src/audio/tracker.cc


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#include "tracker.h"
#include "audio.h"
#include "audio/synth.h"
#include "util/asset_manager.h"
#include <cstring>
#include <vector>

static uint32_t g_last_trigger_idx = 0;

struct ManagedSpectrogram {
  int synth_id;
  float* data;
  bool active;
};

// Simple pool for dynamic spectrograms
static ManagedSpectrogram g_spec_pool[MAX_SPECTROGRAMS];

void tracker_init() {
  g_last_trigger_idx = 0;
  for (int i = 0; i < MAX_SPECTROGRAMS; ++i) {
    g_spec_pool[i].synth_id = -1;
    g_spec_pool[i].data = nullptr;
    g_spec_pool[i].active = false;
  }
}

static int get_free_pool_slot() {
  for (int i = 0; i < MAX_SPECTROGRAMS; ++i) {
    if (!g_spec_pool[i].active)
      return i;
  }
  return -1;
}

void tracker_update(float time_sec) {
  while (g_last_trigger_idx < g_tracker_score.num_triggers) {
    const TrackerPatternTrigger& trigger =
        g_tracker_score.triggers[g_last_trigger_idx];

    if (trigger.time_sec > time_sec)
      break;

    const TrackerPattern& pattern = g_tracker_patterns[trigger.pattern_id];

    int dest_num_frames = 0;
    std::vector<float> pattern_data;

    float beat_to_sec = 60.0f / g_tracker_score.bpm;

    for (uint32_t i = 0; i < pattern.num_events; ++i) {
      const TrackerEvent& event = pattern.events[i];
      
      std::vector<float> note_data;
      int note_frames = 0;

      AssetId aid = g_tracker_sample_assets[event.sample_id];
      if (aid != AssetId::ASSET_LAST_ID) {
        size_t size;
        const uint8_t* data = GetAsset(aid, &size);
        if (data && size >= sizeof(SpecHeader)) {
          const SpecHeader* header = (const SpecHeader*)data;
          note_frames = header->num_frames;
          const float* src_spectral_data = (const float*)(data + sizeof(SpecHeader));
          note_data.assign(src_spectral_data, src_spectral_data + (size_t)note_frames * DCT_SIZE);
        }
      } else {
        const NoteParams& params = g_tracker_samples[event.sample_id];
        note_data = generate_note_spectrogram(params, &note_frames);
      }

      if (note_frames > 0) {
        int frame_offset = (int)(event.beat * beat_to_sec * 32000.0f / DCT_SIZE);
        paste_spectrogram(pattern_data, &dest_num_frames, note_data, note_frames,
                          frame_offset);
      }
    }

    if (dest_num_frames > 0) {
      int slot = get_free_pool_slot();
      if (slot != -1) {
        if (g_spec_pool[slot].synth_id != -1) {
          synth_unregister_spectrogram(g_spec_pool[slot].synth_id);
          delete[] g_spec_pool[slot].data;
        }

        g_spec_pool[slot].data = new float[pattern_data.size()];
        memcpy(g_spec_pool[slot].data, pattern_data.data(),
               pattern_data.size() * sizeof(float));

        Spectrogram spec;
        spec.spectral_data_a = g_spec_pool[slot].data;
        spec.spectral_data_b = g_spec_pool[slot].data;
        spec.num_frames = dest_num_frames;

        g_spec_pool[slot].synth_id = synth_register_spectrogram(&spec);
        g_spec_pool[slot].active = true;

        synth_trigger_voice(g_spec_pool[slot].synth_id, 1.0f, 0.0f);
      }
    }

    g_last_trigger_idx++;
  }
}