feat(demo): Add drum sequence using embedded assets

Incorporates kick1.spec, snare1.spec, and hihat1.spec into the demo sequence.

- Updated assets.txt with new drum identifiers.

- Implemented register_spec_asset helper in main.cc to load spectral data.

- Added 8th-note sequencer triggering a simple drum and bass pattern.

1 files changed, 62 insertions, 22 deletions

diff --git a/src/main.cc b/src/main.cc
index 6428ed2..f612868 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -13,10 +13,34 @@
 #include <stdio.h>
 #include <string.h>
 
-#define DEMO_BPM 120.0f
+#define DEMO_BPM 128.0f
 #define SECONDS_PER_BEAT (60.0f / DEMO_BPM)
 #define SPEC_FRAMES 16
 
+struct SpecHeader {
+  char magic[4];
+  int32_t version;
+  int32_t dct_size;
+  int32_t num_frames;
+};
+
+int register_spec_asset(AssetId id) {
+  size_t size;
+  const uint8_t *data = GetAsset(id, &size);
+  if (!data || size < sizeof(SpecHeader))
+    return -1;
+
+  const SpecHeader *header = (const SpecHeader *)data;
+  const float *spectral_data = (const float *)(data + sizeof(SpecHeader));
+
+  Spectrogram spec;
+  spec.spectral_data_a = spectral_data;
+  spec.spectral_data_b = spectral_data; // No double-buffer for static assets
+  spec.num_frames = header->num_frames;
+
+  return synth_register_spectrogram(&spec);
+}
+
 static float g_spec_buffer_a[SPEC_FRAMES * DCT_SIZE];
 static float g_spec_buffer_b[SPEC_FRAMES * DCT_SIZE];
 
@@ -53,17 +77,16 @@ int main(int argc, char **argv) {
   gpu_init(platform_get_window());
   audio_init();
 
-  generate_tone(g_spec_buffer_a, 440.0f); // A4
-  generate_tone(g_spec_buffer_b, 0.0f);   // A5
-
-  const Spectrogram spec = {g_spec_buffer_a, g_spec_buffer_b, SPEC_FRAMES};
-  int tone_id = synth_register_spectrogram(&spec);
+  // Register drum assets
+  int kick_id = register_spec_asset(AssetId::ASSET_KICK_1);
+  int snare_id = register_spec_asset(AssetId::ASSET_SNARE_1);
+  int hihat_id = register_spec_asset(AssetId::ASSET_HIHAT_1);
 
-  // Dummy call to ensure asset system is linked
-  size_t dummy_size;
-  const uint8_t *dummy_asset = GetAsset(AssetId::ASSET_NULL_ASSET, &dummy_size);
-  (void)dummy_asset;
-  (void)dummy_size;
+  // Still keep the dynamic tone for bass
+  generate_tone(g_spec_buffer_a, 110.0f); // A2
+  generate_tone(g_spec_buffer_b, 110.0f);
+  const Spectrogram bass_spec = {g_spec_buffer_a, g_spec_buffer_b, SPEC_FRAMES};
+  int bass_id = synth_register_spectrogram(&bass_spec);
 
   double last_beat_time = 0.0;
   int beat_count = 0;
@@ -72,21 +95,38 @@ int main(int argc, char **argv) {
     platform_poll();
 
     double current_time = platform_get_time();
-    if (current_time - last_beat_time > SECONDS_PER_BEAT) {
-      const float pan = (beat_count & 1) ? -.8 : .8;
-      synth_trigger_voice(tone_id, 0.8f, pan);
+    if (current_time - last_beat_time > SECONDS_PER_BEAT / 2.0) { // 8th notes
       last_beat_time = current_time;
-      beat_count++;
 
-      if (beat_count % 4 == 0) {
-        // Time to update the sound!
-        float *back_buffer = synth_begin_update(tone_id);
+      const int step = beat_count % 16;
+
+      // Kick on 1, 9, 11, 14...
+      if (step == 0 || step == 8 || step == 10 || step == 13) {
+        synth_trigger_voice(kick_id, 1.0f, 0.0f);
+      }
+
+      // Snare on 4, 12
+      if (step == 4 || step == 12) {
+        synth_trigger_voice(snare_id, 0.8f, 0.0f);
+      }
+
+      // Hihat on every offbeat
+      if (step % 2 == 1) {
+        synth_trigger_voice(hihat_id, 0.5f, 0.3f);
+      }
+
+      // Bass pattern
+      if (step % 4 == 0) {
+        float bass_freq = (step < 8) ? 110.0f : 82.41f; // A2 then E2
+        float *back_buffer = synth_begin_update(bass_id);
         if (back_buffer) {
-          generate_tone(back_buffer,
-                        (beat_count % 8) == 4 ? 220.0f : 480.f); // A3
-          synth_commit_update(tone_id);
+          generate_tone(back_buffer, bass_freq);
+          synth_commit_update(bass_id);
         }
+        synth_trigger_voice(bass_id, 0.6f, -0.2f);
       }
+
+      beat_count++;
     }
 
     int width, height;
@@ -102,4 +142,4 @@ int main(int argc, char **argv) {
   gpu_shutdown();
   platform_shutdown();
   return 0;
-}
\ No newline at end of file
+}