Phase continuity

src/piece.rs

@@ -27,6 +27,19 @@ impl Wave {
             }
         }
     }
+
+    pub fn sample_from_phase(self, phase: f64) -> f64 {
+        match self {
+            Wave::Square => {
+                if phase < 0.5 {
+                    1.0
+                } else {
+                    -1.0
+                }
+            }
+            Wave::Triangle => 4.0 * (phase - 0.5).abs() - 1.0,
+        }
+    }
 }
 
 pub struct NoteEvent {
@@ -50,6 +63,7 @@ pub struct Track {
     pub amplitude: f64,
     pub notes: Vec<NoteEvent>,
     pub current_tick: Tick,
+    pub phase: f64,
 }
 
 impl Track {
@@ -59,6 +73,7 @@ impl Track {
             amplitude,
             notes: vec![],
             current_tick: Tick(0),
+            phase: 0.0,
         }
     }
 
@@ -120,6 +135,8 @@ impl Piece {
         let seconds_per_tick = 60.0 / (self.bpm as u64 * TICKS_PER_BEAT) as f64;
         let params = wav::Params::new();
 
+        let mut track_phases: Vec<f64> = vec![0.0; self.tracks.len()];
+
         let total_samples =
             (self.max_beat() as f64 * seconds_per_beat * params.sampling_rate as f64).ceil() as u32;
 
@@ -134,12 +151,18 @@ impl Piece {
         for i in 0..total_samples {
             let t = i as f64 / params.sampling_rate as f64;
             let mut value: f64 = 0.0;
-            for track in &self.tracks {
+            for (track, phase) in self.tracks.iter().zip(track_phases.iter_mut()) {
                 for event in &track.notes {
                     let start_time = event.start.0 as f64 * seconds_per_tick;
                     let end_time = (event.start + event.duration).0 as f64 * seconds_per_tick;
                     if t >= start_time && t < end_time {
-                        value += track.amplitude * track.wave.sample(&event.note, t);
+                        let freq = event.note.freq();
+                        // value += track.amplitude * track.wave.sample(&event.note, t);
+                        value += track.amplitude * track.wave.sample_from_phase(*phase);
+
+                        // Update phase
+                        *phase += freq / params.sampling_rate as f64;
+                        *phase %= 1.0;
                     }
                 }
             }

src/technology.rs

@@ -14,7 +14,7 @@ pub fn technology() -> Piece {
 }
 
 pub fn bass_track() -> Track {
-    let mut bass_track = Track::new(Wave::Square, 0.05);
+    let mut bass_track = Track::new(Wave::Triangle, 0.5);
     for _ in 0..4 {
         bass_track.add(A1, Tick::bar());
         bass_track.add(G0, Tick::beats(2));
@@ -121,7 +121,7 @@ pub fn chords() -> Track {
 }
 
 pub fn main_track() -> Track {
-    let mut track = Track::new(Wave::Square, 0.1);
+    let mut track = Track::new(Wave::Square, 0.075);
     track.add_silence(Tick::bars(4));
 
     // Lick 1