+struct air_synth_data {
+ f32 speed;
+
+ /* internal */
+ f32 t;
+ struct dsp_biquad lpf;
+ SDL_SpinLock sl;
+}
+static air_data;
+
+static void audio_air_synth_get_samples( void *_data, f32 *buf, u32 count ){
+ struct air_synth_data *data = _data;
+
+ SDL_AtomicLock( &data->sl );
+ f32 spd = data->speed;
+ SDL_AtomicUnlock( &data->sl );
+
+ f32 s0 = sinf(data->t*2.0f),
+ s1 = sinf(data->t*0.43f),
+ s2 = sinf(data->t*1.333f),
+ sm = vg_clampf( data->speed / 45.0f, 0, 1 ),
+ ft = (s0*s1*s2)*0.5f+0.5f,
+ f = vg_lerpf( 200.0f, 1200.0f, sm*0.7f + ft*0.3f ),
+ vol = 0.25f * sm;
+
+ dsp_init_biquad_butterworth_lpf( &data->lpf, f );
+
+ for( u32 i=0; i<count; i ++ ){
+ f32 v = (vg_randf64(&vg_dsp.rand) * 2.0f - 1.0f) * vol;
+ v = dsp_biquad_process( &data->lpf, v );
+
+ buf[i*2+0] = v;
+ buf[i*2+1] = v;
+ }
+
+ data->t += (f32)(count)/44100.0f;
+};
+
+static audio_clip air_synth = {
+ .flags = k_audio_format_gen,
+ .size = 0,
+ .func = audio_air_synth_get_samples,
+ .data = &air_data
+};
+