removed; all tests run natively with cargo test

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

src/main.rs

@@ -1,5 +1,6 @@
 // DungeonCraft – dungeon building & defence in the browser (Rust + macroquad, WASM).
 
+mod audio;
 mod game;
 mod gfx;
 mod i18n;
@@ -9,8 +10,10 @@ mod platform;
 mod render3d;
 mod save;
 mod settings;
+mod sfx;
 mod sound;
 mod ui;
+mod xm;
 
 use game::{Game, Msg};
 use gfx::Gfx;
@@ -61,14 +64,45 @@ fn next_seed(seed: u32) -> u32 {
     seed.wrapping_mul(1103515245).wrapping_add(12345) | 1
 }
 
-fn apply_settings(s: &Settings, r3d: &mut R3d, sounds: &mut SoundBank) {
+fn apply_settings(s: &Settings, r3d: &mut R3d) {
     i18n::set_language(&s.language);
     ui::set_ui_scale(s.ui_scale as f32);
     r3d.outlines = s.outlines;
     r3d.set_wall_detail(s.wall_subdivisions());
     r3d.max_lights = s.max_lights as usize;
-    sounds.volume = s.volume;
-    sounds.muted = s.muted;
+    audio::set_volumes(s.music_volume, s.volume, s.muted);
+}
+
+// Chooses the music for the current situation; build tracks rotate after two loops
+struct MusicDirector {
+    build: usize,
+}
+
+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.ents.iter().any(|e| e.alive && e.guard);
+        let invasion = g.ents.iter().any(|e| e.alive && e.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();
+            }
+            BUILD[self.build]
+        };
+        let fade = if matches!(want, Track::Victory | Track::Defeat) { 1.0 } else { 2.5 };
+        audio::play_music(want, fade);
+    }
 }
 
 fn store_settings(s: &Settings) {
@@ -107,7 +141,7 @@ impl App {
     }
 
     // Load a savegame (settings in the savegame are always applied)
-    fn load_bytes(&mut self, bytes: &[u8], ui: &mut Ui, menu: &mut Menu, r3d: &mut R3d, sounds: &mut SoundBank, now: f64) {
+    fn load_bytes(&mut self, bytes: &[u8], ui: &mut Ui, menu: &mut Menu, r3d: &mut R3d, now: f64) {
         match save::from_bytes(bytes) {
             Ok(l) => {
                 self.game = l.game;
@@ -116,7 +150,7 @@ impl App {
                 }
                 if let Some(s) = l.settings {
                     self.settings = s;
-                    apply_settings(&self.settings, r3d, sounds);
+                    apply_settings(&self.settings, r3d);
                     store_settings(&self.settings);
                 }
                 self.game.hints = self.settings.hints;
@@ -141,7 +175,7 @@ async fn main() {
     let gfx = Gfx::new();
     let mut r3d = R3d::new();
     let mut sounds = SoundBank::new();
-    sounds.generate_all().await;
+    let mut music = MusicDirector { build: 0 };
     let mut ui = Ui::new();
     let mut menu = Menu::new();
 
@@ -154,7 +188,7 @@ async fn main() {
             None => ui.show_langsel = true,
         }
     }
-    apply_settings(&settings, &mut r3d, &mut sounds);
+    apply_settings(&settings, &mut r3d);
     ui.show_help = false;
     menu.has_autosave = platform::storage_get(save::AUTOSAVE_KEY).is_some();
 
@@ -180,7 +214,7 @@ async fn main() {
             }
         }
         if let Some(bytes) = incoming {
-            app.load_bytes(&bytes, &mut ui, &mut menu, &mut r3d, &mut sounds, now);
+            app.load_bytes(&bytes, &mut ui, &mut menu, &mut r3d, now);
         }
 
         // ---------------- key capture for the key binding dialog
@@ -190,12 +224,12 @@ async fn main() {
             } else if let Some(k) = get_last_key_pressed() {
                 if bindable_keys().any(|b| b == k) {
                     app.settings.bind(action, k);
-                    apply_settings(&app.settings, &mut r3d, &mut sounds);
+                    apply_settings(&app.settings, &mut r3d);
                     store_settings(&app.settings);
                     menu.finish_capture();
                 }
             }
-            draw_frame(&mut app, &gfx, &mut r3d, &mut ui, &mut menu, &sounds, &inp, now);
+            draw_frame(&mut app, &gfx, &mut r3d, &mut ui, &mut menu, &inp, now);
             next_frame().await;
             continue;
         }
@@ -391,7 +425,7 @@ async fn main() {
                     }
                     MenuAction::Continue => {
                         if let Some(s) = platform::storage_get(save::AUTOSAVE_KEY) {
-                            app.load_bytes(s.as_bytes(), &mut ui, &mut menu, &mut r3d, &mut sounds, now);
+                            app.load_bytes(s.as_bytes(), &mut ui, &mut menu, &mut r3d, now);
                         }
                     }
                     MenuAction::Load => {
@@ -477,7 +511,7 @@ async fn main() {
         app.cam.tz = app.cam.tz.clamp(0.0, MH as f32);
 
         if settings_changed {
-            apply_settings(&app.settings, &mut r3d, &mut sounds);
+            apply_settings(&app.settings, &mut r3d);
             store_settings(&app.settings);
             app.game.hints = app.settings.hints;
         }
@@ -503,20 +537,22 @@ async fn main() {
             }
         }
         let hear = app.cam.zoom * 1.2;
+        let (right, _) = app.cam.ground_axes();
         for ev in app.game.events.drain(..) {
-            sounds.play(ev, vec2(app.cam.tx, app.cam.tz), hear, now);
+            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, .. })));
         for m in app.game.msgs.drain(..) {
             ui.log.push((m, now));
         }
 
-        draw_frame(&mut app, &gfx, &mut r3d, &mut ui, &mut menu, &sounds, &inp, now);
+        draw_frame(&mut app, &gfx, &mut r3d, &mut ui, &mut menu, &inp, now);
         next_frame().await
     }
 }
 
 #[allow(clippy::too_many_arguments)]
-fn draw_frame(app: &mut App, gfx: &Gfx, r3d: &mut R3d, ui: &mut Ui, menu: &mut Menu, sounds: &SoundBank, inp: &Input, now: f64) {
+fn draw_frame(app: &mut App, gfx: &Gfx, r3d: &mut R3d, ui: &mut Ui, menu: &mut Menu, inp: &Input, now: f64) {
     let (mx, my) = mouse_position();
     let blocked = menu.open() || ui.show_help || ui.show_langsel;
     let over_ui = blocked || ui.over_ui(mx, my);
@@ -552,7 +588,7 @@ fn draw_frame(app: &mut App, gfx: &Gfx, r3d: &mut R3d, ui: &mut Ui, menu: &mut M
             let ent = r3d.pick_ent(&app.game, &app.cam, mx, my, false);
             hover_info(&app.game, ent, hover_tile)
         };
-        ui.draw(&app.game, gfx, &app.cam, sounds, &app.settings, &info, now);
+        ui.draw(&app.game, gfx, &app.cam, &app.settings, &info, now);
     } else {
         ui.rects.clear();
     }